/* 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 dom::attr::{Attr, AttrHelpers, AttrValue};
use dom::bindings::cell::DOMRefCell;
use dom::bindings::codegen::Bindings::DocumentBinding;
use dom::bindings::codegen::Bindings::DocumentBinding::{DocumentMethods, DocumentReadyState};
use dom::bindings::codegen::Bindings::EventHandlerBinding::EventHandlerNonNull;
use dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetMethods;
use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
use dom::bindings::codegen::Bindings::NodeFilterBinding::NodeFilter;
use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
use dom::bindings::codegen::InheritTypes::{DocumentDerived, EventCast, HTMLElementCast};
use dom::bindings::codegen::InheritTypes::{HTMLHeadElementCast, TextCast, ElementCast};
use dom::bindings::codegen::InheritTypes::{DocumentTypeCast, HTMLHtmlElementCast, NodeCast};
use dom::bindings::codegen::InheritTypes::{EventTargetCast, HTMLAnchorElementCast};
use dom::bindings::codegen::InheritTypes::{HTMLAnchorElementDerived, HTMLAppletElementDerived};
use dom::bindings::codegen::InheritTypes::{HTMLAreaElementDerived, HTMLEmbedElementDerived};
use dom::bindings::codegen::InheritTypes::{HTMLFormElementDerived, HTMLImageElementDerived};
use dom::bindings::codegen::InheritTypes::{HTMLScriptElementDerived};
use dom::bindings::error::{ErrorResult, Fallible};
use dom::bindings::error::Error::{NotSupported, InvalidCharacter};
use dom::bindings::error::Error::{HierarchyRequest, NamespaceError};
use dom::bindings::global::GlobalRef;
use dom::bindings::js::{MutNullableJS, JS, JSRef, Temporary, OptionalSettable, TemporaryPushable};
use dom::bindings::js::OptionalRootable;
use dom::bindings::utils::reflect_dom_object;
use dom::bindings::utils::xml_name_type;
use dom::bindings::utils::XMLName::{QName, Name, InvalidXMLName};
use dom::comment::Comment;
use dom::customevent::CustomEvent;
use dom::documentfragment::DocumentFragment;
use dom::documenttype::DocumentType;
use dom::domimplementation::DOMImplementation;
use dom::element::{Element, ElementCreator, AttributeHandlers, get_attribute_parts};
use dom::element::ElementTypeId;
use dom::event::{Event, EventBubbles, EventCancelable};
use dom::eventtarget::{EventTarget, EventTargetTypeId, EventTargetHelpers};
use dom::htmlanchorelement::HTMLAnchorElement;
use dom::htmlcollection::{HTMLCollection, CollectionFilter};
use dom::htmlelement::HTMLElement;
use dom::htmlheadelement::HTMLHeadElement;
use dom::htmlhtmlelement::HTMLHtmlElement;
use dom::htmltitleelement::HTMLTitleElement;
use dom::location::Location;
use dom::mouseevent::MouseEvent;
use dom::keyboardevent::KeyboardEvent;
use dom::messageevent::MessageEvent;
use dom::node::{Node, NodeHelpers, NodeTypeId, CloneChildrenFlag, NodeDamage};
use dom::nodelist::NodeList;
use dom::text::Text;
use dom::processinginstruction::ProcessingInstruction;
use dom::range::Range;
use dom::treewalker::TreeWalker;
use dom::uievent::UIEvent;
use dom::window::{Window, WindowHelpers};
use servo_util::namespace;
use servo_util::str::{DOMString, split_html_space_chars};

use html5ever::tree_builder::{QuirksMode, NoQuirks, LimitedQuirks, Quirks};
use layout_interface::{LayoutChan, Msg};
use string_cache::{Atom, QualName};
use url::Url;

use std::collections::HashMap;
use std::collections::hash_map::{Vacant, Occupied};
use std::ascii::AsciiExt;
use std::cell::{Cell, Ref};
use std::default::Default;
use time;

#[deriving(PartialEq)]
#[jstraceable]
pub enum IsHTMLDocument {
    HTMLDocument,
    NonHTMLDocument,
}

#[dom_struct]
pub struct Document {
    node: Node,
    window: JS<Window>,
    idmap: DOMRefCell<HashMap<Atom, Vec<JS<Element>>>>,
    implementation: MutNullableJS<DOMImplementation>,
    content_type: DOMString,
    last_modified: DOMRefCell<Option<DOMString>>,
    encoding_name: DOMRefCell<DOMString>,
    is_html_document: bool,
    url: Url,
    quirks_mode: Cell<QuirksMode>,
    images: MutNullableJS<HTMLCollection>,
    embeds: MutNullableJS<HTMLCollection>,
    links: MutNullableJS<HTMLCollection>,
    forms: MutNullableJS<HTMLCollection>,
    scripts: MutNullableJS<HTMLCollection>,
    anchors: MutNullableJS<HTMLCollection>,
    applets: MutNullableJS<HTMLCollection>,
    ready_state: Cell<DocumentReadyState>,
    /// The element that has most recently requested focus for itself.
    possibly_focused: MutNullableJS<Element>,
    /// The element that currently has the document focus context.
    focused: MutNullableJS<Element>,
}

impl DocumentDerived for EventTarget {
    fn is_document(&self) -> bool {
        *self.type_id() == EventTargetTypeId::Node(NodeTypeId::Document)
    }
}

