/* 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 cssparser::Parser as CssParser;
use document_loader::LoadType;
use dom::attr::Attr;
use dom::bindings::cell::DOMRefCell;
use dom::bindings::codegen::Bindings::DOMTokenListBinding::DOMTokenListMethods;
use dom::bindings::codegen::Bindings::HTMLLinkElementBinding;
use dom::bindings::codegen::Bindings::HTMLLinkElementBinding::HTMLLinkElementMethods;
use dom::bindings::inheritance::Castable;
use dom::bindings::js::{JS, MutNullableHeap, Root, RootedReference};
use dom::bindings::refcounted::Trusted;
use dom::bindings::reflector::Reflectable;
use dom::bindings::str::DOMString;
use dom::cssstylesheet::CSSStyleSheet;
use dom::document::Document;
use dom::domtokenlist::DOMTokenList;
use dom::element::{AttributeMutation, Element, ElementCreator};
use dom::eventtarget::EventTarget;
use dom::globalscope::GlobalScope;
use dom::htmlelement::HTMLElement;
use dom::node::{Node, document_from_node, window_from_node};
use dom::stylesheet::StyleSheet as DOMStyleSheet;
use dom::virtualmethods::VirtualMethods;
use encoding::EncodingRef;
use encoding::all::UTF_8;
use html5ever_atoms::LocalName;
use hyper::header::ContentType;
use hyper::mime::{Mime, TopLevel, SubLevel};
use hyper_serde::Serde;
use ipc_channel::ipc;
use ipc_channel::router::ROUTER;
use net_traits::{FetchResponseListener, FetchMetadata, Metadata, NetworkError, ReferrerPolicy};
use net_traits::request::{CredentialsMode, Destination, RequestInit, Type as RequestType};
use network_listener::{NetworkListener, PreInvoke};
use script_layout_interface::message::Msg;
use script_traits::{MozBrowserEvent, ScriptMsg as ConstellationMsg};
use servo_url::ServoUrl;
use std::ascii::AsciiExt;
use std::borrow::ToOwned;
use std::cell::Cell;
use std::default::Default;
use std::mem;
use std::sync::{Arc, Mutex};
use style::attr::AttrValue;
use style::media_queries::{MediaList, parse_media_query_list};
use style::parser::ParserContextExtraData;
use style::str::HTML_SPACE_CHARACTERS;
use style::stylesheets::{Stylesheet, Origin};

unsafe_no_jsmanaged_fields!(Stylesheet);

#[dom_struct]
pub struct HTMLLinkElement {
    htmlelement: HTMLElement,
    rel_list: MutNullableHeap<JS<DOMTokenList>>,
    #[ignore_heap_size_of = "Arc"]
    stylesheet: DOMRefCell<Option<Arc<Stylesheet>>>,
    cssom_stylesheet: MutNullableHeap<JS<CSSStyleSheet>>,

    /// https://html.spec.whatwg.org/multipage/#a-style-sheet-that-is-blocking-scripts
    parser_inserted: Cell<bool>,
}

impl HTMLLinkElement {
    fn new_inherited(local_name: LocalName, prefix: Option<DOMString>, document: &Document,
                     creator: ElementCreator) -> HTMLLinkElement {
        HTMLLinkElement {
            htmlelement: HTMLElement::new_inherited(local_name, prefix, document),
            rel_list: Default::default(),
            parser_inserted: Cell::new(creator == ElementCreator::ParserCreated),
            stylesheet: DOMRefCell::new(None),
            cssom_stylesheet: MutNullableHeap::new(None),
        }
    }

    #[allow(unrooted_must_root)]
    pub fn new(local_name: LocalName,
               prefix: Option<DOMString>,
               document: &Document,
               creator: ElementCreator) -> Root<HTMLLinkElement> {
        Node::reflect_node(box HTMLLinkElement::new_inherited(local_name, prefix, document, creator),
                           document,
                           HTMLLinkElementBinding::Wrap)
    }

    pub fn get_stylesheet(&self) -> Option<Arc<Stylesheet>> {
        self.stylesheet.borrow().clone()
    }

