pub(crate) mod dap;
pub(crate) mod lsp;
pub(crate) mod typed;

pub use dap::*;
pub use lsp::*;
pub use typed::*;

use helix_core::{
    comment, coords_at_pos, find_first_non_whitespace_char, find_root, graphemes,
    history::UndoKind,
    increment::date_time::DateTimeIncrementor,
    increment::{number::NumberIncrementor, Increment},
    indent,
    indent::IndentStyle,
    line_ending::{get_line_ending_of_str, line_end_char_index, str_is_line_ending},
    match_brackets,
    movement::{self, Direction},
    object, pos_at_coords,
    regex::{self, Regex, RegexBuilder},
    search::{self, CharMatcher},
    selection, shellwords, surround, textobject,
    tree_sitter::Node,
    unicode::width::UnicodeWidthChar,
    LineEnding, Position, Range, Rope, RopeGraphemes, RopeSlice, Selection, SmallVec, Tendril,
    Transaction,
};
use helix_view::{
    clipboard::ClipboardType,
    document::{Mode, SCRATCH_BUFFER_NAME},
    editor::{Action, Motion},
    info::Info,
    input::KeyEvent,
    keyboard::KeyCode,
    view::View,
    Document, DocumentId, Editor, ViewId,
};

use anyhow::{anyhow, bail, ensure, Context as _};
use fuzzy_matcher::FuzzyMatcher;
use insert::*;
use movement::Movement;

use crate::{
    args,
    compositor::{self, Component, Compositor},
    ui::{self, overlay::overlayed, FilePicker, Picker, Popup, Prompt, PromptEvent},
};

use crate::job::{self, Job, Jobs};
use futures_util::{FutureExt, StreamExt};
use std::{collections::HashMap, fmt, future::Future};
use std::{collections::HashSet, num::NonZeroUsize};

use std::{
    borrow::Cow,
    path::{Path, PathBuf},
};

use once_cell::sync::Lazy;
use serde::de::{self, Deserialize, Deserializer};

use grep_regex::RegexMatcherBuilder;
use grep_searcher::{sinks, BinaryDetection, SearcherBuilder};
use ignore::{DirEntry, WalkBuilder, WalkState};
use tokio_stream::wrappers::UnboundedReceiverStream;

pub struct Context<'a> {
    pub register: Option<char>,
    pub count: Option<NonZeroUsize>,
    pub editor: &'a mut Editor,

    pub callback: Option<crate::compositor::Callback>,
    pub on_next_key_callback: Option<Box<dyn FnOnce(&mut Context, KeyEvent)>>,
    pub jobs: &'a mut Jobs,
}

impl<'a> Context<'a> {
    /// Push a new component onto the compositor.
    pub fn push_layer(&mut self, component: Box<dyn Component>) {
        self.callback = Some(Box::new(|compositor: &mut Compositor, _| {
            compositor.push(component)
        }));
    }

    #[inline]
    pub fn on_next_key(
        &mut self,
        on_next_key_callback: impl FnOnce(&mut Context, KeyEvent) + 'static,
    ) {
        self.on_next_key_callback = Some(Box::new(on_next_key_callback));
    }

    #[inline]
    pub fn callback<T, F>(
        &mut self,
        call: impl Future<Output = helix_lsp::Result<serde_json::Value>> + 'static + Send,
        callback: F,
    ) where
        T: for<'de> serde::Deserialize<'de> + Send + 'static,
        F: FnOnce(&mut Editor, &mut Compositor, T) + Send + 'static,
    {
        let callback = Box::pin(async move {
            let json = call.await?;
            let response = serde_json::from_value(json)?;
            let call: job::Callback =
                Box::new(move |editor: &mut Editor, compositor: &mut Compositor| {
                    callback(editor, compositor, response)
                });
            Ok(call)
        });
        self.jobs.callback(callback);
    }

    /// Returns 1 if no explicit count was provided
    #[inline]
    pub fn count(&self) -> usize {
        self.count.map_or(1, |v| v.get())
    }
}

use helix_view::{align_view, Align};

/// A MappableCommand is either a static command like "jump_view_up" or a Typable command like
/// :format. It causes a side-effect on the state (usually by creating and applying a transaction).
/// Both of these types of commands can be mapped with keybindings in the config.toml.
#[derive(Clone)]
pub enum MappableCommand {
    Typable {
        name: String,
        args: Vec<String>,
        doc: String,
    },
    Static {
        name: &'static str,
        fun: fn(cx: &mut Context),
        doc: &'static str,
    },
}

macro_rules! static_commands {
    ( $($name:ident, $doc:literal,)* ) => {
        $(
            #[allow(non_upper_case_globals)]
            pub const $name: Self = Self::Static {
                name: stringify!($name),
                fun: $name,
                doc: $doc
            };
        )*

        pub const STATIC_COMMAND_LIST: &'static [Self] = &[
            $( Self::$name, )*
        ];
    }
}

impl MappableCommand {
    pub fn execute(&self, cx: &mut Context) {
        match &self {
            Self::Typable { name, args, doc: _ } => {
                let args: Vec<Cow<str>> = args.iter().map(Cow::from).collect();
                if let Some(command) = typed::TYPABLE_COMMAND_MAP.get(name.as_str()) {
                    let mut cx = compositor::Context {
                        editor: cx.editor,
                        jobs: cx.jobs,
                        scroll: None,
                    };
                    if let Err(e) = (command.fun)(&mut cx, &args[..], PromptEvent::Validate) {
                        cx.editor.set_error(format!("{}", e));
                    }
                }
            }
            Self::Static { fun, .. } => (fun)(cx),
        }
    }

    pub fn name(&self) -> &str {
        match &self {
            Self::Typable { name, .. } => name,
            Self::Static { name, .. } => name,
        }
    }

    pub fn doc(&self) -> &str {
        match &self {
            Self::Typable { doc, .. } => doc,
            Self::Static { doc, .. } => doc,
        }
    }

    #[rustfmt::skip]
    static_commands!(
        no_op, "Do nothing",
        move_char_left, "Move left",
        move_char_right, "Move right",
        move_line_up, "Move up",
        move_line_down, "Move down",
        extend_char_left, "Extend left",
        extend_char_right, "Extend right",
        extend_line_up, "Extend up",
        extend_line_down, "Extend down",
        copy_selection_on_next_line, "Copy selection on next line",
        copy_selection_on_prev_line, "Copy selection on previous line",
        move_next_word_start, "Move to beginning of next word",
        move_prev_word_start, "Move to beginning of previous word",
        move_prev_word_end, "Move to end of previous word",
        move_next_word_end, "Move to end of next word",
        move_next_long_word_start, "Move to beginning of next long word",
        move_prev_long_word_start, "Move to beginning of previous long word",
        move_next_long_word_end, "Move to end of next long word",
        extend_next_word_start, "Extend to beginning of next word",
        extend_prev_word_start, "Extend to beginning of previous word",
        extend_next_long_word_start, "Extend to beginning of next long word",
        extend_prev_long_word_start, "Extend to beginning of previous long word",
        extend_next_long_word_end, "Extend to end of next long word",
        extend_next_word_end, "Extend to end of next word",
        find_till_char, "Move till next occurrence of char",
        find_next_char, "Move to next occurrence of char",
        extend_till_char, "Extend till next occurrence of char",
        extend_next_char, "Extend to next occurrence of char",
        till_prev_char, "Move till previous occurrence of char",
        find_prev_char, "Move to previous occurrence of char",
        extend_till_prev_char, "Extend till previous occurrence of char",
        extend_prev_char, "Extend to previous occurrence of char",
        repeat_last_motion, "repeat last motion(extend_next_char, extend_till_char, find_next_char, find_till_char...)",
        replace, "Replace with new char",
        switch_case, "Switch (toggle) case",
        switch_to_uppercase, "Switch to uppercase",
        switch_to_lowercase, "Switch to lowercase",
        page_up, "Move page up",
        page_down, "Move page down",
        half_page_up, "Move half page up",
        half_page_down, "Move half page down",
        select_all, "Select whole document",
        select_regex, "Select all regex matches inside selections",
        split_selection, "Split selection into subselections on regex matches",
        split_selection_on_newline, "Split selection on newlines",
        search, "Search for regex pattern",
        rsearch, "Reverse search for regex pattern",
        search_next, "Select next search match",
        search_prev, "Select previous search match",
        extend_search_next, "Add next search match to selection",
        extend_search_prev, "Add previous search match to selection",
        search_selection, "Use current selection as search pattern",
        global_search, "Global Search in workspace folder",
        extend_line, "Select current line, if already selected, extend to next line",
        extend_line_above, "Select current line, if already selected, extend to previous line",
        extend_to_line_bounds, "Extend selection to line bounds (line-wise selection)",
        delete_selection, "Delete selection",
        delete_selection_noyank, "Delete selection, without yanking",
        change_selection, "Change selection (delete and enter insert mode)",
        change_selection_noyank, "Change selection (delete and enter insert mode, without yanking)",
        collapse_selection, "Collapse selection onto a single cursor",
        flip_selections, "Flip selection cursor and anchor",
        ensure_selections_forward, "Ensure the selection is in forward direction",
        insert_mode, "Insert before selection",
        append_mode, "Insert after selection (append)",
        command_mode, "Enter command mode",
        file_picker, "Open file picker",
        file_picker_in_current_directory, "Open file picker at current working directory",
        code_action, "Perform code action",
        buffer_picker, "Open buffer picker",
        symbol_picker, "Open symbol picker",
        workspace_symbol_picker, "Open workspace symbol picker",
        last_picker, "Open last picker",
        prepend_to_line, "Insert at start of line",
        append_to_line, "Insert at end of line",
        open_below, "Open new line below selection",
        open_above, "Open new line above selection",
        normal_mode, "Enter normal mode",
        select_mode, "Enter selection extend mode",
        exit_select_mode, "Exit selection mode",
        goto_definition, "Goto definition",
        add_newline_above, "Add newline above",
        add_newline_below, "Add newline below",
        goto_type_definition, "Goto type definition",
        goto_implementation, "Goto implementation",
        goto_file_start, "Goto line number <n> else file start",
        goto_file_end, "Goto file end",
        goto_file, "Goto files in selection",
        goto_file_hsplit, "Goto files in selection (hsplit)",
        goto_file_vsplit, "Goto files in selection (vsplit)",
        goto_reference, "Goto references",
        goto_window_top, "Goto window top",
        goto_window_center, "Goto window center",
        goto_window_bottom, "Goto window bottom",
        goto_last_accessed_file, "Goto last accessed file",
        goto_last_modified_file, "Goto last modified file",
        goto_last_modification, "Goto last modification",
        goto_line, "Goto line",
        goto_last_line, "Goto last line",
        goto_first_diag, "Goto first diagnostic",
        goto_last_diag, "Goto last diagnostic",
        goto_next_diag, "Goto next diagnostic",
        goto_prev_diag, "Goto previous diagnostic",
        goto_line_start, "Goto line start",
        goto_line_end, "Goto line end",
        goto_next_buffer, "Goto next buffer",
        goto_previous_buffer, "Goto previous buffer",
        // TODO: different description ?
        goto_line_end_newline, "Goto line end",
        goto_first_nonwhitespace, "Goto first non-blank in line",
        trim_selections, "Trim whitespace from selections",
        extend_to_line_start, "Extend to line start",
        extend_to_line_end, "Extend to line end",
        extend_to_line_end_newline, "Extend to line end",
        signature_help, "Show signature help",
        insert_tab, "Insert tab char",
        insert_newline, "Insert newline char",
        delete_char_backward, "Delete previous char",
        delete_char_forward, "Delete next char",
        delete_word_backward, "Delete previous word",
        delete_word_forward, "Delete next word",
        kill_to_line_start, "Delete content till the start of the line",
        kill_to_line_end, "Delete content till the end of the line",
        undo, "Undo change",
        redo, "Redo change",
        earlier, "Move backward in history",
        later, "Move forward in history",
        yank, "Yank selection",
        yank_joined_to_clipboard, "Join and yank selections to clipboard",
        yank_main_selection_to_clipboard, "Yank main selection to clipboard",
        yank_joined_to_primary_clipboard, "Join and yank selections to primary clipboard",
        yank_main_selection_to_primary_clipboard, "Yank main selection to primary clipboard",
        replace_with_yanked, "Replace with yanked text",
        replace_selections_with_clipboard, "Replace selections by clipboard content",
        replace_selections_with_primary_clipboard, "Replace selections by primary clipboard content",
        paste_after, "Paste after selection",
        paste_before, "Paste before selection",
        paste_clipboard_after, "Paste clipboard after selections",
        paste_clipboard_before, "Paste clipboard before selections",
        paste_primary_clipboard_after, "Paste primary clipboard after selections",
        paste_primary_clipboard_before, "Paste primary clipboard before selections",
        indent, "Indent selection",
        unindent, "Unindent selection",
        format_selections, "Format selection",
        join_selections, "Join lines inside selection",
        keep_selections, "Keep selections matching regex",
        remove_selections, "Remove selections matching regex",
        align_selections, "Align selections in column",
        keep_primary_selection, "Keep primary selection",
        remove_primary_selection, "Remove primary selection",
        completion, "Invoke completion popup",
        hover, "Show docs for item under cursor",
        toggle_comments, "Comment/uncomment selections",
        rotate_selections_forward, "Rotate selections forward",
        rotate_selections_backward, "Rotate selections backward",
        rotate_selection_contents_forward, "Rotate selection contents forward",
        rotate_selection_contents_backward, "Rotate selections contents backward",
        expand_selection, "Expand selection to parent syntax node",
        shrink_selection, "Shrink selection to previously expanded syntax node",
        select_next_sibling, "Select the next sibling in the syntax tree",
        select_prev_sibling, "Select the previous sibling in the syntax tree",
        jump_forward, "Jump forward on jumplist",
        jump_backward, "Jump backward on jumplist",
        save_selection, "Save the current selection to the jumplist",
        jump_view_right, "Jump to the split to the right",
        jump_view_left, "Jump to the split to the left",
        jump_view_up, "Jump to the split above",
        jump_view_down, "Jump to the split below",
        rotate_view, "Goto next window",
        hsplit, "Horizontal bottom split",
        hsplit_new, "Horizontal bottom split scratch buffer",
        vsplit, "Vertical right split",
        vsplit_new, "Vertical right split scratch buffer",
        wclose, "Close window",
        wonly, "Current window only",
        select_register, "Select register",
        insert_register, "Insert register",
        align_view_middle, "Align view middle",
        align_view_top, "Align view top",
        align_view_center, "Align view center",
        align_view_bottom, "Align view bottom",
        scroll_up, "Scroll view up",
        scroll_down, "Scroll view down",
        match_brackets, "Goto matching bracket",
        surround_add, "Surround add",
        surround_replace, "Surround replace",
        surround_delete, "Surround delete",
        select_textobject_around, "Select around object",
        select_textobject_inner, "Select inside object",
        goto_next_function, "Goto next function",
        goto_prev_function, "Goto previous function",
        goto_next_class, "Goto next class",
        goto_prev_class, "Goto previous class",
        goto_next_parameter, "Goto next parameter",
        goto_prev_parameter, "Goto previous parameter",
        goto_next_comment, "Goto next comment",
        goto_prev_comment, "Goto previous comment",
        goto_next_paragraph, "Goto next paragraph",
        goto_prev_paragraph, "Goto previous paragraph",
        dap_launch, "Launch debug target",
        dap_toggle_breakpoint, "Toggle breakpoint",
        dap_continue, "Continue program execution",
        dap_pause, "Pause program execution",
        dap_step_in, "Step in",
        dap_step_out, "Step out",
        dap_next, "Step to next",
        dap_variables, "List variables",
        dap_terminate, "End debug session",
        dap_edit_condition, "Edit condition of the breakpoint on the current line",
        dap_edit_log, "Edit log message of the breakpoint on the current line",
        dap_switch_thread, "Switch current thread",
        dap_switch_stack_frame, "Switch stack frame",
        dap_enable_exceptions, "Enable exception breakpoints",
        dap_disable_exceptions, "Disable exception breakpoints",
        shell_pipe, "Pipe selections through shell command",
        shell_pipe_to, "Pipe selections into shell command, ignoring command output",
        shell_insert_output, "Insert output of shell command before each selection",
        shell_append_output, "Append output of shell command after each selection",
        shell_keep_pipe, "Filter selections with shell predicate",
        suspend, "Suspend",
        rename_symbol, "Rename symbol",
        increment, "Increment",
        decrement, "Decrement",
        record_macro, "Record macro",
        replay_macro, "Replay macro",
        command_palette, "Open command palette",
    );
}

