use super::Route;

use http::uri::URI;
use http::MediaType;
use request::Request;

/// The Collider trait is used to determine if two items that can be routed on
/// can match against a given request. That is, if two items `collide`, they
/// will both match against _some_ request.
pub trait Collider<T: ?Sized = Self> {
    fn collides_with(&self, other: &T) -> bool;
}

#[inline(always)]
fn index_match_until(break_c: char,
                     a: &str,
                     b: &str,
                     dir: bool) -> Option<(isize, isize)> {
    let (a_len, b_len) = (a.len() as isize, b.len() as isize);
    let (mut i, mut j, delta) = if dir {
        (0, 0, 1)
    } else {
        (a_len - 1, b_len - 1, -1)
    };

    let break_b = break_c as u8;
    while i >= 0 && j >= 0 && i < a_len && j < b_len {
        let (c1, c2) = (a.as_bytes()[i as usize], b.as_bytes()[j as usize]);
        if c1 == break_b || c2 == break_b {
            break;
        } else if c1 != c2 {
            return None;
        } else {
            i += delta;
            j += delta;
        }
    }

    Some((i, j))
}

#[inline(always)]
fn do_match_until(break_c: char, a: &str, b: &str, dir: bool) -> bool {
    index_match_until(break_c, a, b, dir).is_some()
}

impl<'a> Collider<str> for &'a str {
    #[inline(always)]
    fn collides_with(&self, other: &str) -> bool {
        let (a, b) = (self, other);
        do_match_until('<', a, b, true) && do_match_until('>', a, b, false)
    }
}

// This _only_ checks the `path` component of the URI.
impl<'a, 'b> Collider<URI<'b>> for URI<'a> {
    fn collides_with(&self, other: &URI<'b>) -> bool {
        for (seg_a, seg_b) in self.segments().zip(other.segments()) {
            if seg_a.ends_with("..>") || seg_b.ends_with("..>") {
                return true;
            }

            if !seg_a.collides_with(seg_b) {
                return false;
            }
        }

        if self.segment_count() != other.segment_count() {
            return false;
        }

        true
    }
}

impl Collider for MediaType  {
    #[inline(always)]
    fn collides_with(&self, other: &MediaType) -> bool {
        let collide = |a, b| a == "*" || b == "*" || a == b;
        collide(self.top(), other.top()) && collide(self.sub(), other.sub())
    }
}

// This implementation is used at initialization to check if two user routes
// collide before launching. Format collisions works like this:
//   * If route specifies format, it only gets requests for that format.
//   * If route doesn't specify format, it gets requests for any format.
// Query collisions work like this:
//   * If route specifies qeury, it only gets request that have queries.
//   * If route doesn't specify qeury, requests with and without queries match.
// As a result, as long as everything else collides, whether a route has a query
// or not is irrelevant: it will collide.
impl Collider for Route {
    fn collides_with(&self, b: &Route) -> bool {
        self.method == b.method
            && self.rank == b.rank
            && self.uri.collides_with(&b.uri)
            && match (self.format.as_ref(), b.format.as_ref()) {
                (Some(mt_a), Some(mt_b)) => mt_a.collides_with(mt_b),
                (Some(_), None) => true,
                (None, Some(_)) => true,
                (None, None) => true
            }
    }
}

// This implementation is used at runtime to check if a given request is
// intended for this Route. Format collisions works like this:
//   * If route specifies format, it only gets requests for that format.
//   * If route doesn't specify format, it gets requests for any format.
// Query collisions work like this:
//   * If route specifies a query, it only gets request that have queries.
//   * If route doesn't specify query, requests with & without queries collide.
impl<'r> Collider<Request<'r>> for Route {
    fn collides_with(&self, req: &Request<'r>) -> bool {
        self.method == req.method()
            && self.uri.collides_with(req.uri())
            && self.uri.query().map_or(true, |_| req.uri().query().is_some())
            && match self.format {
                Some(ref mt_a) => match req.format() {
                    Some(ref mt_b) => mt_a.collides_with(mt_b),
                    None => false
                },
                None => true
            }
    }
}

