/* 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 https://mozilla.org/MPL/2.0/. */

use std::cell::Cell;
use std::sync::atomic::{AtomicBool, Ordering};

use dom_struct::dom_struct;
use html5ever::{LocalName, Prefix, local_name};
use js::context::JSContext;
use js::rust::HandleObject;
use net_traits::ReferrerPolicy;
use script_bindings::root::Dom;
use servo_arc::Arc;
use style::media_queries::MediaList as StyleMediaList;
use style::stylesheets::{Stylesheet, StylesheetInDocument, UrlExtraData};
use stylo_atoms::Atom;

use crate::dom::attr::Attr;
use crate::dom::bindings::cell::DomRefCell;
use crate::dom::bindings::codegen::Bindings::DOMTokenListBinding::DOMTokenList_Binding::DOMTokenListMethods;
use crate::dom::bindings::codegen::Bindings::HTMLStyleElementBinding::HTMLStyleElementMethods;
use crate::dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
use crate::dom::bindings::inheritance::Castable;
use crate::dom::bindings::root::{DomRoot, MutNullableDom};
use crate::dom::bindings::str::DOMString;
use crate::dom::csp::{CspReporting, InlineCheckType};
use crate::dom::css::cssstylesheet::CSSStyleSheet;
use crate::dom::css::stylesheet::StyleSheet as DOMStyleSheet;
use crate::dom::css::stylesheetcontentscache::{
    StylesheetContentsCache, StylesheetContentsCacheKey,
};
use crate::dom::document::Document;
use crate::dom::documentorshadowroot::StylesheetSource;
use crate::dom::domtokenlist::DOMTokenList;
use crate::dom::element::{AttributeMutation, Element, ElementCreator};
use crate::dom::html::htmlelement::HTMLElement;
use crate::dom::medialist::MediaList;
use crate::dom::node::{BindContext, ChildrenMutation, Node, NodeTraits, UnbindContext};
use crate::dom::virtualmethods::VirtualMethods;
use crate::script_runtime::CanGc;
use crate::stylesheet_loader::StylesheetOwner;

#[dom_struct]
pub(crate) struct HTMLStyleElement {
    htmlelement: HTMLElement,
    #[conditional_malloc_size_of]
    #[no_trace]
    stylesheet: DomRefCell<Option<Arc<Stylesheet>>>,
    #[no_trace]
    stylesheetcontents_cache_key: DomRefCell<Option<StylesheetContentsCacheKey>>,
    cssom_stylesheet: MutNullableDom<CSSStyleSheet>,
    /// <https://html.spec.whatwg.org/multipage/#a-style-sheet-that-is-blocking-scripts>
    parser_inserted: Cell<bool>,
    in_stack_of_open_elements: Cell<bool>,
    pending_loads: Cell<u32>,
    any_failed_load: Cell<bool>,
    /// <https://html.spec.whatwg.org/multipage/#dom-style-blocking>
    blocking: MutNullableDom<DOMTokenList>,
}

impl HTMLStyleElement {
    fn new_inherited(
        local_name: LocalName,
        prefix: Option<Prefix>,
        document: &Document,
        creator: ElementCreator,
    ) -> HTMLStyleElement {
        HTMLStyleElement {
            htmlelement: HTMLElement::new_inherited(local_name, prefix, document),
            stylesheet: DomRefCell::new(None),
            stylesheetcontents_cache_key: DomRefCell::new(None),
            cssom_stylesheet: MutNullableDom::new(None),
            parser_inserted: Cell::new(creator.is_parser_created()),
            in_stack_of_open_elements: Cell::new(creator.is_parser_created()),
            pending_loads: Cell::new(0),
            any_failed_load: Cell::new(false),
            blocking: Default::default(),
        }
    }

    pub(crate) fn new(
        cx: &mut js::context::JSContext,
        local_name: LocalName,
        prefix: Option<Prefix>,
        document: &Document,
        proto: Option<HandleObject>,
        creator: ElementCreator,
    ) -> DomRoot<HTMLStyleElement> {
        Node::reflect_node_with_proto(
            cx,
            Box::new(HTMLStyleElement::new_inherited(
                local_name, prefix, document, creator,
            )),
            document,
            proto,
        )
    }

    #[inline]
    fn create_media_list(&self, mq_str: &str) -> StyleMediaList {
        MediaList::parse_media_list(mq_str, &self.owner_window())
    }

    /// <https://html.spec.whatwg.org/multipage/#update-a-style-block>
    pub(crate) fn update_a_style_block(&self) {
        // Step 1. Let element be the style element.
        //
        // That's self

