//! [`egui`] bindings for web apps (compiling to WASM).
//!
//! This library is an [`epi`] backend.
//!
//! If you are writing an app, you may want to look at [`eframe`](https://docs.rs/eframe) instead.

#![forbid(unsafe_code)]
#![cfg_attr(not(debug_assertions), deny(warnings))] // Forbid warnings in release builds
#![warn(clippy::all, rust_2018_idioms)]

pub mod backend;
#[cfg(feature = "http")]
pub mod http;
mod painter;
pub mod webgl1;
pub mod webgl2;

pub use backend::*;

pub use wasm_bindgen;
pub use web_sys;

pub use painter::Painter;
use wasm_bindgen::prelude::*;

// ----------------------------------------------------------------------------
// Helpers to hide some of the verbosity of web_sys

/// Log some text to the developer console (`console.log(...)` in JS)
pub fn console_log(s: impl Into<JsValue>) {
    web_sys::console::log_1(&s.into());
}

/// Log a warning to the developer console (`console.warn(...)` in JS)
pub fn console_warn(s: impl Into<JsValue>) {
    web_sys::console::warn_1(&s.into());
}

/// Log an error to the developer console (`console.error(...)` in JS)
pub fn console_error(s: impl Into<JsValue>) {
    web_sys::console::error_1(&s.into());
}

/// Current time in seconds (since undefined point in time)
pub fn now_sec() -> f64 {
    web_sys::window()
        .expect("should have a Window")
        .performance()
        .expect("should have a Performance")
        .now()
        / 1000.0
}

pub fn screen_size_in_native_points() -> Option<egui::Vec2> {
    let window = web_sys::window()?;
    Some(egui::Vec2::new(
        window.inner_width().ok()?.as_f64()? as f32,
        window.inner_height().ok()?.as_f64()? as f32,
    ))
}

pub fn native_pixels_per_point() -> f32 {
    let pixels_per_point = web_sys::window().unwrap().device_pixel_ratio() as f32;
    if pixels_per_point > 0.0 && pixels_per_point.is_finite() {
        pixels_per_point
    } else {
        1.0
    }
}

pub fn canvas_element(canvas_id: &str) -> Option<web_sys::HtmlCanvasElement> {
    use wasm_bindgen::JsCast;
    let document = web_sys::window()?.document()?;
    let canvas = document.get_element_by_id(canvas_id)?;
    canvas.dyn_into::<web_sys::HtmlCanvasElement>().ok()
}

pub fn canvas_element_or_die(canvas_id: &str) -> web_sys::HtmlCanvasElement {
    crate::canvas_element(canvas_id)
        .unwrap_or_else(|| panic!("Failed to find canvas with id '{}'", canvas_id))
}

pub fn resize_canvas_to_screen_size(canvas_id: &str, max_size_points: egui::Vec2) -> Option<()> {
    let canvas = canvas_element(canvas_id)?;

    let screen_size_points = screen_size_in_native_points()?;
    let pixels_per_point = native_pixels_per_point();

    let max_size_pixels = pixels_per_point * max_size_points;

    let canvas_size_pixels = pixels_per_point * screen_size_points;
    let canvas_size_pixels = canvas_size_pixels.min(max_size_pixels);
    let canvas_size_points = canvas_size_pixels / pixels_per_point;

    // Make sure that the height and width are always even numbers.
    // otherwise, the page renders blurry on some platforms.
    // See https://github.com/emilk/egui/issues/103
    fn round_to_even(v: f32) -> f32 {
        (v / 2.0).round() * 2.0
    }

    canvas
        .style()
        .set_property(
            "width",
            &format!("{}px", round_to_even(canvas_size_points.x)),
        )
        .ok()?;
    canvas
        .style()
        .set_property(
            "height",
            &format!("{}px", round_to_even(canvas_size_points.y)),
        )
        .ok()?;
    canvas.set_width(round_to_even(canvas_size_pixels.x) as u32);
    canvas.set_height(round_to_even(canvas_size_pixels.y) as u32);

    Some(())
}

// ----------------------------------------------------------------------------

pub fn local_storage() -> Option<web_sys::Storage> {
    web_sys::window()?.local_storage().ok()?
}

pub fn local_storage_get(key: &str) -> Option<String> {
    local_storage().map(|storage| storage.get_item(key).ok())??
}

pub fn local_storage_set(key: &str, value: &str) {
    if let Some(_) = local_storage_get("storage_ok") {
        local_storage().map(|storage| storage.set_item(key, value));
    }
}

pub fn local_storage_remove(key: &str) {
    local_storage().map(|storage| storage.remove_item(key));
}

#[cfg(feature = "persistence")]
pub fn load_memory(ctx: &egui::Context) {
    if let Some(memory_string) = local_storage_get("egui_memory_json") {
        match serde_json::from_str(&memory_string) {
            Ok(memory) => {
                *ctx.memory() = memory;
            }
            Err(err) => {
                console_error(format!("Failed to parse memory json: {}", err));
            }
        }
    }
}

#[cfg(not(feature = "persistence"))]
pub fn load_memory(_: &egui::Context) {}

#[cfg(feature = "persistence")]
pub fn save_memory(ctx: &egui::Context) {
    match serde_json::to_string(&*ctx.memory()) {
        Ok(json) => {
            local_storage_set("egui_memory_json", &json);
        }
        Err(err) => {
            console_error(format!("Failed to serialize memory as json: {}", err));
        }
    }
}