#[jstraceable]
struct ImagesFilter;
impl CollectionFilter for ImagesFilter {
    fn filter(&self, elem: JSRef<Element>, _root: JSRef<Node>) -> bool {
        elem.is_htmlimageelement()
    }
}

#[jstraceable]
struct EmbedsFilter;
impl CollectionFilter for EmbedsFilter {
    fn filter(&self, elem: JSRef<Element>, _root: JSRef<Node>) -> bool {
        elem.is_htmlembedelement()
    }
}

#[jstraceable]
struct LinksFilter;
impl CollectionFilter for LinksFilter {
    fn filter(&self, elem: JSRef<Element>, _root: JSRef<Node>) -> bool {
        (elem.is_htmlanchorelement() || elem.is_htmlareaelement()) &&
            elem.has_attribute(&atom!("href"))
    }
}

#[jstraceable]
struct FormsFilter;
impl CollectionFilter for FormsFilter {
    fn filter(&self, elem: JSRef<Element>, _root: JSRef<Node>) -> bool {
        elem.is_htmlformelement()
    }
}

#[jstraceable]
struct ScriptsFilter;
impl CollectionFilter for ScriptsFilter {
    fn filter(&self, elem: JSRef<Element>, _root: JSRef<Node>) -> bool {
        elem.is_htmlscriptelement()
    }
}

#[jstraceable]
struct AnchorsFilter;
impl CollectionFilter for AnchorsFilter {
    fn filter(&self, elem: JSRef<Element>, _root: JSRef<Node>) -> bool {
        elem.is_htmlanchorelement() && elem.has_attribute(&atom!("href"))
    }
}

#[jstraceable]
struct AppletsFilter;
impl CollectionFilter for AppletsFilter {
    fn filter(&self, elem: JSRef<Element>, _root: JSRef<Node>) -> bool {
        elem.is_htmlappletelement()
    }
}

pub trait DocumentHelpers<'a> {
    fn window(self) -> Temporary<Window>;
    fn encoding_name(self) -> Ref<'a, DOMString>;
    fn is_html_document(self) -> bool;
    fn url(self) -> &'a Url;
    fn quirks_mode(self) -> QuirksMode;
    fn set_quirks_mode(self, mode: QuirksMode);
    fn set_last_modified(self, value: DOMString);
    fn set_encoding_name(self, name: DOMString);
    fn content_changed(self, node: JSRef<Node>, damage: NodeDamage);
    fn content_and_heritage_changed(self, node: JSRef<Node>, damage: NodeDamage);
    fn unregister_named_element(self, to_unregister: JSRef<Element>, id: Atom);
    fn register_named_element(self, element: JSRef<Element>, id: Atom);
    fn load_anchor_href(self, href: DOMString);
    fn find_fragment_node(self, fragid: DOMString) -> Option<Temporary<Element>>;
    fn set_ready_state(self, state: DocumentReadyState);
    fn get_focused_element(self) -> Option<Temporary<Element>>;
    fn begin_focus_transaction(self);
    fn request_focus(self, elem: JSRef<Element>);
    fn commit_focus_transaction(self);
    fn send_title_to_compositor(self);
    fn dirty_all_nodes(self);
}

impl<'a> DocumentHelpers<'a> for JSRef<'a, Document> {
    #[inline]
    fn window(self) -> Temporary<Window> {
        Temporary::new(self.window)
    }

    #[inline]
    fn encoding_name(self) -> Ref<'a, DOMString> {
        self.extended_deref().encoding_name.borrow()
    }

