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

type DynHandlerFn = dyn Fn(Request) -> Response + Send + Sync;
type BoxedHandlerFn = Box<DynHandlerFn>;
type HandlersMap = HashMap<String, Arc<BoxedHandlerFn>>;

// Collection of handlers for requests
pub struct Handlers {
    matchers: HandlersMap,
}

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: impl Fn(Request) -> Response + Send + Sync + 'static,
    ) {
        self.matchers
            .insert(path.to_string(), Arc::new(Box::from(handler)));
    }

    /// Bind these handlers to a listener in order to handle incoming requests.
    /// You will need to pass in a TcpListener.
    /// This method creates a ThreadPool to handle incoming requests so no multithreading is needed on the part of the caller.
    ///
    /// !! Call this *after* adding all your handlers with add_handler !!
    ///
    /// listener: TcpListener to bind to
    pub fn bind(&self, listener: TcpListener) -> UnitOrBoxedError {
        let pool = match ThreadPool::build(4) {
            Some(pool) => pool,
            None => return Err(Box::from("Failed to create ThreadPool")),
        };

        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")
                            });
                            continue;
                        }
                    };

                    let handler = match Handlers::match_handler(&self.matchers, &request.url) {
                        Some(handler) => handler.clone(),
                        None => {
                            Response::new(request, 404, Body::Static("Not Found")).send()?;
                            continue;
                        }
                    };

                    pool.execute(move || {
                        handler.as_ref()(request)
                            .send()
                            .unwrap_or_else(|_| eprintln!("Failed to send response"));
                    })
                    .unwrap_or_else(|_| {
                        eprintln!("Failed to send job to ThreadPool");
                    });
                }
                Err(e) => {
                    eprintln!("Failed to establish connection: {}", e);
                }
            };
        }

        return Ok(());
    }

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

            // Segment matching
            let url_segments = 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_segments.len() != path_segments.len()) || (path_segments.len() == 0) {
                continue;
            }

            // Check each segment of the url
            for (url_segment, path_segment) in url_segments.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;
                    }

                    continue 'matching_loop;
                }

                if url_segment == path_segment {
                    continue;
                }

                continue 'matching_loop;
            }

            return Some(handler);
        }

        None
    }
}