use std::net::{TcpListener, TcpStream, Shutdown};
use std::io::Write;
use std::str;

use crate::request::Request;
use crate::response::Response;
use crate::http_method::HttpMethod;

pub trait HttpHandler {
    // TODO(andrew): add default behaviour to handlers?
    fn do_get(&self, request: Request) -> Response;
    fn do_post(&self, request: Request) -> Response;
}

pub struct HttpServer<T: HttpHandler> {
    host: String,
    port: u16,
    socket: TcpListener,
    handler: T
}

impl<T> HttpServer<T> where T: HttpHandler {
    // TODO(andrew): add explanations for errors?
    pub fn new(host: &str, port: u16, handler: T) -> Result<HttpServer<T>, &str> {
        let addr = format!("{}:{}", host, port);
        let sock = TcpListener::bind(addr);
        match sock {
            Ok(s) => {
                let server = HttpServer {
                    host: String::from(host),
                    port: port,
                    socket: s,
                    handler: handler,
                };
                return Ok(server);
            },
            Err(_) => return Err("Couldn't start server")
        };
    }

    pub fn serve_forever(&self) -> Result<(), &str> {
        for stream in self.socket.incoming() {
            match stream {
                Ok(s) => {
                    // TODO(andrew): replace println with logging.
                    println!("Got connection!");
                    match self.handle_client(&s) {
                        Ok(_) => (),
                        Err(msg) => return Err(msg)
                    };
                    match s.shutdown(Shutdown::Both) {
                        Ok(_) => println!("Closed connection"),
                        Err(_) => return Err("Couldn't close client socket")
                    };
                },
                Err(_) => break
            };
        }
        return Ok(());
    }

    fn handle_client(&self, mut stream: &TcpStream) -> Result<(), &str> {
        let mut buf: [u8; 1024] = [0; 1024];
        // TODO(andrew): read all body, not first 1024 bytes.
        stream.peek(&mut buf).expect("Couldn't read from socket");

        let request = Request::from(&buf);
        let request = match request {
            Some(r) => r,
            None => return Err("Request parsed with errors")
        };

        // TODO(andrew): add more methods.
        let response = match request.method {
            HttpMethod::GET  => self.handler.do_get(request),
            HttpMethod::POST => self.handler.do_post(request)
        };
        let response = response.format();
        match stream.write(&response) {
            Ok(_) => return Ok(()),
            Err(_) => return Err("Couldn't write to client socket")
        };
    }
}