#[cfg(test)]
mod tests {
    use std::str::FromStr;

    use super::Collider;
    use rocket::Rocket;
    use config::Config;
    use request::Request;
    use data::Data;
    use handler::Outcome;
    use router::route::Route;
    use http::{Method, MediaType, ContentType, Accept};
    use http::uri::URI;
    use http::Method::*;

    type SimpleRoute = (Method, &'static str);

    fn dummy_handler(req: &Request, _: Data) -> Outcome<'static> {
        Outcome::from(req, "hi")
    }

    fn m_collide(a: SimpleRoute, b: SimpleRoute) -> bool {
        let route_a = Route::new(a.0, a.1.to_string(), dummy_handler);
        route_a.collides_with(&Route::new(b.0, b.1.to_string(), dummy_handler))
    }

    fn unranked_collide(a: &'static str, b: &'static str) -> bool {
        let route_a = Route::ranked(0, Get, a.to_string(), dummy_handler);
        route_a.collides_with(&Route::ranked(0, Get, b.to_string(), dummy_handler))
    }

    fn s_s_collide(a: &'static str, b: &'static str) -> bool {
        URI::new(a).collides_with(&URI::new(b))
    }

    #[test]
    fn simple_collisions() {
        assert!(unranked_collide("a", "a"));
        assert!(unranked_collide("/a", "/a"));
        assert!(unranked_collide("/hello", "/hello"));
        assert!(unranked_collide("/hello", "/hello/"));
        assert!(unranked_collide("/hello/there/how/ar", "/hello/there/how/ar"));
        assert!(unranked_collide("/hello/there", "/hello/there/"));
    }

    #[test]
    fn simple_param_collisions() {
        assert!(unranked_collide("/hello/<name>", "/hello/<person>"));
        assert!(unranked_collide("/hello/<name>/hi", "/hello/<person>/hi"));
        assert!(unranked_collide("/hello/<name>/hi/there", "/hello/<person>/hi/there"));
        assert!(unranked_collide("/<name>/hi/there", "/<person>/hi/there"));
        assert!(unranked_collide("/<name>/hi/there", "/dude/<name>/there"));
        assert!(unranked_collide("/<name>/<a>/<b>", "/<a>/<b>/<c>"));
        assert!(unranked_collide("/<name>/<a>/<b>/", "/<a>/<b>/<c>/"));
        assert!(unranked_collide("/<a..>", "/hi"));
        assert!(unranked_collide("/<a..>", "/hi/hey"));
        assert!(unranked_collide("/<a..>", "/hi/hey/hayo"));
        assert!(unranked_collide("/a/<a..>", "/a/hi/hey/hayo"));
        assert!(unranked_collide("/a/<b>/<a..>", "/a/hi/hey/hayo"));
        assert!(unranked_collide("/a/<b>/<c>/<a..>", "/a/hi/hey/hayo"));
        assert!(unranked_collide("/<b>/<c>/<a..>", "/a/hi/hey/hayo"));
        assert!(unranked_collide("/<b>/<c>/hey/hayo", "/a/hi/hey/hayo"));
    }

    #[test]
    fn medium_param_collisions() {
        assert!(unranked_collide("/hello/<name>", "/hello/bob"));
        assert!(unranked_collide("/<name>", "//bob"));
    }

    #[test]
    fn hard_param_collisions() {
        assert!(unranked_collide("/<name>bob", "/<name>b"));
        assert!(unranked_collide("/a<b>c", "/abc"));
        assert!(unranked_collide("/a<b>c", "/azooc"));
        assert!(unranked_collide("/a<b>", "/a"));
        assert!(unranked_collide("/<b>", "/a"));
        assert!(unranked_collide("/<a>/<b>", "/a/b<c>"));
        assert!(unranked_collide("/<a>/bc<b>", "/a/b<c>"));
        assert!(unranked_collide("/<a>/bc<b>d", "/a/b<c>"));
        assert!(unranked_collide("/<a..>", "///a///"));
    }

    #[test]
    fn query_collisions() {
        assert!(unranked_collide("/?<a>", "/?<a>"));
        assert!(unranked_collide("/a/?<a>", "/a/?<a>"));
        assert!(unranked_collide("/a?<a>", "/a?<a>"));
        assert!(unranked_collide("/<r>?<a>", "/<r>?<a>"));
        assert!(unranked_collide("/a/b/c?<a>", "/a/b/c?<a>"));
        assert!(unranked_collide("/<a>/b/c?<d>", "/a/b/<c>?<d>"));
        assert!(unranked_collide("/?<a>", "/"));
        assert!(unranked_collide("/a?<a>", "/a"));
        assert!(unranked_collide("/a?<a>", "/a"));
        assert!(unranked_collide("/a/b?<a>", "/a/b"));
        assert!(unranked_collide("/a/b", "/a/b?<c>"));
    }