impl fmt::Debug for MappableCommand {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_tuple("MappableCommand")
            .field(&self.name())
            .finish()
    }
}

impl fmt::Display for MappableCommand {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.name())
    }
}

impl std::str::FromStr for MappableCommand {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        if let Some(suffix) = s.strip_prefix(':') {
            let mut typable_command = suffix.split(' ').into_iter().map(|arg| arg.trim());
            let name = typable_command
                .next()
                .ok_or_else(|| anyhow!("Expected typable command name"))?;
            let args = typable_command
                .map(|s| s.to_owned())
                .collect::<Vec<String>>();
            typed::TYPABLE_COMMAND_MAP
                .get(name)
                .map(|cmd| MappableCommand::Typable {
                    name: cmd.name.to_owned(),
                    doc: format!(":{} {:?}", cmd.name, args),
                    args,
                })
                .ok_or_else(|| anyhow!("No TypableCommand named '{}'", s))
        } else {
            MappableCommand::STATIC_COMMAND_LIST
                .iter()
                .find(|cmd| cmd.name() == s)
                .cloned()
                .ok_or_else(|| anyhow!("No command named '{}'", s))
        }
    }
}

impl<'de> Deserialize<'de> for MappableCommand {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        let s = String::deserialize(deserializer)?;
        s.parse().map_err(de::Error::custom)
    }
}

impl PartialEq for MappableCommand {
    fn eq(&self, other: &Self) -> bool {
        match (self, other) {
            (
                MappableCommand::Typable {
                    name: first_name, ..
                },
                MappableCommand::Typable {
                    name: second_name, ..
                },
            ) => first_name == second_name,
            (
                MappableCommand::Static {
                    name: first_name, ..
                },
                MappableCommand::Static {
                    name: second_name, ..
                },
            ) => first_name == second_name,
            _ => false,
        }
    }
}

fn no_op(_cx: &mut Context) {}

fn move_impl<F>(cx: &mut Context, move_fn: F, dir: Direction, behaviour: Movement)
where
    F: Fn(RopeSlice, Range, Direction, usize, Movement) -> Range,
{
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let selection = doc
        .selection(view.id)
        .clone()
        .transform(|range| move_fn(text, range, dir, count, behaviour));
    doc.set_selection(view.id, selection);
}

use helix_core::movement::{move_horizontally, move_vertically};

fn move_char_left(cx: &mut Context) {
    move_impl(cx, move_horizontally, Direction::Backward, Movement::Move)
}

fn move_char_right(cx: &mut Context) {
    move_impl(cx, move_horizontally, Direction::Forward, Movement::Move)
}

fn move_line_up(cx: &mut Context) {
    move_impl(cx, move_vertically, Direction::Backward, Movement::Move)
}

fn move_line_down(cx: &mut Context) {
    move_impl(cx, move_vertically, Direction::Forward, Movement::Move)
}

fn extend_char_left(cx: &mut Context) {
    move_impl(cx, move_horizontally, Direction::Backward, Movement::Extend)
}

fn extend_char_right(cx: &mut Context) {
    move_impl(cx, move_horizontally, Direction::Forward, Movement::Extend)
}

fn extend_line_up(cx: &mut Context) {
    move_impl(cx, move_vertically, Direction::Backward, Movement::Extend)
}

fn extend_line_down(cx: &mut Context) {
    move_impl(cx, move_vertically, Direction::Forward, Movement::Extend)
}

fn goto_line_end_impl(view: &mut View, doc: &mut Document, movement: Movement) {
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let line = range.cursor_line(text);
        let line_start = text.line_to_char(line);

        let pos = graphemes::prev_grapheme_boundary(text, line_end_char_index(&text, line))
            .max(line_start);

        range.put_cursor(text, pos, movement == Movement::Extend)
    });
    doc.set_selection(view.id, selection);
}

fn goto_line_end(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    goto_line_end_impl(
        view,
        doc,
        if doc.mode == Mode::Select {
            Movement::Extend
        } else {
            Movement::Move
        },
    )
}

fn extend_to_line_end(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    goto_line_end_impl(view, doc, Movement::Extend)
}

fn goto_line_end_newline_impl(view: &mut View, doc: &mut Document, movement: Movement) {
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let line = range.cursor_line(text);
        let pos = line_end_char_index(&text, line);

        range.put_cursor(text, pos, movement == Movement::Extend)
    });
    doc.set_selection(view.id, selection);
}

fn goto_line_end_newline(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    goto_line_end_newline_impl(
        view,
        doc,
        if doc.mode == Mode::Select {
            Movement::Extend
        } else {
            Movement::Move
        },
    )
}

fn extend_to_line_end_newline(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    goto_line_end_newline_impl(view, doc, Movement::Extend)
}

fn goto_line_start_impl(view: &mut View, doc: &mut Document, movement: Movement) {
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let line = range.cursor_line(text);

        // adjust to start of the line
        let pos = text.line_to_char(line);
        range.put_cursor(text, pos, movement == Movement::Extend)
    });
    doc.set_selection(view.id, selection);
}

fn goto_line_start(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    goto_line_start_impl(
        view,
        doc,
        if doc.mode == Mode::Select {
            Movement::Extend
        } else {
            Movement::Move
        },
    )
}

fn goto_next_buffer(cx: &mut Context) {
    goto_buffer(cx.editor, Direction::Forward);
}

fn goto_previous_buffer(cx: &mut Context) {
    goto_buffer(cx.editor, Direction::Backward);
}

fn goto_buffer(editor: &mut Editor, direction: Direction) {
    let current = view!(editor).doc;

    let id = match direction {
        Direction::Forward => {
            let iter = editor.documents.keys();
            let mut iter = iter.skip_while(|id| *id != &current);
            iter.next(); // skip current item
            iter.next().or_else(|| editor.documents.keys().next())
        }
        Direction::Backward => {
            let iter = editor.documents.keys();
            let mut iter = iter.rev().skip_while(|id| *id != &current);
            iter.next(); // skip current item
            iter.next().or_else(|| editor.documents.keys().rev().next())
        }
    }
    .unwrap();

    let id = *id;

    editor.switch(id, Action::Replace);
}

fn extend_to_line_start(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    goto_line_start_impl(view, doc, Movement::Extend)
}

fn kill_to_line_start(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let line = range.cursor_line(text);
        let first_char = text.line_to_char(line);
        let anchor = range.cursor(text);
        let head = if anchor == first_char && line != 0 {
            // select until previous line
            line_end_char_index(&text, line - 1)
        } else if let Some(pos) = find_first_non_whitespace_char(text.line(line)) {
            if first_char + pos < anchor {
                // select until first non-blank in line if cursor is after it
                first_char + pos
            } else {
                // select until start of line
                first_char
            }
        } else {
            // select until start of line
            first_char
        };
        Range::new(head, anchor)
    });
    delete_selection_insert_mode(doc, view, &selection);
}

fn kill_to_line_end(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let line = range.cursor_line(text);
        let line_end_pos = line_end_char_index(&text, line);
        let pos = range.cursor(text);

        let mut new_range = range.put_cursor(text, line_end_pos, true);
        // don't want to remove the line separator itself if the cursor doesn't reach the end of line.
        if pos != line_end_pos {
            new_range.head = line_end_pos;
        }
        new_range
    });
    delete_selection_insert_mode(doc, view, &selection);
}

fn goto_first_nonwhitespace(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let line = range.cursor_line(text);

        if let Some(pos) = find_first_non_whitespace_char(text.line(line)) {
            let pos = pos + text.line_to_char(line);
            range.put_cursor(text, pos, doc.mode == Mode::Select)
        } else {
            range
        }
    });
    doc.set_selection(view.id, selection);
}

fn trim_selections(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let ranges: SmallVec<[Range; 1]> = doc
        .selection(view.id)
        .iter()
        .filter_map(|range| {
            if range.is_empty() || range.fragment(text).chars().all(|ch| ch.is_whitespace()) {
                return None;
            }
            let mut start = range.from();
            let mut end = range.to();
            start = movement::skip_while(text, start, |x| x.is_whitespace()).unwrap_or(start);
            end = movement::backwards_skip_while(text, end, |x| x.is_whitespace()).unwrap_or(end);
            if range.anchor < range.head {
                Some(Range::new(start, end))
            } else {
                Some(Range::new(end, start))
            }
        })
        .collect();

    if !ranges.is_empty() {
        let primary = doc.selection(view.id).primary();
        let idx = ranges
            .iter()
            .position(|range| range.overlaps(&primary))
            .unwrap_or(ranges.len() - 1);
        doc.set_selection(view.id, Selection::new(ranges, idx));
    } else {
        collapse_selection(cx);
        keep_primary_selection(cx);
    };
}

// align text in selection
fn align_selections(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);
    let selection = doc.selection(view.id);

    let mut column_widths: Vec<Vec<_>> = Vec::new();
    let mut last_line = text.len_lines() + 1;
    let mut col = 0;

    for range in selection {
        let coords = coords_at_pos(text, range.head);
        let anchor_coords = coords_at_pos(text, range.anchor);

        if coords.row != anchor_coords.row {
            cx.editor
                .set_error("align cannot work with multi line selections");
            return;
        }

        col = if coords.row == last_line { col + 1 } else { 0 };

        if col >= column_widths.len() {
            column_widths.push(Vec::new());
        }
        column_widths[col].push((range.from(), coords.col));

        last_line = coords.row;
    }

    let mut changes = Vec::with_capacity(selection.len());

    // Account for changes on each row
    let len = column_widths.first().map(|cols| cols.len()).unwrap_or(0);
    let mut offs = vec![0; len];

    for col in column_widths {
        let max_col = col
            .iter()
            .enumerate()
            .map(|(row, (_, cursor))| *cursor + offs[row])
            .max()
            .unwrap_or(0);

        for (row, (insert_pos, last_col)) in col.into_iter().enumerate() {
            let ins_count = max_col - (last_col + offs[row]);

            if ins_count == 0 {
                continue;
            }

            offs[row] += ins_count;

            changes.push((insert_pos, insert_pos, Some(" ".repeat(ins_count).into())));
        }
    }

    // The changeset has to be sorted
    changes.sort_unstable_by_key(|(from, _, _)| *from);

    let transaction = Transaction::change(doc.text(), changes.into_iter());
    doc.apply(&transaction, view.id);
}

fn goto_window(cx: &mut Context, align: Align) {
    let count = cx.count() - 1;
    let config = cx.editor.config();
    let (view, doc) = current!(cx.editor);

    let height = view.inner_area().height as usize;

    // respect user given count if any
    // - 1 so we have at least one gap in the middle.
    // a height of 6 with padding of 3 on each side will keep shifting the view back and forth
    // as we type
    let scrolloff = config.scrolloff.min(height.saturating_sub(1) / 2);

    let last_line = view.last_line(doc);

    let line = match align {
        Align::Top => (view.offset.row + scrolloff + count),
        Align::Center => (view.offset.row + ((last_line - view.offset.row) / 2)),
        Align::Bottom => last_line.saturating_sub(scrolloff + count),
    }
    .max(view.offset.row + scrolloff)
    .min(last_line.saturating_sub(scrolloff));

    let pos = doc.text().line_to_char(line);

    doc.set_selection(view.id, Selection::point(pos));
}

fn goto_window_top(cx: &mut Context) {
    goto_window(cx, Align::Top)
}

fn goto_window_center(cx: &mut Context) {
    goto_window(cx, Align::Center)
}

fn goto_window_bottom(cx: &mut Context) {
    goto_window(cx, Align::Bottom)
}

fn move_word_impl<F>(cx: &mut Context, move_fn: F)
where
    F: Fn(RopeSlice, Range, usize) -> Range,
{
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let selection = doc
        .selection(view.id)
        .clone()
        .transform(|range| move_fn(text, range, count));
    doc.set_selection(view.id, selection);
}

fn move_next_word_start(cx: &mut Context) {
    move_word_impl(cx, movement::move_next_word_start)
}

fn move_prev_word_start(cx: &mut Context) {
    move_word_impl(cx, movement::move_prev_word_start)
}

fn move_prev_word_end(cx: &mut Context) {
    move_word_impl(cx, movement::move_prev_word_end)
}

fn move_next_word_end(cx: &mut Context) {
    move_word_impl(cx, movement::move_next_word_end)
}

fn move_next_long_word_start(cx: &mut Context) {
    move_word_impl(cx, movement::move_next_long_word_start)
}

fn move_prev_long_word_start(cx: &mut Context) {
    move_word_impl(cx, movement::move_prev_long_word_start)
}

fn move_next_long_word_end(cx: &mut Context) {
    move_word_impl(cx, movement::move_next_long_word_end)
}

fn goto_para_impl<F>(cx: &mut Context, move_fn: F)
where
    F: Fn(RopeSlice, Range, usize, Movement) -> Range + 'static,
{
    let count = cx.count();
    let motion = move |editor: &mut Editor| {
        let (view, doc) = current!(editor);
        let text = doc.text().slice(..);
        let behavior = if doc.mode == Mode::Select {
            Movement::Extend
        } else {
            Movement::Move
        };

        let selection = doc
            .selection(view.id)
            .clone()
            .transform(|range| move_fn(text, range, count, behavior));
        doc.set_selection(view.id, selection);
    };
    motion(cx.editor);
    cx.editor.last_motion = Some(Motion(Box::new(motion)));
}

fn goto_prev_paragraph(cx: &mut Context) {
    goto_para_impl(cx, movement::move_prev_paragraph)
}

fn goto_next_paragraph(cx: &mut Context) {
    goto_para_impl(cx, movement::move_next_paragraph)
}

fn goto_file_start(cx: &mut Context) {
    if cx.count.is_some() {
        goto_line(cx);
    } else {
        push_jump(cx.editor);
        let (view, doc) = current!(cx.editor);
        let text = doc.text().slice(..);
        let selection = doc
            .selection(view.id)
            .clone()
            .transform(|range| range.put_cursor(text, 0, doc.mode == Mode::Select));
        doc.set_selection(view.id, selection);
    }
}

fn goto_file_end(cx: &mut Context) {
    push_jump(cx.editor);
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);
    let pos = doc.text().len_chars();
    let selection = doc
        .selection(view.id)
        .clone()
        .transform(|range| range.put_cursor(text, pos, doc.mode == Mode::Select));
    doc.set_selection(view.id, selection);
}

fn goto_file(cx: &mut Context) {
    goto_file_impl(cx, Action::Replace);
}

fn goto_file_hsplit(cx: &mut Context) {
    goto_file_impl(cx, Action::HorizontalSplit);
}

fn goto_file_vsplit(cx: &mut Context) {
    goto_file_impl(cx, Action::VerticalSplit);
}

fn goto_file_impl(cx: &mut Context, action: Action) {
    let (view, doc) = current_ref!(cx.editor);
    let text = doc.text();
    let selections = doc.selection(view.id);
    let mut paths: Vec<_> = selections
        .iter()
        .map(|r| text.slice(r.from()..r.to()).to_string())
        .collect();
    let primary = selections.primary();
    if selections.len() == 1 && primary.to() - primary.from() == 1 {
        let current_word = movement::move_next_long_word_start(
            text.slice(..),
            movement::move_prev_long_word_start(text.slice(..), primary, 1),
            1,
        );
        paths.clear();
        paths.push(
            text.slice(current_word.from()..current_word.to())
                .to_string(),
        );
    }
    for sel in paths {
        let p = sel.trim();
        if !p.is_empty() {
            if let Err(e) = cx.editor.open(PathBuf::from(p), action) {
                cx.editor.set_error(format!("Open file failed: {:?}", e));
            }
        }
    }
}

fn extend_word_impl<F>(cx: &mut Context, extend_fn: F)
where
    F: Fn(RopeSlice, Range, usize) -> Range,
{
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let word = extend_fn(text, range, count);
        let pos = word.cursor(text);
        range.put_cursor(text, pos, true)
    });
    doc.set_selection(view.id, selection);
}

fn extend_next_word_start(cx: &mut Context) {
    extend_word_impl(cx, movement::move_next_word_start)
}

fn extend_prev_word_start(cx: &mut Context) {
    extend_word_impl(cx, movement::move_prev_word_start)
}

fn extend_next_word_end(cx: &mut Context) {
    extend_word_impl(cx, movement::move_next_word_end)
}

fn extend_next_long_word_start(cx: &mut Context) {
    extend_word_impl(cx, movement::move_next_long_word_start)
}

fn extend_prev_long_word_start(cx: &mut Context) {
    extend_word_impl(cx, movement::move_prev_long_word_start)
}

fn extend_next_long_word_end(cx: &mut Context) {
    extend_word_impl(cx, movement::move_next_long_word_end)
}

fn will_find_char<F>(cx: &mut Context, search_fn: F, inclusive: bool, extend: bool)
where
    F: Fn(RopeSlice, char, usize, usize, bool) -> Option<usize> + 'static,
{
    // TODO: count is reset to 1 before next key so we move it into the closure here.
    // Would be nice to carry over.
    let count = cx.count();

