// Copyright 2021 The Dawn & Tint Authors
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "dawn/platform/WorkerThread.h"

#include <condition_variable>
#include <functional>
#include <thread>

#include "dawn/common/Assert.h"

namespace {

class AsyncWaitableEventImpl {
  public:
    AsyncWaitableEventImpl() : mIsComplete(false) {}

    void Wait() {
        std::unique_lock<std::mutex> lock(mMutex);
        mCondition.wait(lock, [this] { return mIsComplete; });
    }

    bool IsComplete() {
        std::lock_guard<std::mutex> lock(mMutex);
        return mIsComplete;
    }

    void MarkAsComplete() {
        {
            std::lock_guard<std::mutex> lock(mMutex);
            mIsComplete = true;
        }
        mCondition.notify_all();
    }

  private:
    std::mutex mMutex;
    std::condition_variable mCondition;
    bool mIsComplete;
};

class AsyncWaitableEvent final : public dawn::platform::WaitableEvent {
  public:
    AsyncWaitableEvent() : mWaitableEventImpl(std::make_shared<AsyncWaitableEventImpl>()) {}

    void Wait() override { mWaitableEventImpl->Wait(); }

    bool IsComplete() override { return mWaitableEventImpl->IsComplete(); }

    std::shared_ptr<AsyncWaitableEventImpl> GetWaitableEventImpl() const {
        return mWaitableEventImpl;
    }

  private:
    std::shared_ptr<AsyncWaitableEventImpl> mWaitableEventImpl;
};

}  // anonymous namespace

namespace dawn::platform {

std::unique_ptr<dawn::platform::WaitableEvent> AsyncWorkerThreadPool::PostWorkerTask(
    dawn::platform::PostWorkerTaskCallback callback,
    void* userdata) {
    std::unique_ptr<AsyncWaitableEvent> waitableEvent = std::make_unique<AsyncWaitableEvent>();

    std::function<void()> doTask = [callback, userdata,
                                    waitableEventImpl = waitableEvent->GetWaitableEventImpl()] {
        callback(userdata);
        waitableEventImpl->MarkAsComplete();
    };

    std::thread thread(doTask);
    thread.detach();

    return waitableEvent;
}

}  // namespace dawn::platform