    #[inline]
    fn is_html_document(self) -> bool {
        self.is_html_document
    }

    fn url(self) -> &'a Url {
        &self.extended_deref().url
    }

    fn quirks_mode(self) -> QuirksMode {
        self.quirks_mode.get()
    }

    fn set_quirks_mode(self, mode: QuirksMode) {
        self.quirks_mode.set(mode);

        match mode {
            Quirks => {
                let window = self.window.root();
                let LayoutChan(ref layout_chan) = window.page().layout_chan;
                layout_chan.send(Msg::SetQuirksMode);
            }
            NoQuirks | LimitedQuirks => {}
        }
    }

    fn set_last_modified(self, value: DOMString) {
        *self.last_modified.borrow_mut() = Some(value);
    }

    fn set_encoding_name(self, name: DOMString) {
        *self.encoding_name.borrow_mut() = name;
    }

    fn content_changed(self, node: JSRef<Node>, damage: NodeDamage) {
        node.dirty(damage);
    }

    fn content_and_heritage_changed(self, node: JSRef<Node>, damage: NodeDamage) {
        debug!("content_and_heritage_changed on {}", node.debug_str());
        node.force_dirty_ancestors(damage);
        node.dirty(damage);
    }

    /// Remove any existing association between the provided id and any elements in this document.
    fn unregister_named_element(self,
                                to_unregister: JSRef<Element>,
                                id: Atom) {
        let mut idmap = self.idmap.borrow_mut();
        let is_empty = match idmap.get_mut(&id) {
            None => false,
            Some(elements) => {
                let position = elements.iter()
                                       .map(|elem| elem.root())
                                       .position(|element| *element == to_unregister)
                                       .expect("This element should be in registered.");
                elements.remove(position);
                elements.is_empty()
            }
        };
        if is_empty {
            idmap.remove(&id);
        }
    }

    /// Associate an element present in this document with the provided id.
    fn register_named_element(self,
                              element: JSRef<Element>,
                              id: Atom) {
        assert!({
            let node: JSRef<Node> = NodeCast::from_ref(element);
            node.is_in_doc()
        });
        assert!(!id.as_slice().is_empty());

        let mut idmap = self.idmap.borrow_mut();

        let root = self.GetDocumentElement().expect("The element is in the document, so there must be a document element.").root();

        match idmap.entry(id) {
            Vacant(entry) => {
                entry.set(vec!(element.unrooted()));
            }
            Occupied(entry) => {
                let elements = entry.into_mut();

                let new_node: JSRef<Node> = NodeCast::from_ref(element);
                let mut head: uint = 0u;
                let root: JSRef<Node> = NodeCast::from_ref(*root);
                for node in root.traverse_preorder() {
                    let elem: Option<JSRef<Element>> = ElementCast::to_ref(node);
                    match elem {
                        None => {},
                        Some(elem) => {
                            if *(*elements)[head].root() == elem {
                                head += 1;
                            }
                            if new_node == node || head == elements.len() {
                                break;
                            }
                        }
                    }
                }

                elements.insert_unrooted(head, &element);
            }
        }
    }

    fn load_anchor_href(self, href: DOMString) {
        let window = self.window.root();
        window.load_url(href);
    }

    /// Attempt to find a named element in this page's document.
    /// https://html.spec.whatwg.org/multipage/#the-indicated-part-of-the-document
    fn find_fragment_node(self, fragid: DOMString) -> Option<Temporary<Element>> {
        self.GetElementById(fragid.clone()).or_else(|| {
            let check_anchor = |&node: &JSRef<HTMLAnchorElement>| {
                let elem: JSRef<Element> = ElementCast::from_ref(node);
                elem.get_attribute(ns!(""), &atom!("name")).root().map_or(false, |attr| {
                    attr.value().as_slice() == fragid.as_slice()
                })
            };
            let doc_node: JSRef<Node> = NodeCast::from_ref(self);
            doc_node.traverse_preorder()
                    .filter_map(|node| HTMLAnchorElementCast::to_ref(node))
                    .find(check_anchor)
                    .map(|node| Temporary::from_rooted(ElementCast::from_ref(node)))
        })
    }

    // https://html.spec.whatwg.org/multipage/dom.html#current-document-readiness
    fn set_ready_state(self, state: DocumentReadyState) {
        self.ready_state.set(state);

        let window = self.window.root();
        let event = Event::new(GlobalRef::Window(*window), "readystatechange".into_string(),
                               EventBubbles::DoesNotBubble,
                               EventCancelable::NotCancelable).root();
        let target: JSRef<EventTarget> = EventTargetCast::from_ref(self);
        let _ = target.DispatchEvent(*event);
    }

    /// Return the element that currently has focus.
    // https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#events-focusevent-doc-focus
    fn get_focused_element(self) -> Option<Temporary<Element>> {
        self.focused.get()
    }

    /// Initiate a new round of checking for elements requesting focus. The last element to call
    /// `request_focus` before `commit_focus_transaction` is called will receive focus.
    fn begin_focus_transaction(self) {
        self.possibly_focused.clear();
    }

    /// Request that the given element receive focus once the current transaction is complete.
    fn request_focus(self, elem: JSRef<Element>) {
        self.possibly_focused.assign(Some(elem))
    }

