/* 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 blob_loader::load_blob_sync;
use data_loader::decode;
use devtools_traits::DevtoolsControlMsg;
use fetch::cors_cache::CorsCache;
use filemanager_thread::FileManager;
use http_loader::{HttpState, determine_request_referrer, http_fetch, set_default_accept_language};
use hyper::header::{Accept, AcceptLanguage, ContentLanguage, ContentType};
use hyper::header::{HeaderView, QualityItem, Referer as RefererHeader, q, qitem};
use hyper::method::Method;
use hyper::mime::{Mime, SubLevel, TopLevel};
use hyper::status::StatusCode;
use mime_guess::guess_mime_type;
use net_traits::{FetchTaskTarget, NetworkError, ReferrerPolicy};
use net_traits::request::{RedirectMode, Referrer, Request, RequestMode, ResponseTainting};
use net_traits::request::{Type, Origin, Window};
use net_traits::response::{Response, ResponseBody, ResponseType};
use std::borrow::Cow;
use std::fs::File;
use std::io::Read;
use std::rc::Rc;
use std::sync::mpsc::{Sender, Receiver};

pub type Target = Option<Box<FetchTaskTarget + Send>>;

pub enum Data {
    Payload(Vec<u8>),
    Done,
}

pub struct FetchContext {
    pub state: HttpState,
    pub user_agent: Cow<'static, str>,
    pub devtools_chan: Option<Sender<DevtoolsControlMsg>>,
    pub filemanager: FileManager,
}

pub type DoneChannel = Option<(Sender<Data>, Receiver<Data>)>;

/// [Fetch](https://fetch.spec.whatwg.org#concept-fetch)
pub fn fetch(request: Rc<Request>,
             target: &mut Target,
             context: &FetchContext)
             -> Response {
    fetch_with_cors_cache(request, &mut CorsCache::new(), target, context)
}

pub fn fetch_with_cors_cache(request: Rc<Request>,
                             cache: &mut CorsCache,
                             target: &mut Target,
                             context: &FetchContext)
                             -> Response {
    // Step 1
    if request.window.get() == Window::Client {
        // TODO: Set window to request's client object if client is a Window object
    } else {
        request.window.set(Window::NoWindow);
    }

    // Step 2
    if *request.origin.borrow() == Origin::Client {
        // TODO: set request's origin to request's client's origin
        unimplemented!()
    }

    // Step 3
    if !request.headers.borrow().has::<Accept>() {
        let value = match request.type_ {
            // Substep 2
            _ if request.is_navigation_request() =>
                vec![qitem(mime!(Text / Html)),
                     // FIXME: This should properly generate a MimeType that has a
                     // SubLevel of xhtml+xml (https://github.com/hyperium/mime.rs/issues/22)
                     qitem(mime!(Application / ("xhtml+xml") )),
                     QualityItem::new(mime!(Application / Xml), q(0.9)),
                     QualityItem::new(mime!(_ / _), q(0.8))],

            // Substep 3
            Type::Image =>
                vec![qitem(mime!(Image / Png)),
                     // FIXME: This should properly generate a MimeType that has a
                     // SubLevel of svg+xml (https://github.com/hyperium/mime.rs/issues/22)
                     qitem(mime!(Image / ("svg+xml") )),
                     QualityItem::new(mime!(Image / _), q(0.8)),
                     QualityItem::new(mime!(_ / _), q(0.5))],

            // Substep 3
            Type::Style =>
                vec![qitem(mime!(Text / Css)),
                     QualityItem::new(mime!(_ / _), q(0.1))],
            // Substep 1
            _ => vec![qitem(mime!(_ / _))]
        };

        // Substep 4
        request.headers.borrow_mut().set(Accept(value));
    }

    // Step 4
    set_default_accept_language(&mut request.headers.borrow_mut());

    // Step 5
    // TODO: Figure out what a Priority object is

    // Step 6
    if request.is_subresource_request() {
        // TODO: create a fetch record and append it to request's client's fetch group list
    }

    // Step 7
    main_fetch(request, cache, false, false, target, &mut None, &context)
}

