// Copyright 2021 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// AsyncTaskTests:
//     Simple tests for dawn_native::AsyncTask and dawn_native::AsnycTaskManager.

#include <gtest/gtest.h>

#include <memory>
#include <mutex>

#include "common/NonCopyable.h"
#include "dawn_native/AsyncTask.h"
#include "dawn_platform/DawnPlatform.h"

namespace {

    struct SimpleTaskResult {
        uint32_t id;
    };

    // A thread-safe queue that stores the task results.
    class ConcurrentTaskResultQueue : public NonCopyable {
      public:
        void AddResult(std::unique_ptr<SimpleTaskResult> result) {
            std::lock_guard<std::mutex> lock(mMutex);
            mTaskResults.push_back(std::move(result));
        }

        std::vector<std::unique_ptr<SimpleTaskResult>> GetAllResults() {
            std::vector<std::unique_ptr<SimpleTaskResult>> outputResults;
            {
                std::lock_guard<std::mutex> lock(mMutex);
                outputResults.swap(mTaskResults);
            }
            return outputResults;
        }

      private:
        std::mutex mMutex;
        std::vector<std::unique_ptr<SimpleTaskResult>> mTaskResults;
    };

    void DoTask(ConcurrentTaskResultQueue* resultQueue, uint32_t id) {
        std::unique_ptr<SimpleTaskResult> result = std::make_unique<SimpleTaskResult>();
        result->id = id;
        resultQueue->AddResult(std::move(result));
    }

}  // anonymous namespace

class AsyncTaskTest : public testing::Test {};

// Emulate the basic usage of worker thread pool in Create*PipelineAsync().
TEST_F(AsyncTaskTest, Basic) {
    dawn_platform::Platform platform;
    std::unique_ptr<dawn_platform::WorkerTaskPool> pool = platform.CreateWorkerTaskPool();

    dawn_native::AsyncTaskManager taskManager(pool.get());
    ConcurrentTaskResultQueue taskResultQueue;

    constexpr size_t kTaskCount = 4u;
    std::set<uint32_t> idset;
    for (uint32_t i = 0; i < kTaskCount; ++i) {
        dawn_native::AsyncTask asyncTask([&taskResultQueue, i] { DoTask(&taskResultQueue, i); });
        taskManager.PostTask(std::move(asyncTask));
        idset.insert(i);
    }

    taskManager.WaitAllPendingTasks();

    std::vector<std::unique_ptr<SimpleTaskResult>> results = taskResultQueue.GetAllResults();
    ASSERT_EQ(kTaskCount, results.size());
    for (std::unique_ptr<SimpleTaskResult>& result : results) {
        idset.erase(result->id);
    }
    ASSERT_TRUE(idset.empty());
}