    #[test]
    fn non_collisions() {
        assert!(!unranked_collide("/a", "/b"));
        assert!(!unranked_collide("/a/b", "/a"));
        assert!(!unranked_collide("/a/b", "/a/c"));
        assert!(!unranked_collide("/a/hello", "/a/c"));
        assert!(!unranked_collide("/hello", "/a/c"));
        assert!(!unranked_collide("/hello/there", "/hello/there/guy"));
        assert!(!unranked_collide("/b<a>/there", "/hi/there"));
        assert!(!unranked_collide("/<a>/<b>c", "/hi/person"));
        assert!(!unranked_collide("/<a>/<b>cd", "/hi/<a>e"));
        assert!(!unranked_collide("/a<a>/<b>", "/b<b>/<a>"));
        assert!(!unranked_collide("/a/<b>", "/b/<b>"));
        assert!(!unranked_collide("/a<a>/<b>", "/b/<b>"));
        assert!(!unranked_collide("/<a..>", "/"));
        assert!(!unranked_collide("/hi/<a..>", "/hi"));
        assert!(!unranked_collide("/hi/<a..>", "/hi/"));
        assert!(!unranked_collide("/<a..>", "//////"));
    }

    #[test]
    fn query_non_collisions() {
        assert!(!unranked_collide("/a?<b>", "/b"));
        assert!(!unranked_collide("/a/b", "/a?<b>"));
        assert!(!unranked_collide("/a/b/c?<d>", "/a/b/c/d"));
        assert!(!unranked_collide("/a/hello", "/a/?<hello>"));
        assert!(!unranked_collide("/?<a>", "/hi"));
    }

    #[test]
    fn method_dependent_non_collisions() {
        assert!(!m_collide((Get, "/"), (Post, "/")));
        assert!(!m_collide((Post, "/"), (Put, "/")));
        assert!(!m_collide((Put, "/a"), (Put, "/")));
        assert!(!m_collide((Post, "/a"), (Put, "/")));
        assert!(!m_collide((Get, "/a"), (Put, "/")));
        assert!(!m_collide((Get, "/hello"), (Put, "/hello")));
    }

    #[test]
    fn test_str_non_collisions() {
        assert!(!s_s_collide("/a", "/b"));
        assert!(!s_s_collide("/a/b", "/a"));
        assert!(!s_s_collide("/a/b", "/a/c"));
        assert!(!s_s_collide("/a/hello", "/a/c"));
        assert!(!s_s_collide("/hello", "/a/c"));
        assert!(!s_s_collide("/hello/there", "/hello/there/guy"));
        assert!(!s_s_collide("/b<a>/there", "/hi/there"));
        assert!(!s_s_collide("/<a>/<b>c", "/hi/person"));
        assert!(!s_s_collide("/<a>/<b>cd", "/hi/<a>e"));
        assert!(!s_s_collide("/a<a>/<b>", "/b<b>/<a>"));
        assert!(!s_s_collide("/a/<b>", "/b/<b>"));
        assert!(!s_s_collide("/a<a>/<b>", "/b/<b>"));
        assert!(!s_s_collide("/a", "/b"));
        assert!(!s_s_collide("/a/b", "/a"));
        assert!(!s_s_collide("/a/b", "/a/c"));
        assert!(!s_s_collide("/a/hello", "/a/c"));
        assert!(!s_s_collide("/hello", "/a/c"));
        assert!(!s_s_collide("/hello/there", "/hello/there/guy"));
        assert!(!s_s_collide("/b<a>/there", "/hi/there"));
        assert!(!s_s_collide("/<a>/<b>c", "/hi/person"));
        assert!(!s_s_collide("/<a>/<b>cd", "/hi/<a>e"));
        assert!(!s_s_collide("/a<a>/<b>", "/b<b>/<a>"));
        assert!(!s_s_collide("/a/<b>", "/b/<b>"));
        assert!(!s_s_collide("/a<a>/<b>", "/b/<b>"));
        assert!(!s_s_collide("/a", "/b"));
        assert!(!s_s_collide("/a/b", "/a"));
        assert!(!s_s_collide("/a/b", "/a/c"));
        assert!(!s_s_collide("/a/hello", "/a/c"));
        assert!(!s_s_collide("/hello", "/a/c"));
        assert!(!s_s_collide("/hello/there", "/hello/there/guy"));
        assert!(!s_s_collide("/b<a>/there", "/hi/there"));
        assert!(!s_s_collide("/<a>/<b>c", "/hi/person"));
        assert!(!s_s_collide("/<a>/<b>cd", "/hi/<a>e"));
        assert!(!s_s_collide("/a<a>/<b>", "/b<b>/<a>"));
        assert!(!s_s_collide("/a/<b>", "/b/<b>"));
        assert!(!s_s_collide("/a<a>/<b>", "/b/<b>"));
        assert!(!s_s_collide("/<a..>", "/"));
        assert!(!s_s_collide("/hi/<a..>", "/hi/"));
        assert!(!s_s_collide("/a/hi/<a..>", "/a/hi/"));
    }