    pub fn get_cssom_stylesheet(&self) -> Option<Root<CSSStyleSheet>> {
        self.get_stylesheet().map(|sheet| {
            self.cssom_stylesheet.or_init(|| {
                CSSStyleSheet::new(&window_from_node(self),
                                   self.upcast::<Element>(),
                                   "text/css".into(),
                                   None, // todo handle location
                                   None, // todo handle title
                                   sheet)
            })
        })
    }
}

fn get_attr(element: &Element, local_name: &LocalName) -> Option<String> {
    let elem = element.get_attribute(&ns!(), local_name);
    elem.map(|e| {
        let value = e.value();
        (**value).to_owned()
    })
}

fn string_is_stylesheet(value: &Option<String>) -> bool {
    match *value {
        Some(ref value) => {
            let mut found_stylesheet = false;
            for s in value.split(HTML_SPACE_CHARACTERS).into_iter() {
                if s.eq_ignore_ascii_case("alternate") {
                    return false;
                }

                if s.eq_ignore_ascii_case("stylesheet") {
                    found_stylesheet = true;
                }
            }
            found_stylesheet
        },
        None => false,
    }
}

/// Favicon spec usage in accordance with CEF implementation:
/// only url of icon is required/used
/// https://html.spec.whatwg.org/multipage/#rel-icon
fn is_favicon(value: &Option<String>) -> bool {
    match *value {
        Some(ref value) => {
            value.split(HTML_SPACE_CHARACTERS)
                .any(|s| s.eq_ignore_ascii_case("icon") || s.eq_ignore_ascii_case("apple-touch-icon"))
        },
        None => false,
    }
}

impl VirtualMethods for HTMLLinkElement {
    fn super_type(&self) -> Option<&VirtualMethods> {
        Some(self.upcast::<HTMLElement>() as &VirtualMethods)
    }

    fn attribute_mutated(&self, attr: &Attr, mutation: AttributeMutation) {
        self.super_type().unwrap().attribute_mutated(attr, mutation);
        if !self.upcast::<Node>().is_in_doc() || mutation == AttributeMutation::Removed {
            return;
        }

        let rel = get_attr(self.upcast(), &local_name!("rel"));
        match attr.local_name() {
            &local_name!("href") => {
                if string_is_stylesheet(&rel) {
                    self.handle_stylesheet_url(&attr.value());
                } else if is_favicon(&rel) {
                    let sizes = get_attr(self.upcast(), &local_name!("sizes"));
                    self.handle_favicon_url(rel.as_ref().unwrap(), &attr.value(), &sizes);
                }
            },
            &local_name!("sizes") => {
                if is_favicon(&rel) {
                    if let Some(ref href) = get_attr(self.upcast(), &local_name!("href")) {
                        self.handle_favicon_url(rel.as_ref().unwrap(), href, &Some(attr.value().to_string()));
                    }
                }
            },
            &local_name!("media") => {
                if string_is_stylesheet(&rel) {
                    if let Some(href) = self.upcast::<Element>().get_attribute(&ns!(), &local_name!("href")) {
                        self.handle_stylesheet_url(&href.value());
                    }
                }
            },
            _ => {},
        }
    }

    fn parse_plain_attribute(&self, name: &LocalName, value: DOMString) -> AttrValue {
        match name {
            &local_name!("rel") => AttrValue::from_serialized_tokenlist(value.into()),
            _ => self.super_type().unwrap().parse_plain_attribute(name, value),
        }
    }

    fn bind_to_tree(&self, tree_in_doc: bool) {
        if let Some(ref s) = self.super_type() {
            s.bind_to_tree(tree_in_doc);
        }

        if tree_in_doc {
            let element = self.upcast();

            let rel = get_attr(element, &local_name!("rel"));
            let href = get_attr(element, &local_name!("href"));
            let sizes = get_attr(self.upcast(), &local_name!("sizes"));

            match href {
                Some(ref href) if string_is_stylesheet(&rel) => {
                    self.handle_stylesheet_url(href);
                }
                Some(ref href) if is_favicon(&rel) => {
                    self.handle_favicon_url(rel.as_ref().unwrap(), href, &sizes);
                }
                _ => {}
            }
        }
    }
}


impl HTMLLinkElement {
    /// https://html.spec.whatwg.org/multipage/#concept-link-obtain
    fn handle_stylesheet_url(&self, href: &str) {
        let document = document_from_node(self);
        if document.browsing_context().is_none() {
            return;
        }

