/*
 * Copyright (c) 2023-2025, Andreas Kling <andreas@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Checked.h>
#include <AK/NumericLimits.h>
#include <LibGfx/Bitmap.h>
#include <LibGfx/DecodedImageFrame.h>
#include <LibGfx/PaintingSurface.h>
#include <LibJS/Runtime/ExternalMemory.h>
#include <LibWeb/Bindings/MainThreadVM.h>
#include <LibWeb/CSS/ComputedProperties.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/Navigable.h>
#include <LibWeb/HTML/NavigationParams.h>
#include <LibWeb/HTML/Parser/HTMLParser.h>
#include <LibWeb/HTML/TraversableNavigable.h>
#include <LibWeb/HTML/Window.h>
#include <LibWeb/HTML/WindowProxy.h>
#include <LibWeb/Page/Page.h>
#include <LibWeb/Painting/DisplayListPlayerSkia.h>
#include <LibWeb/Painting/DisplayListRecordingContext.h>
#include <LibWeb/Painting/DisplayListResourceStorage.h>
#include <LibWeb/Painting/ViewportPaintable.h>
#include <LibWeb/SVG/SVGDecodedImageData.h>
#include <LibWeb/SVG/SVGSVGElement.h>
#include <LibWeb/XML/XMLDocumentBuilder.h>
#include <LibXML/Parser/Parser.h>

namespace Web::SVG {

GC_DEFINE_ALLOCATOR(SVGDecodedImageData);
GC_DEFINE_ALLOCATOR(SVGDecodedImageData::SVGPageClient);

ErrorOr<GC::Ref<SVGDecodedImageData>> SVGDecodedImageData::create(JS::Realm& realm, GC::Ref<Page> host_page, URL::URL const& url, ReadonlyBytes data)
{
    auto page_client = SVGPageClient::create(Bindings::main_thread_vm(), host_page);
    auto page = Page::create(Bindings::main_thread_vm(), *page_client);
    page->set_is_scripting_enabled(false);
    page_client->m_svg_page = page.ptr();
    page->set_top_level_traversable(Web::HTML::TraversableNavigable::create_a_new_top_level_traversable(*page, nullptr, {}));
    GC::Ref<HTML::Navigable> navigable = page->top_level_traversable();
    auto response = Fetch::Infrastructure::Response::create(navigable->vm());
    response->url_list().append(url);
    auto origin = URL::Origin::create_opaque();
    auto navigation_params = navigable->heap().allocate<HTML::NavigationParams>(OptionalNone {},
        navigable,
        nullptr,
        response,
        nullptr,
        nullptr,
        HTML::OpenerPolicyEnforcementResult { .url = url, .origin = origin, .opener_policy = HTML::OpenerPolicy {} },
        nullptr,
        origin,
        navigable->heap().allocate<HTML::PolicyContainer>(realm.heap()),
        HTML::SandboxingFlagSet {},
        ReferrerPolicy::ReferrerPolicy::EmptyString,
        HTML::OpenerPolicy {},
        OptionalNone {},
        HTML::UserNavigationInvolvement::None);

    // FIXME: Use Navigable::navigate() instead of manually replacing the navigable's document.
    auto document = MUST(DOM::Document::create_and_initialize(DOM::Document::Type::XML, "image/svg+xml"_string, navigation_params));
    navigable->set_ongoing_navigation({});
    navigable->active_document()->destroy();
    navigable->set_active_document(document);
    auto& window = as<HTML::Window>(HTML::relevant_global_object(document));
    document->browsing_context()->window_proxy()->set_window(window);

    XML::Parser parser(data, { .resolve_named_html_entity = resolve_named_html_entity });
    XMLDocumentBuilder builder { document, XMLScriptingSupport::Disabled };
    auto result = parser.parse_with_listener(builder);
    if (result.is_error())
        dbgln("SVGDecodedImageData: Failed to parse SVG: {}", result.error());

    // Mark the document as completely loaded so that <use> elements
    // (which defer cloning until the document is complete) resolve
    // forward references to elements parsed after them.
    document->completely_finish_loading();

    auto* svg_root = document->first_child_of_type<SVG::SVGSVGElement>();
    if (!svg_root) {
        dbgln("SVGDecodedImageData: Invalid SVG input (no SVGSVGElement found)");
        return Error::from_string_literal("SVGDecodedImageData: Invalid SVG input");
    }
    return realm.create<SVGDecodedImageData>(page, page_client, document, *svg_root);
}

SVGDecodedImageData::SVGDecodedImageData(GC::Ref<Page> page, GC::Ref<SVGPageClient> page_client, GC::Ref<DOM::Document> document, GC::Ref<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);
}

static size_t surface_external_memory_size(Gfx::PaintingSurface const& surface)
{
    auto surface_size = surface.size();
    if (surface_size.is_empty())
        return 0;