    fn mt_mt_collide(mt1: &str, mt2: &str) -> bool {
        let mt_a = MediaType::from_str(mt1).expect(mt1);
        let mt_b = MediaType::from_str(mt2).expect(mt2);
        mt_a.collides_with(&mt_b)
    }

    #[test]
    fn test_content_type_colliions() {
        assert!(mt_mt_collide("application/json", "application/json"));
        assert!(mt_mt_collide("*/json", "application/json"));
        assert!(mt_mt_collide("*/*", "application/json"));
        assert!(mt_mt_collide("application/*", "application/json"));
        assert!(mt_mt_collide("application/*", "*/json"));
        assert!(mt_mt_collide("something/random", "something/random"));

        assert!(!mt_mt_collide("text/*", "application/*"));
        assert!(!mt_mt_collide("*/text", "*/json"));
        assert!(!mt_mt_collide("*/text", "application/test"));
        assert!(!mt_mt_collide("something/random", "something_else/random"));
        assert!(!mt_mt_collide("something/random", "*/else"));
        assert!(!mt_mt_collide("*/random", "*/else"));
        assert!(!mt_mt_collide("something/*", "random/else"));
    }

    fn r_mt_mt_collide<S1, S2>(m1: Method, mt1: S1, m2: Method, mt2: S2) -> bool
        where S1: Into<Option<&'static str>>, S2: Into<Option<&'static str>>
    {
        let mut route_a = Route::new(m1, "/", dummy_handler);
        if let Some(mt_str) = mt1.into() {
            route_a.format = Some(mt_str.parse::<MediaType>().unwrap());
        }

        let mut route_b = Route::new(m2, "/", dummy_handler);
        if let Some(mt_str) = mt2.into() {
            route_b.format = Some(mt_str.parse::<MediaType>().unwrap());
        }

        route_a.collides_with(&route_b)
    }

    #[test]
    fn test_route_content_type_colliions() {
        assert!(r_mt_mt_collide(Get, "application/json", Get, "application/json"));
        assert!(r_mt_mt_collide(Get, "*/json", Get, "application/json"));
        assert!(r_mt_mt_collide(Get, "*/json", Get, "application/*"));
        assert!(r_mt_mt_collide(Get, "text/html", Get, "text/*"));
        assert!(r_mt_mt_collide(Get, "any/thing", Get, "*/*"));

        assert!(r_mt_mt_collide(Get, None, Get, "text/*"));
        assert!(r_mt_mt_collide(Get, None, Get, "text/html"));
        assert!(r_mt_mt_collide(Get, None, Get, "*/*"));
        assert!(r_mt_mt_collide(Get, "text/html", Get, None));
        assert!(r_mt_mt_collide(Get, "*/*", Get, None));
        assert!(r_mt_mt_collide(Get, "application/json", Get, None));

        assert!(!r_mt_mt_collide(Get, "text/html", Get, "application/*"));
        assert!(!r_mt_mt_collide(Get, "application/html", Get, "text/*"));
        assert!(!r_mt_mt_collide(Get, "*/json", Get, "text/html"));
        assert!(!r_mt_mt_collide(Get, "text/html", Get, "text/css"));
    }

