/*

 * Copyright (c) 2023, Andreas Kling <kling@serenityos.org>

 *

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

 */

#include <LibGfx/Bitmap.h>

#include <LibWeb/Bindings/MainThreadVM.h>

#include <LibWeb/DOM/Document.h>

#include <LibWeb/Fetch/Infrastructure/HTTP/Responses.h>

#include <LibWeb/HTML/BrowsingContext.h>

#include <LibWeb/HTML/DocumentState.h>

#include <LibWeb/HTML/NavigationParams.h>

#include <LibWeb/HTML/Parser/HTMLParser.h>

#include <LibWeb/HTML/TraversableNavigable.h>

#include <LibWeb/Layout/Viewport.h>

#include <LibWeb/Page/Page.h>

#include <LibWeb/Painting/DisplayListPlayerCPU.h>

#include <LibWeb/Painting/PaintContext.h>

#include <LibWeb/Painting/ViewportPaintable.h>

#include <LibWeb/SVG/SVGDecodedImageData.h>

#include <LibWeb/SVG/SVGSVGElement.h>

namespace Web::SVG {

JS_DEFINE_ALLOCATOR(SVGDecodedImageData);

JS_DEFINE_ALLOCATOR(SVGDecodedImageData::SVGPageClient);

ErrorOr<JS::NonnullGCPtr<SVGDecodedImageData>> SVGDecodedImageData::create(JS::Realm& realm, JS::NonnullGCPtr<Page> host_page, URL::URL const& url, ByteBuffer data)

{

    auto page_client = SVGPageClient::create(Bindings::main_thread_vm(), host_page);

    auto page = Page::create(Bindings::main_thread_vm(), *page_client);

    page_client->m_svg_page = page.ptr();

    page->set_top_level_traversable(MUST(Web::HTML::TraversableNavigable::create_a_new_top_level_traversable(*page, nullptr, {})));

    JS::NonnullGCPtr<HTML::Navigable> navigable = page->top_level_traversable();

    auto response = Fetch::Infrastructure::Response::create(navigable->vm());

    response->url_list().append(url);

    auto navigation_params = navigable->heap().allocate_without_realm<HTML::NavigationParams>();

    navigation_params->navigable = navigable;

    navigation_params->response = response;

    navigation_params->origin = URL::Origin {};

    navigation_params->policy_container = HTML::PolicyContainer {};

    navigation_params->final_sandboxing_flag_set = HTML::SandboxingFlagSet {};

    navigation_params->opener_policy = HTML::OpenerPolicy {};

    // FIXME: Use Navigable::navigate() instead of manually replacing the navigable's document.

    auto document = DOM::Document::create_and_initialize(DOM::Document::Type::HTML, "text/html"_string, navigation_params).release_value_but_fixme_should_propagate_errors();

    navigable->set_ongoing_navigation({});

    navigable->active_document()->destroy();

    navigable->active_session_history_entry()->document_state()->set_document(document);

    auto parser = HTML::HTMLParser::create_with_uncertain_encoding(document, data);

    parser->run(document->url());

    // Perform some DOM surgery to make the SVG root element be the first child of the Document.

    // FIXME: This is a huge hack until we figure out how to actually parse separate SVG files.

    auto* svg_root = document->body()->first_child_of_type<SVG::SVGSVGElement>();

    if (!svg_root)

        return Error::from_string_literal("SVGDecodedImageData: Invalid SVG input");

    svg_root->remove();

    document->remove_all_children();

    MUST(document->append_child(*svg_root));

    return realm.heap().allocate<SVGDecodedImageData>(realm, page, page_client, document, *svg_root);

}

SVGDecodedImageData::SVGDecodedImageData(JS::NonnullGCPtr<Page> page, JS::NonnullGCPtr<SVGPageClient> page_client, JS::NonnullGCPtr<DOM::Document> document, JS::NonnullGCPtr<SVG::SVGSVGElement> root_element)

    : m_page(page)

    , m_page_client(page_client)

    , m_document(document)

    , m_root_element(root_element)

{

}

SVGDecodedImageData::~SVGDecodedImageData() = default;

void SVGDecodedImageData::visit_edges(Cell::Visitor& visitor)

