use chan::Sender;
use hyper;
use hyper::{Encoder, Decoder, Next};
use hyper::client::{Client as HyperClient, Handler, HttpsConnector,
                    Request as HyperRequest, Response as HyperResponse};
use hyper::header::{Authorization, Basic, Bearer, ContentLength, ContentType, Location};
use hyper::mime::{Attr, Mime, TopLevel, SubLevel, Value};
use hyper::net::{HttpStream, HttpsStream, OpensslStream};
use hyper::status::StatusCode;
use std::{io, mem};
use std::io::{ErrorKind, Write};
use std::str;
use std::time::Duration;
use time;

use datatype::{Auth, Error};
use http::{Client, get_openssl, Request, Response, ResponseData};


/// The `AuthClient` will attach an `Authentication` header to each outgoing
/// HTTP request.
#[derive(Clone)]
pub struct AuthClient {
    auth:   Auth,
    client: HyperClient<AuthHandler>,
}

impl Default for AuthClient {
    fn default() -> Self {
        Self::from(Auth::None)
    }
}

impl AuthClient {
    /// Instantiates a new client ready to make requests for the given `Auth` type.
    pub fn from(auth: Auth) -> Self {
        let client  = HyperClient::<AuthHandler>::configure()
            .keep_alive(true)
            .max_sockets(1024)
            .connector(HttpsConnector::new(get_openssl()))
            .build()
            .expect("unable to create a new hyper Client");

        AuthClient {
            auth:   auth,
            client: client,
        }
    }
}

impl Client for AuthClient {
    fn chan_request(&self, req: Request, resp_tx: Sender<Response>) {
        info!("{} {}", req.method, req.url);
        let _ = self.client.request((*req.url).clone(), AuthHandler {
            auth:      self.auth.clone(),
            req:       req,
            timeout:   Duration::from_secs(20),
            started:   None,
            written:   0,
            resp_code: StatusCode::InternalServerError,
            resp_body: Vec::new(),
            resp_tx:   resp_tx.clone(),
        }).map_err(|err| resp_tx.send(Response::Error(Error::from(err))));
    }
}


/// The async handler for outgoing HTTP requests.
#[derive(Debug)]
pub struct AuthHandler {
    auth:      Auth,
    req:       Request,
    timeout:   Duration,
    started:   Option<u64>,
    written:   usize,
    resp_code: StatusCode,
    resp_body: Vec<u8>,
    resp_tx:   Sender<Response>,
}

/// The `AuthClient` may be used for both HTTP and HTTPS connections.
pub type Stream = HttpsStream<OpensslStream<HttpStream>>;

impl Handler<Stream> for AuthHandler {
    fn on_request(&mut self, req: &mut HyperRequest) -> Next {
        req.set_method(self.req.method.clone().into());
        self.started    = Some(time::precise_time_ns());
        let mut headers = req.headers_mut();

        // empty Charset to keep RVI happy
        let mime_json = Mime(TopLevel::Application, SubLevel::Json, vec![]);
        let mime_form = Mime(TopLevel::Application, SubLevel::WwwFormUrlEncoded,
                             vec![(Attr::Charset, Value::Utf8)]);

        match self.auth {
            Auth::None => {
                headers.set(ContentType(mime_json));
            }

            Auth::Credentials(ref cred) => {
                headers.set(Authorization(Basic {
                    username: cred.client_id.clone(),
                    password: Some(cred.client_secret.clone())
                }));
                headers.set(ContentType(mime_form));
            }

            Auth::Token(ref token) => {
                headers.set(Authorization(Bearer { token: token.access_token.clone() }));
                headers.set(ContentType(mime_json));
            }
        };

        self.req.body.as_ref().map_or(Next::read().timeout(self.timeout), |body| {
            headers.set(ContentLength(body.len() as u64));
            Next::write()
        })
    }

    fn on_request_writable(&mut self, encoder: &mut Encoder<Stream>) -> Next {
        let body = self.req.body.as_ref().expect("on_request_writable expects a body");

        match encoder.write(&body[self.written..]) {
            Ok(0) => {
                info!("Request length: {} bytes", body.len());
                if let Ok(body) = str::from_utf8(body) {
                    debug!("body:\n{}", body);
                }
                Next::read().timeout(self.timeout)
            },

            Ok(n) => {
                self.written += n;
                trace!("{} bytes written to request body", n);
                Next::write()
            }

            Err(ref err) if err.kind() == ErrorKind::WouldBlock => {
                trace!("retry on_request_writable");
                Next::write()
            }