    fn req_route_mt_collide<S1, S2>(m: Method, mt1: S1, mt2: S2) -> bool
        where S1: Into<Option<&'static str>>, S2: Into<Option<&'static str>>
    {
        let rocket = Rocket::custom(Config::development().unwrap(), true);
        let mut req = Request::new(&rocket, m, "/");
        if let Some(mt_str) = mt1.into() {
            if m.supports_payload() {
                req.replace_header(mt_str.parse::<ContentType>().unwrap());
            } else {
                req.replace_header(mt_str.parse::<Accept>().unwrap());
            }
        }

        let mut route = Route::new(m, "/", dummy_handler);
        if let Some(mt_str) = mt2.into() {
            route.format = Some(mt_str.parse::<MediaType>().unwrap());
        }

        route.collides_with(&req)
    }

    #[test]
    fn test_req_route_mt_collisions() {
        assert!(req_route_mt_collide(Post, "application/json", "application/json"));
        assert!(req_route_mt_collide(Post, "application/json", "application/*"));
        assert!(req_route_mt_collide(Post, "application/json", "*/json"));
        assert!(req_route_mt_collide(Post, "text/html", "*/*"));

        assert!(req_route_mt_collide(Get, "application/json", "application/json"));
        assert!(req_route_mt_collide(Get, "text/html", "text/html"));
        assert!(req_route_mt_collide(Get, "text/html", "*/*"));
        assert!(req_route_mt_collide(Get, None, "text/html"));
        assert!(req_route_mt_collide(Get, None, "*/*"));
        assert!(req_route_mt_collide(Get, None, "application/json"));

        assert!(req_route_mt_collide(Post, "text/html", None));
        assert!(req_route_mt_collide(Post, "application/json", None));
        assert!(req_route_mt_collide(Post, "x-custom/anything", None));
        assert!(req_route_mt_collide(Post, None, None));

        assert!(req_route_mt_collide(Get, "text/html", None));
        assert!(req_route_mt_collide(Get, "application/json", None));
        assert!(req_route_mt_collide(Get, "x-custom/anything", None));
        assert!(req_route_mt_collide(Get, None, None));

        assert!(req_route_mt_collide(Get, "text/html, text/plain", "text/html"));
        assert!(req_route_mt_collide(Get, "text/html; q=0.5, text/xml", "text/xml"));

        assert!(!req_route_mt_collide(Post, "application/json", "text/html"));
        assert!(!req_route_mt_collide(Post, "application/json", "text/*"));
        assert!(!req_route_mt_collide(Post, "application/json", "*/xml"));
        assert!(!req_route_mt_collide(Get, "application/json", "text/html"));
        assert!(!req_route_mt_collide(Get, "application/json", "text/*"));
        assert!(!req_route_mt_collide(Get, "application/json", "*/xml"));

        assert!(!req_route_mt_collide(Post, None, "text/html"));
        assert!(!req_route_mt_collide(Post, None, "*/*"));
        assert!(!req_route_mt_collide(Post, None, "application/json"));
    }

    fn req_route_path_collide(a: &'static str, b: &'static str) -> bool {
        let rocket = Rocket::custom(Config::development().unwrap(), true);
        let req = Request::new(&rocket, Get, a.to_string());
        let route = Route::ranked(0, Get, b.to_string(), dummy_handler);
        route.collides_with(&req)
    }

    #[test]
    fn test_req_route_query_collisions() {
        assert!(req_route_path_collide("/a/b?a=b", "/a/b?<c>"));
        assert!(req_route_path_collide("/a/b?a=b", "/<a>/b?<c>"));
        assert!(req_route_path_collide("/a/b?a=b", "/<a>/<b>?<c>"));
        assert!(req_route_path_collide("/a/b?a=b", "/a/<b>?<c>"));
        assert!(req_route_path_collide("/?b=c", "/?<b>"));

        assert!(req_route_path_collide("/a/b?a=b", "/a/b"));
        assert!(req_route_path_collide("/a/b", "/a/b"));
        assert!(req_route_path_collide("/a/b/c/d?", "/a/b/c/d"));
        assert!(req_route_path_collide("/a/b/c/d?v=1&v=2", "/a/b/c/d"));

        assert!(!req_route_path_collide("/a/b", "/a/b?<c>"));
        assert!(!req_route_path_collide("/a/b/c", "/a/b?<c>"));
        assert!(!req_route_path_collide("/a?b=c", "/a/b?<c>"));
        assert!(!req_route_path_collide("/?b=c", "/a/b?<c>"));
        assert!(!req_route_path_collide("/?b=c", "/a?<c>"));
    }
}
