use crate::http::{
    requests::{Request, RequestStatus, URL},
    responses::{Response, UnitOrBoxedError},
};
use std::{
    collections::HashMap,
    net::{Shutdown, TcpListener},
};

type HandlerFn = fn(Request) -> Response<'static>;

// Collection of handlers for requests
pub struct Handlers {
    matchers: HashMap<String, HandlerFn>,
}

impl Handlers {
    /// Create a new Handlers struct to handle requests
    ///
    /// !! This struct does nothing until you add handlers to it (add_handler) and then bind it to a TcpListener !!
    pub fn new() -> Self {
        Handlers {
            matchers: HashMap::new(),
        }
    }

    /// Add a request handler
    ///
    /// !! Be sure to bind this Handlers struct to a TcpListener to actually handle requests !!
    ///
    /// path: Path to match (no trailing /)
    /// handler: Function to handle the request. Must return a Response
    pub fn add_handler(&mut self, path: &str, handler: HandlerFn) {
        self.matchers.insert(path.to_string(), handler);
    }

    /// Bind these handlers to a listener in order to handle incoming requests
    /// You will need to pass in a TcpListener
    ///
    /// !! Call this *after* adding all your handlers with add_handler !!
    ///
    /// listener: TcpListener to bind to
    pub fn bind(&self, listener: TcpListener) {
        for stream in listener.incoming() {
            match stream {
                Ok(stream) => {
                    let request = match Request::parse_stream(stream) {
                        RequestStatus::Ok(req) => req,
                        RequestStatus::MalformedHTTP(stream) => {
                            stream.shutdown(Shutdown::Both).unwrap_or_else(|_| {
                                eprintln!("Failed to close malformed HTTP stream")
                            });
                            return;
                        }
                    };

                    self.handle_req(request)
                        .unwrap_or_else(|_| eprintln!("Failed to send handle request"));
                }
                Err(e) => {
                    eprintln!("Failed to establish connection: {}", e);
                    return;
                }
            }
        }
    }

    fn match_handler(&self, url: &URL) -> Option<HandlerFn> {
        'matching_loop: for (path, handler) in self.matchers.iter() {
            // Exact match
            if path == &url.path {
                return Some(*handler);
            };

            // Segment matching
            let url_segements = url.path.split('/').collect::<Vec<&str>>();
            let path_segments = path.split('/').collect::<Vec<&str>>();

            // If the URL has more segments than the path, it can't match
            // or if the path has no segments, it can't match
            if (url_segements.len() != path_segments.len()) || (path_segments.len() == 0) {
                continue;
            }

            // Check each segment of the url
            for (url_segment, path_segment) in url_segements.iter().zip(path_segments.iter()) {
                if path_segment.starts_with('[') {
                    // e.g. /path/[id]
                    if path_segment.ends_with(']') { 
                        continue;
                    }
                    
                    // e.g. /path/prefix[id].suffix
                    let prefix = path_segment.split('[').collect::<Vec<_>>()[0];
                    let suffix = path_segment.split(']').collect::<Vec<_>>()[1];

                    // begins_with and starts_with always return true on empty strings
                    if url_segment.starts_with(prefix) && url_segment.ends_with(suffix) {
                        continue;
                    }

                    break 'matching_loop;
                }

                if url_segment == path_segment {
                    continue;
                }

                break 'matching_loop;
            }

            return Some(*handler);
        }

        None
    }

    fn handle_req(&self, req: Request) -> UnitOrBoxedError {
        match self.match_handler(&req.url) {
            Some(handler) => handler(req).send()?,
            None => {
                return Response::new(req, 404, "Not Found").send();
            }
        };

        Ok(())
    }
}