#[cfg(not(feature = "persistence"))]
pub fn save_memory(_: &egui::Context) {}

// ----------------------------------------------------------------------------

pub fn handle_output(output: &egui::Output) {
    let egui::Output {
        cursor_icon,
        open_url,
        copied_text,
        needs_repaint: _, // handled elsewhere
    } = output;

    set_cursor_icon(*cursor_icon);
    if let Some(url) = open_url {
        crate::open_url(url);
    }

    #[cfg(web_sys_unstable_apis)]
    if !copied_text.is_empty() {
        set_clipboard_text(copied_text);
    }

    #[cfg(not(web_sys_unstable_apis))]
    let _ = copied_text;
}

pub fn set_cursor_icon(cursor: egui::CursorIcon) -> Option<()> {
    let document = web_sys::window()?.document()?;
    document
        .body()?
        .style()
        .set_property("cursor", cursor_web_name(cursor))
        .ok()
}

#[cfg(web_sys_unstable_apis)]
pub fn set_clipboard_text(s: &str) {
    if let Some(window) = web_sys::window() {
        let clipboard = window.navigator().clipboard();
        let promise = clipboard.write_text(s);
        let future = wasm_bindgen_futures::JsFuture::from(promise);
        let future = async move {
            if let Err(err) = future.await {
                console_error(format!("Copy/cut action denied: {:?}", err));
            }
        };
        wasm_bindgen_futures::spawn_local(future);
    }
}

pub fn spawn_future<F>(future: F)
where
    F: std::future::Future<Output = ()> + 'static,
{
    wasm_bindgen_futures::spawn_local(future);
}

fn cursor_web_name(cursor: egui::CursorIcon) -> &'static str {
    use egui::CursorIcon::*;
    match cursor {
        Default => "default",
        PointingHand => "pointer",
        ResizeHorizontal => "ew-resize",
        ResizeNeSw => "nesw-resize",
        ResizeNwSe => "nwse-resize",
        ResizeVertical => "ns-resize",
        Text => "text",
        Grab => "grab",
        Grabbing => "grabbing",
        // "no-drop"
        // "not-allowed"
        // default, help, pointer, progress, wait, cell, crosshair, text, alias, copy, move
    }
}

pub fn open_url(url: &str) -> Option<()> {
    web_sys::window()?
        .open_with_url_and_target(url, "_self")
        .ok()?;
    Some(())
}

/// e.g. "#fragment" part of "www.example.com/index.html#fragment"
pub fn location_hash() -> Option<String> {
    web_sys::window()?.location().hash().ok()
}

/// Web sends all all keys as strings, so it is up to us to figure out if it is
/// a real text input or the name of a key.
pub fn translate_key(key: &str) -> Option<egui::Key> {
    match key {
        "ArrowDown" => Some(egui::Key::ArrowDown),
        "ArrowLeft" => Some(egui::Key::ArrowLeft),
        "ArrowRight" => Some(egui::Key::ArrowRight),
        "ArrowUp" => Some(egui::Key::ArrowUp),

        "Esc" | "Escape" => Some(egui::Key::Escape),
        "Tab" => Some(egui::Key::Tab),
        "Backspace" => Some(egui::Key::Backspace),
        "Enter" => Some(egui::Key::Enter),
        "Space" => Some(egui::Key::Space),

        "Help" | "Insert" => Some(egui::Key::Insert),
        "Delete" => Some(egui::Key::Delete),
        "Home" => Some(egui::Key::Home),
        "End" => Some(egui::Key::End),
        "PageUp" => Some(egui::Key::PageUp),
        "PageDown" => Some(egui::Key::PageDown),

        "0" => Some(egui::Key::Num0),
        "1" => Some(egui::Key::Num1),
        "2" => Some(egui::Key::Num2),
        "3" => Some(egui::Key::Num3),
        "4" => Some(egui::Key::Num4),
        "5" => Some(egui::Key::Num5),
        "6" => Some(egui::Key::Num6),
        "7" => Some(egui::Key::Num7),
        "8" => Some(egui::Key::Num8),
        "9" => Some(egui::Key::Num9),

        "a" | "A" => Some(egui::Key::A),
        "b" | "B" => Some(egui::Key::B),
        "c" | "C" => Some(egui::Key::C),
        "d" | "D" => Some(egui::Key::D),
        "e" | "E" => Some(egui::Key::E),
        "f" | "F" => Some(egui::Key::F),
        "g" | "G" => Some(egui::Key::G),
        "h" | "H" => Some(egui::Key::H),
        "i" | "I" => Some(egui::Key::I),
        "j" | "J" => Some(egui::Key::J),
        "k" | "K" => Some(egui::Key::K),
        "l" | "L" => Some(egui::Key::L),
        "m" | "M" => Some(egui::Key::M),
        "n" | "N" => Some(egui::Key::N),
        "o" | "O" => Some(egui::Key::O),
        "p" | "P" => Some(egui::Key::P),
        "q" | "Q" => Some(egui::Key::Q),
        "r" | "R" => Some(egui::Key::R),
        "s" | "S" => Some(egui::Key::S),
        "t" | "T" => Some(egui::Key::T),
        "u" | "U" => Some(egui::Key::U),
        "v" | "V" => Some(egui::Key::V),
        "w" | "W" => Some(egui::Key::W),
        "x" | "X" => Some(egui::Key::X),
        "y" | "Y" => Some(egui::Key::Y),
        "z" | "Z" => Some(egui::Key::Z),

        _ => None,
    }
}
