/*

 * Copyright (c) 2022, the SerenityOS developers.

 * Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>

 *

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

 */

#pragma once

#include <AK/Function.h>

#include <AK/HashMap.h>

#include <LibCore/Timer.h>

#include <LibWeb/HTML/EventLoop/EventLoop.h>

#include <LibWeb/WebIDL/Types.h>

namespace Web::HTML {

struct AnimationFrameCallbackDriver {

    using Callback = Function<void(double)>;

    AnimationFrameCallbackDriver()

    {

        m_timer = Core::Timer::create_single_shot(16, [] {

            HTML::main_thread_event_loop().schedule();

        });

    }

    [[nodiscard]] WebIDL::UnsignedLong add(Callback handler)

    {

        auto id = ++m_animation_frame_callback_identifier;

        m_callbacks.set(id, move(handler));

        if (!m_timer->is_active())

            m_timer->start();

        return id;

    }

    bool remove(WebIDL::UnsignedLong id)

    {

        auto it = m_callbacks.find(id);

        if (it == m_callbacks.end())

            return false;

        m_callbacks.remove(it);

        return true;

    }

    void run(double now)

    {

        auto taken_callbacks = move(m_callbacks);

        for (auto& [id, callback] : taken_callbacks)

            callback(now);

    }

    bool has_callbacks() const

    {

        return !m_callbacks.is_empty();

    }

private:

    // https://html.spec.whatwg.org/multipage/imagebitmap-and-animations.html#animation-frame-callback-identifier

    WebIDL::UnsignedLong m_animation_frame_callback_identifier { 0 };

    OrderedHashMap<WebIDL::UnsignedLong, Callback> m_callbacks;

    RefPtr<Core::Timer> m_timer;

};

}