    /// Reassign the focus context to the element that last requested focus during this
    /// transaction, or none if no elements requested it.
    fn commit_focus_transaction(self) {
        //TODO: dispatch blur, focus, focusout, and focusin events
        self.focused.assign(self.possibly_focused.get());
    }

    /// Sends this document's title to the compositor.
    fn send_title_to_compositor(self) {
        let window = self.window().root();
        window.page().send_title_to_compositor();
    }

    fn dirty_all_nodes(self) {
        let root: JSRef<Node> = NodeCast::from_ref(self);
        for node in root.traverse_preorder() {
            node.dirty(NodeDamage::OtherNodeDamage)
        }
    }
}

#[deriving(PartialEq)]
pub enum DocumentSource {
    FromParser,
    NotFromParser,
}

pub trait LayoutDocumentHelpers {
    unsafe fn is_html_document_for_layout(&self) -> bool;
}

impl LayoutDocumentHelpers for JS<Document> {
    #[allow(unrooted_must_root)]
    #[inline]
    unsafe fn is_html_document_for_layout(&self) -> bool {
        (*self.unsafe_get()).is_html_document
    }
}

impl Document {
    fn new_inherited(window: JSRef<Window>,
                     url: Option<Url>,
                     is_html_document: IsHTMLDocument,
                     content_type: Option<DOMString>,
                     source: DocumentSource) -> Document {
        let url = url.unwrap_or_else(|| Url::parse("about:blank").unwrap());

        let ready_state = if source == DocumentSource::FromParser {
            DocumentReadyState::Loading
        } else {
            DocumentReadyState::Complete
        };

        Document {
            node: Node::new_without_doc(NodeTypeId::Document),
            window: JS::from_rooted(window),
            idmap: DOMRefCell::new(HashMap::new()),
            implementation: Default::default(),
            content_type: match content_type {
                Some(string) => string.clone(),
                None => match is_html_document {
                    // http://dom.spec.whatwg.org/#dom-domimplementation-createhtmldocument
                    IsHTMLDocument::HTMLDocument => "text/html".into_string(),
                    // http://dom.spec.whatwg.org/#concept-document-content-type
                    IsHTMLDocument::NonHTMLDocument => "application/xml".into_string()
                }
            },
            last_modified: DOMRefCell::new(None),
            url: url,
            // http://dom.spec.whatwg.org/#concept-document-quirks
            quirks_mode: Cell::new(NoQuirks),
            // http://dom.spec.whatwg.org/#concept-document-encoding
            encoding_name: DOMRefCell::new("UTF-8".into_string()),
            is_html_document: is_html_document == IsHTMLDocument::HTMLDocument,
            images: Default::default(),
            embeds: Default::default(),
            links: Default::default(),
            forms: Default::default(),
            scripts: Default::default(),
            anchors: Default::default(),
            applets: Default::default(),
            ready_state: Cell::new(ready_state),
            possibly_focused: Default::default(),
            focused: Default::default(),
        }
    }

    // http://dom.spec.whatwg.org/#dom-document
    pub fn Constructor(global: &GlobalRef) -> Fallible<Temporary<Document>> {
        Ok(Document::new(global.as_window(), None,
                         IsHTMLDocument::NonHTMLDocument, None,
                         DocumentSource::NotFromParser))
    }

    pub fn new(window: JSRef<Window>,
               url: Option<Url>,
               doctype: IsHTMLDocument,
               content_type: Option<DOMString>,
               source: DocumentSource) -> Temporary<Document> {
        let document = reflect_dom_object(box Document::new_inherited(window, url, doctype,
                                                                      content_type, source),
                                          GlobalRef::Window(window),
                                          DocumentBinding::Wrap).root();

        let node: JSRef<Node> = NodeCast::from_ref(*document);
        node.set_owner_doc(*document);
        Temporary::from_rooted(*document)
    }
}

trait PrivateDocumentHelpers {
    fn createNodeList(self, callback: |node: JSRef<Node>| -> bool) -> Temporary<NodeList>;
    fn get_html_element(self) -> Option<Temporary<HTMLHtmlElement>>;
}

impl<'a> PrivateDocumentHelpers for JSRef<'a, Document> {
    fn createNodeList(self, callback: |node: JSRef<Node>| -> bool) -> Temporary<NodeList> {
        let window = self.window.root();
        let nodes = match self.GetDocumentElement().root() {
            None => vec!(),
            Some(root) => {
                let root: JSRef<Node> = NodeCast::from_ref(*root);
                root.traverse_preorder().filter(|&node| callback(node)).collect()
            }
        };
        NodeList::new_simple_list(*window, nodes)
    }

    fn get_html_element(self) -> Option<Temporary<HTMLHtmlElement>> {
        self.GetDocumentElement().root().and_then(|element| {
            HTMLHtmlElementCast::to_ref(*element)
        }).map(Temporary::from_rooted)
    }
}

impl<'a> DocumentMethods for JSRef<'a, Document> {
    // http://dom.spec.whatwg.org/#dom-document-implementation
    fn Implementation(self) -> Temporary<DOMImplementation> {
        self.implementation.or_init(|| DOMImplementation::new(self))
    }