/// [Main fetch](https://fetch.spec.whatwg.org/#concept-main-fetch)
pub fn main_fetch(request: Rc<Request>,
                  cache: &mut CorsCache,
                  cors_flag: bool,
                  recursive_flag: bool,
                  target: &mut Target,
                  done_chan: &mut DoneChannel,
                  context: &FetchContext)
                  -> Response {
    // TODO: Implement main fetch spec

    // Step 1
    let mut response = None;

    // Step 2
    if request.local_urls_only {
        match request.current_url().scheme() {
            "about" | "blob" | "data" | "filesystem" => (), // Ok, the URL is local.
            _ => response = Some(Response::network_error(NetworkError::Internal("Non-local scheme".into())))
        }
    }

    // Step 3
    // TODO be able to execute report CSP

    // Step 4
    // TODO this step, based off of http_loader.rs (upgrade)

    // Step 5
    // TODO this step (CSP port/content blocking)

    // Step 6
    // TODO this step (referrer policy)
    // currently the clients themselves set referrer policy in RequestInit

    // Step 7
    if request.referrer_policy.get().is_none() {
        request.referrer_policy.set(Some(ReferrerPolicy::NoReferrerWhenDowngrade));
    }

    // Step 8
    if *request.referrer.borrow() != Referrer::NoReferrer {
        // remove Referrer headers set in past redirects/preflights
        // this stops the assertion in determine_request_referrer from failing
        request.headers.borrow_mut().remove::<RefererHeader>();
        let referrer_url = determine_request_referrer(&mut *request.headers.borrow_mut(),
                                                      request.referrer_policy.get(),
                                                      request.referrer.borrow_mut().take(),
                                                      request.current_url().clone());
        *request.referrer.borrow_mut() = Referrer::from_url(referrer_url);
    }

    // Step 9
    // TODO this step (HSTS)

    // Step 10
    // this step is obsoleted by fetch_async

    // Step 11
    let response = match response {
        Some(response) => response,
        None => {
            let current_url = request.current_url();
            let same_origin = if let Origin::Origin(ref origin) = *request.origin.borrow() {
                *origin == current_url.origin()
            } else {
                false
            };

            if (same_origin && !cors_flag ) ||
                current_url.scheme() == "data" ||
                current_url.scheme() == "file" ||
                current_url.scheme() == "about" ||
                request.mode == RequestMode::Navigate {
                basic_fetch(request.clone(), cache, target, done_chan, context)

            } else if request.mode == RequestMode::SameOrigin {
                Response::network_error(NetworkError::Internal("Cross-origin response".into()))

            } else if request.mode == RequestMode::NoCors {
                request.response_tainting.set(ResponseTainting::Opaque);
                basic_fetch(request.clone(), cache, target, done_chan, context)

            } else if !matches!(current_url.scheme(), "http" | "https") {
                Response::network_error(NetworkError::Internal("Non-http scheme".into()))

            } else if request.use_cors_preflight ||
                (request.unsafe_request &&
                 (!is_simple_method(&request.method.borrow()) ||
                  request.headers.borrow().iter().any(|h| !is_simple_header(&h)))) {
                request.response_tainting.set(ResponseTainting::CorsTainting);
                request.redirect_mode.set(RedirectMode::Error);
                let response = http_fetch(request.clone(), cache, true, true, false,
                                          target, done_chan, context);
                if response.is_network_error() {
                    // TODO clear cache entries using request
                }
                response

            } else {
                request.response_tainting.set(ResponseTainting::CorsTainting);
                http_fetch(request.clone(), cache, true, false, false, target, done_chan, context)
            }
        }
    };

    // Step 12
    if recursive_flag {
        return response;
    }

    // Step 13
    // no need to check if response is a network error, since the type would not be `Default`
    let response = if response.response_type == ResponseType::Default {
        let response_type = match request.response_tainting.get() {
            ResponseTainting::Basic => ResponseType::Basic,
            ResponseTainting::CorsTainting => ResponseType::Cors,
            ResponseTainting::Opaque => ResponseType::Opaque,
        };
        response.to_filtered(response_type)
    } else {
        response
    };