    // need to wait for next key
    // TODO: should this be done by grapheme rather than char?  For example,
    // we can't properly handle the line-ending CRLF case here in terms of char.
    cx.on_next_key(move |cx, event| {
        let ch = match event {
            KeyEvent {
                code: KeyCode::Enter,
                ..
            } =>
            // TODO: this isn't quite correct when CRLF is involved.
            // This hack will work in most cases, since documents don't
            // usually mix line endings.  But we should fix it eventually
            // anyway.
            {
                doc!(cx.editor).line_ending.as_str().chars().next().unwrap()
            }

            KeyEvent {
                code: KeyCode::Char(ch),
                ..
            } => ch,
            _ => return,
        };

        find_char_impl(cx.editor, &search_fn, inclusive, extend, ch, count);
        cx.editor.last_motion = Some(Motion(Box::new(move |editor: &mut Editor| {
            find_char_impl(editor, &search_fn, inclusive, true, ch, 1);
        })));
    })
}

//

#[inline]
fn find_char_impl<F, M: CharMatcher + Clone + Copy>(
    editor: &mut Editor,
    search_fn: &F,
    inclusive: bool,
    extend: bool,
    char_matcher: M,
    count: usize,
) where
    F: Fn(RopeSlice, M, usize, usize, bool) -> Option<usize> + 'static,
{
    let (view, doc) = current!(editor);
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        // TODO: use `Range::cursor()` here instead.  However, that works in terms of
        // graphemes, whereas this function doesn't yet.  So we're doing the same logic
        // here, but just in terms of chars instead.
        let search_start_pos = if range.anchor < range.head {
            range.head - 1
        } else {
            range.head
        };

        search_fn(text, char_matcher, search_start_pos, count, inclusive).map_or(range, |pos| {
            if extend {
                range.put_cursor(text, pos, true)
            } else {
                Range::point(range.cursor(text)).put_cursor(text, pos, true)
            }
        })
    });
    doc.set_selection(view.id, selection);
}

fn find_next_char_impl(
    text: RopeSlice,
    ch: char,
    pos: usize,
    n: usize,
    inclusive: bool,
) -> Option<usize> {
    let pos = (pos + 1).min(text.len_chars());
    if inclusive {
        search::find_nth_next(text, ch, pos, n)
    } else {
        let n = match text.get_char(pos) {
            Some(next_ch) if next_ch == ch => n + 1,
            _ => n,
        };
        search::find_nth_next(text, ch, pos, n).map(|n| n.saturating_sub(1))
    }
}

fn find_prev_char_impl(
    text: RopeSlice,
    ch: char,
    pos: usize,
    n: usize,
    inclusive: bool,
) -> Option<usize> {
    if inclusive {
        search::find_nth_prev(text, ch, pos, n)
    } else {
        let n = match text.get_char(pos.saturating_sub(1)) {
            Some(next_ch) if next_ch == ch => n + 1,
            _ => n,
        };
        search::find_nth_prev(text, ch, pos, n).map(|n| (n + 1).min(text.len_chars()))
    }
}

fn find_till_char(cx: &mut Context) {
    will_find_char(cx, find_next_char_impl, false, false)
}

fn find_next_char(cx: &mut Context) {
    will_find_char(cx, find_next_char_impl, true, false)
}

fn extend_till_char(cx: &mut Context) {
    will_find_char(cx, find_next_char_impl, false, true)
}

fn extend_next_char(cx: &mut Context) {
    will_find_char(cx, find_next_char_impl, true, true)
}

fn till_prev_char(cx: &mut Context) {
    will_find_char(cx, find_prev_char_impl, false, false)
}

fn find_prev_char(cx: &mut Context) {
    will_find_char(cx, find_prev_char_impl, true, false)
}

fn extend_till_prev_char(cx: &mut Context) {
    will_find_char(cx, find_prev_char_impl, false, true)
}

fn extend_prev_char(cx: &mut Context) {
    will_find_char(cx, find_prev_char_impl, true, true)
}

fn repeat_last_motion(cx: &mut Context) {
    let last_motion = cx.editor.last_motion.take();
    if let Some(m) = &last_motion {
        m.run(cx.editor);
        cx.editor.last_motion = last_motion;
    }
}

fn replace(cx: &mut Context) {
    let mut buf = [0u8; 4]; // To hold utf8 encoded char.

    // need to wait for next key
    cx.on_next_key(move |cx, event| {
        let (view, doc) = current!(cx.editor);
        let ch = match event {
            KeyEvent {
                code: KeyCode::Char(ch),
                ..
            } => Some(&ch.encode_utf8(&mut buf[..])[..]),
            KeyEvent {
                code: KeyCode::Enter,
                ..
            } => Some(doc.line_ending.as_str()),
            _ => None,
        };

        let selection = doc.selection(view.id);

        if let Some(ch) = ch {
            let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
                if !range.is_empty() {
                    let text: String =
                        RopeGraphemes::new(doc.text().slice(range.from()..range.to()))
                            .map(|g| {
                                let cow: Cow<str> = g.into();
                                if str_is_line_ending(&cow) {
                                    cow
                                } else {
                                    ch.into()
                                }
                            })
                            .collect();

                    (range.from(), range.to(), Some(text.into()))
                } else {
                    // No change.
                    (range.from(), range.to(), None)
                }
            });

            doc.apply(&transaction, view.id);
        }
    })
}

fn switch_case_impl<F>(cx: &mut Context, change_fn: F)
where
    F: Fn(Cow<str>) -> Tendril,
{
    let (view, doc) = current!(cx.editor);
    let selection = doc.selection(view.id);
    let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
        let text: Tendril = change_fn(range.fragment(doc.text().slice(..)));

        (range.from(), range.to(), Some(text))
    });

    doc.apply(&transaction, view.id);
}

fn switch_case(cx: &mut Context) {
    switch_case_impl(cx, |string| {
        string
            .chars()
            .flat_map(|ch| {
                if ch.is_lowercase() {
                    ch.to_uppercase().collect()
                } else if ch.is_uppercase() {
                    ch.to_lowercase().collect()
                } else {
                    vec![ch]
                }
            })
            .collect()
    });
}

fn switch_to_uppercase(cx: &mut Context) {
    switch_case_impl(cx, |string| string.to_uppercase().into());
}

fn switch_to_lowercase(cx: &mut Context) {
    switch_case_impl(cx, |string| string.to_lowercase().into());
}

pub fn scroll(cx: &mut Context, offset: usize, direction: Direction) {
    use Direction::*;
    let config = cx.editor.config();
    let (view, doc) = current!(cx.editor);

    let range = doc.selection(view.id).primary();
    let text = doc.text().slice(..);

    let cursor = coords_at_pos(text, range.cursor(text));
    let doc_last_line = doc.text().len_lines().saturating_sub(1);

    let last_line = view.last_line(doc);

    if direction == Backward && view.offset.row == 0
        || direction == Forward && last_line == doc_last_line
    {
        return;
    }

    let height = view.inner_area().height;

    let scrolloff = config.scrolloff.min(height as usize / 2);

    view.offset.row = match direction {
        Forward => view.offset.row + offset,
        Backward => view.offset.row.saturating_sub(offset),
    }
    .min(doc_last_line);

    // recalculate last line
    let last_line = view.last_line(doc);

    // clamp into viewport
    let line = cursor
        .row
        .max(view.offset.row + scrolloff)
        .min(last_line.saturating_sub(scrolloff));

    // If cursor needs moving, replace primary selection
    if line != cursor.row {
        let head = pos_at_coords(text, Position::new(line, cursor.col), true); // this func will properly truncate to line end

        let anchor = if doc.mode == Mode::Select {
            range.anchor
        } else {
            head
        };

        // replace primary selection with an empty selection at cursor pos
        let prim_sel = Range::new(anchor, head);
        let mut sel = doc.selection(view.id).clone();
        let idx = sel.primary_index();
        sel = sel.replace(idx, prim_sel);
        doc.set_selection(view.id, sel);
    }
}

fn page_up(cx: &mut Context) {
    let view = view!(cx.editor);
    let offset = view.inner_area().height as usize;
    scroll(cx, offset, Direction::Backward);
}

fn page_down(cx: &mut Context) {
    let view = view!(cx.editor);
    let offset = view.inner_area().height as usize;
    scroll(cx, offset, Direction::Forward);
}

fn half_page_up(cx: &mut Context) {
    let view = view!(cx.editor);
    let offset = view.inner_area().height as usize / 2;
    scroll(cx, offset, Direction::Backward);
}

fn half_page_down(cx: &mut Context) {
    let view = view!(cx.editor);
    let offset = view.inner_area().height as usize / 2;
    scroll(cx, offset, Direction::Forward);
}

fn copy_selection_on_line(cx: &mut Context, direction: Direction) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);
    let selection = doc.selection(view.id);
    let mut ranges = SmallVec::with_capacity(selection.ranges().len() * (count + 1));
    ranges.extend_from_slice(selection.ranges());
    let mut primary_index = 0;
    for range in selection.iter() {
        let is_primary = *range == selection.primary();

        // The range is always head exclusive
        let head = if range.anchor < range.head {
            range.head - 1
        } else {
            range.head
        };

        // TODO: this should use visual offsets / pos_at_screen_coords
        let head_pos = coords_at_pos(text, head);
        let anchor_pos = coords_at_pos(text, range.anchor);

        let height = std::cmp::max(head_pos.row, anchor_pos.row)
            - std::cmp::min(head_pos.row, anchor_pos.row)
            + 1;

        if is_primary {
            primary_index = ranges.len();
        }
        ranges.push(*range);

        let mut sels = 0;
        let mut i = 0;
        while sels < count {
            let offset = (i + 1) * height;

            let anchor_row = match direction {
                Direction::Forward => anchor_pos.row + offset,
                Direction::Backward => anchor_pos.row.saturating_sub(offset),
            };

            let head_row = match direction {
                Direction::Forward => head_pos.row + offset,
                Direction::Backward => head_pos.row.saturating_sub(offset),
            };

            if anchor_row >= text.len_lines() || head_row >= text.len_lines() {
                break;
            }

            let anchor = pos_at_coords(text, Position::new(anchor_row, anchor_pos.col), true);
            let head = pos_at_coords(text, Position::new(head_row, head_pos.col), true);

            // skip lines that are too short
            if coords_at_pos(text, anchor).col == anchor_pos.col
                && coords_at_pos(text, head).col == head_pos.col
            {
                if is_primary {
                    primary_index = ranges.len();
                }
                // This is Range::new(anchor, head), but it will place the cursor on the correct column
                ranges.push(Range::point(anchor).put_cursor(text, head, true));
                sels += 1;
            }

            i += 1;
        }
    }

    let selection = Selection::new(ranges, primary_index);
    doc.set_selection(view.id, selection);
}

fn copy_selection_on_prev_line(cx: &mut Context) {
    copy_selection_on_line(cx, Direction::Backward)
}

fn copy_selection_on_next_line(cx: &mut Context) {
    copy_selection_on_line(cx, Direction::Forward)
}

fn select_all(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);

    let end = doc.text().len_chars();
    doc.set_selection(view.id, Selection::single(0, end))
}

fn select_regex(cx: &mut Context) {
    let reg = cx.register.unwrap_or('/');
    ui::regex_prompt(
        cx,
        "select:".into(),
        Some(reg),
        ui::completers::none,
        move |view, doc, regex, event| {
            if event != PromptEvent::Update {
                return;
            }
            let text = doc.text().slice(..);
            if let Some(selection) =
                selection::select_on_matches(text, doc.selection(view.id), &regex)
            {
                doc.set_selection(view.id, selection);
            }
        },
    );
}

fn split_selection(cx: &mut Context) {
    let reg = cx.register.unwrap_or('/');
    ui::regex_prompt(
        cx,
        "split:".into(),
        Some(reg),
        ui::completers::none,
        move |view, doc, regex, event| {
            if event != PromptEvent::Update {
                return;
            }
            let text = doc.text().slice(..);
            let selection = selection::split_on_matches(text, doc.selection(view.id), &regex);
            doc.set_selection(view.id, selection);
        },
    );
}

fn split_selection_on_newline(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);
    // only compile the regex once
    #[allow(clippy::trivial_regex)]
    static REGEX: Lazy<Regex> =
        Lazy::new(|| Regex::new(r"\r\n|[\n\r\u{000B}\u{000C}\u{0085}\u{2028}\u{2029}]").unwrap());
    let selection = selection::split_on_matches(text, doc.selection(view.id), &REGEX);
    doc.set_selection(view.id, selection);
}

#[allow(clippy::too_many_arguments)]
fn search_impl(
    doc: &mut Document,
    view: &mut View,
    contents: &str,
    regex: &Regex,
    movement: Movement,
    direction: Direction,
    scrolloff: usize,
    wrap_around: bool,
) {
    let text = doc.text().slice(..);
    let selection = doc.selection(view.id);

    // Get the right side of the primary block cursor for forward search, or the
    // grapheme before the start of the selection for reverse search.
    let start = match direction {
        Direction::Forward => text.char_to_byte(graphemes::ensure_grapheme_boundary_next(
            text,
            selection.primary().to(),
        )),
        Direction::Backward => text.char_to_byte(graphemes::ensure_grapheme_boundary_prev(
            text,
            selection.primary().from(),
        )),
    };

    // A regex::Match returns byte-positions in the str. In the case where we
    // do a reverse search and wraparound to the end, we don't need to search
    // the text before the current cursor position for matches, but by slicing
    // it out, we need to add it back to the position of the selection.
    let mut offset = 0;

    // use find_at to find the next match after the cursor, loop around the end
    // Careful, `Regex` uses `bytes` as offsets, not character indices!
    let mut mat = match direction {
        Direction::Forward => regex.find_at(contents, start),
        Direction::Backward => regex.find_iter(&contents[..start]).last(),
    };

    if wrap_around && mat.is_none() {
        mat = match direction {
            Direction::Forward => regex.find(contents),
            Direction::Backward => {
                offset = start;
                regex.find_iter(&contents[start..]).last()
            }
        }
        // TODO: message on wraparound
    }

    if let Some(mat) = mat {
        let start = text.byte_to_char(mat.start() + offset);
        let end = text.byte_to_char(mat.end() + offset);

        if end == 0 {
            // skip empty matches that don't make sense
            return;
        }

        // Determine range direction based on the primary range
        let primary = selection.primary();
        let range = if primary.head < primary.anchor {
            Range::new(end, start)
        } else {
            Range::new(start, end)
        };

        let selection = match movement {
            Movement::Extend => selection.clone().push(range),
            Movement::Move => selection.clone().replace(selection.primary_index(), range),
        };

        doc.set_selection(view.id, selection);
        // TODO: is_cursor_in_view does the same calculation as ensure_cursor_in_view
        if view.is_cursor_in_view(doc, 0) {
            view.ensure_cursor_in_view(doc, scrolloff);
        } else {
            align_view(doc, view, Align::Center)
        }
    };
}

fn search_completions(cx: &mut Context, reg: Option<char>) -> Vec<String> {
    let mut items = reg
        .and_then(|reg| cx.editor.registers.get(reg))
        .map_or(Vec::new(), |reg| reg.read().iter().take(200).collect());
    items.sort_unstable();
    items.dedup();
    items.into_iter().cloned().collect()
}

fn search(cx: &mut Context) {
    searcher(cx, Direction::Forward)
}

fn rsearch(cx: &mut Context) {
    searcher(cx, Direction::Backward)
}

fn searcher(cx: &mut Context, direction: Direction) {
    let reg = cx.register.unwrap_or('/');
    let config = cx.editor.config();
    let scrolloff = config.scrolloff;
    let wrap_around = config.search.wrap_around;

    let doc = doc!(cx.editor);

    // TODO: could probably share with select_on_matches?

