/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use cookie_storage::CookieSource;
use resource_task::{Metadata, TargetedLoadResponse, LoadData, start_sending_opt, ResponseSenders};
use resource_task::ControlMsg;
use resource_task::ProgressMsg::{Payload, Done};

use log;
use std::collections::HashSet;
use file_loader;
use hyper::client::Request;
use hyper::header::{ContentLength, ContentType, Host, Location};
use hyper::HttpError;
use hyper::method::Method;
use hyper::net::HttpConnector;
use hyper::status::{StatusCode, StatusClass};
use std::error::Error;
use openssl::ssl::{SslContext, SslVerifyMode};
use std::old_io::{IoError, IoErrorKind, Reader};
use std::sync::mpsc::{Sender, channel};
use std::thunk::Invoke;
use util::task::spawn_named;
use util::resource_files::resources_dir_path;
use url::{Url, UrlParser};

use std::borrow::ToOwned;

pub fn factory(cookies_chan: Sender<ControlMsg>)
               -> Box<Invoke<(LoadData, Sender<TargetedLoadResponse>)> + Send> {
    box move |(load_data, start_chan)| {
        spawn_named("http_loader".to_owned(), move || load(load_data, start_chan, cookies_chan))
    }
}

fn send_error(url: Url, err: String, senders: ResponseSenders) {
    let mut metadata = Metadata::default(url);
    metadata.status = None;

    match start_sending_opt(senders, metadata) {
        Ok(p) => p.send(Done(Err(err))).unwrap(),
        _ => {}
    };
}

fn load(mut load_data: LoadData, start_chan: Sender<TargetedLoadResponse>, cookies_chan: Sender<ControlMsg>) {
    // FIXME: At the time of writing this FIXME, servo didn't have any central
    //        location for configuration. If you're reading this and such a
    //        repository DOES exist, please update this constant to use it.
    let max_redirects = 50u;
    let mut iters = 0u;
    let mut url = load_data.url.clone();
    let mut redirected_to = HashSet::new();

    let senders = ResponseSenders {
        immediate_consumer: start_chan,
        eventual_consumer: load_data.consumer
    };

    // Loop to handle redirects.
    loop {
        iters = iters + 1;

        if iters > max_redirects {
            send_error(url, "too many redirects".to_string(), senders);
            return;
        }

        match url.scheme.as_slice() {
            "http" | "https" => {}
            _ => {
                let s = format!("{} request, but we don't support that scheme", url.scheme);
                send_error(url, s, senders);
                return;
            }
        }

        info!("requesting {}", url.serialize());

        fn verifier(ssl: &mut SslContext) {
            ssl.set_verify(SslVerifyMode::SslVerifyPeer, None);
            let mut certs = resources_dir_path();
            certs.push("certs");
            ssl.set_CA_file(&certs);
        };

        let ssl_err_string = "[UnknownError { library: \"SSL routines\", \
function: \"SSL3_GET_SERVER_CERTIFICATE\", \
reason: \"certificate verify failed\" }]";

        let mut connector = HttpConnector(Some(box verifier as Box<FnMut(&mut SslContext)>));
        let mut req = match Request::with_connector(load_data.method.clone(), url.clone(), &mut connector) {
            Ok(req) => req,
            Err(HttpError::HttpIoError(IoError {kind: IoErrorKind::OtherIoError,
                                                desc: "Error in OpenSSL",
                                                detail: Some(ref det)})) if det.as_slice() == ssl_err_string => {
                let mut image = resources_dir_path();
                image.push("badcert.html");
                let load_data = LoadData::new(Url::from_file_path(&image).unwrap(), senders.eventual_consumer);
                file_loader::factory(load_data, senders.immediate_consumer);
                return;
            },
            Err(e) => {
                println!("{:?}", e);
                send_error(url, e.description().to_string(), senders);
                return;
            }
        };

        // Preserve the `host` header set automatically by Request.
        let host = req.headers().get::<Host>().unwrap().clone();

        // Avoid automatically preserving request headers when redirects occur.
        // See https://bugzilla.mozilla.org/show_bug.cgi?id=401564 and
        // https://bugzilla.mozilla.org/show_bug.cgi?id=216828 .
        // Only preserve ones which have been explicitly marked as such.
        if iters == 1 {
            let mut combined_headers = load_data.headers.clone();
            combined_headers.extend(load_data.preserved_headers.iter());
            *req.headers_mut() = combined_headers;
        } else {
            *req.headers_mut() = load_data.preserved_headers.clone();
        }

        req.headers_mut().set(host);

        let (tx, rx) = channel();
        cookies_chan.send(ControlMsg::GetCookiesForUrl(url.clone(), tx, CookieSource::HTTP)).unwrap();
        if let Some(cookie_list) = rx.recv().unwrap() {
            let mut v = Vec::new();
            v.push(cookie_list.into_bytes());
            req.headers_mut().set_raw("Cookie".to_owned(), v);
        }