    // http://dom.spec.whatwg.org/#dom-document-url
    fn URL(self) -> DOMString {
        self.url().serialize()
    }

    // http://dom.spec.whatwg.org/#dom-document-documenturi
    fn DocumentURI(self) -> DOMString {
        self.URL()
    }

    // http://dom.spec.whatwg.org/#dom-document-compatmode
    fn CompatMode(self) -> DOMString {
        match self.quirks_mode.get() {
            LimitedQuirks | NoQuirks => "CSS1Compat".into_string(),
            Quirks => "BackCompat".into_string()
        }
    }

    // http://dom.spec.whatwg.org/#dom-document-characterset
    fn CharacterSet(self) -> DOMString {
        self.encoding_name.borrow().clone()
    }

    // http://dom.spec.whatwg.org/#dom-document-inputencoding
    fn InputEncoding(self) -> DOMString {
        self.encoding_name.borrow().clone()
    }

    // http://dom.spec.whatwg.org/#dom-document-content_type
    fn ContentType(self) -> DOMString {
        self.content_type.clone()
    }

    // http://dom.spec.whatwg.org/#dom-document-doctype
    fn GetDoctype(self) -> Option<Temporary<DocumentType>> {
        let node: JSRef<Node> = NodeCast::from_ref(self);
        node.children()
            .filter_map(DocumentTypeCast::to_ref)
            .next()
            .map(Temporary::from_rooted)
    }

    // http://dom.spec.whatwg.org/#dom-document-documentelement
    fn GetDocumentElement(self) -> Option<Temporary<Element>> {
        let node: JSRef<Node> = NodeCast::from_ref(self);
        node.child_elements().next().map(Temporary::from_rooted)
    }

    // http://dom.spec.whatwg.org/#dom-document-getelementsbytagname
    fn GetElementsByTagName(self, tag_name: DOMString) -> Temporary<HTMLCollection> {
        let window = self.window.root();
        HTMLCollection::by_tag_name(*window, NodeCast::from_ref(self), tag_name)
    }

    // http://dom.spec.whatwg.org/#dom-document-getelementsbytagnamens
    fn GetElementsByTagNameNS(self, maybe_ns: Option<DOMString>, tag_name: DOMString) -> Temporary<HTMLCollection> {
        let window = self.window.root();
        HTMLCollection::by_tag_name_ns(*window, NodeCast::from_ref(self), tag_name, maybe_ns)
    }

    // http://dom.spec.whatwg.org/#dom-document-getelementsbyclassname
    fn GetElementsByClassName(self, classes: DOMString) -> Temporary<HTMLCollection> {
        let window = self.window.root();

        HTMLCollection::by_class_name(*window, NodeCast::from_ref(self), classes)
    }

    // http://dom.spec.whatwg.org/#dom-nonelementparentnode-getelementbyid
    fn GetElementById(self, id: DOMString) -> Option<Temporary<Element>> {
        let id = Atom::from_slice(id.as_slice());
        match self.idmap.borrow().get(&id) {
            None => None,
            Some(ref elements) => Some(Temporary::new((*elements)[0].clone())),
        }
    }

    // http://dom.spec.whatwg.org/#dom-document-createelement
    fn CreateElement(self, local_name: DOMString) -> Fallible<Temporary<Element>> {
        if xml_name_type(local_name.as_slice()) == InvalidXMLName {
            debug!("Not a valid element name");
            return Err(InvalidCharacter);
        }
        let local_name = if self.is_html_document {
            local_name.as_slice().to_ascii_lower()
        } else {
            local_name
        };
        let name = QualName::new(ns!(HTML), Atom::from_slice(local_name.as_slice()));
        Ok(Element::create(name, None, self, ElementCreator::ScriptCreated))
    }

