// Copyright 2015, 2016 Ethcore (UK) Ltd.
// This file is part of Parity.

// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity.  If not, see <http://www.gnu.org/licenses/>.

//! Router implementation
//! Processes request handling authorization and dispatching it to proper application.

mod url;
mod redirect;
pub mod auth;

use std::sync::Arc;
use hyper;
use hyper::{server, uri, header};
use hyper::{Next, Encoder, Decoder};
use hyper::net::HttpStream;
use endpoint::{Endpoint, Endpoints};
use self::url::Url;
use self::auth::{Authorization, Authorized};
use self::redirect::Redirection;

pub struct Router<A: Authorization + 'static> {
	main_page: &'static str,
	endpoints: Arc<Endpoints>,
	rpc: Arc<Box<Endpoint>>,
	api: Arc<Box<Endpoint>>,
	authorization: Arc<A>,
	handler: Box<server::Handler<HttpStream>>,
}

impl<A: Authorization + 'static> server::Handler<HttpStream> for Router<A> {

	fn on_request(&mut self, req: server::Request) -> Next {
		let auth = self.authorization.is_authorized(&req);
		self.handler = match auth {
			Authorized::No(handler) => handler,
			Authorized::Yes => {
				let path = self.extract_request_path(&req);
				match path {
					Some(ref url) if self.endpoints.contains_key(url) => {
						let prefix = "/".to_owned() + url;
						self.endpoints.get(url).unwrap().to_handler(&prefix)
					},
					Some(ref url) if url == "api" => {
						self.api.to_handler("/api")
					},
					_ if *req.method() == hyper::method::Method::Get => {
						Redirection::new(self.main_page)
					},
					_ => {
						self.rpc.to_handler(&"/")
					}
				}
			}
		};
		self.handler.on_request(req)
		// Check authorization
		// Choose proper handler depending on path
		// Delegate on_request to proper handler
	}

	/// This event occurs each time the `Request` is ready to be read from.
	fn on_request_readable(&mut self, decoder: &mut Decoder<HttpStream>) -> Next {
		self.handler.on_request_readable(decoder)
	}

	/// This event occurs after the first time this handled signals `Next::write()`.
	fn on_response(&mut self, response: &mut server::Response) -> Next {
		self.handler.on_response(response)
	}

	/// This event occurs each time the `Response` is ready to be written to.
	fn on_response_writable(&mut self, encoder: &mut Encoder<HttpStream>) -> Next {
		self.handler.on_response_writable(encoder)
	}
}

impl<A: Authorization> Router<A> {
	pub fn new(
		main_page: &'static str,
		endpoints: Arc<Endpoints>,
		rpc: Arc<Box<Endpoint>>,
		api: Arc<Box<Endpoint>>,
		authorization: Arc<A>) -> Self {

		let handler = rpc.to_handler(&"/");
		Router {
			main_page: main_page,
			endpoints: endpoints,
			rpc: rpc,
			api: api,
			authorization: authorization,
			handler: handler,
		}
	}

	fn extract_url(&self, req: &server::Request) -> Option<Url> {
		match *req.uri() {
			uri::RequestUri::AbsoluteUri(ref url) => {
				match Url::from_generic_url(url.clone()) {
					Ok(url) => Some(url),
					_ => None,
				}
			},
			uri::RequestUri::AbsolutePath(ref path) => {
				// Attempt to prepend the Host header (mandatory in HTTP/1.1)
				let url_string = match req.headers().get::<header::Host>() {
					Some(ref host) => {
						format!("http://{}:{}{}", host.hostname, host.port.unwrap_or(80), path)
					},
					None => return None,
				};

				match Url::parse(&url_string) {
					Ok(url) => Some(url),
					_ => None,
				}
			},
			_ => None,
		}
	}

	fn extract_request_path(&self, req: &server::Request) -> Option<String> {
		let url = self.extract_url(&req);
		match url {
			Some(ref url) if url.path.len() > 1 => {
				let part = url.path[0].clone();
				Some(part)
			},
			_ => {
				None
			},
		}
	}
}