        // FIXME(seanmonstar): use AcceptEncoding from Hyper once available
        //if !req.headers.has::<AcceptEncoding>() {
            // We currently don't support HTTP Compression (FIXME #2587)
            req.headers_mut().set_raw("Accept-Encoding".to_owned(), vec![b"identity".to_vec()]);
        //}
        if log_enabled!(log::INFO) {
            info!("{}", load_data.method);
            for header in req.headers().iter() {
                info!(" - {}", header);
            }
            info!("{:?}", load_data.data);
        }

        // Avoid automatically sending request body if a redirect has occurred.
        let writer = match load_data.data {
            Some(ref data) if iters == 1 => {
                req.headers_mut().set(ContentLength(data.len() as u64));
                let mut writer = match req.start() {
                    Ok(w) => w,
                    Err(e) => {
                        send_error(url, e.description().to_string(), senders);
                        return;
                    }
                };
                match writer.write_all(&*data) {
                    Err(e) => {
                        send_error(url, e.desc.to_string(), senders);
                        return;
                    }
                    _ => {}
                };
                writer
            },
            _ => {
                match load_data.method {
                    Method::Get | Method::Head => (),
                    _ => req.headers_mut().set(ContentLength(0))
                }
                match req.start() {
                    Ok(w) => w,
                    Err(e) => {
                        send_error(url, e.description().to_string(), senders);
                        return;
                    }
                }
            }
        };
        let mut response = match writer.send() {
            Ok(r) => r,
            Err(e) => {
                send_error(url, e.description().to_string(), senders);
                return;
            }
        };

        // Dump headers, but only do the iteration if info!() is enabled.
        info!("got HTTP response {}, headers:", response.status);
        if log_enabled!(log::INFO) {
            for header in response.headers.iter() {
                info!(" - {}", header);
            }
        }

        if let Some(cookies) = response.headers.get_raw("set-cookie") {
            for cookie in cookies.iter() {
                if let Ok(cookies) = String::from_utf8(cookie.clone()) {
                    cookies_chan.send(ControlMsg::SetCookiesForUrl(url.clone(),
                                                                   cookies,
                                                                   CookieSource::HTTP)).unwrap();
                }
            }
        }

        if response.status.class() == StatusClass::Redirection {
            match response.headers.get::<Location>() {
                Some(&Location(ref new_url)) => {
                    // CORS (http://fetch.spec.whatwg.org/#http-fetch, status section, point 9, 10)
                    match load_data.cors {
                        Some(ref c) => {
                            if c.preflight {
                                // The preflight lied
                                send_error(url, "Preflight fetch inconsistent with main fetch".to_string(), senders);
                                return;
                            } else {
                                // XXXManishearth There are some CORS-related steps here,
                                // but they don't seem necessary until credentials are implemented
                            }
                        }
                        _ => {}
                    }
                    let new_url = match UrlParser::new().base_url(&url).parse(new_url.as_slice()) {
                        Ok(u) => u,
                        Err(e) => {
                            send_error(url, e.to_string(), senders);
                            return;
                        }
                    };
                    info!("redirecting to {}", new_url);
                    url = new_url;

                    // According to https://tools.ietf.org/html/rfc7231#section-6.4.2,
                    // historically UAs have rewritten POST->GET on 301 and 302 responses.
                    if load_data.method == Method::Post &&
                        (response.status == StatusCode::MovedPermanently ||
                         response.status == StatusCode::Found) {
                        load_data.method = Method::Get;
                    }

                    if redirected_to.contains(&url) {
                        send_error(url, "redirect loop".to_string(), senders);
                        return;
                    }

                    redirected_to.insert(url.clone());
                    continue;
                }
                None => ()
            }
        }

        let mut metadata = Metadata::default(url);
        metadata.set_content_type(match response.headers.get() {
            Some(&ContentType(ref mime)) => Some(mime),
            None => None
        });
        metadata.headers = Some(response.headers.clone());
        metadata.status = Some(response.status_raw().clone());

        let progress_chan = match start_sending_opt(senders, metadata) {
            Ok(p) => p,
            _ => return
        };
        loop {
            let mut buf = Vec::with_capacity(1024);

            unsafe { buf.set_len(1024); }
            match response.read(buf.as_mut_slice()) {
                Ok(len) => {
                    unsafe { buf.set_len(len); }
                    if progress_chan.send(Payload(buf)).is_err() {
                        // The send errors when the receiver is out of scope,
                        // which will happen if the fetch has timed out (or has been aborted)
                        // so we don't need to continue with the loading of the file here.
                        return;
                    }
                }
                Err(_) => {
                    let _ = progress_chan.send(Done(Ok(())));
                    break;
                }
            }
        }

        // We didn't get redirected.
        break;
    }
}