    // http://dom.spec.whatwg.org/#dom-document-createelementns
    fn CreateElementNS(self,
                       namespace: Option<DOMString>,
                       qualified_name: DOMString) -> Fallible<Temporary<Element>> {
        let ns = namespace::from_domstring(namespace);
        match xml_name_type(qualified_name.as_slice()) {
            InvalidXMLName => {
                debug!("Not a valid element name");
                return Err(InvalidCharacter);
            },
            Name => {
                debug!("Not a valid qualified element name");
                return Err(NamespaceError);
            },
            QName => {}
        }

        let (prefix_from_qname, local_name_from_qname)
            = get_attribute_parts(qualified_name.as_slice());
        match (&ns, prefix_from_qname, local_name_from_qname) {
            // throw if prefix is not null and namespace is null
            (&ns!(""), Some(_), _) => {
                debug!("Namespace can't be null with a non-null prefix");
                return Err(NamespaceError);
            },
            // throw if prefix is "xml" and namespace is not the XML namespace
            (_, Some(ref prefix), _) if "xml" == prefix.as_slice() && ns != ns!(XML) => {
                debug!("Namespace must be the xml namespace if the prefix is 'xml'");
                return Err(NamespaceError);
            },
            // throw if namespace is the XMLNS namespace and neither qualifiedName nor prefix is "xmlns"
            (&ns!(XMLNS), Some(ref prefix), _) if "xmlns" == prefix.as_slice() => {},
            (&ns!(XMLNS), _, "xmlns") => {},
            (&ns!(XMLNS), _, _) => {
                debug!("The prefix or the qualified name must be 'xmlns' if namespace is the XMLNS namespace ");
                return Err(NamespaceError);
            },
            _ => {}
        }

        let name = QualName::new(ns, Atom::from_slice(local_name_from_qname));
        Ok(Element::create(name, prefix_from_qname.map(|s| s.into_string()), self,
                           ElementCreator::ScriptCreated))
    }

    // http://dom.spec.whatwg.org/#dom-document-createattribute
    fn CreateAttribute(self, local_name: DOMString) -> Fallible<Temporary<Attr>> {
        if xml_name_type(local_name.as_slice()) == InvalidXMLName {
            debug!("Not a valid element name");
            return Err(InvalidCharacter);
        }

        let window = self.window.root();
        let name = Atom::from_slice(local_name.as_slice());
        // repetition used because string_cache::atom::Atom is non-copyable
        let l_name = Atom::from_slice(local_name.as_slice());
        let value = AttrValue::String("".into_string());

        Ok(Attr::new(*window, name, value, l_name, ns!(""), None, None))
    }

    // http://dom.spec.whatwg.org/#dom-document-createdocumentfragment
    fn CreateDocumentFragment(self) -> Temporary<DocumentFragment> {
        DocumentFragment::new(self)
    }

    // http://dom.spec.whatwg.org/#dom-document-createtextnode
    fn CreateTextNode(self, data: DOMString)
                          -> Temporary<Text> {
        Text::new(data, self)
    }

    // http://dom.spec.whatwg.org/#dom-document-createcomment
    fn CreateComment(self, data: DOMString) -> Temporary<Comment> {
        Comment::new(data, self)
    }

    // http://dom.spec.whatwg.org/#dom-document-createprocessinginstruction
    fn CreateProcessingInstruction(self, target: DOMString,
                                       data: DOMString) -> Fallible<Temporary<ProcessingInstruction>> {
        // Step 1.
        if xml_name_type(target.as_slice()) == InvalidXMLName {
            return Err(InvalidCharacter);
        }

        // Step 2.
        if data.as_slice().contains("?>") {
            return Err(InvalidCharacter);
        }

        // Step 3.
        Ok(ProcessingInstruction::new(target, data, self))
    }

    // http://dom.spec.whatwg.org/#dom-document-importnode
    fn ImportNode(self, node: JSRef<Node>, deep: bool) -> Fallible<Temporary<Node>> {
        // Step 1.
        if node.is_document() {
            return Err(NotSupported);
        }

        // Step 2.
        let clone_children = match deep {
            true => CloneChildrenFlag::CloneChildren,
            false => CloneChildrenFlag::DoNotCloneChildren
        };

        Ok(Node::clone(node, Some(self), clone_children))
    }

    // http://dom.spec.whatwg.org/#dom-document-adoptnode
    fn AdoptNode(self, node: JSRef<Node>) -> Fallible<Temporary<Node>> {
        // Step 1.
        if node.is_document() {
            return Err(NotSupported);
        }

        // Step 2.
        Node::adopt(node, self);

        // Step 3.
        Ok(Temporary::from_rooted(node))
    }

    // http://dom.spec.whatwg.org/#dom-document-createevent
    fn CreateEvent(self, interface: DOMString) -> Fallible<Temporary<Event>> {
        let window = self.window.root();

        match interface.as_slice().to_ascii_lower().as_slice() {
            "uievents" | "uievent" => Ok(EventCast::from_temporary(
                UIEvent::new_uninitialized(*window))),
            "mouseevents" | "mouseevent" => Ok(EventCast::from_temporary(
                MouseEvent::new_uninitialized(*window))),
            "customevent" => Ok(EventCast::from_temporary(
                CustomEvent::new_uninitialized(GlobalRef::Window(*window)))),
            "htmlevents" | "events" | "event" => Ok(Event::new_uninitialized(
                GlobalRef::Window(*window))),
            "keyboardevent" | "keyevents" => Ok(EventCast::from_temporary(
                KeyboardEvent::new_uninitialized(*window))),
            "messageevent" => Ok(EventCast::from_temporary(
                MessageEvent::new_uninitialized(GlobalRef::Window(*window)))),
            _ => Err(NotSupported)
        }
    }