        // Step 1.
        if href.is_empty() {
            return;
        }

        // Step 2.
        let url = match document.base_url().join(href) {
            Err(e) => return debug!("Parsing url {} failed: {}", href, e),
            Ok(url) => url,
        };

        let element = self.upcast::<Element>();

        let mq_attribute = element.get_attribute(&ns!(), &local_name!("media"));
        let value = mq_attribute.r().map(|a| a.value());
        let mq_str = match value {
            Some(ref value) => &***value,
            None => "",
        };
        let mut css_parser = CssParser::new(&mq_str);
        let media = parse_media_query_list(&mut css_parser);

        // TODO: #8085 - Don't load external stylesheets if the node's mq doesn't match.
        let elem = Trusted::new(self);

        let context = Arc::new(Mutex::new(StylesheetContext {
            elem: elem,
            media: Some(media),
            data: vec!(),
            metadata: None,
            url: url.clone(),
        }));

        let (action_sender, action_receiver) = ipc::channel().unwrap();
        let listener = NetworkListener {
            context: context,
            task_source: document.window().networking_task_source(),
            wrapper: Some(document.window().get_runnable_wrapper())
        };
        ROUTER.add_route(action_receiver.to_opaque(), box move |message| {
            listener.notify_fetch(message.to().unwrap());
        });

        if self.parser_inserted.get() {
            document.increment_script_blocking_stylesheet_count();
        }

        let referrer_policy = match self.RelList().Contains("noreferrer".into()) {
            true => Some(ReferrerPolicy::NoReferrer),
            false => document.get_referrer_policy(),
        };

        let request = RequestInit {
            url: url.clone(),
            type_: RequestType::Style,
            destination: Destination::Style,
            credentials_mode: CredentialsMode::Include,
            use_url_credentials: true,
            origin: document.url(),
            pipeline_id: Some(self.global().pipeline_id()),
            referrer_url: Some(document.url()),
            referrer_policy: referrer_policy,
            .. RequestInit::default()
        };

        document.fetch_async(LoadType::Stylesheet(url), request, action_sender);
    }

    fn handle_favicon_url(&self, rel: &str, href: &str, sizes: &Option<String>) {
        let document = document_from_node(self);
        match document.base_url().join(href) {
            Ok(url) => {
                let event = ConstellationMsg::NewFavicon(url.clone());
                document.window().upcast::<GlobalScope>().constellation_chan().send(event).unwrap();

                let mozbrowser_event = match *sizes {
                    Some(ref sizes) => MozBrowserEvent::IconChange(rel.to_owned(), url.to_string(), sizes.to_owned()),
                    None => MozBrowserEvent::IconChange(rel.to_owned(), url.to_string(), "".to_owned())
                };
                document.trigger_mozbrowser_event(mozbrowser_event);
            }
            Err(e) => debug!("Parsing url {} failed: {}", href, e)
        }
    }
}

/// The context required for asynchronously loading an external stylesheet.
struct StylesheetContext {
    /// The element that initiated the request.
    elem: Trusted<HTMLLinkElement>,
    media: Option<MediaList>,
    /// The response body received to date.
    data: Vec<u8>,
    /// The response metadata received to date.
    metadata: Option<Metadata>,
    /// The initial URL requested.
    url: ServoUrl,
}

impl PreInvoke for StylesheetContext {}

impl FetchResponseListener for StylesheetContext {
    fn process_request_body(&mut self) {}

    fn process_request_eof(&mut self) {}

    fn process_response(&mut self,
                        metadata: Result<FetchMetadata, NetworkError>) {
        self.metadata = metadata.ok().map(|m| {
            match m {
                FetchMetadata::Unfiltered(m) => m,
                FetchMetadata::Filtered { unsafe_, .. } => unsafe_
            }
        });
        if let Some(ref meta) = self.metadata {
            if let Some(Serde(ContentType(Mime(TopLevel::Text, SubLevel::Css, _)))) = meta.content_type {
            } else {
                self.elem.root().upcast::<EventTarget>().fire_event(atom!("error"));
            }
        }
    }

    fn process_response_chunk(&mut self, mut payload: Vec<u8>) {
        self.data.append(&mut payload);
    }

    fn process_response_eof(&mut self, status: Result<(), NetworkError>) {
        let elem = self.elem.root();
        let document = document_from_node(&*elem);
        let mut successful = false;

        if status.is_ok() {
            let metadata = match self.metadata.take() {
                Some(meta) => meta,
                None => return,
            };
            let is_css = metadata.content_type.map_or(false, |Serde(ContentType(Mime(top, sub, _)))|
                top == TopLevel::Text && sub == SubLevel::Css);

            let data = if is_css { mem::replace(&mut self.data, vec!()) } else { vec!() };