    // HAXX: sadly we can't avoid allocating a single string for the whole buffer since we can't
    // feed chunks into the regex yet
    let contents = doc.text().slice(..).to_string();
    let completions = search_completions(cx, Some(reg));

    ui::regex_prompt(
        cx,
        "search:".into(),
        Some(reg),
        move |_editor: &Editor, input: &str| {
            completions
                .iter()
                .filter(|comp| comp.starts_with(input))
                .map(|comp| (0.., std::borrow::Cow::Owned(comp.clone())))
                .collect()
        },
        move |view, doc, regex, event| {
            if event != PromptEvent::Update {
                return;
            }
            search_impl(
                doc,
                view,
                &contents,
                &regex,
                Movement::Move,
                direction,
                scrolloff,
                wrap_around,
            );
        },
    );
}

fn search_next_or_prev_impl(cx: &mut Context, movement: Movement, direction: Direction) {
    let config = cx.editor.config();
    let scrolloff = config.scrolloff;
    let (view, doc) = current!(cx.editor);
    let registers = &cx.editor.registers;
    if let Some(query) = registers.read('/') {
        let query = query.last().unwrap();
        let contents = doc.text().slice(..).to_string();
        let search_config = &config.search;
        let case_insensitive = if search_config.smart_case {
            !query.chars().any(char::is_uppercase)
        } else {
            false
        };
        let wrap_around = search_config.wrap_around;
        if let Ok(regex) = RegexBuilder::new(query)
            .case_insensitive(case_insensitive)
            .multi_line(true)
            .build()
        {
            search_impl(
                doc,
                view,
                &contents,
                &regex,
                movement,
                direction,
                scrolloff,
                wrap_around,
            );
        } else {
            let error = format!("Invalid regex: {}", query);
            cx.editor.set_error(error);
        }
    }
}

fn search_next(cx: &mut Context) {
    search_next_or_prev_impl(cx, Movement::Move, Direction::Forward);
}

fn search_prev(cx: &mut Context) {
    search_next_or_prev_impl(cx, Movement::Move, Direction::Backward);
}
fn extend_search_next(cx: &mut Context) {
    search_next_or_prev_impl(cx, Movement::Extend, Direction::Forward);
}

fn extend_search_prev(cx: &mut Context) {
    search_next_or_prev_impl(cx, Movement::Extend, Direction::Backward);
}

fn search_selection(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let contents = doc.text().slice(..);
    let query = doc.selection(view.id).primary().fragment(contents);
    let regex = regex::escape(&query);
    cx.editor.registers.get_mut('/').push(regex);
    let msg = format!("register '{}' set to '{}'", '/', query);
    cx.editor.set_status(msg);
}

fn global_search(cx: &mut Context) {
    let (all_matches_sx, all_matches_rx) =
        tokio::sync::mpsc::unbounded_channel::<(usize, PathBuf)>();
    let config = cx.editor.config();
    let smart_case = config.search.smart_case;
    let file_picker_config = config.file_picker.clone();

    let completions = search_completions(cx, None);
    ui::regex_prompt(
        cx,
        "global-search:".into(),
        None,
        move |_editor: &Editor, input: &str| {
            completions
                .iter()
                .filter(|comp| comp.starts_with(input))
                .map(|comp| (0.., std::borrow::Cow::Owned(comp.clone())))
                .collect()
        },
        move |_view, _doc, regex, event| {
            if event != PromptEvent::Validate {
                return;
            }

            if let Ok(matcher) = RegexMatcherBuilder::new()
                .case_smart(smart_case)
                .build(regex.as_str())
            {
                let searcher = SearcherBuilder::new()
                    .binary_detection(BinaryDetection::quit(b'\x00'))
                    .build();

                let search_root = std::env::current_dir()
                    .expect("Global search error: Failed to get current dir");
                WalkBuilder::new(search_root)
                    .hidden(file_picker_config.hidden)
                    .parents(file_picker_config.parents)
                    .ignore(file_picker_config.ignore)
                    .git_ignore(file_picker_config.git_ignore)
                    .git_global(file_picker_config.git_global)
                    .git_exclude(file_picker_config.git_exclude)
                    .max_depth(file_picker_config.max_depth)
                    .build_parallel()
                    .run(|| {
                        let mut searcher = searcher.clone();
                        let matcher = matcher.clone();
                        let all_matches_sx = all_matches_sx.clone();
                        Box::new(move |entry: Result<DirEntry, ignore::Error>| -> WalkState {
                            let entry = match entry {
                                Ok(entry) => entry,
                                Err(_) => return WalkState::Continue,
                            };

                            match entry.file_type() {
                                Some(entry) if entry.is_file() => {}
                                // skip everything else
                                _ => return WalkState::Continue,
                            };

                            let result = searcher.search_path(
                                &matcher,
                                entry.path(),
                                sinks::UTF8(|line_num, _| {
                                    all_matches_sx
                                        .send((line_num as usize - 1, entry.path().to_path_buf()))
                                        .unwrap();

                                    Ok(true)
                                }),
                            );

                            if let Err(err) = result {
                                log::error!(
                                    "Global search error: {}, {}",
                                    entry.path().display(),
                                    err
                                );
                            }
                            WalkState::Continue
                        })
                    });
            } else {
                // Otherwise do nothing
                // log::warn!("Global Search Invalid Pattern")
            }
        },
    );

    let current_path = doc_mut!(cx.editor).path().cloned();

    let show_picker = async move {
        let all_matches: Vec<(usize, PathBuf)> =
            UnboundedReceiverStream::new(all_matches_rx).collect().await;
        let call: job::Callback =
            Box::new(move |editor: &mut Editor, compositor: &mut Compositor| {
                if all_matches.is_empty() {
                    editor.set_status("No matches found");
                    return;
                }

                let picker = FilePicker::new(
                    all_matches,
                    move |(_line_num, path)| {
                        let relative_path = helix_core::path::get_relative_path(path)
                            .to_string_lossy()
                            .into_owned();
                        if current_path.as_ref().map(|p| p == path).unwrap_or(false) {
                            format!("{} (*)", relative_path).into()
                        } else {
                            relative_path.into()
                        }
                    },
                    move |cx, (line_num, path), action| {
                        match cx.editor.open(path.into(), action) {
                            Ok(_) => {}
                            Err(e) => {
                                cx.editor.set_error(format!(
                                    "Failed to open file '{}': {}",
                                    path.display(),
                                    e
                                ));
                                return;
                            }
                        }

                        let line_num = *line_num;
                        let (view, doc) = current!(cx.editor);
                        let text = doc.text();
                        let start = text.line_to_char(line_num);
                        let end = text.line_to_char((line_num + 1).min(text.len_lines()));

                        doc.set_selection(view.id, Selection::single(start, end));
                        align_view(doc, view, Align::Center);
                    },
                    |_editor, (line_num, path)| Some((path.clone(), Some((*line_num, *line_num)))),
                );
                compositor.push(Box::new(overlayed(picker)));
            });
        Ok(call)
    };
    cx.jobs.callback(show_picker);
}

enum Extend {
    Above,
    Below,
}

fn extend_line(cx: &mut Context) {
    extend_line_impl(cx, Extend::Below);
}

fn extend_line_above(cx: &mut Context) {
    extend_line_impl(cx, Extend::Above);
}

fn extend_line_impl(cx: &mut Context, extend: Extend) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);

    let text = doc.text();
    let selection = doc.selection(view.id).clone().transform(|range| {
        let (start_line, end_line) = range.line_range(text.slice(..));

        let start = text.line_to_char(start_line);
        let end = text.line_to_char((end_line + count).min(text.len_lines()));

        // extend to previous/next line if current line is selected
        let (anchor, head) = if range.from() == start && range.to() == end {
            match extend {
                Extend::Above => (end, text.line_to_char(start_line.saturating_sub(1))),
                Extend::Below => (
                    start,
                    text.line_to_char((end_line + count + 1).min(text.len_lines())),
                ),
            }
        } else {
            (start, end)
        };

        Range::new(anchor, head)
    });

    doc.set_selection(view.id, selection);
}

fn extend_to_line_bounds(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);

    doc.set_selection(
        view.id,
        doc.selection(view.id).clone().transform(|range| {
            let text = doc.text();

            let (start_line, end_line) = range.line_range(text.slice(..));
            let start = text.line_to_char(start_line);
            let end = text.line_to_char((end_line + 1).min(text.len_lines()));

            if range.anchor <= range.head {
                Range::new(start, end)
            } else {
                Range::new(end, start)
            }
        }),
    );
}

enum Operation {
    Delete,
    Change,
}

fn delete_selection_impl(cx: &mut Context, op: Operation) {
    let (view, doc) = current!(cx.editor);

    let text = doc.text().slice(..);
    let selection = doc.selection(view.id);

    if cx.register != Some('_') {
        // first yank the selection
        let values: Vec<String> = selection.fragments(text).map(Cow::into_owned).collect();
        let reg_name = cx.register.unwrap_or('"');
        let registers = &mut cx.editor.registers;
        let reg = registers.get_mut(reg_name);
        reg.write(values);
    };

    // then delete
    let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
        (range.from(), range.to(), None)
    });
    doc.apply(&transaction, view.id);

    match op {
        Operation::Delete => {
            // exit select mode, if currently in select mode
            exit_select_mode(cx);
        }
        Operation::Change => {
            enter_insert_mode(doc);
        }
    }
}

#[inline]
fn delete_selection_insert_mode(doc: &mut Document, view: &View, selection: &Selection) {
    let view_id = view.id;

    // then delete
    let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
        (range.from(), range.to(), None)
    });
    doc.apply(&transaction, view_id);
}

fn delete_selection(cx: &mut Context) {
    delete_selection_impl(cx, Operation::Delete);
}

fn delete_selection_noyank(cx: &mut Context) {
    cx.register = Some('_');
    delete_selection_impl(cx, Operation::Delete);
}

fn change_selection(cx: &mut Context) {
    delete_selection_impl(cx, Operation::Change);
}

fn change_selection_noyank(cx: &mut Context) {
    cx.register = Some('_');
    delete_selection_impl(cx, Operation::Change);
}

fn collapse_selection(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let pos = range.cursor(text);
        Range::new(pos, pos)
    });
    doc.set_selection(view.id, selection);
}

fn flip_selections(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);

    let selection = doc
        .selection(view.id)
        .clone()
        .transform(|range| range.flip());
    doc.set_selection(view.id, selection);
}

fn ensure_selections_forward(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);

    let selection = doc
        .selection(view.id)
        .clone()
        .transform(|r| match r.direction() {
            Direction::Forward => r,
            Direction::Backward => r.flip(),
        });

    doc.set_selection(view.id, selection);
}

fn enter_insert_mode(doc: &mut Document) {
    doc.mode = Mode::Insert;
}

// inserts at the start of each selection
fn insert_mode(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    enter_insert_mode(doc);

    let selection = doc
        .selection(view.id)
        .clone()
        .transform(|range| Range::new(range.to(), range.from()));
    doc.set_selection(view.id, selection);
}

// inserts at the end of each selection
fn append_mode(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    enter_insert_mode(doc);
    doc.restore_cursor = true;
    let text = doc.text().slice(..);

    // Make sure there's room at the end of the document if the last
    // selection butts up against it.
    let end = text.len_chars();
    let last_range = doc.selection(view.id).iter().last().unwrap();
    if !last_range.is_empty() && last_range.head == end {
        let transaction = Transaction::change(
            doc.text(),
            [(end, end, Some(doc.line_ending.as_str().into()))].into_iter(),
        );
        doc.apply(&transaction, view.id);
    }

    let selection = doc.selection(view.id).clone().transform(|range| {
        Range::new(
            range.from(),
            graphemes::next_grapheme_boundary(doc.text().slice(..), range.to()),
        )
    });
    doc.set_selection(view.id, selection);
}

fn file_picker(cx: &mut Context) {
    // We don't specify language markers, root will be the root of the current git repo
    let root = find_root(None, &[]).unwrap_or_else(|| PathBuf::from("./"));
    let picker = ui::file_picker(root, &cx.editor.config());
    cx.push_layer(Box::new(overlayed(picker)));
}

fn file_picker_in_current_directory(cx: &mut Context) {
    let cwd = std::env::current_dir().unwrap_or_else(|_| PathBuf::from("./"));
    let picker = ui::file_picker(cwd, &cx.editor.config());
    cx.push_layer(Box::new(picker));
}

fn buffer_picker(cx: &mut Context) {
    let current = view!(cx.editor).doc;

    struct BufferMeta {
        id: DocumentId,
        path: Option<PathBuf>,
        is_modified: bool,
        is_current: bool,
    }

    impl BufferMeta {
        fn format(&self) -> Cow<str> {
            let path = self
                .path
                .as_deref()
                .map(helix_core::path::get_relative_path);
            let path = match path.as_deref().and_then(Path::to_str) {
                Some(path) => path,
                None => SCRATCH_BUFFER_NAME,
            };

            let mut flags = Vec::new();
            if self.is_modified {
                flags.push("+");
            }
            if self.is_current {
                flags.push("*");
            }

            let flag = if flags.is_empty() {
                "".into()
            } else {
                format!(" ({})", flags.join(""))
            };
            Cow::Owned(format!("{} {}{}", self.id, path, flag))
        }
    }

    let new_meta = |doc: &Document| BufferMeta {
        id: doc.id(),
        path: doc.path().cloned(),
        is_modified: doc.is_modified(),
        is_current: doc.id() == current,
    };

    let picker = FilePicker::new(
        cx.editor
            .documents
            .iter()
            .map(|(_, doc)| new_meta(doc))
            .collect(),
        BufferMeta::format,
        |cx, meta, action| {
            cx.editor.switch(meta.id, action);
        },
        |editor, meta| {
            let doc = &editor.documents.get(&meta.id)?;
            let &view_id = doc.selections().keys().next()?;
            let line = doc
                .selection(view_id)
                .primary()
                .cursor_line(doc.text().slice(..));
            Some((meta.path.clone()?, Some((line, line))))
        },
    );
    cx.push_layer(Box::new(overlayed(picker)));
}

pub fn command_palette(cx: &mut Context) {
    cx.callback = Some(Box::new(
        move |compositor: &mut Compositor, cx: &mut compositor::Context| {
            let doc = doc_mut!(cx.editor);
            let keymap =
                compositor.find::<ui::EditorView>().unwrap().keymaps.map()[&doc.mode].reverse_map();

            let mut commands: Vec<MappableCommand> = MappableCommand::STATIC_COMMAND_LIST.into();
            commands.extend(typed::TYPABLE_COMMAND_LIST.iter().map(|cmd| {
                MappableCommand::Typable {
                    name: cmd.name.to_owned(),
                    doc: cmd.doc.to_owned(),
                    args: Vec::new(),
                }
            }));

            // formats key bindings, multiple bindings are comma separated,
            // individual key presses are joined with `+`
            let fmt_binding = |bindings: &Vec<Vec<KeyEvent>>| -> String {
                bindings
                    .iter()
                    .map(|bind| {
                        bind.iter()
                            .map(|key| key.to_string())
                            .collect::<Vec<String>>()
                            .join("+")
                    })
                    .collect::<Vec<String>>()
                    .join(", ")
            };

            let picker = Picker::new(
                commands,
                move |command| match command {
                    MappableCommand::Typable { doc, name, .. } => match keymap.get(name as &String)
                    {
                        Some(bindings) => format!("{} ({})", doc, fmt_binding(bindings)).into(),
                        None => doc.into(),
                    },
                    MappableCommand::Static { doc, name, .. } => match keymap.get(*name) {
                        Some(bindings) => format!("{} ({})", doc, fmt_binding(bindings)).into(),
                        None => (*doc).into(),
                    },
                },
                move |cx, command, _action| {
                    let mut ctx = Context {
                        register: None,
                        count: std::num::NonZeroUsize::new(1),
                        editor: cx.editor,
                        callback: None,
                        on_next_key_callback: None,
                        jobs: cx.jobs,
                    };
                    command.execute(&mut ctx);
                },
            );
            compositor.push(Box::new(picker));
        },
    ));
}

fn last_picker(cx: &mut Context) {
    // TODO: last picker does not seem to work well with buffer_picker
    cx.callback = Some(Box::new(|compositor: &mut Compositor, _| {
        if let Some(picker) = compositor.last_picker.take() {
            compositor.push(picker);
        }
        // XXX: figure out how to show error when no last picker lifetime
        // cx.editor.set_error("no last picker")
    }));
}