    // http://www.whatwg.org/html/#dom-document-lastmodified
    fn LastModified(self) -> DOMString {
        match *self.last_modified.borrow() {
            Some(ref t) => t.clone(),
            None => format!("{}", time::now().strftime("%m/%d/%Y %H:%M:%S").unwrap()),
        }
    }

    // http://dom.spec.whatwg.org/#dom-document-createrange
    fn CreateRange(self) -> Temporary<Range> {
        Range::new(self)
    }

    // http://dom.spec.whatwg.org/#dom-document-createtreewalker
    fn CreateTreeWalker(self, root: JSRef<Node>, whatToShow: u32, filter: Option<NodeFilter>)
                        -> Temporary<TreeWalker> {
        TreeWalker::new(self, root, whatToShow, filter)
    }

    // http://www.whatwg.org/specs/web-apps/current-work/#document.title
    fn Title(self) -> DOMString {
        let mut title = String::new();
        self.GetDocumentElement().root().map(|root| {
            let root: JSRef<Node> = NodeCast::from_ref(*root);
            root.traverse_preorder()
                .find(|node| node.type_id() == NodeTypeId::Element(ElementTypeId::HTMLTitleElement))
                .map(|title_elem| {
                    for text in title_elem.children().filter_map::<JSRef<Text>>(TextCast::to_ref) {
                        title.push_str(text.characterdata().data().as_slice());
                    }
                });
        });
        let v: Vec<&str> = split_html_space_chars(title.as_slice()).collect();
        v.connect(" ")
    }

    // http://www.whatwg.org/specs/web-apps/current-work/#document.title
    fn SetTitle(self, title: DOMString) -> ErrorResult {
        self.GetDocumentElement().root().map(|root| {
            let root: JSRef<Node> = NodeCast::from_ref(*root);
            let head_node = root.traverse_preorder().find(|child| {
                child.type_id() == NodeTypeId::Element(ElementTypeId::HTMLHeadElement)
            });
            head_node.map(|head| {
                let title_node = head.children().find(|child| {
                    child.type_id() == NodeTypeId::Element(ElementTypeId::HTMLTitleElement)
                });

                match title_node {
                    Some(ref title_node) => {
                        for title_child in title_node.children() {
                            assert!(title_node.RemoveChild(title_child).is_ok());
                        }
                        if !title.is_empty() {
                            let new_text = self.CreateTextNode(title.clone()).root();
                            assert!(title_node.AppendChild(NodeCast::from_ref(*new_text)).is_ok());
                        }
                    },
                    None => {
                        let new_title = HTMLTitleElement::new("title".into_string(), None, self).root();
                        let new_title: JSRef<Node> = NodeCast::from_ref(*new_title);

                        if !title.is_empty() {
                            let new_text = self.CreateTextNode(title.clone()).root();
                            assert!(new_title.AppendChild(NodeCast::from_ref(*new_text)).is_ok());
                        }
                        assert!(head.AppendChild(new_title).is_ok());
                    },
                }
            });
        });
        Ok(())
    }

    // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-head
    fn GetHead(self) -> Option<Temporary<HTMLHeadElement>> {
        self.get_html_element().and_then(|root| {
            let root = root.root();
            let node: JSRef<Node> = NodeCast::from_ref(*root);
            node.children().filter_map(HTMLHeadElementCast::to_ref).next().map(Temporary::from_rooted)
        })
    }

    // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-body
    fn GetBody(self) -> Option<Temporary<HTMLElement>> {
        self.get_html_element().and_then(|root| {
            let root = root.root();
            let node: JSRef<Node> = NodeCast::from_ref(*root);
            node.children().find(|child| {
                match child.type_id() {
                    NodeTypeId::Element(ElementTypeId::HTMLBodyElement) |
                    NodeTypeId::Element(ElementTypeId::HTMLFrameSetElement) => true,
                    _ => false
                }
            }).map(|node| {
                Temporary::from_rooted(HTMLElementCast::to_ref(node).unwrap())
            })
        })
    }

    // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-body
    fn SetBody(self, new_body: Option<JSRef<HTMLElement>>) -> ErrorResult {
        // Step 1.
        let new_body = match new_body {
            Some(new_body) => new_body,
            None => return Err(HierarchyRequest),
        };

        let node: JSRef<Node> = NodeCast::from_ref(new_body);
        match node.type_id() {
            NodeTypeId::Element(ElementTypeId::HTMLBodyElement) |
            NodeTypeId::Element(ElementTypeId::HTMLFrameSetElement) => {}
            _ => return Err(HierarchyRequest)
        }

