/*
 * Copyright (c) 2021-2024, Andreas Kling <andreas@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/DistinctNumeric.h>
#include <LibGC/CellAllocator.h>
#include <LibJS/Heap/Cell.h>
#include <LibWeb/Export.h>
#include <LibWeb/Forward.h>

namespace Web::HTML {

struct UniqueTaskSource;

AK_TYPEDEF_DISTINCT_NUMERIC_GENERAL(u64, TaskID, Comparison);

class Task final : public JS::Cell {
    GC_CELL(Task, JS::Cell);
    GC_DECLARE_ALLOCATOR(Task);

public:
    // https://html.spec.whatwg.org/multipage/webappapis.html#generic-task-sources
    enum class Source {
        Unspecified,
        DOMManipulation,
        UserInteraction,
        Networking,
        HistoryTraversal,
        IdleTask,
        PostedMessage,
        Microtask,
        TimerTask,
        JavaScriptEngine,

        // https://w3c.github.io/geolocation/#dfn-geolocation-task-source
        Geolocation,

        // https://html.spec.whatwg.org/multipage/imagebitmap-and-animations.html#bitmap-task-source
        BitmapTask,

        // https://html.spec.whatwg.org/multipage/webappapis.html#navigation-and-traversal-task-source
        NavigationAndTraversal,

        // https://w3c.github.io/FileAPI/#fileReadingTaskSource
        FileReading,

        // https://www.w3.org/TR/intersection-observer/#intersectionobserver-task-source
        IntersectionObserver,

        // https://w3c.github.io/performance-timeline/#dfn-performance-timeline-task-source
        PerformanceTimeline,

        // https://html.spec.whatwg.org/multipage/canvas.html#canvas-blob-serialisation-task-source
        CanvasBlobSerializationTask,

        // https://w3c.github.io/clipboard-apis/#clipboard-task-source
        Clipboard,

        // https://w3c.github.io/permissions/#permissions-task-source
        Permissions,

        // https://drafts.csswg.org/css-font-loading/#task-source
        FontLoading,

        // https://html.spec.whatwg.org/multipage/server-sent-events.html#remote-event-task-source
        RemoteEvent,

        // https://html.spec.whatwg.org/multipage/webappapis.html#rendering-task-source
        Rendering,

        // https://w3c.github.io/IndexedDB/#database-access-task-source
        DatabaseAccess,

        // https://websockets.spec.whatwg.org/#websocket-task-source
        WebSocket,

        // https://w3c.github.io/media-capabilities/#media-capabilities-task-source
        MediaCapabilities,

        // https://w3c.github.io/gamepad/#dfn-gamepad-task-source
        Gamepad,

        // !!! IMPORTANT: Keep this field last!
        // This serves as the base value of all unique task sources.
        // Some elements, such as the HTMLMediaElement, must have a unique task source per instance.
        UniqueTaskSourceStart
    };

    static GC::Ref<Task> create(JS::VM&, Source, GC::Ptr<DOM::Document const>, GC::Ref<GC::Function<void()>> steps);

    virtual ~Task() override;

    [[nodiscard]] TaskID id() const { return m_id; }
    Source source() const { return m_source; }
    void execute();

    DOM::Document const* document() const;

    bool is_runnable() const;

private:
    Task(Source, GC::Ptr<DOM::Document const>, GC::Ref<GC::Function<void()>> steps);

    virtual void visit_edges(Visitor&) override;

    TaskID m_id {};
    Source m_source { Source::Unspecified };
    GC::Ref<GC::Function<void()>> m_steps;
    GC::Ptr<DOM::Document const> m_document;
};

struct WEB_API UniqueTaskSource {
    UniqueTaskSource();
    ~UniqueTaskSource();

    Task::Source const source;
};

class WEB_API ParallelQueue : public RefCounted<ParallelQueue> {
public:
    static NonnullRefPtr<ParallelQueue> create();
    TaskID enqueue(GC::Ref<GC::Function<void()>>);

private:
    UniqueTaskSource m_task_source;
};

}