// I inserts at the first nonwhitespace character of each line with a selection
fn prepend_to_line(cx: &mut Context) {
    goto_first_nonwhitespace(cx);
    let doc = doc_mut!(cx.editor);
    enter_insert_mode(doc);
}

// A inserts at the end of each line with a selection
fn append_to_line(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    enter_insert_mode(doc);

    let selection = doc.selection(view.id).clone().transform(|range| {
        let text = doc.text().slice(..);
        let line = range.cursor_line(text);
        let pos = line_end_char_index(&text, line);
        Range::new(pos, pos)
    });
    doc.set_selection(view.id, selection);
}

/// Sometimes when applying formatting changes we want to mark the buffer as unmodified, for
/// example because we just applied the same changes while saving.
enum Modified {
    SetUnmodified,
    LeaveModified,
}

// Creates an LspCallback that waits for formatting changes to be computed. When they're done,
// it applies them, but only if the doc hasn't changed.
//
// TODO: provide some way to cancel this, probably as part of a more general job cancellation
// scheme
async fn make_format_callback(
    doc_id: DocumentId,
    doc_version: i32,
    modified: Modified,
    format: impl Future<Output = helix_lsp::util::LspFormatting> + Send + 'static,
) -> anyhow::Result<job::Callback> {
    let format = format.await;
    let call: job::Callback = Box::new(move |editor, _compositor| {
        let view_id = view!(editor).id;
        if let Some(doc) = editor.document_mut(doc_id) {
            if doc.version() == doc_version {
                doc.apply(&Transaction::from(format), view_id);
                doc.append_changes_to_history(view_id);
                if let Modified::SetUnmodified = modified {
                    doc.reset_modified();
                }
            } else {
                log::info!("discarded formatting changes because the document changed");
            }
        }
    });
    Ok(call)
}

enum Open {
    Below,
    Above,
}

fn open(cx: &mut Context, open: Open) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    enter_insert_mode(doc);

    let text = doc.text().slice(..);
    let contents = doc.text();
    let selection = doc.selection(view.id);

    let mut ranges = SmallVec::with_capacity(selection.len());
    let mut offs = 0;

    let mut transaction = Transaction::change_by_selection(contents, selection, |range| {
        let cursor_line = text.char_to_line(match open {
            Open::Below => graphemes::prev_grapheme_boundary(text, range.to()),
            Open::Above => range.from(),
        });
        let new_line = match open {
            // adjust position to the end of the line (next line - 1)
            Open::Below => cursor_line + 1,
            // adjust position to the end of the previous line (current line - 1)
            Open::Above => cursor_line,
        };

        // Index to insert newlines after, as well as the char width
        // to use to compensate for those inserted newlines.
        let (line_end_index, line_end_offset_width) = if new_line == 0 {
            (0, 0)
        } else {
            (
                line_end_char_index(&doc.text().slice(..), new_line.saturating_sub(1)),
                doc.line_ending.len_chars(),
            )
        };

        let indent = indent::indent_for_newline(
            doc.language_config(),
            doc.syntax(),
            &doc.indent_style,
            doc.tab_width(),
            text,
            new_line.saturating_sub(1),
            line_end_index,
            cursor_line,
        );
        let indent_len = indent.len();
        let mut text = String::with_capacity(1 + indent_len);
        text.push_str(doc.line_ending.as_str());
        text.push_str(&indent);
        let text = text.repeat(count);

        // calculate new selection ranges
        let pos = offs + line_end_index + line_end_offset_width;
        for i in 0..count {
            // pos                    -> beginning of reference line,
            // + (i * (1+indent_len)) -> beginning of i'th line from pos
            // + indent_len ->        -> indent for i'th line
            ranges.push(Range::point(pos + (i * (1 + indent_len)) + indent_len));
        }

        offs += text.chars().count();

        (line_end_index, line_end_index, Some(text.into()))
    });

    transaction = transaction.with_selection(Selection::new(ranges, selection.primary_index()));

    doc.apply(&transaction, view.id);
}

// o inserts a new line after each line with a selection
fn open_below(cx: &mut Context) {
    open(cx, Open::Below)
}

// O inserts a new line before each line with a selection
fn open_above(cx: &mut Context) {
    open(cx, Open::Above)
}

fn normal_mode(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);

    if doc.mode == Mode::Normal {
        return;
    }

    doc.mode = Mode::Normal;

    try_restore_indent(doc, view.id);

    // if leaving append mode, move cursor back by 1
    if doc.restore_cursor {
        let text = doc.text().slice(..);
        let selection = doc.selection(view.id).clone().transform(|range| {
            Range::new(
                range.from(),
                graphemes::prev_grapheme_boundary(text, range.to()),
            )
        });
        doc.set_selection(view.id, selection);

        doc.restore_cursor = false;
    }
}

fn try_restore_indent(doc: &mut Document, view_id: ViewId) {
    use helix_core::chars::char_is_whitespace;
    use helix_core::Operation;

    fn inserted_a_new_blank_line(changes: &[Operation], pos: usize, line_end_pos: usize) -> bool {
        if let [Operation::Retain(move_pos), Operation::Insert(ref inserted_str), Operation::Retain(_)] =
            changes
        {
            move_pos + inserted_str.len() == pos
                && inserted_str.starts_with('\n')
                && inserted_str.chars().skip(1).all(char_is_whitespace)
                && pos == line_end_pos // ensure no characters exists after current position
        } else {
            false
        }
    }

    let doc_changes = doc.changes().changes();
    let text = doc.text().slice(..);
    let range = doc.selection(view_id).primary();
    let pos = range.cursor(text);
    let line_end_pos = line_end_char_index(&text, range.cursor_line(text));

    if inserted_a_new_blank_line(doc_changes, pos, line_end_pos) {
        // Removes tailing whitespaces.
        let transaction =
            Transaction::change_by_selection(doc.text(), doc.selection(view_id), |range| {
                let line_start_pos = text.line_to_char(range.cursor_line(text));
                (line_start_pos, pos, None)
            });
        doc.apply(&transaction, view_id);
    }
}

// Store a jump on the jumplist.
fn push_jump(editor: &mut Editor) {
    let (view, doc) = current!(editor);
    let jump = (doc.id(), doc.selection(view.id).clone());
    view.jumps.push(jump);
}

fn goto_line(cx: &mut Context) {
    goto_line_impl(cx.editor, cx.count)
}

fn goto_line_impl(editor: &mut Editor, count: Option<NonZeroUsize>) {
    if let Some(count) = count {
        push_jump(editor);

        let (view, doc) = current!(editor);
        let max_line = if doc.text().line(doc.text().len_lines() - 1).len_chars() == 0 {
            // If the last line is blank, don't jump to it.
            doc.text().len_lines().saturating_sub(2)
        } else {
            doc.text().len_lines() - 1
        };
        let line_idx = std::cmp::min(count.get() - 1, max_line);
        let text = doc.text().slice(..);
        let pos = doc.text().line_to_char(line_idx);
        let selection = doc
            .selection(view.id)
            .clone()
            .transform(|range| range.put_cursor(text, pos, doc.mode == Mode::Select));
        doc.set_selection(view.id, selection);
    }
}

fn goto_last_line(cx: &mut Context) {
    push_jump(cx.editor);

    let (view, doc) = current!(cx.editor);
    let line_idx = if doc.text().line(doc.text().len_lines() - 1).len_chars() == 0 {
        // If the last line is blank, don't jump to it.
        doc.text().len_lines().saturating_sub(2)
    } else {
        doc.text().len_lines() - 1
    };
    let text = doc.text().slice(..);
    let pos = doc.text().line_to_char(line_idx);
    let selection = doc
        .selection(view.id)
        .clone()
        .transform(|range| range.put_cursor(text, pos, doc.mode == Mode::Select));
    doc.set_selection(view.id, selection);
}

fn goto_last_accessed_file(cx: &mut Context) {
    let alternate_file = view!(cx.editor).last_accessed_doc;
    if let Some(alt) = alternate_file {
        cx.editor.switch(alt, Action::Replace);
    } else {
        cx.editor.set_error("no last accessed buffer")
    }
}

fn goto_last_modification(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let pos = doc.history.get_mut().last_edit_pos();
    let text = doc.text().slice(..);
    if let Some(pos) = pos {
        let selection = doc
            .selection(view.id)
            .clone()
            .transform(|range| range.put_cursor(text, pos, doc.mode == Mode::Select));
        doc.set_selection(view.id, selection);
    }
}

fn goto_last_modified_file(cx: &mut Context) {
    let view = view!(cx.editor);
    let alternate_file = view
        .last_modified_docs
        .into_iter()
        .flatten()
        .find(|&id| id != view.doc);
    if let Some(alt) = alternate_file {
        cx.editor.switch(alt, Action::Replace);
    } else {
        cx.editor.set_error("no last modified buffer")
    }
}

fn select_mode(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    // Make sure end-of-document selections are also 1-width.
    // (With the exception of being in an empty document, of course.)
    let selection = doc.selection(view.id).clone().transform(|range| {
        if range.is_empty() && range.head == text.len_chars() {
            Range::new(
                graphemes::prev_grapheme_boundary(text, range.anchor),
                range.head,
            )
        } else {
            range
        }
    });
    doc.set_selection(view.id, selection);

    doc_mut!(cx.editor).mode = Mode::Select;
}

fn exit_select_mode(cx: &mut Context) {
    let doc = doc_mut!(cx.editor);
    if doc.mode == Mode::Select {
        doc.mode = Mode::Normal;
    }
}

fn goto_pos(editor: &mut Editor, pos: usize) {
    push_jump(editor);

    let (view, doc) = current!(editor);

    doc.set_selection(view.id, Selection::point(pos));
    align_view(doc, view, Align::Center);
}

fn goto_first_diag(cx: &mut Context) {
    let doc = doc!(cx.editor);
    let pos = match doc.diagnostics().first() {
        Some(diag) => diag.range.start,
        None => return,
    };
    goto_pos(cx.editor, pos);
}

fn goto_last_diag(cx: &mut Context) {
    let doc = doc!(cx.editor);
    let pos = match doc.diagnostics().last() {
        Some(diag) => diag.range.start,
        None => return,
    };
    goto_pos(cx.editor, pos);
}

fn goto_next_diag(cx: &mut Context) {
    let editor = &mut cx.editor;
    let (view, doc) = current!(editor);

    let cursor_pos = doc
        .selection(view.id)
        .primary()
        .cursor(doc.text().slice(..));

    let diag = doc
        .diagnostics()
        .iter()
        .find(|diag| diag.range.start > cursor_pos)
        .or_else(|| doc.diagnostics().first());

    let pos = match diag {
        Some(diag) => diag.range.start,
        None => return,
    };

    goto_pos(editor, pos);
}

fn goto_prev_diag(cx: &mut Context) {
    let editor = &mut cx.editor;
    let (view, doc) = current!(editor);

    let cursor_pos = doc
        .selection(view.id)
        .primary()
        .cursor(doc.text().slice(..));

    let diag = doc
        .diagnostics()
        .iter()
        .rev()
        .find(|diag| diag.range.start < cursor_pos)
        .or_else(|| doc.diagnostics().last());

    let pos = match diag {
        Some(diag) => diag.range.start,
        None => return,
    };

    goto_pos(editor, pos);
}

pub mod insert {
    use super::*;
    pub type Hook = fn(&Rope, &Selection, char) -> Option<Transaction>;
    pub type PostHook = fn(&mut Context, char);

    // It trigger completion when idle timer reaches deadline
    // Only trigger completion if the word under cursor is longer than n characters
    pub fn idle_completion(cx: &mut Context) {
        let config = cx.editor.config();
        let (view, doc) = current!(cx.editor);
        let text = doc.text().slice(..);
        let cursor = doc.selection(view.id).primary().cursor(text);

        use helix_core::chars::char_is_word;
        let mut iter = text.chars_at(cursor);
        iter.reverse();
        for _ in 0..config.completion_trigger_len {
            match iter.next() {
                Some(c) if char_is_word(c) => {}
                _ => return,
            }
        }
        super::completion(cx);
    }

    fn language_server_completion(cx: &mut Context, ch: char) {
        use helix_lsp::lsp;
        // if ch matches completion char, trigger completion
        let doc = doc_mut!(cx.editor);
        let language_server = match doc.language_server() {
            Some(language_server) => language_server,
            None => return,
        };

        let capabilities = language_server.capabilities();

        if let Some(lsp::CompletionOptions {
            trigger_characters: Some(triggers),
            ..
        }) = &capabilities.completion_provider
        {
            // TODO: what if trigger is multiple chars long
            if triggers.iter().any(|trigger| trigger.contains(ch)) {
                cx.editor.clear_idle_timer();
                super::completion(cx);
            }
        }
    }

    fn signature_help(cx: &mut Context, ch: char) {
        use helix_lsp::lsp;
        // if ch matches signature_help char, trigger
        let doc = doc_mut!(cx.editor);
        let language_server = match doc.language_server() {
            Some(language_server) => language_server,
            None => return,
        };

        let capabilities = language_server.capabilities();

        if let lsp::ServerCapabilities {
            signature_help_provider:
                Some(lsp::SignatureHelpOptions {
                    trigger_characters: Some(triggers),
                    // TODO: retrigger_characters
                    ..
                }),
            ..
        } = capabilities
        {
            // TODO: what if trigger is multiple chars long
            let is_trigger = triggers.iter().any(|trigger| trigger.contains(ch));

            if is_trigger {
                super::signature_help(cx);
            }
        }

        // SignatureHelp {
        // signatures: [
        //  SignatureInformation {
        //      label: "fn open(&mut self, path: PathBuf, action: Action) -> Result<DocumentId, Error>",
        //      documentation: None,
        //      parameters: Some(
        //          [ParameterInformation { label: Simple("path: PathBuf"), documentation: None },
        //          ParameterInformation { label: Simple("action: Action"), documentation: None }]
        //      ),
        //      active_parameter: Some(0)
        //  }
        // ],
        // active_signature: None, active_parameter: Some(0)
        // }
    }

    // The default insert hook: simply insert the character
    #[allow(clippy::unnecessary_wraps)] // need to use Option<> because of the Hook signature
    fn insert(doc: &Rope, selection: &Selection, ch: char) -> Option<Transaction> {
        let cursors = selection.clone().cursors(doc.slice(..));
        let mut t = Tendril::new();
        t.push(ch);
        let transaction = Transaction::insert(doc, &cursors, t);
        Some(transaction)
    }

    use helix_core::auto_pairs;

    pub fn insert_char(cx: &mut Context, c: char) {
        let (view, doc) = current_ref!(cx.editor);
        let text = doc.text();
        let selection = doc.selection(view.id);
        let auto_pairs = doc.auto_pairs(cx.editor);

        let transaction = auto_pairs
            .as_ref()
            .and_then(|ap| auto_pairs::hook(text, selection, c, ap))
            .or_else(|| insert(text, selection, c));

        let (view, doc) = current!(cx.editor);
        if let Some(t) = transaction {
            doc.apply(&t, view.id);
        }

        // TODO: need a post insert hook too for certain triggers (autocomplete, signature help, etc)
        // this could also generically look at Transaction, but it's a bit annoying to look at
        // Operation instead of Change.
        for hook in &[language_server_completion, signature_help] {
            // for hook in &[signature_help] {
            hook(cx, c);
        }
    }

    pub fn insert_tab(cx: &mut Context) {
        let (view, doc) = current!(cx.editor);
        // TODO: round out to nearest indentation level (for example a line with 3 spaces should
        // indent by one to reach 4 spaces).

        let indent = Tendril::from(doc.indent_unit());
        let transaction = Transaction::insert(
            doc.text(),
            &doc.selection(view.id).clone().cursors(doc.text().slice(..)),
            indent,
        );
        doc.apply(&transaction, view.id);
    }

    pub fn insert_newline(cx: &mut Context) {
        let (view, doc) = current_ref!(cx.editor);
        let text = doc.text().slice(..);

        let contents = doc.text();
        let selection = doc.selection(view.id).clone().cursors(text);
        let mut ranges = SmallVec::with_capacity(selection.len());