        // Step 2. If element has an associated CSS style sheet, remove the CSS style sheet in question.
        self.remove_stylesheet();

        // Step 3. If element is not connected, then return.
        let node = self.upcast::<Node>();
        if !node.is_connected() {
            return;
        }
        assert!(
            node.is_in_a_document_tree() || node.is_in_a_shadow_tree(),
            "This stylesheet does not have an owner, so there's no reason to parse its contents"
        );

        // Step 4. If element's type attribute is present and its value is neither the empty string
        // nor an ASCII case-insensitive match for "text/css", then return.
        let mut type_attribute = self.Type();
        type_attribute.make_ascii_lowercase();
        if !type_attribute.is_empty() && type_attribute != "text/css" {
            return;
        }

        // Step 5: If the Should element's inline behavior be blocked by Content Security Policy? algorithm
        // returns "Blocked" when executed upon the style element, "style",
        // and the style element's child text content, then return. [CSP]
        let doc = self.owner_document();
        let global = &self.owner_global();
        if global
            .get_csp_list()
            .should_elements_inline_type_behavior_be_blocked(
                global,
                self.upcast(),
                InlineCheckType::Style,
                &node.child_text_content().str(),
                doc.get_current_parser_line(),
            )
        {
            return;
        }

        // Step 6. Create a CSS style sheet with the following properties:
        let data = node
            .GetTextContent()
            .expect("Element.textContent must be a string");
        let shared_lock = node.owner_doc().style_shared_lock().clone();
        let mq = Arc::new(shared_lock.wrap(self.create_media_list(&self.Media().str())));

        // For duplicate style sheets with identical content, `StylesheetContents` can be reused
        // to avoid reedundant parsing of the style sheets. Additionally, the cache hit rate of
        // stylo's `CascadeDataCache` can now be significantly improved. When shared `StylesheetContents`
        // is modified, copy-on-write will occur, see `CSSStyleSheet::will_modify`.
        let (cache_key, contents) = StylesheetContentsCache::get_or_insert_with(
            &data.str(),
            &shared_lock,
            UrlExtraData(doc.base_url().get_arc()),
            doc.quirks_mode(),
            self.upcast(),
        );

        let sheet = Arc::new(Stylesheet {
            contents: shared_lock.wrap(contents),
            shared_lock,
            media: mq,
            disabled: AtomicBool::new(false),
        });

        // From here we differ from the spec. Since we have a cache,
        // we have two situations:
        //
        // 1. We hit the cache. No fetch ever runs, hence we don't
        // need to muddy with render-/load-blocking
        // 2. We don't hit the cache. In this scenario, we once again
        // have two sub-scenarios:
        //   a. We synchronously parse the contents without any `@import`.
        //      This means we can proceed as in situation 1
        //   b. We synchronously parse the contents and we encounter 1+
        //      `@import` rules. In that case, we do start to load urls.
        //
        // For situation 1 and 2a, we can immediately fire the load event
        // since we are done.
        if self.pending_loads.get() == 0 {
            // Step 4 of https://html.spec.whatwg.org/multipage/#the-style-element:critical-subresources
            //
            // Step 4. Queue an element task on the networking task source given element and the following steps:
            // Step 4.1. If success is true, fire an event named load at element.
            self.owner_global()
                .task_manager()
                .networking_task_source()
                .queue_simple_event(self.upcast(), atom!("load"));
        }

        // For situation 2b, we need to do more work.
        // Therefore, the following steps are actually implemented in
        // `ElementStylesheetLoader::load_with_element`.
        //
        //     Step 7. If element contributes a script-blocking style sheet,
        //     append element to its node document's script-blocking style sheet set.
        //
        //     Step 8. If element's media attribute's value matches the environment
        //     and element is potentially render-blocking, then block rendering on element.

        // Finally, update our stylesheet, regardless of which scenario we ran into
        self.clean_stylesheet_ownership();
        self.set_stylesheet(sheet, cache_key);
    }

    // FIXME(emilio): This is duplicated with HTMLLinkElement::set_stylesheet.
    //
    // With the reuse of `StylesheetContent` for same stylesheet string content,
    // this function has a bit difference with `HTMLLinkElement::set_stylesheet` now.
    pub(crate) fn set_stylesheet(
        &self,
        s: Arc<Stylesheet>,
        cache_key: Option<StylesheetContentsCacheKey>,
    ) {
        *self.stylesheet.borrow_mut() = Some(s.clone());
        *self.stylesheetcontents_cache_key.borrow_mut() = cache_key;
        self.stylesheet_list_owner()
            .add_owned_stylesheet(self.upcast(), s);
    }

    pub(crate) fn will_modify_stylesheet(&self) {
        if let Some(stylesheet_with_owned_contents) = self.create_owned_contents_stylesheet() {
            self.remove_stylesheet();
            if let Some(cssom_stylesheet) = self.cssom_stylesheet.get() {
                let guard = stylesheet_with_owned_contents.shared_lock.read();
                cssom_stylesheet.update_style_stylesheet(&stylesheet_with_owned_contents, &guard);
            }
            self.set_stylesheet(stylesheet_with_owned_contents, None);
        }
    }