{

    Base::visit_edges(visitor);

    visitor.visit(m_page);

    visitor.visit(m_document);

    visitor.visit(m_page_client);

    visitor.visit(m_root_element);

}

RefPtr<Gfx::Bitmap> SVGDecodedImageData::render(Gfx::IntSize size) const

{

    auto bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, size).release_value_but_fixme_should_propagate_errors();

    VERIFY(m_document->navigable());

    m_document->navigable()->set_viewport_size(size.to_type<CSSPixels>());

    m_document->update_layout();

    auto display_list = Painting::DisplayList::create();

    Painting::DisplayListRecorder display_list_recorder(display_list);

    m_document->navigable()->record_display_list(display_list_recorder, {});

    auto painting_command_executor_type = m_page_client->display_list_player_type();

    switch (painting_command_executor_type) {

    case DisplayListPlayerType::CPU:

    case DisplayListPlayerType::CPUWithExperimentalTransformSupport:

    case DisplayListPlayerType::GPU: { // GPU painter does not have any path rasterization support so we always fall back to CPU painter

        Painting::DisplayListPlayerCPU display_list_player { *bitmap };

        display_list_player.execute(display_list);

        break;

    }

    default:

        VERIFY_NOT_REACHED();

    }

    return bitmap;

}

RefPtr<Gfx::ImmutableBitmap> SVGDecodedImageData::bitmap(size_t, Gfx::IntSize size) const

{

    if (size.is_empty())

        return nullptr;

    if (auto it = m_cached_rendered_bitmaps.find(size); it != m_cached_rendered_bitmaps.end())

        return it->value;

    // Prevent the cache from growing too big.

    // FIXME: Evict least used entries.

    if (m_cached_rendered_bitmaps.size() > 10)

        m_cached_rendered_bitmaps.remove(m_cached_rendered_bitmaps.begin());

    auto immutable_bitmap = Gfx::ImmutableBitmap::create(*render(size));

    m_cached_rendered_bitmaps.set(size, immutable_bitmap);

    return immutable_bitmap;

}

Optional<CSSPixels> SVGDecodedImageData::intrinsic_width() const

{

    // https://www.w3.org/TR/SVG2/coords.html#SizingSVGInCSS

    m_document->update_style();

    auto const* root_element_style = m_root_element->computed_css_values();

    VERIFY(root_element_style);

    auto const& width_value = root_element_style->size_value(CSS::PropertyID::Width);

    if (width_value.is_length() && width_value.length().is_absolute())

        return width_value.length().absolute_length_to_px();

    return {};

}

Optional<CSSPixels> SVGDecodedImageData::intrinsic_height() const

{

    // https://www.w3.org/TR/SVG2/coords.html#SizingSVGInCSS

    m_document->update_style();

    auto const* root_element_style = m_root_element->computed_css_values();

    VERIFY(root_element_style);

    auto const& height_value = root_element_style->size_value(CSS::PropertyID::Height);

    if (height_value.is_length() && height_value.length().is_absolute())

        return height_value.length().absolute_length_to_px();

    return {};

}

Optional<CSSPixelFraction> SVGDecodedImageData::intrinsic_aspect_ratio() const

{

    // https://www.w3.org/TR/SVG2/coords.html#SizingSVGInCSS

    auto width = intrinsic_width();

    auto height = intrinsic_height();

    if (height.has_value() && *height == 0)

        return {};

    if (width.has_value() && height.has_value())

        return *width / *height;

    if (auto const& viewbox = m_root_element->view_box(); viewbox.has_value()) {

        auto viewbox_width = CSSPixels::nearest_value_for(viewbox->width);

        if (viewbox_width == 0)

            return {};

        auto viewbox_height = CSSPixels::nearest_value_for(viewbox->height);

        if (viewbox_height == 0)

            return {};

        return viewbox_width / viewbox_height;

    }

    return {};

}

void SVGDecodedImageData::SVGPageClient::visit_edges(Visitor& visitor)

{

    Base::visit_edges(visitor);

    visitor.visit(m_host_page);

    visitor.visit(m_svg_page);

}

}