        // TODO: this is annoying, but we need to do it to properly calculate pos after edits
        let mut offs = 0;

        let mut transaction = Transaction::change_by_selection(contents, &selection, |range| {
            let pos = range.head;

            let prev = if pos == 0 {
                ' '
            } else {
                contents.char(pos - 1)
            };
            let curr = contents.get_char(pos).unwrap_or(' ');

            let current_line = text.char_to_line(pos);
            let indent = indent::indent_for_newline(
                doc.language_config(),
                doc.syntax(),
                &doc.indent_style,
                doc.tab_width(),
                text,
                current_line,
                pos,
                current_line,
            );
            let mut text = String::new();
            // If we are between pairs (such as brackets), we want to
            // insert an additional line which is indented one level
            // more and place the cursor there
            let on_auto_pair = doc
                .auto_pairs(cx.editor)
                .and_then(|pairs| pairs.get(prev))
                .and_then(|pair| if pair.close == curr { Some(pair) } else { None })
                .is_some();

            let new_head_pos = if on_auto_pair {
                let inner_indent = indent.clone() + doc.indent_style.as_str();
                text.reserve_exact(2 + indent.len() + inner_indent.len());
                text.push_str(doc.line_ending.as_str());
                text.push_str(&inner_indent);
                let new_head_pos = pos + offs + text.chars().count();
                text.push_str(doc.line_ending.as_str());
                text.push_str(&indent);
                new_head_pos
            } else {
                text.reserve_exact(1 + indent.len());
                text.push_str(doc.line_ending.as_str());
                text.push_str(&indent);
                pos + offs + text.chars().count()
            };

            // TODO: range replace or extend
            // range.replace(|range| range.is_empty(), head); -> fn extend if cond true, new head pos
            // can be used with cx.mode to do replace or extend on most changes
            ranges.push(Range::new(new_head_pos, new_head_pos));
            offs += text.chars().count();

            (pos, pos, Some(text.into()))
        });

        transaction = transaction.with_selection(Selection::new(ranges, selection.primary_index()));

        let (view, doc) = current!(cx.editor);
        doc.apply(&transaction, view.id);
    }

    pub fn delete_char_backward(cx: &mut Context) {
        let count = cx.count();
        let (view, doc) = current!(cx.editor);
        let text = doc.text().slice(..);
        let indent_unit = doc.indent_unit();
        let tab_size = doc.tab_width();

        let transaction =
            Transaction::change_by_selection(doc.text(), doc.selection(view.id), |range| {
                let pos = range.cursor(text);
                let line_start_pos = text.line_to_char(range.cursor_line(text));
                // considier to delete by indent level if all characters before `pos` are indent units.
                let fragment = Cow::from(text.slice(line_start_pos..pos));
                if !fragment.is_empty() && fragment.chars().all(|ch| ch.is_whitespace()) {
                    if text.get_char(pos.saturating_sub(1)) == Some('\t') {
                        // fast path, delete one char
                        (
                            graphemes::nth_prev_grapheme_boundary(text, pos, 1),
                            pos,
                            None,
                        )
                    } else {
                        let unit_len = indent_unit.chars().count();
                        // NOTE: indent_unit always contains 'only spaces' or 'only tab' according to `IndentStyle` definition.
                        let unit_size = if indent_unit.starts_with('\t') {
                            tab_size * unit_len
                        } else {
                            unit_len
                        };
                        let width: usize = fragment
                            .chars()
                            .map(|ch| {
                                if ch == '\t' {
                                    tab_size
                                } else {
                                    // it can be none if it still meet control characters other than '\t'
                                    // here just set the width to 1 (or some value better?).
                                    ch.width().unwrap_or(1)
                                }
                            })
                            .sum();
                        let mut drop = width % unit_size; // round down to nearest unit
                        if drop == 0 {
                            drop = unit_size
                        }; // if it's already at a unit, consume a whole unit
                        let mut chars = fragment.chars().rev();
                        let mut start = pos;
                        for _ in 0..drop {
                            // delete up to `drop` spaces
                            match chars.next() {
                                Some(' ') => start -= 1,
                                _ => break,
                            }
                        }
                        (start, pos, None) // delete!
                    }
                } else {
                    // delete char
                    (
                        graphemes::nth_prev_grapheme_boundary(text, pos, count),
                        pos,
                        None,
                    )
                }
            });
        doc.apply(&transaction, view.id);
    }

    pub fn delete_char_forward(cx: &mut Context) {
        let count = cx.count();
        let (view, doc) = current!(cx.editor);
        let text = doc.text().slice(..);
        let transaction =
            Transaction::change_by_selection(doc.text(), doc.selection(view.id), |range| {
                let pos = range.cursor(text);
                (
                    pos,
                    graphemes::nth_next_grapheme_boundary(text, pos, count),
                    None,
                )
            });
        doc.apply(&transaction, view.id);
    }

    pub fn delete_word_backward(cx: &mut Context) {
        let count = cx.count();
        let (view, doc) = current!(cx.editor);
        let text = doc.text().slice(..);

        let selection = doc
            .selection(view.id)
            .clone()
            .transform(|range| movement::move_prev_word_start(text, range, count));
        delete_selection_insert_mode(doc, view, &selection);
    }

    pub fn delete_word_forward(cx: &mut Context) {
        let count = cx.count();
        let (view, doc) = current!(cx.editor);
        let text = doc.text().slice(..);

        let selection = doc
            .selection(view.id)
            .clone()
            .transform(|range| movement::move_next_word_start(text, range, count));
        delete_selection_insert_mode(doc, view, &selection);
    }
}

// Undo / Redo

fn undo(cx: &mut Context) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    for _ in 0..count {
        if !doc.undo(view.id) {
            cx.editor.set_status("Already at oldest change");
            break;
        }
    }
}

fn redo(cx: &mut Context) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    for _ in 0..count {
        if !doc.redo(view.id) {
            cx.editor.set_status("Already at newest change");
            break;
        }
    }
}

fn earlier(cx: &mut Context) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    for _ in 0..count {
        // rather than doing in batch we do this so get error halfway
        if !doc.earlier(view.id, UndoKind::Steps(1)) {
            cx.editor.set_status("Already at oldest change");
            break;
        }
    }
}

fn later(cx: &mut Context) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    for _ in 0..count {
        // rather than doing in batch we do this so get error halfway
        if !doc.later(view.id, UndoKind::Steps(1)) {
            cx.editor.set_status("Already at newest change");
            break;
        }
    }
}

// Yank / Paste

fn yank(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let values: Vec<String> = doc
        .selection(view.id)
        .fragments(text)
        .map(Cow::into_owned)
        .collect();

    let msg = format!(
        "yanked {} selection(s) to register {}",
        values.len(),
        cx.register.unwrap_or('"')
    );

    cx.editor
        .registers
        .write(cx.register.unwrap_or('"'), values);

    cx.editor.set_status(msg);
    exit_select_mode(cx);
}

fn yank_joined_to_clipboard_impl(
    editor: &mut Editor,
    separator: &str,
    clipboard_type: ClipboardType,
) -> anyhow::Result<()> {
    let (view, doc) = current!(editor);
    let text = doc.text().slice(..);

    let values: Vec<String> = doc
        .selection(view.id)
        .fragments(text)
        .map(Cow::into_owned)
        .collect();

    let msg = format!(
        "joined and yanked {} selection(s) to system clipboard",
        values.len(),
    );

    let joined = values.join(separator);

    editor
        .clipboard_provider
        .set_contents(joined, clipboard_type)
        .context("Couldn't set system clipboard content")?;

    editor.set_status(msg);

    Ok(())
}

fn yank_joined_to_clipboard(cx: &mut Context) {
    let line_ending = doc!(cx.editor).line_ending;
    let _ =
        yank_joined_to_clipboard_impl(cx.editor, line_ending.as_str(), ClipboardType::Clipboard);
    exit_select_mode(cx);
}

fn yank_main_selection_to_clipboard_impl(
    editor: &mut Editor,
    clipboard_type: ClipboardType,
) -> anyhow::Result<()> {
    let (view, doc) = current!(editor);
    let text = doc.text().slice(..);

    let value = doc.selection(view.id).primary().fragment(text);

    if let Err(e) = editor
        .clipboard_provider
        .set_contents(value.into_owned(), clipboard_type)
    {
        bail!("Couldn't set system clipboard content: {}", e);
    }

    editor.set_status("yanked main selection to system clipboard");
    Ok(())
}

fn yank_main_selection_to_clipboard(cx: &mut Context) {
    let _ = yank_main_selection_to_clipboard_impl(cx.editor, ClipboardType::Clipboard);
}

fn yank_joined_to_primary_clipboard(cx: &mut Context) {
    let line_ending = doc!(cx.editor).line_ending;
    let _ =
        yank_joined_to_clipboard_impl(cx.editor, line_ending.as_str(), ClipboardType::Selection);
}

fn yank_main_selection_to_primary_clipboard(cx: &mut Context) {
    let _ = yank_main_selection_to_clipboard_impl(cx.editor, ClipboardType::Selection);
    exit_select_mode(cx);
}

#[derive(Copy, Clone)]
enum Paste {
    Before,
    After,
    Cursor,
}

fn paste_impl(
    values: &[String],
    doc: &mut Document,
    view: &View,
    action: Paste,
    count: usize,
) -> Option<Transaction> {
    let repeat = std::iter::repeat(
        values
            .last()
            .map(|value| Tendril::from(value.repeat(count)))
            .unwrap(),
    );

    // if any of values ends with a line ending, it's linewise paste
    let linewise = values
        .iter()
        .any(|value| get_line_ending_of_str(value).is_some());

    // Only compiled once.
    #[allow(clippy::trivial_regex)]
    static REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"\r\n|\r|\n").unwrap());
    let mut values = values
        .iter()
        .map(|value| REGEX.replace_all(value, doc.line_ending.as_str()))
        .map(|value| Tendril::from(value.as_ref().repeat(count)))
        .chain(repeat);

    let text = doc.text();
    let selection = doc.selection(view.id);

    let transaction = Transaction::change_by_selection(text, selection, |range| {
        let pos = match (action, linewise) {
            // paste linewise before
            (Paste::Before, true) => text.line_to_char(text.char_to_line(range.from())),
            // paste linewise after
            (Paste::After, true) => {
                let line = range.line_range(text.slice(..)).1;
                text.line_to_char((line + 1).min(text.len_lines()))
            }
            // paste insert
            (Paste::Before, false) => range.from(),
            // paste append
            (Paste::After, false) => range.to(),
            // paste at cursor
            (Paste::Cursor, _) => range.cursor(text.slice(..)),
        };
        (pos, pos, values.next())
    });

    Some(transaction)
}

fn paste_clipboard_impl(
    editor: &mut Editor,
    action: Paste,
    clipboard_type: ClipboardType,
    count: usize,
) -> anyhow::Result<()> {
    let (view, doc) = current!(editor);

    match editor
        .clipboard_provider
        .get_contents(clipboard_type)
        .map(|contents| paste_impl(&[contents], doc, view, action, count))
    {
        Ok(Some(transaction)) => {
            doc.apply(&transaction, view.id);
            doc.append_changes_to_history(view.id);
            Ok(())
        }
        Ok(None) => Ok(()),
        Err(e) => Err(e.context("Couldn't get system clipboard contents")),
    }
}

fn paste_clipboard_after(cx: &mut Context) {
    let _ = paste_clipboard_impl(
        cx.editor,
        Paste::After,
        ClipboardType::Clipboard,
        cx.count(),
    );
}

fn paste_clipboard_before(cx: &mut Context) {
    let _ = paste_clipboard_impl(
        cx.editor,
        Paste::Before,
        ClipboardType::Clipboard,
        cx.count(),
    );
}

fn paste_primary_clipboard_after(cx: &mut Context) {
    let _ = paste_clipboard_impl(
        cx.editor,
        Paste::After,
        ClipboardType::Selection,
        cx.count(),
    );
}

fn paste_primary_clipboard_before(cx: &mut Context) {
    let _ = paste_clipboard_impl(
        cx.editor,
        Paste::Before,
        ClipboardType::Selection,
        cx.count(),
    );
}

fn replace_with_yanked(cx: &mut Context) {
    let count = cx.count();
    let reg_name = cx.register.unwrap_or('"');
    let (view, doc) = current!(cx.editor);
    let registers = &mut cx.editor.registers;

    if let Some(values) = registers.read(reg_name) {
        if !values.is_empty() {
            let repeat = std::iter::repeat(
                values
                    .last()
                    .map(|value| Tendril::from(&value.repeat(count)))
                    .unwrap(),
            );
            let mut values = values
                .iter()
                .map(|value| Tendril::from(&value.repeat(count)))
                .chain(repeat);
            let selection = doc.selection(view.id);
            let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
                if !range.is_empty() {
                    (range.from(), range.to(), Some(values.next().unwrap()))
                } else {
                    (range.from(), range.to(), None)
                }
            });

            doc.apply(&transaction, view.id);
        }
    }
}

fn replace_selections_with_clipboard_impl(
    editor: &mut Editor,
    clipboard_type: ClipboardType,
    count: usize,
) -> anyhow::Result<()> {
    let (view, doc) = current!(editor);

    match editor.clipboard_provider.get_contents(clipboard_type) {
        Ok(contents) => {
            let selection = doc.selection(view.id);
            let transaction = Transaction::change_by_selection(doc.text(), selection, |range| {
                (
                    range.from(),
                    range.to(),
                    Some(contents.repeat(count).as_str().into()),
                )
            });

            doc.apply(&transaction, view.id);
            doc.append_changes_to_history(view.id);
            Ok(())
        }
        Err(e) => Err(e.context("Couldn't get system clipboard contents")),
    }
}

fn replace_selections_with_clipboard(cx: &mut Context) {
    let _ = replace_selections_with_clipboard_impl(cx.editor, ClipboardType::Clipboard, cx.count());
}

fn replace_selections_with_primary_clipboard(cx: &mut Context) {
    let _ = replace_selections_with_clipboard_impl(cx.editor, ClipboardType::Selection, cx.count());
}

fn paste(cx: &mut Context, pos: Paste) {
    let count = cx.count();
    let reg_name = cx.register.unwrap_or('"');
    let (view, doc) = current!(cx.editor);
    let registers = &mut cx.editor.registers;

    if let Some(transaction) = registers
        .read(reg_name)
        .and_then(|values| paste_impl(values, doc, view, pos, count))
    {
        doc.apply(&transaction, view.id);
    }
}

fn paste_after(cx: &mut Context) {
    paste(cx, Paste::After)
}

fn paste_before(cx: &mut Context) {
    paste(cx, Paste::Before)
}

fn get_lines(doc: &Document, view_id: ViewId) -> Vec<usize> {
    let mut lines = Vec::new();

    // Get all line numbers
    for range in doc.selection(view_id) {
        let (start, end) = range.line_range(doc.text().slice(..));

        for line in start..=end {
            lines.push(line)
        }
    }
    lines.sort_unstable(); // sorting by usize so _unstable is preferred
    lines.dedup();
    lines
}

fn indent(cx: &mut Context) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let lines = get_lines(doc, view.id);

    // Indent by one level
    let indent = Tendril::from(doc.indent_unit().repeat(count));

    let transaction = Transaction::change(
        doc.text(),
        lines.into_iter().filter_map(|line| {
            let is_blank = doc.text().line(line).chunks().all(|s| s.trim().is_empty());
            if is_blank {
                return None;
            }
            let pos = doc.text().line_to_char(line);
            Some((pos, pos, Some(indent.clone())))
        }),
    );
    doc.apply(&transaction, view.id);
}

fn unindent(cx: &mut Context) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let lines = get_lines(doc, view.id);
    let mut changes = Vec::with_capacity(lines.len());
    let tab_width = doc.tab_width();
    let indent_width = count * tab_width;

    for line_idx in lines {
        let line = doc.text().line(line_idx);
        let mut width = 0;
        let mut pos = 0;

        for ch in line.chars() {
            match ch {
                ' ' => width += 1,
                '\t' => width = (width / tab_width + 1) * tab_width,
                _ => break,
            }

            pos += 1;

            if width >= indent_width {
                break;
            }
        }

        // now delete from start to first non-blank
        if pos > 0 {
            let start = doc.text().line_to_char(line_idx);
            changes.push((start, start + pos, None))
        }
    }

    let transaction = Transaction::change(doc.text(), changes.into_iter());

    doc.apply(&transaction, view.id);
}

fn format_selections(cx: &mut Context) {
    use helix_lsp::{lsp, util::range_to_lsp_range};

    let (view, doc) = current!(cx.editor);