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

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

    fn create_owned_contents_stylesheet(&self) -> Option<Arc<Stylesheet>> {
        let cache_key = self.stylesheetcontents_cache_key.borrow_mut().take()?;
        if cache_key.is_uniquely_owned() {
            StylesheetContentsCache::remove(cache_key);
            return None;
        }

        let stylesheet_with_shared_contents = self.stylesheet.borrow().clone()?;
        let lock = stylesheet_with_shared_contents.shared_lock.clone();
        let guard = stylesheet_with_shared_contents.shared_lock.read();
        let stylesheet_with_owned_contents = Arc::new(Stylesheet {
            contents: lock.wrap(
                stylesheet_with_shared_contents
                    .contents(&guard)
                    .deep_clone(&lock, None, &guard),
            ),
            shared_lock: lock,
            media: stylesheet_with_shared_contents.media.clone(),
            disabled: AtomicBool::new(
                stylesheet_with_shared_contents
                    .disabled
                    .load(Ordering::SeqCst),
            ),
        });

        Some(stylesheet_with_owned_contents)
    }

    fn clean_stylesheet_ownership(&self) {
        if let Some(cssom_stylesheet) = self.cssom_stylesheet.get() {
            // If the CSSOMs change from having an owner node to being ownerless, they may still
            // potentially modify shared stylesheets. Thus, create an new `Stylesheet` with owned
            // `StylesheetContents` to ensure that the potentially modifications are only made on
            // the owned `StylesheetContents`.
            if let Some(stylesheet) = self.create_owned_contents_stylesheet() {
                let guard = stylesheet.shared_lock.read();
                cssom_stylesheet.update_style_stylesheet(&stylesheet, &guard);
            }
            cssom_stylesheet.set_owner_node(None);
        }
        self.cssom_stylesheet.set(None);
    }

    fn remove_stylesheet(&self) {
        self.clean_stylesheet_ownership();
        if let Some(s) = self.stylesheet.borrow_mut().take() {
            self.stylesheet_list_owner()
                .remove_stylesheet(StylesheetSource::Element(Dom::from_ref(self.upcast())), &s);
            let _ = self.stylesheetcontents_cache_key.borrow_mut().take();
        }
    }
}

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

    fn children_changed(&self, cx: &mut JSContext, mutation: &ChildrenMutation) {
        self.super_type().unwrap().children_changed(cx, mutation);

        // https://html.spec.whatwg.org/multipage/#update-a-style-block
        // > The element is not on the stack of open elements of an HTML parser or XML parser, and its children changed steps run.
        if !self.in_stack_of_open_elements.get() {
            self.update_a_style_block();
        }
    }

    fn bind_to_tree(&self, cx: &mut JSContext, context: &BindContext) {
        self.super_type().unwrap().bind_to_tree(cx, context);

        // https://html.spec.whatwg.org/multipage/#update-a-style-block
        // > The element is not on the stack of open elements of an HTML parser or XML parser, and it becomes connected or disconnected.
        if !self.in_stack_of_open_elements.get() {
            self.update_a_style_block();
        }
    }

    fn pop(&self) {
        self.super_type().unwrap().pop();
        self.in_stack_of_open_elements.set(false);

        // https://html.spec.whatwg.org/multipage/#update-a-style-block
        // > The element is popped off the stack of open elements of an HTML parser or XML parser.
        self.update_a_style_block();
    }

    fn unbind_from_tree(&self, cx: &mut js::context::JSContext, context: &UnbindContext) {
        if let Some(s) = self.super_type() {
            s.unbind_from_tree(cx, context);
        }