    {
        // Step 14
        let network_error_res;
        let internal_response = if let Some(error) = response.get_network_error() {
            network_error_res = Response::network_error(error.clone());
            &network_error_res
        } else {
            response.actual_response()
        };

        // Step 15
        if internal_response.url_list.borrow().is_empty() {
            *internal_response.url_list.borrow_mut() = request.url_list.borrow().clone();
        }

        // Step 16
        // TODO this step (CSP/blocking)

        // Step 17
        if !response.is_network_error() && (is_null_body_status(&internal_response.status) ||
            match *request.method.borrow() {
                Method::Head | Method::Connect => true,
                _ => false })
            {
            // when Fetch is used only asynchronously, we will need to make sure
            // that nothing tries to write to the body at this point
            let mut body = internal_response.body.lock().unwrap();
            *body = ResponseBody::Empty;
        }

        // Step 18
        // TODO be able to compare response integrity against request integrity metadata
        // if !response.is_network_error() {

        //     // Substep 1
        //     response.wait_until_done();

        //     // Substep 2
        //     if response.termination_reason.is_none() {
        //         response = Response::network_error();
        //         internal_response = Response::network_error();
        //     }
        // }
    }

    // Step 19
    if request.synchronous {
        if let Some(ref mut target) = *target {
            // process_response is not supposed to be used
            // by sync fetch, but we overload it here for simplicity
            target.process_response(&response);
        }

        if let Some(ref ch) = *done_chan {
            loop {
                match ch.1.recv()
                        .expect("fetch worker should always send Done before terminating") {
                    Data::Payload(vec) => {
                        if let Some(ref mut target) = *target {
                            target.process_response_chunk(vec);
                        }
                    }
                    Data::Done => break,
                }
            }
        } else {
            let body = response.body.lock().unwrap();
            if let ResponseBody::Done(ref vec) = *body {
                // in case there was no channel to wait for, the body was
                // obtained synchronously via basic_fetch for data/file/about/etc
                // We should still send the body across as a chunk
                if let Some(ref mut target) = *target {
                    target.process_response_chunk(vec.clone());
                }
            } else {
                assert!(*body == ResponseBody::Empty)
            }
        }

        // overloaded similarly to process_response
        if let Some(ref mut target) = *target {
            target.process_response_eof(&response);
        }
        return response;
    }

    // Step 20
    if request.body.borrow().is_some() && matches!(request.current_url().scheme(), "http" | "https") {
        if let Some(ref mut target) = *target {
            // XXXManishearth: We actually should be calling process_request
            // in http_network_fetch. However, we can't yet follow the request
            // upload progress, so I'm keeping it here for now and pretending
            // the body got sent in one chunk
            target.process_request_body(&request);
            target.process_request_eof(&request);
        }
    }

    // Step 21
    if let Some(ref mut target) = *target {
        target.process_response(&response);
    }

    // Step 22
    if let Some(ref ch) = *done_chan {
        loop {
            match ch.1.recv()
                    .expect("fetch worker should always send Done before terminating") {
                Data::Payload(vec) => {
                    if let Some(ref mut target) = *target {
                        target.process_response_chunk(vec);
                    }
                }
                Data::Done => break,
            }
        }
    } else if let Some(ref mut target) = *target {
        let body = response.body.lock().unwrap();
        if let ResponseBody::Done(ref vec) = *body {
            // in case there was no channel to wait for, the body was
            // obtained synchronously via basic_fetch for data/file/about/etc
            // We should still send the body across as a chunk
            target.process_response_chunk(vec.clone());
        } else {
            assert!(*body == ResponseBody::Empty)
        }
    }

    // Step 23
    request.done.set(true);

    // Step 24
    if let Some(ref mut target) = *target {
        target.process_response_eof(&response);
    }

    // TODO remove this line when only asynchronous fetches are used
    return response;
}