    // via lsp if available
    // else via tree-sitter indentation calculations

    let language_server = match doc.language_server() {
        Some(language_server) => language_server,
        None => return,
    };

    let ranges: Vec<lsp::Range> = doc
        .selection(view.id)
        .iter()
        .map(|range| range_to_lsp_range(doc.text(), *range, language_server.offset_encoding()))
        .collect();

    // TODO: all of the TODO's and commented code inside the loop,
    // to make this actually work.
    for _range in ranges {
        let _language_server = match doc.language_server() {
            Some(language_server) => language_server,
            None => return,
        };
        // TODO: handle fails
        // TODO: concurrent map

        // TODO: need to block to get the formatting

        // let edits = block_on(language_server.text_document_range_formatting(
        //     doc.identifier(),
        //     range,
        //     lsp::FormattingOptions::default(),
        // ))
        // .unwrap_or_default();

        // let transaction = helix_lsp::util::generate_transaction_from_edits(
        //     doc.text(),
        //     edits,
        //     language_server.offset_encoding(),
        // );

        // doc.apply(&transaction, view.id);
    }
}

fn join_selections(cx: &mut Context) {
    use movement::skip_while;
    let (view, doc) = current!(cx.editor);
    let text = doc.text();
    let slice = doc.text().slice(..);

    let mut changes = Vec::new();
    let fragment = Tendril::from(" ");

    for selection in doc.selection(view.id) {
        let (start, mut end) = selection.line_range(slice);
        if start == end {
            end = (end + 1).min(text.len_lines() - 1);
        }
        let lines = start..end;

        changes.reserve(lines.len());

        for line in lines {
            let start = line_end_char_index(&slice, line);
            let mut end = text.line_to_char(line + 1);
            end = skip_while(slice, end, |ch| matches!(ch, ' ' | '\t')).unwrap_or(end);

            // need to skip from start, not end
            let change = (start, end, Some(fragment.clone()));
            changes.push(change);
        }
    }

    changes.sort_unstable_by_key(|(from, _to, _text)| *from);
    changes.dedup();

    // TODO: joining multiple empty lines should be replaced by a single space.
    // need to merge change ranges that touch

    let transaction = Transaction::change(doc.text(), changes.into_iter());
    // TODO: select inserted spaces
    // .with_selection(selection);

    doc.apply(&transaction, view.id);
}

fn keep_or_remove_selections_impl(cx: &mut Context, remove: bool) {
    // keep or remove selections matching regex
    let reg = cx.register.unwrap_or('/');
    ui::regex_prompt(
        cx,
        if remove { "remove:" } else { "keep:" }.into(),
        Some(reg),
        ui::completers::none,
        move |view, doc, regex, event| {
            if event != PromptEvent::Update {
                return;
            }
            let text = doc.text().slice(..);

            if let Some(selection) =
                selection::keep_or_remove_matches(text, doc.selection(view.id), &regex, remove)
            {
                doc.set_selection(view.id, selection);
            }
        },
    )
}

fn keep_selections(cx: &mut Context) {
    keep_or_remove_selections_impl(cx, false)
}

fn remove_selections(cx: &mut Context) {
    keep_or_remove_selections_impl(cx, true)
}

fn keep_primary_selection(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    // TODO: handle count

    let range = doc.selection(view.id).primary();
    doc.set_selection(view.id, Selection::single(range.anchor, range.head));
}

fn remove_primary_selection(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    // TODO: handle count

    let selection = doc.selection(view.id);
    if selection.len() == 1 {
        cx.editor.set_error("no selections remaining");
        return;
    }
    let index = selection.primary_index();
    let selection = selection.clone().remove(index);

    doc.set_selection(view.id, selection);
}

pub fn completion(cx: &mut Context) {
    use helix_lsp::{lsp, util::pos_to_lsp_pos};

    let (view, doc) = current!(cx.editor);

    let language_server = match doc.language_server() {
        Some(language_server) => language_server,
        None => return,
    };

    let offset_encoding = language_server.offset_encoding();
    let text = doc.text().slice(..);
    let cursor = doc.selection(view.id).primary().cursor(text);

    let pos = pos_to_lsp_pos(doc.text(), cursor, offset_encoding);

    let future = language_server.completion(doc.identifier(), pos, None);

    let trigger_offset = cursor;

    // TODO: trigger_offset should be the cursor offset but we also need a starting offset from where we want to apply
    // completion filtering. For example logger.te| should filter the initial suggestion list with "te".

    use helix_core::chars;
    let mut iter = text.chars_at(cursor);
    iter.reverse();
    let offset = iter.take_while(|ch| chars::char_is_word(*ch)).count();
    let start_offset = cursor.saturating_sub(offset);
    let prefix = text.slice(start_offset..cursor).to_string();

    cx.callback(
        future,
        move |editor, compositor, response: Option<lsp::CompletionResponse>| {
            let doc = doc!(editor);
            if doc.mode() != Mode::Insert {
                // we're not in insert mode anymore
                return;
            }

            let mut items = match response {
                Some(lsp::CompletionResponse::Array(items)) => items,
                // TODO: do something with is_incomplete
                Some(lsp::CompletionResponse::List(lsp::CompletionList {
                    is_incomplete: _is_incomplete,
                    items,
                })) => items,
                None => Vec::new(),
            };

            if !prefix.is_empty() {
                items = items
                    .into_iter()
                    .filter(|item| {
                        item.filter_text
                            .as_ref()
                            .unwrap_or(&item.label)
                            .starts_with(&prefix)
                    })
                    .collect();
            }

            if items.is_empty() {
                // editor.set_error("No completion available");
                return;
            }
            let size = compositor.size();
            let ui = compositor.find::<ui::EditorView>().unwrap();
            ui.set_completion(
                editor,
                items,
                offset_encoding,
                start_offset,
                trigger_offset,
                size,
            );
        },
    );
}

// comments
fn toggle_comments(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let token = doc
        .language_config()
        .and_then(|lc| lc.comment_token.as_ref())
        .map(|tc| tc.as_ref());
    let transaction = comment::toggle_line_comments(doc.text(), doc.selection(view.id), token);

    doc.apply(&transaction, view.id);
    exit_select_mode(cx);
}

fn rotate_selections(cx: &mut Context, direction: Direction) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let mut selection = doc.selection(view.id).clone();
    let index = selection.primary_index();
    let len = selection.len();
    selection.set_primary_index(match direction {
        Direction::Forward => (index + count) % len,
        Direction::Backward => (index + (len.saturating_sub(count) % len)) % len,
    });
    doc.set_selection(view.id, selection);
}
fn rotate_selections_forward(cx: &mut Context) {
    rotate_selections(cx, Direction::Forward)
}
fn rotate_selections_backward(cx: &mut Context) {
    rotate_selections(cx, Direction::Backward)
}

fn rotate_selection_contents(cx: &mut Context, direction: Direction) {
    let count = cx.count;
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);

    let selection = doc.selection(view.id);
    let mut fragments: Vec<_> = selection
        .fragments(text)
        .map(|fragment| Tendril::from(fragment.as_ref()))
        .collect();

    let group = count
        .map(|count| count.get())
        .unwrap_or(fragments.len()) // default to rotating everything as one group
        .min(fragments.len());

    for chunk in fragments.chunks_mut(group) {
        // TODO: also modify main index
        match direction {
            Direction::Forward => chunk.rotate_right(1),
            Direction::Backward => chunk.rotate_left(1),
        };
    }

    let transaction = Transaction::change(
        doc.text(),
        selection
            .ranges()
            .iter()
            .zip(fragments)
            .map(|(range, fragment)| (range.from(), range.to(), Some(fragment))),
    );

    doc.apply(&transaction, view.id);
}

fn rotate_selection_contents_forward(cx: &mut Context) {
    rotate_selection_contents(cx, Direction::Forward)
}
fn rotate_selection_contents_backward(cx: &mut Context) {
    rotate_selection_contents(cx, Direction::Backward)
}

// tree sitter node selection

fn expand_selection(cx: &mut Context) {
    let motion = |editor: &mut Editor| {
        let (view, doc) = current!(editor);

        if let Some(syntax) = doc.syntax() {
            let text = doc.text().slice(..);

            let current_selection = doc.selection(view.id);

            // save current selection so it can be restored using shrink_selection
            view.object_selections.push(current_selection.clone());

            let selection = object::expand_selection(syntax, text, current_selection.clone());
            doc.set_selection(view.id, selection);
        }
    };
    motion(cx.editor);
    cx.editor.last_motion = Some(Motion(Box::new(motion)));
}

fn shrink_selection(cx: &mut Context) {
    let motion = |editor: &mut Editor| {
        let (view, doc) = current!(editor);
        let current_selection = doc.selection(view.id);
        // try to restore previous selection
        if let Some(prev_selection) = view.object_selections.pop() {
            if current_selection.contains(&prev_selection) {
                // allow shrinking the selection only if current selection contains the previous object selection
                doc.set_selection(view.id, prev_selection);
                return;
            } else {
                // clear existing selection as they can't be shrinked to anyway
                view.object_selections.clear();
            }
        }
        // if not previous selection, shrink to first child
        if let Some(syntax) = doc.syntax() {
            let text = doc.text().slice(..);
            let selection = object::shrink_selection(syntax, text, current_selection.clone());
            doc.set_selection(view.id, selection);
        }
    };
    motion(cx.editor);
    cx.editor.last_motion = Some(Motion(Box::new(motion)));
}

fn select_sibling_impl<F>(cx: &mut Context, sibling_fn: &'static F)
where
    F: Fn(Node) -> Option<Node>,
{
    let motion = |editor: &mut Editor| {
        let (view, doc) = current!(editor);

        if let Some(syntax) = doc.syntax() {
            let text = doc.text().slice(..);
            let current_selection = doc.selection(view.id);
            let selection =
                object::select_sibling(syntax, text, current_selection.clone(), sibling_fn);
            doc.set_selection(view.id, selection);
        }
    };
    motion(cx.editor);
    cx.editor.last_motion = Some(Motion(Box::new(motion)));
}

fn select_next_sibling(cx: &mut Context) {
    select_sibling_impl(cx, &|node| Node::next_sibling(&node))
}

fn select_prev_sibling(cx: &mut Context) {
    select_sibling_impl(cx, &|node| Node::prev_sibling(&node))
}

fn match_brackets(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);

    if let Some(syntax) = doc.syntax() {
        let text = doc.text().slice(..);
        let selection = doc.selection(view.id).clone().transform(|range| {
            if let Some(pos) =
                match_brackets::find_matching_bracket_fuzzy(syntax, doc.text(), range.cursor(text))
            {
                range.put_cursor(text, pos, doc.mode == Mode::Select)
            } else {
                range
            }
        });
        doc.set_selection(view.id, selection);
    }
}

//

fn jump_forward(cx: &mut Context) {
    let count = cx.count();
    let view = view_mut!(cx.editor);

    if let Some((id, selection)) = view.jumps.forward(count) {
        view.doc = *id;
        let selection = selection.clone();
        let (view, doc) = current!(cx.editor); // refetch doc
        doc.set_selection(view.id, selection);

        align_view(doc, view, Align::Center);
    };
}

fn jump_backward(cx: &mut Context) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);

    if let Some((id, selection)) = view.jumps.backward(view.id, doc, count) {
        // manually set the alternate_file as we cannot use the Editor::switch function here.
        if view.doc != *id {
            view.last_accessed_doc = Some(view.doc)
        }
        view.doc = *id;
        let selection = selection.clone();
        let (view, doc) = current!(cx.editor); // refetch doc
        doc.set_selection(view.id, selection);

        align_view(doc, view, Align::Center);
    };
}

fn save_selection(cx: &mut Context) {
    push_jump(cx.editor);
    cx.editor.set_status("Selection saved to jumplist");
}

fn rotate_view(cx: &mut Context) {
    cx.editor.focus_next()
}

fn jump_view_right(cx: &mut Context) {
    cx.editor.focus_right()
}

fn jump_view_left(cx: &mut Context) {
    cx.editor.focus_left()
}

fn jump_view_up(cx: &mut Context) {
    cx.editor.focus_up()
}

fn jump_view_down(cx: &mut Context) {
    cx.editor.focus_down()
}

// split helper, clear it later
fn split(cx: &mut Context, action: Action) {
    let (view, doc) = current!(cx.editor);
    let id = doc.id();
    let selection = doc.selection(view.id).clone();
    let offset = view.offset;

    cx.editor.switch(id, action);

    // match the selection in the previous view
    let (view, doc) = current!(cx.editor);
    view.offset = offset;
    doc.set_selection(view.id, selection);
}

fn hsplit(cx: &mut Context) {
    split(cx, Action::HorizontalSplit);
}

fn hsplit_new(cx: &mut Context) {
    cx.editor.new_file(Action::HorizontalSplit);
}

fn vsplit(cx: &mut Context) {
    split(cx, Action::VerticalSplit);
}

fn vsplit_new(cx: &mut Context) {
    cx.editor.new_file(Action::VerticalSplit);
}

fn wclose(cx: &mut Context) {
    if cx.editor.tree.views().count() == 1 {
        if let Err(err) = typed::buffers_remaining_impl(cx.editor) {
            cx.editor.set_error(err.to_string());
            return;
        }
    }
    let view_id = view!(cx.editor).id;
    // close current split
    cx.editor.close(view_id);
}

fn wonly(cx: &mut Context) {
    let views = cx
        .editor
        .tree
        .views()
        .map(|(v, focus)| (v.id, focus))
        .collect::<Vec<_>>();
    for (view_id, focus) in views {
        if !focus {
            cx.editor.close(view_id);
        }
    }
}

fn select_register(cx: &mut Context) {
    cx.editor.autoinfo = Some(Info::from_registers(&cx.editor.registers));
    cx.on_next_key(move |cx, event| {
        if let Some(ch) = event.char() {
            cx.editor.autoinfo = None;
            cx.editor.selected_register = Some(ch);
        }
    })
}

fn insert_register(cx: &mut Context) {
    cx.editor.autoinfo = Some(Info::from_registers(&cx.editor.registers));
    cx.on_next_key(move |cx, event| {
        if let Some(ch) = event.char() {
            cx.editor.autoinfo = None;
            cx.register = Some(ch);
            paste(cx, Paste::Cursor);
        }
    })
}

fn align_view_top(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    align_view(doc, view, Align::Top);
}

fn align_view_center(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    align_view(doc, view, Align::Center);
}

fn align_view_bottom(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    align_view(doc, view, Align::Bottom);
}

fn align_view_middle(cx: &mut Context) {
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);
    let pos = doc.selection(view.id).primary().cursor(text);
    let pos = coords_at_pos(text, pos);

    view.offset.col = pos
        .col
        .saturating_sub((view.inner_area().width as usize) / 2);
}

fn scroll_up(cx: &mut Context) {
    scroll(cx, cx.count(), Direction::Backward);
}

fn scroll_down(cx: &mut Context) {
    scroll(cx, cx.count(), Direction::Forward);
}

fn goto_ts_object_impl(cx: &mut Context, object: &str, direction: Direction) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let text = doc.text().slice(..);
    let range = doc.selection(view.id).primary();

    let new_range = match doc.language_config().zip(doc.syntax()) {
        Some((lang_config, syntax)) => movement::goto_treesitter_object(
            text,
            range,
            object,
            direction,
            syntax.tree().root_node(),
            lang_config,
            count,
        ),
        None => range,
    };

    doc.set_selection(view.id, Selection::single(new_range.anchor, new_range.head));
}

fn goto_next_function(cx: &mut Context) {
    goto_ts_object_impl(cx, "function", Direction::Forward)
}

fn goto_prev_function(cx: &mut Context) {
    goto_ts_object_impl(cx, "function", Direction::Backward)
}

fn goto_next_class(cx: &mut Context) {
    goto_ts_object_impl(cx, "class", Direction::Forward)
}

fn goto_prev_class(cx: &mut Context) {
    goto_ts_object_impl(cx, "class", Direction::Backward)
}

fn goto_next_parameter(cx: &mut Context) {
    goto_ts_object_impl(cx, "parameter", Direction::Forward)
}

fn goto_prev_parameter(cx: &mut Context) {
    goto_ts_object_impl(cx, "parameter", Direction::Backward)
}

fn goto_next_comment(cx: &mut Context) {
    goto_ts_object_impl(cx, "comment", Direction::Forward)
}