        // https://html.spec.whatwg.org/multipage/#update-a-style-block
        // > The element is not on the stack of open elements of an HTML parser or XML parser, and it becomes connected or disconnected.
        if !self.in_stack_of_open_elements.get() {
            self.update_a_style_block();
        }
    }

    fn attribute_mutated(
        &self,
        cx: &mut js::context::JSContext,
        attr: &Attr,
        mutation: AttributeMutation,
    ) {
        if let Some(s) = self.super_type() {
            s.attribute_mutated(cx, attr, mutation);
        }

        let node = self.upcast::<Node>();
        if !(node.is_in_a_document_tree() || node.is_in_a_shadow_tree()) ||
            self.in_stack_of_open_elements.get()
        {
            return;
        }

        if attr.name() == "type" {
            if let AttributeMutation::Set(Some(old_value), _) = mutation {
                if **old_value == **attr.value() {
                    return;
                }
            }
            self.remove_stylesheet();
            self.update_a_style_block();
        } else if attr.name() == "media" {
            if let Some(ref stylesheet) = *self.stylesheet.borrow_mut() {
                let shared_lock = node.owner_doc().style_shared_lock().clone();
                let mut guard = shared_lock.write();
                let media = stylesheet.media.write_with(&mut guard);
                match mutation {
                    AttributeMutation::Set(..) => *media = self.create_media_list(&attr.value()),
                    AttributeMutation::Removed => *media = StyleMediaList::empty(),
                };
                self.owner_document().invalidate_stylesheets();
            }
        }
    }
}

impl StylesheetOwner for HTMLStyleElement {
    fn increment_pending_loads_count(&self) {
        self.pending_loads.set(self.pending_loads.get() + 1)
    }

    fn load_finished(&self, succeeded: bool) -> Option<bool> {
        assert!(self.pending_loads.get() > 0, "What finished?");
        if !succeeded {
            self.any_failed_load.set(true);
        }

        self.pending_loads.set(self.pending_loads.get() - 1);
        if self.pending_loads.get() != 0 {
            return None;
        }

        let any_failed = self.any_failed_load.get();
        self.any_failed_load.set(false);
        Some(any_failed)
    }

    fn parser_inserted(&self) -> bool {
        self.parser_inserted.get()
    }

    /// <https://html.spec.whatwg.org/multipage/#potentially-render-blocking>
    fn potentially_render_blocking(&self) -> bool {
        // An element is potentially render-blocking if its blocking tokens set contains "render",
        // or if it is implicitly potentially render-blocking, which will be defined at the individual elements.
        // By default, an element is not implicitly potentially render-blocking.
        //
        // https://html.spec.whatwg.org/multipage/#the-style-element:implicitly-potentially-render-blocking
        // > A style element is implicitly potentially render-blocking if the element was created by its node document's parser.
        self.parser_inserted() ||
            self.blocking
                .get()
                .is_some_and(|list| list.Contains("render".into()))
    }

    fn referrer_policy(&self) -> ReferrerPolicy {
        ReferrerPolicy::EmptyString
    }

    fn set_origin_clean(&self, origin_clean: bool) {
        if let Some(stylesheet) = self.get_cssom_stylesheet() {
            stylesheet.set_origin_clean(origin_clean);
        }
    }
}

impl HTMLStyleElementMethods<crate::DomTypeHolder> for HTMLStyleElement {
    /// <https://drafts.csswg.org/cssom/#dom-linkstyle-sheet>
    fn GetSheet(&self) -> Option<DomRoot<DOMStyleSheet>> {
        self.get_cssom_stylesheet().map(DomRoot::upcast)
    }

    /// <https://html.spec.whatwg.org/multipage/#dom-style-disabled>
    fn Disabled(&self) -> bool {
        self.get_cssom_stylesheet()
            .is_some_and(|sheet| sheet.disabled())
    }

    /// <https://html.spec.whatwg.org/multipage/#dom-style-disabled>
    fn SetDisabled(&self, value: bool) {
        if let Some(sheet) = self.get_cssom_stylesheet() {
            sheet.set_disabled(value);
        }
    }

    // <https://html.spec.whatwg.org/multipage/#HTMLStyleElement-partial>
    make_getter!(Type, "type");

    // <https://html.spec.whatwg.org/multipage/#HTMLStyleElement-partial>
    make_setter!(SetType, "type");

    // <https://html.spec.whatwg.org/multipage/#attr-style-media>
    make_getter!(Media, "media");

    // <https://html.spec.whatwg.org/multipage/#attr-style-media>
    make_setter!(SetMedia, "media");

    /// <https://html.spec.whatwg.org/multipage/#attr-style-blocking>
    fn Blocking(&self, can_gc: CanGc) -> DomRoot<DOMTokenList> {
        self.blocking.or_init(|| {
            DOMTokenList::new(
                self.upcast(),
                &local_name!("blocking"),
                Some(vec![Atom::from("render")]),
                can_gc,
            )
        })
    }
}