    Checked<size_t> pixel_size = static_cast<size_t>(surface_size.width());
    pixel_size *= static_cast<size_t>(surface_size.height());
    pixel_size *= sizeof(u32);
    if (pixel_size.has_overflow())
        return NumericLimits<size_t>::max();
    return pixel_size.value();
}

size_t SVGDecodedImageData::external_memory_size() const
{
    size_t size = Base::external_memory_size();
    size = JS::saturating_add_external_memory_size(size, JS::hash_map_external_memory_size(m_cached_rendered_frames));
    for (auto const& cached_frame : m_cached_rendered_frames)
        size = JS::saturating_add_external_memory_size(size, cached_frame.value.bitmap().data_size());

    size = JS::saturating_add_external_memory_size(size, JS::hash_map_external_memory_size(m_cached_rendered_surfaces));
    for (auto const& cached_surface : m_cached_rendered_surfaces)
        size = JS::saturating_add_external_memory_size(size, surface_external_memory_size(*cached_surface.value));

    return size;
}

static void copy_referenced_resources_to(
    Painting::DisplayListResourceStorage& destination,
    Painting::DisplayListResourceStorage const& source,
    Painting::DisplayListResourceSet const& referenced_resources)
{
    Painting::DisplayListResourceSet empty_resource_set;
    destination.apply_transaction(source.create_transaction(empty_resource_set, referenced_resources));
}

void SVGDecodedImageData::prune_cached_display_list_resources() const
{
    auto& resource_storage = m_document->navigable()->display_list_resource_storage();

    Painting::DisplayListResourceSet retained_resources;
    for (auto const& cached_display_list : m_cached_display_lists) {
        retained_resources.include(
            resource_storage.collect_referenced_resources(*cached_display_list.value.display_list));
    }
    resource_storage.retain_only(retained_resources);
}

Optional<Painting::DisplayListResource> SVGDecodedImageData::record_display_list(Gfx::IntSize size, Painting::DisplayListResourceStorage& destination_resource_storage) const
{
    auto& resource_storage = m_document->navigable()->display_list_resource_storage();

    if (auto it = m_cached_display_lists.find(size); it != m_cached_display_lists.end()) {
        auto referenced_resources = resource_storage.collect_referenced_resources(*it->value.display_list);
        copy_referenced_resources_to(destination_resource_storage, resource_storage, referenced_resources);
        return Painting::DisplayListResource { *it->value.display_list, it->value.visual_context_tree };
    }

    // FIXME: Evict least used entries.
    if (m_cached_display_lists.size() > 10) {
        m_cached_display_lists.remove(m_cached_display_lists.begin());
        prune_cached_display_list_resources();
    }

    m_document->navigable()->set_viewport_size(size.to_type<CSSPixels>());
    m_document->update_layout(DOM::UpdateLayoutReason::SVGDecodedImageDataRender);
    auto display_list = m_document->record_display_list({}, resource_storage);
    if (!display_list)
        return {};

    auto referenced_resources = resource_storage.collect_referenced_resources(*display_list);
    copy_referenced_resources_to(destination_resource_storage, resource_storage, referenced_resources);
    auto document_paintable = m_document->paintable();
    VERIFY(document_paintable);
    auto visual_context_tree = document_paintable->visual_context_tree();
    auto display_list_resource = Painting::DisplayListResource { *display_list, visual_context_tree };
    m_cached_display_lists.set(size, CachedDisplayList { NonnullRefPtr<Painting::DisplayList> { *display_list }, move(visual_context_tree) });
    prune_cached_display_list_resources();
    return display_list_resource;
}

RefPtr<Gfx::PaintingSurface> SVGDecodedImageData::render_to_surface(Gfx::IntSize size) const
{
    VERIFY(m_document->navigable());

    if (size.is_empty())
        return {};

    if (auto it = m_cached_rendered_surfaces.find(size); it != m_cached_rendered_surfaces.end())
        return it->value;

    // Prevent the cache from growing too big.
    // FIXME: Evict least used entries.
    if (m_cached_rendered_surfaces.size() > 10)
        m_cached_rendered_surfaces.remove(m_cached_rendered_surfaces.begin());

    auto surface = Gfx::PaintingSurface::create_with_size(size, Gfx::BitmapFormat::BGRA8888, Gfx::AlphaType::Premultiplied);
    Painting::DisplayListResourceStorage resource_storage;
    auto display_list = record_display_list(size, resource_storage);
    if (!display_list.has_value())
        return nullptr;

    Painting::DisplayListPlayerSkia display_list_player;
    display_list_player.execute(*display_list->display_list, display_list->visual_context_tree, resource_storage, {}, surface);
    display_list_player.flush(*surface);

    m_cached_rendered_surfaces.set(size, *surface);
    return surface;
}

Optional<Gfx::DecodedImageFrame> SVGDecodedImageData::current_frame(Gfx::IntSize size) const
{
    if (size.is_empty())
        return {};

    if (auto it = m_cached_rendered_frames.find(size); it != m_cached_rendered_frames.end())
        return it->value;

    // Prevent the cache from growing too big.
    // FIXME: Evict least used entries.
    if (m_cached_rendered_frames.size() > 10)
        m_cached_rendered_frames.remove(m_cached_rendered_frames.begin());

    auto decoded_frame = Gfx::DecodedImageFrame { *render_to_surface(size)->snapshot_bitmap() };
    m_cached_rendered_frames.set(size, decoded_frame);
    return decoded_frame;
}

Optional<Gfx::DecodedImageFrame> SVGDecodedImageData::default_frame(Gfx::IntSize size) const
{
    // FIXME: Implement this properly once we support animated SVGs, potentially by creating a temporary internal
    //        document which has animations disabled.
    return current_frame(size);
}

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_properties();
    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_properties();
    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 (width.has_value() && height.has_value() && *width > 0 && *height > 0)
        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);
}

void SVGDecodedImageData::paint(DisplayListRecordingContext& context, Gfx::IntRect dst_rect, CSS::ImageRendering) const
{
    auto display_list = record_display_list(dst_rect.size(), context.display_list_recorder().resource_storage());
    if (!display_list.has_value())
        return;

    context.display_list_recorder().paint_nested_display_list(*display_list, dst_rect);
}

}