fn goto_prev_comment(cx: &mut Context) {
    goto_ts_object_impl(cx, "comment", Direction::Backward)
}

fn select_textobject_around(cx: &mut Context) {
    select_textobject(cx, textobject::TextObject::Around);
}

fn select_textobject_inner(cx: &mut Context) {
    select_textobject(cx, textobject::TextObject::Inside);
}

fn select_textobject(cx: &mut Context, objtype: textobject::TextObject) {
    let count = cx.count();

    cx.on_next_key(move |cx, event| {
        cx.editor.autoinfo = None;
        cx.editor.pseudo_pending = None;
        if let Some(ch) = event.char() {
            let textobject = move |editor: &mut Editor| {
                let (view, doc) = current!(editor);
                let text = doc.text().slice(..);

                let textobject_treesitter = |obj_name: &str, range: Range| -> Range {
                    let (lang_config, syntax) = match doc.language_config().zip(doc.syntax()) {
                        Some(t) => t,
                        None => return range,
                    };
                    textobject::textobject_treesitter(
                        text,
                        range,
                        objtype,
                        obj_name,
                        syntax.tree().root_node(),
                        lang_config,
                        count,
                    )
                };

                let selection = doc.selection(view.id).clone().transform(|range| {
                    match ch {
                        'w' => textobject::textobject_word(text, range, objtype, count, false),
                        'W' => textobject::textobject_word(text, range, objtype, count, true),
                        'c' => textobject_treesitter("class", range),
                        'f' => textobject_treesitter("function", range),
                        'a' => textobject_treesitter("parameter", range),
                        'o' => textobject_treesitter("comment", range),
                        'p' => textobject::textobject_paragraph(text, range, objtype, count),
                        'm' => {
                            let ch = text.char(range.cursor(text));
                            if !ch.is_ascii_alphanumeric() {
                                textobject::textobject_surround(text, range, objtype, ch, count)
                            } else {
                                range
                            }
                        }
                        // TODO: cancel new ranges if inconsistent surround matches across lines
                        ch if !ch.is_ascii_alphanumeric() => {
                            textobject::textobject_surround(text, range, objtype, ch, count)
                        }
                        _ => range,
                    }
                });
                doc.set_selection(view.id, selection);
            };
            textobject(cx.editor);
            cx.editor.last_motion = Some(Motion(Box::new(textobject)));
        }
    });

    if let Some((title, abbrev)) = match objtype {
        textobject::TextObject::Inside => Some(("Match inside", "mi")),
        textobject::TextObject::Around => Some(("Match around", "ma")),
        _ => return,
    } {
        let help_text = [
            ("w", "Word"),
            ("W", "WORD"),
            ("p", "Paragraph"),
            ("c", "Class (tree-sitter)"),
            ("f", "Function (tree-sitter)"),
            ("a", "Argument/parameter (tree-sitter)"),
            ("o", "Comment (tree-sitter)"),
            ("m", "Matching delimiter under cursor"),
            (" ", "... or any character acting as a pair"),
        ];

        cx.editor.autoinfo = Some(Info::new(
            title,
            help_text
                .into_iter()
                .map(|(col1, col2)| (col1.to_string(), col2.to_string()))
                .collect(),
        ));
        cx.editor.pseudo_pending = Some(abbrev.to_string());
    };
}

fn surround_add(cx: &mut Context) {
    cx.on_next_key(move |cx, event| {
        let ch = match event.char() {
            Some(ch) => ch,
            None => return,
        };
        let (view, doc) = current!(cx.editor);
        let selection = doc.selection(view.id);
        let (open, close) = surround::get_pair(ch);

        let mut changes = Vec::with_capacity(selection.len() * 2);
        for range in selection.iter() {
            let mut o = Tendril::new();
            o.push(open);
            let mut c = Tendril::new();
            c.push(close);
            changes.push((range.from(), range.from(), Some(o)));
            changes.push((range.to(), range.to(), Some(c)));
        }

        let transaction = Transaction::change(doc.text(), changes.into_iter());
        doc.apply(&transaction, view.id);
    })
}

fn surround_replace(cx: &mut Context) {
    let count = cx.count();
    cx.on_next_key(move |cx, event| {
        let from = match event.char() {
            Some(from) => from,
            None => return,
        };
        let (view, doc) = current!(cx.editor);
        let text = doc.text().slice(..);
        let selection = doc.selection(view.id);

        let change_pos = match surround::get_surround_pos(text, selection, from, count) {
            Ok(c) => c,
            Err(err) => {
                cx.editor.set_error(err.to_string());
                return;
            }
        };

        cx.on_next_key(move |cx, event| {
            let (view, doc) = current!(cx.editor);
            let to = match event.char() {
                Some(to) => to,
                None => return,
            };
            let (open, close) = surround::get_pair(to);
            let transaction = Transaction::change(
                doc.text(),
                change_pos.iter().enumerate().map(|(i, &pos)| {
                    let mut t = Tendril::new();
                    t.push(if i % 2 == 0 { open } else { close });
                    (pos, pos + 1, Some(t))
                }),
            );
            doc.apply(&transaction, view.id);
        });
    })
}

fn surround_delete(cx: &mut Context) {
    let count = cx.count();
    cx.on_next_key(move |cx, event| {
        let ch = match event.char() {
            Some(ch) => ch,
            None => return,
        };
        let (view, doc) = current!(cx.editor);
        let text = doc.text().slice(..);
        let selection = doc.selection(view.id);

        let change_pos = match surround::get_surround_pos(text, selection, ch, count) {
            Ok(c) => c,
            Err(err) => {
                cx.editor.set_error(err.to_string());
                return;
            }
        };

        let transaction =
            Transaction::change(doc.text(), change_pos.into_iter().map(|p| (p, p + 1, None)));
        doc.apply(&transaction, view.id);
    })
}

#[derive(Eq, PartialEq)]
enum ShellBehavior {
    Replace,
    Ignore,
    Insert,
    Append,
}

fn shell_pipe(cx: &mut Context) {
    shell_prompt(cx, "pipe:".into(), ShellBehavior::Replace);
}

fn shell_pipe_to(cx: &mut Context) {
    shell_prompt(cx, "pipe-to:".into(), ShellBehavior::Ignore);
}

fn shell_insert_output(cx: &mut Context) {
    shell_prompt(cx, "insert-output:".into(), ShellBehavior::Insert);
}

fn shell_append_output(cx: &mut Context) {
    shell_prompt(cx, "append-output:".into(), ShellBehavior::Append);
}

fn shell_keep_pipe(cx: &mut Context) {
    ui::prompt(
        cx,
        "keep-pipe:".into(),
        Some('|'),
        ui::completers::none,
        move |cx, input: &str, event: PromptEvent| {
            let shell = &cx.editor.config().shell;
            if event != PromptEvent::Validate {
                return;
            }
            if input.is_empty() {
                return;
            }
            let (view, doc) = current!(cx.editor);
            let selection = doc.selection(view.id);

            let mut ranges = SmallVec::with_capacity(selection.len());
            let old_index = selection.primary_index();
            let mut index: Option<usize> = None;
            let text = doc.text().slice(..);

            for (i, range) in selection.ranges().iter().enumerate() {
                let fragment = range.fragment(text);
                let (_output, success) = match shell_impl(shell, input, Some(fragment.as_bytes())) {
                    Ok(result) => result,
                    Err(err) => {
                        cx.editor.set_error(err.to_string());
                        return;
                    }
                };

                // if the process exits successfully, keep the selection
                if success {
                    ranges.push(*range);
                    if i >= old_index && index.is_none() {
                        index = Some(ranges.len() - 1);
                    }
                }
            }

            if ranges.is_empty() {
                cx.editor.set_error("No selections remaining");
                return;
            }

            let index = index.unwrap_or_else(|| ranges.len() - 1);
            doc.set_selection(view.id, Selection::new(ranges, index));
        },
    );
}

fn shell_impl(
    shell: &[String],
    cmd: &str,
    input: Option<&[u8]>,
) -> anyhow::Result<(Tendril, bool)> {
    use std::io::Write;
    use std::process::{Command, Stdio};
    ensure!(!shell.is_empty(), "No shell set");

    let mut process = match Command::new(&shell[0])
        .args(&shell[1..])
        .arg(cmd)
        .stdin(Stdio::piped())
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .spawn()
    {
        Ok(process) => process,
        Err(e) => {
            log::error!("Failed to start shell: {}", e);
            return Err(e.into());
        }
    };
    if let Some(input) = input {
        let mut stdin = process.stdin.take().unwrap();
        stdin.write_all(input)?;
    }
    let output = process.wait_with_output()?;

    if !output.stderr.is_empty() {
        log::error!("Shell error: {}", String::from_utf8_lossy(&output.stderr));
    }

    let str = std::str::from_utf8(&output.stdout)
        .map_err(|_| anyhow!("Process did not output valid UTF-8"))?;
    let tendril = Tendril::from(str);
    Ok((tendril, output.status.success()))
}

fn shell(cx: &mut compositor::Context, cmd: &str, behavior: &ShellBehavior) {
    let pipe = match behavior {
        ShellBehavior::Replace | ShellBehavior::Ignore => true,
        ShellBehavior::Insert | ShellBehavior::Append => false,
    };

    let config = cx.editor.config();
    let shell = &config.shell;
    let (view, doc) = current!(cx.editor);
    let selection = doc.selection(view.id);

    let mut changes = Vec::with_capacity(selection.len());
    let text = doc.text().slice(..);

    for range in selection.ranges() {
        let fragment = range.fragment(text);
        let (output, success) = match shell_impl(shell, cmd, pipe.then(|| fragment.as_bytes())) {
            Ok(result) => result,
            Err(err) => {
                cx.editor.set_error(err.to_string());
                return;
            }
        };

        if !success {
            cx.editor.set_error("Command failed");
            return;
        }

        let (from, to) = match behavior {
            ShellBehavior::Replace => (range.from(), range.to()),
            ShellBehavior::Insert => (range.from(), range.from()),
            ShellBehavior::Append => (range.to(), range.to()),
            _ => (range.from(), range.from()),
        };
        changes.push((from, to, Some(output)));
    }

    if behavior != &ShellBehavior::Ignore {
        let transaction = Transaction::change(doc.text(), changes.into_iter());
        doc.apply(&transaction, view.id);
    }

    // after replace cursor may be out of bounds, do this to
    // make sure cursor is in view and update scroll as well
    view.ensure_cursor_in_view(doc, config.scrolloff);
}

fn shell_prompt(cx: &mut Context, prompt: Cow<'static, str>, behavior: ShellBehavior) {
    ui::prompt(
        cx,
        prompt,
        Some('|'),
        ui::completers::none,
        move |cx, input: &str, event: PromptEvent| {
            if event != PromptEvent::Validate {
                return;
            }
            if input.is_empty() {
                return;
            }

            shell(cx, input, &behavior);
        },
    );
}

fn suspend(_cx: &mut Context) {
    #[cfg(not(windows))]
    signal_hook::low_level::raise(signal_hook::consts::signal::SIGTSTP).unwrap();
}

fn add_newline_above(cx: &mut Context) {
    add_newline_impl(cx, Open::Above);
}

fn add_newline_below(cx: &mut Context) {
    add_newline_impl(cx, Open::Below)
}

fn add_newline_impl(cx: &mut Context, open: Open) {
    let count = cx.count();
    let (view, doc) = current!(cx.editor);
    let selection = doc.selection(view.id);
    let text = doc.text();
    let slice = text.slice(..);

    let changes = selection.into_iter().map(|range| {
        let (start, end) = range.line_range(slice);
        let line = match open {
            Open::Above => start,
            Open::Below => end + 1,
        };
        let pos = text.line_to_char(line);
        (
            pos,
            pos,
            Some(doc.line_ending.as_str().repeat(count).into()),
        )
    });

    let transaction = Transaction::change(text, changes);
    doc.apply(&transaction, view.id);
}

/// Increment object under cursor by count.
fn increment(cx: &mut Context) {
    increment_impl(cx, cx.count() as i64);
}

/// Decrement object under cursor by count.
fn decrement(cx: &mut Context) {
    increment_impl(cx, -(cx.count() as i64));
}

/// This function differs from find_next_char_impl in that it stops searching at the newline, but also
/// starts searching at the current character, instead of the next.
/// It does not want to start at the next character because this function is used for incrementing
/// number and we don't want to move forward if we're already on a digit.
fn find_next_char_until_newline<M: CharMatcher>(
    text: RopeSlice,
    char_matcher: M,
    pos: usize,
    _count: usize,
    _inclusive: bool,
) -> Option<usize> {
    // Since we send the current line to find_nth_next instead of the whole text, we need to adjust
    // the position we send to this function so that it's relative to that line and its returned
    // position since it's expected this function returns a global position.
    let line_index = text.char_to_line(pos);
    let pos_delta = text.line_to_char(line_index);
    let pos = pos - pos_delta;
    search::find_nth_next(text.line(line_index), char_matcher, pos, 1).map(|pos| pos + pos_delta)
}

/// Decrement object under cursor by `amount`.
fn increment_impl(cx: &mut Context, amount: i64) {
    // TODO: when incrementing or decrementing a number that gets a new digit or lose one, the
    // selection is updated improperly.
    find_char_impl(
        cx.editor,
        &find_next_char_until_newline,
        true,
        true,
        char::is_ascii_digit,
        1,
    );

    let (view, doc) = current!(cx.editor);
    let selection = doc.selection(view.id);
    let text = doc.text().slice(..);

    let changes: Vec<_> = selection
        .ranges()
        .iter()
        .filter_map(|range| {
            let incrementor: Box<dyn Increment> =
                if let Some(incrementor) = DateTimeIncrementor::from_range(text, *range) {
                    Box::new(incrementor)
                } else if let Some(incrementor) = NumberIncrementor::from_range(text, *range) {
                    Box::new(incrementor)
                } else {
                    return None;
                };

            let (range, new_text) = incrementor.increment(amount);

            Some((range.from(), range.to(), Some(new_text)))
        })
        .collect();

    // Overlapping changes in a transaction will panic, so we need to find and remove them.
    // For example, if there are cursors on each of the year, month, and day of `2021-11-29`,
    // incrementing will give overlapping changes, with each change incrementing a different part of
    // the date. Since these conflict with each other we remove these changes from the transaction
    // so nothing happens.
    let mut overlapping_indexes = HashSet::new();
    for (i, changes) in changes.windows(2).enumerate() {
        if changes[0].1 > changes[1].0 {
            overlapping_indexes.insert(i);
            overlapping_indexes.insert(i + 1);
        }
    }
    let changes = changes.into_iter().enumerate().filter_map(|(i, change)| {
        if overlapping_indexes.contains(&i) {
            None
        } else {
            Some(change)
        }
    });

    if changes.clone().count() > 0 {
        let transaction = Transaction::change(doc.text(), changes);
        let transaction = transaction.with_selection(selection.clone());

        doc.apply(&transaction, view.id);
    }
}

fn record_macro(cx: &mut Context) {
    if let Some((reg, mut keys)) = cx.editor.macro_recording.take() {
        // Remove the keypress which ends the recording
        keys.pop();
        let s = keys
            .into_iter()
            .map(|key| {
                let s = key.to_string();
                if s.chars().count() == 1 {
                    s
                } else {
                    format!("<{}>", s)
                }
            })
            .collect::<String>();
        cx.editor.registers.get_mut(reg).write(vec![s]);
        cx.editor
            .set_status(format!("Recorded to register [{}]", reg));
    } else {
        let reg = cx.register.take().unwrap_or('@');
        cx.editor.macro_recording = Some((reg, Vec::new()));
        cx.editor
            .set_status(format!("Recording to register [{}]", reg));
    }
}

fn replay_macro(cx: &mut Context) {
    let reg = cx.register.unwrap_or('@');
    let keys: Vec<KeyEvent> = if let Some([keys_str]) = cx.editor.registers.read(reg) {
        match helix_view::input::parse_macro(keys_str) {
            Ok(keys) => keys,
            Err(err) => {
                cx.editor.set_error(format!("Invalid macro: {}", err));
                return;
            }
        }
    } else {
        cx.editor.set_error(format!("Register [{}] empty", reg));
        return;
    };

    let count = cx.count();
    cx.callback = Some(Box::new(move |compositor, cx| {
        for _ in 0..count {
            for &key in keys.iter() {
                compositor.handle_event(crossterm::event::Event::Key(key.into()), cx);
            }
        }
    }));
}