            // TODO: Get the actual value. http://dev.w3.org/csswg/css-syntax/#environment-encoding
            let environment_encoding = UTF_8 as EncodingRef;
            let protocol_encoding_label = metadata.charset.as_ref().map(|s| &**s);
            let final_url = metadata.final_url;

            let win = window_from_node(&*elem);

            let sheet = Arc::new(Stylesheet::from_bytes(
                &data, final_url, protocol_encoding_label, Some(environment_encoding),
                Origin::Author, self.media.take().unwrap(), win.css_error_reporter(),
                ParserContextExtraData::default()));

            let win = window_from_node(&*elem);
            win.layout_chan().send(Msg::AddStylesheet(sheet.clone())).unwrap();

            *elem.stylesheet.borrow_mut() = Some(sheet);
            document.invalidate_stylesheets();

            // FIXME: Revisit once consensus is reached at: https://github.com/whatwg/html/issues/1142
            successful = metadata.status.map_or(false, |(code, _)| code == 200);
        }

        if elem.parser_inserted.get() {
            document.decrement_script_blocking_stylesheet_count();
        }

        document.finish_load(LoadType::Stylesheet(self.url.clone()));

        let event = if successful { atom!("load") } else { atom!("error") };

        elem.upcast::<EventTarget>().fire_event(event);
    }
}

impl HTMLLinkElementMethods for HTMLLinkElement {
    // https://html.spec.whatwg.org/multipage/#dom-link-href
    make_url_getter!(Href, "href");

    // https://html.spec.whatwg.org/multipage/#dom-link-href
    make_setter!(SetHref, "href");

    // https://html.spec.whatwg.org/multipage/#dom-link-rel
    make_getter!(Rel, "rel");

    // https://html.spec.whatwg.org/multipage/#dom-link-rel
    fn SetRel(&self, rel: DOMString) {
        self.upcast::<Element>().set_tokenlist_attribute(&local_name!("rel"), rel);
    }

    // https://html.spec.whatwg.org/multipage/#dom-link-media
    make_getter!(Media, "media");

    // https://html.spec.whatwg.org/multipage/#dom-link-media
    make_setter!(SetMedia, "media");

    // https://html.spec.whatwg.org/multipage/#dom-link-hreflang
    make_getter!(Hreflang, "hreflang");

    // https://html.spec.whatwg.org/multipage/#dom-link-hreflang
    make_setter!(SetHreflang, "hreflang");

    // https://html.spec.whatwg.org/multipage/#dom-link-type
    make_getter!(Type, "type");

    // https://html.spec.whatwg.org/multipage/#dom-link-type
    make_setter!(SetType, "type");

    // https://html.spec.whatwg.org/multipage/#dom-link-rellist
    fn RelList(&self) -> Root<DOMTokenList> {
        self.rel_list.or_init(|| DOMTokenList::new(self.upcast(), &local_name!("rel")))
    }

    // https://html.spec.whatwg.org/multipage/#dom-link-charset
    make_getter!(Charset, "charset");

    // https://html.spec.whatwg.org/multipage/#dom-link-charset
    make_setter!(SetCharset, "charset");

    // https://html.spec.whatwg.org/multipage/#dom-link-rev
    make_getter!(Rev, "rev");

    // https://html.spec.whatwg.org/multipage/#dom-link-rev
    make_setter!(SetRev, "rev");

    // https://html.spec.whatwg.org/multipage/#dom-link-target
    make_getter!(Target, "target");

    // https://html.spec.whatwg.org/multipage/#dom-link-target
    make_setter!(SetTarget, "target");

    // https://drafts.csswg.org/cssom/#dom-linkstyle-sheet
    fn GetSheet(&self) -> Option<Root<DOMStyleSheet>> {
        self.get_cssom_stylesheet().map(Root::upcast)
    }
}