/*

 * Copyright (c) 2023, Preston Taylor <PrestonLeeTaylor@proton.me>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#include <LibWeb/CSS/Parser/Parser.h>

#include <LibWeb/CSS/StyleComputer.h>

#include <LibWeb/DOM/Document.h>

#include <LibWeb/DOM/ShadowRoot.h>

#include <LibWeb/DOM/StyleElementUtils.h>

#include <LibWeb/Infra/Strings.h>

namespace Web::DOM {

// The user agent must run the "update a style block" algorithm whenever one of the following conditions occur:

// FIXME: The element is popped off the stack of open elements of an HTML parser or XML parser.

//

// NOTE: This is basically done by children_changed() today:

// The element's children changed steps run.

//

// NOTE: This is basically done by inserted() and removed_from() today:

// The element is not on the stack of open elements of an HTML parser or XML parser, and it becomes connected or disconnected.

//

// https://html.spec.whatwg.org/multipage/semantics.html#update-a-style-block

void StyleElementUtils::update_a_style_block(DOM::Element& style_element)

{

    // OPTIMIZATION: Skip parsing CSS if we're in the middle of parsing a HTML fragment.

    //               The style block will be parsed upon insertion into a proper document.

    if (style_element.document().is_temporary_document_for_fragment_parsing())

        return;

    // 1. Let element be the style element.

    // 2. If element has an associated CSS style sheet, remove the CSS style sheet in question.

    if (m_associated_css_style_sheet) {

        m_style_sheet_list->remove_a_css_style_sheet(*m_associated_css_style_sheet);

        m_style_sheet_list = nullptr;

        // FIXME: This should probably be handled by StyleSheet::set_owner_node().

        m_associated_css_style_sheet = nullptr;

    }

    // 3. If element is not connected, then return.

    if (!style_element.is_connected())

        return;

    // 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.

    auto type_attribute = style_element.attribute(HTML::AttributeNames::type);

    if (type_attribute.has_value() && !type_attribute->is_empty() && !Infra::is_ascii_case_insensitive_match(type_attribute->bytes_as_string_view(), "text/css"sv))

        return;

    // FIXME: 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]

    // FIXME: This is a bit awkward, as the spec doesn't actually tell us when to parse the CSS text,

    //        so we just do it here and pass the parsed sheet to create_a_css_style_sheet().

    auto* sheet = parse_css_stylesheet(CSS::Parser::ParsingContext(style_element.document()), style_element.text_content().value_or(String {}));

    if (!sheet)

        return;

    // FIXME: This should probably be handled by StyleSheet::set_owner_node().

    m_associated_css_style_sheet = sheet;

    // 6. Create a CSS style sheet with the following properties...

    m_style_sheet_list = style_element.document_or_shadow_root_style_sheets();

    m_style_sheet_list->create_a_css_style_sheet(

        "text/css"_string,

        &style_element,

        style_element.attribute(HTML::AttributeNames::media).value_or({}),

        style_element.in_a_document_tree()

            ? style_element.attribute(HTML::AttributeNames::title).value_or({})

            : String {},

        false,

        true,

        {},

        nullptr,

        nullptr,

        *sheet);

}

void StyleElementUtils::visit_edges(JS::Cell::Visitor& visitor)

{

    visitor.visit(m_associated_css_style_sheet);

    visitor.visit(m_style_sheet_list);

}

}