/// [Basic fetch](https://fetch.spec.whatwg.org#basic-fetch)
fn basic_fetch(request: Rc<Request>,
               cache: &mut CorsCache,
               target: &mut Target,
               done_chan: &mut DoneChannel,
               context: &FetchContext)
               -> Response {
    let url = request.current_url();

    match url.scheme() {
        "about" if url.path() == "blank" => {
            let mut response = Response::new(url);
            response.headers.set(ContentType(mime!(Text / Html; Charset = Utf8)));
            *response.body.lock().unwrap() = ResponseBody::Done(vec![]);
            response
        },

        "http" | "https" => {
            http_fetch(request.clone(), cache, false, false, false, target, done_chan, context)
        },

        "data" => {
            if *request.method.borrow() == Method::Get {
                match decode(&url) {
                    Ok((mime, bytes)) => {
                        let mut response = Response::new(url);
                        *response.body.lock().unwrap() = ResponseBody::Done(bytes);
                        response.headers.set(ContentType(mime));
                        response
                    },
                    Err(_) => Response::network_error(NetworkError::Internal("Decoding data URL failed".into()))
                }
            } else {
                Response::network_error(NetworkError::Internal("Unexpected method for data".into()))
            }
        },

        "file" => {
            if *request.method.borrow() == Method::Get {
                match url.to_file_path() {
                    Ok(file_path) => {
                        match File::open(file_path.clone()) {
                            Ok(mut file) => {
                                let mut bytes = vec![];
                                let _ = file.read_to_end(&mut bytes);
                                let mime = guess_mime_type(file_path);

                                let mut response = Response::new(url);
                                *response.body.lock().unwrap() = ResponseBody::Done(bytes);
                                response.headers.set(ContentType(mime));
                                response
                            },
                            _ => Response::network_error(NetworkError::Internal("Opening file failed".into())),
                        }
                    },
                    _ => Response::network_error(NetworkError::Internal("Constructing file path failed".into()))
                }
            } else {
                Response::network_error(NetworkError::Internal("Unexpected method for file".into()))
            }
        },

        "blob" => {
            println!("Loading blob {}", url.as_str());
            // Step 2.
            if *request.method.borrow() != Method::Get {
                return Response::network_error(NetworkError::Internal("Unexpected method for blob".into()));
            }

            match load_blob_sync(url.clone(), context.filemanager.clone()) {
                Ok((headers, bytes)) => {
                    let mut response = Response::new(url);
                    response.headers = headers;
                    *response.body.lock().unwrap() = ResponseBody::Done(bytes);
                    response
                },
                Err(e) => {
                    debug!("Failed to load {}: {:?}", url, e);
                    Response::network_error(e)
                },
            }
        },

        "ftp" => {
            debug!("ftp is not implemented");
            Response::network_error(NetworkError::Internal("Unexpected scheme".into()))
        },

        _ => Response::network_error(NetworkError::Internal("Unexpected scheme".into()))
    }
}

/// https://fetch.spec.whatwg.org/#cors-safelisted-request-header
pub fn is_simple_header(h: &HeaderView) -> bool {
    if h.is::<ContentType>() {
        match h.value() {
            Some(&ContentType(Mime(TopLevel::Text, SubLevel::Plain, _))) |
            Some(&ContentType(Mime(TopLevel::Application, SubLevel::WwwFormUrlEncoded, _))) |
            Some(&ContentType(Mime(TopLevel::Multipart, SubLevel::FormData, _))) => true,
            _ => false

        }
    } else {
        h.is::<Accept>() || h.is::<AcceptLanguage>() || h.is::<ContentLanguage>()
    }
}

pub fn is_simple_method(m: &Method) -> bool {
    match *m {
        Method::Get | Method::Head | Method::Post => true,
        _ => false
    }
}

// fn modify_request_headers(headers: &mut Headers) -> {
//     // TODO this function

// }

fn is_null_body_status(status: &Option<StatusCode>) -> bool {
    match *status {
        Some(status) => match status {
            StatusCode::SwitchingProtocols | StatusCode::NoContent |
                StatusCode::ResetContent | StatusCode::NotModified => true,
            _ => false
        },
        _ => false
    }
}