        // Step 2.
        let old_body = self.GetBody().root();
        if old_body.as_ref().map(|body| **body) == Some(new_body) {
            return Ok(());
        }

        // Step 3.
        match self.get_html_element().root() {
            // Step 4.
            None => return Err(HierarchyRequest),
            Some(ref root) => {
                let new_body: JSRef<Node> = NodeCast::from_ref(new_body);

                let root: JSRef<Node> = NodeCast::from_ref(**root);
                match old_body {
                    Some(ref child) => {
                        let child: JSRef<Node> = NodeCast::from_ref(**child);

                        assert!(root.ReplaceChild(new_body, child).is_ok())
                    }
                    None => assert!(root.AppendChild(new_body).is_ok())
                };
            }
        }
        Ok(())
    }

    // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-getelementsbyname
    fn GetElementsByName(self, name: DOMString) -> Temporary<NodeList> {
        self.createNodeList(|node| {
            let element: JSRef<Element> = match ElementCast::to_ref(node) {
                Some(element) => element,
                None => return false,
            };
            element.get_attribute(ns!(""), &atom!("name")).root().map_or(false, |attr| {
                attr.value().as_slice() == name.as_slice()
            })
        })
    }

    fn Images(self) -> Temporary<HTMLCollection> {
        self.images.or_init(|| {
            let window = self.window.root();
            let root = NodeCast::from_ref(self);
            let filter = box ImagesFilter;
            HTMLCollection::create(*window, root, filter)
        })
    }

    fn Embeds(self) -> Temporary<HTMLCollection> {
        self.embeds.or_init(|| {
            let window = self.window.root();
            let root = NodeCast::from_ref(self);
            let filter = box EmbedsFilter;
            HTMLCollection::create(*window, root, filter)
        })
    }

    fn Plugins(self) -> Temporary<HTMLCollection> {
        self.Embeds()
    }

    fn Links(self) -> Temporary<HTMLCollection> {
        self.links.or_init(|| {
            let window = self.window.root();
            let root = NodeCast::from_ref(self);
            let filter = box LinksFilter;
            HTMLCollection::create(*window, root, filter)
        })
    }

    fn Forms(self) -> Temporary<HTMLCollection> {
        self.forms.or_init(|| {
            let window = self.window.root();
            let root = NodeCast::from_ref(self);
            let filter = box FormsFilter;
            HTMLCollection::create(*window, root, filter)
        })
    }

    fn Scripts(self) -> Temporary<HTMLCollection> {
        self.scripts.or_init(|| {
            let window = self.window.root();
            let root = NodeCast::from_ref(self);
            let filter = box ScriptsFilter;
            HTMLCollection::create(*window, root, filter)
        })
    }

    fn Anchors(self) -> Temporary<HTMLCollection> {
        self.anchors.or_init(|| {
            let window = self.window.root();
            let root = NodeCast::from_ref(self);
            let filter = box AnchorsFilter;
            HTMLCollection::create(*window, root, filter)
        })
    }

    fn Applets(self) -> Temporary<HTMLCollection> {
        // FIXME: This should be return OBJECT elements containing applets.
        self.applets.or_init(|| {
            let window = self.window.root();
            let root = NodeCast::from_ref(self);
            let filter = box AppletsFilter;
            HTMLCollection::create(*window, root, filter)
        })
    }

    fn Location(self) -> Temporary<Location> {
        let window = self.window.root();
        window.Location()
    }

    // http://dom.spec.whatwg.org/#dom-parentnode-children
    fn Children(self) -> Temporary<HTMLCollection> {
        let window = self.window.root();
        HTMLCollection::children(*window, NodeCast::from_ref(self))
    }

    // http://dom.spec.whatwg.org/#dom-parentnode-queryselector
    fn QuerySelector(self, selectors: DOMString) -> Fallible<Option<Temporary<Element>>> {
        let root: JSRef<Node> = NodeCast::from_ref(self);
        root.query_selector(selectors)
    }

    // http://dom.spec.whatwg.org/#dom-parentnode-queryselectorall
    fn QuerySelectorAll(self, selectors: DOMString) -> Fallible<Temporary<NodeList>> {
        let root: JSRef<Node> = NodeCast::from_ref(self);
        root.query_selector_all(selectors)
    }

    // https://html.spec.whatwg.org/multipage/dom.html#dom-document-readystate
    fn ReadyState(self) -> DocumentReadyState {
        self.ready_state.get()
    }

    global_event_handlers!()
    event_handler!(readystatechange, GetOnreadystatechange, SetOnreadystatechange)
}