            Err(err) => {
                error!("unable to write request body: {}", err);
                self.resp_tx.send(Response::Error(Error::from(err)));
                Next::remove()
            }
        }
    }

    fn on_response(&mut self, resp: HyperResponse) -> Next {
        info!("Response status: {}", resp.status());
        debug!("on_response headers:\n{}", resp.headers());
        let started = self.started.expect("expected start time");
        let latency = time::precise_time_ns() as f64 - started as f64;
        debug!("on_response latency: {}ms", (latency / 1e6) as u32);

        if resp.status().is_redirection() {
            self.redirect_request(resp);
            Next::end()
        } else if let None = resp.headers().get::<ContentLength>() {
            self.send_response(ResponseData { code: *resp.status(), body: Vec::new() });
            Next::end()
        } else {
            self.resp_code = *resp.status();
            Next::read()
        }
    }

    fn on_response_readable(&mut self, decoder: &mut Decoder<Stream>) -> Next {
        match io::copy(decoder, &mut self.resp_body) {
            Ok(0) => {
                debug!("on_response_readable body size: {}", self.resp_body.len());
                let code = self.resp_code.clone();
                let body = mem::replace(&mut self.resp_body, Vec::new());
                self.send_response(ResponseData { code: code, body: body });
                Next::end()
            }

            Ok(n) => {
                trace!("{} more response bytes read", n);
                Next::read()
            }

            Err(ref err) if err.kind() == ErrorKind::WouldBlock => {
                trace!("retry on_response_readable");
                Next::read()
            }

            Err(err) => {
                error!("unable to read response body: {}", err);
                self.resp_tx.send(Response::Error(Error::from(err)));
                Next::end()
            }
        }
    }

    fn on_error(&mut self, err: hyper::Error) -> Next {
        error!("on_error: {}", err);
        self.resp_tx.send(Response::Error(Error::from(err)));
        Next::remove()
    }
}

impl AuthHandler {
    fn send_response(&mut self, resp: ResponseData) {
        if resp.code == StatusCode::Unauthorized || resp.code == StatusCode::Forbidden {
            self.resp_tx.send(Response::Error(Error::HttpAuth(resp)));
        } else if resp.code.is_success() {
            self.resp_tx.send(Response::Success(resp));
        } else {
            self.resp_tx.send(Response::Failed(resp));
        }
    }

    fn redirect_request(&mut self, resp: HyperResponse) {
        match resp.headers().get::<Location>() {
            Some(&Location(ref loc)) => self.req.url.join(loc).map(|url| {
                debug!("redirecting to {}", url);
                // drop Authorization Header on redirect
                let client  = AuthClient::default();
                let resp_rx = client.send_request(Request {
                    url:    url,
                    method: self.req.method.clone(),
                    body:   mem::replace(&mut self.req.body, None),
                });
                self.resp_tx.send(resp_rx.recv().expect("no redirect_request response"))
            }).unwrap_or_else(|err| self.resp_tx.send(Response::Error(Error::from(err)))),

            None => self.resp_tx.send(Response::Error((Error::Client("redirect missing Location header".to_string()))))
        }
    }
}


#[cfg(test)]
mod tests {
    use rustc_serialize::json::Json;
    use std::path::Path;

    use super::*;
    use http::{Client, Response, set_ca_certificates};


    fn get_client() -> AuthClient {
        set_ca_certificates(&Path::new("run/sota_certificates"));
        AuthClient::default()
    }

    #[test]
    fn test_send_get_request() {
        let client  = get_client();
        let url     = "http://eu.httpbin.org/bytes/16?seed=123".parse().unwrap();
        let resp_rx = client.get(url, None);
        let resp    = resp_rx.recv().unwrap();
        let expect  = vec![13, 22, 104, 27, 230, 9, 137, 85, 218, 40, 86, 85, 62, 0, 111, 22];
        match resp {
            Response::Success(data) => assert_eq!(data.body, expect),
            Response::Failed(data)  => panic!("failed response: {}", data),
            Response::Error(err)    => panic!("error response: {}", err)
        };
    }

    #[test]
    fn test_send_post_request() {
        let client  = get_client();
        let url     = "https://eu.httpbin.org/post".parse().unwrap();
        let resp_rx = client.post(url, Some(br#"foo"#.to_vec()));
        let resp    = resp_rx.recv().unwrap();
        let body    = match resp {
            Response::Success(data) => String::from_utf8(data.body).unwrap(),
            Response::Failed(data)  => panic!("failed response: {}", data),
            Response::Error(err)    => panic!("error response: {}", err)
        };
        let json    = Json::from_str(&body).unwrap();
        let obj     = json.as_object().unwrap();
        let data    = obj.get("data").unwrap().as_string().unwrap();
        assert_eq!(data, "foo");
    }
}