// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#define FML_USED_ON_EMBEDDER

#include "flutter/shell/common/animator.h"

#include <functional>
#include <future>
#include <memory>

#include "flutter/shell/common/shell_test.h"
#include "flutter/shell/common/shell_test_platform_view.h"
#include "flutter/testing/testing.h"
#include "gtest/gtest.h"

namespace flutter {
namespace testing {

class FakeAnimatorDelegate : public Animator::Delegate {
 public:
  void OnAnimatorBeginFrame(fml::TimePoint frame_target_time,
                            uint64_t frame_number) override {}

  void OnAnimatorNotifyIdle(int64_t deadline) override {
    notify_idle_called_ = true;
  }

  void OnAnimatorDraw(
      std::shared_ptr<Pipeline<flutter::LayerTree>> pipeline,
      std::unique_ptr<FrameTimingsRecorder> frame_timings_recorder) override {}

  void OnAnimatorDrawLastLayerTree(
      std::unique_ptr<FrameTimingsRecorder> frame_timings_recorder) override {}

  bool notify_idle_called_ = false;
};

TEST_F(ShellTest, VSyncTargetTime) {
  // Add native callbacks to listen for window.onBeginFrame
  int64_t target_time;
  fml::AutoResetWaitableEvent on_target_time_latch;
  auto nativeOnBeginFrame = [&on_target_time_latch,
                             &target_time](Dart_NativeArguments args) {
    Dart_Handle exception = nullptr;
    target_time =
        tonic::DartConverter<int64_t>::FromArguments(args, 0, exception);
    on_target_time_latch.Signal();
  };
  AddNativeCallback("NativeOnBeginFrame",
                    CREATE_NATIVE_ENTRY(nativeOnBeginFrame));

  // Create all te prerequisites for a shell.
  ASSERT_FALSE(DartVMRef::IsInstanceRunning());
  auto settings = CreateSettingsForFixture();

  std::unique_ptr<Shell> shell;

  TaskRunners task_runners = GetTaskRunnersForFixture();
  // this is not used as we are not using simulated events.
  const auto vsync_clock = std::make_shared<ShellTestVsyncClock>();
  CreateVsyncWaiter create_vsync_waiter = [&]() {
    return static_cast<std::unique_ptr<VsyncWaiter>>(
        std::make_unique<ConstantFiringVsyncWaiter>(task_runners));
  };

  // create a shell with a constant firing vsync waiter.
  auto platform_task = std::async(std::launch::async, [&]() {
    fml::MessageLoop::EnsureInitializedForCurrentThread();

    shell = Shell::Create(
        flutter::PlatformData(), task_runners, settings,
        [vsync_clock, &create_vsync_waiter](Shell& shell) {
          return ShellTestPlatformView::Create(
              shell, shell.GetTaskRunners(), vsync_clock,
              std::move(create_vsync_waiter),
              ShellTestPlatformView::BackendType::kDefaultBackend, nullptr);
        },
        [](Shell& shell) { return std::make_unique<Rasterizer>(shell); });
    ASSERT_TRUE(DartVMRef::IsInstanceRunning());

    auto configuration = RunConfiguration::InferFromSettings(settings);
    ASSERT_TRUE(configuration.IsValid());
    configuration.SetEntrypoint("onBeginFrameMain");

    RunEngine(shell.get(), std::move(configuration));
  });
  platform_task.wait();

  // schedule a frame to trigger window.onBeginFrame
  fml::TaskRunner::RunNowOrPostTask(shell->GetTaskRunners().GetUITaskRunner(),
                                    [engine = shell->GetEngine()]() {
                                      if (engine) {
                                        // Engine needs a surface for frames to
                                        // be scheduled.
                                        engine->OnOutputSurfaceCreated();
                                        // this implies we can re-use the last
                                        // frame to trigger begin frame rather
                                        // than re-generating the layer tree.
                                        engine->ScheduleFrame(true);
                                      }
                                    });

  on_target_time_latch.Wait();
  const auto vsync_waiter_target_time =
      ConstantFiringVsyncWaiter::frame_target_time;
  ASSERT_EQ(vsync_waiter_target_time.ToEpochDelta().ToMicroseconds(),
            target_time);

  // validate that the latest target time has also been updated.
  ASSERT_EQ(GetLatestFrameTargetTime(shell.get()), vsync_waiter_target_time);

  // teardown.
  DestroyShell(std::move(shell), std::move(task_runners));
  ASSERT_FALSE(DartVMRef::IsInstanceRunning());
}

TEST_F(ShellTest, AnimatorStartsPaused) {
  // Create all te prerequisites for a shell.
  ASSERT_FALSE(DartVMRef::IsInstanceRunning());
  auto settings = CreateSettingsForFixture();
  TaskRunners task_runners = GetTaskRunnersForFixture();

  auto shell = CreateShell(std::move(settings), task_runners,
                           /* simulate_vsync=*/true);
  ASSERT_TRUE(DartVMRef::IsInstanceRunning());

  auto configuration = RunConfiguration::InferFromSettings(settings);
  ASSERT_TRUE(configuration.IsValid());

  configuration.SetEntrypoint("emptyMain");

  RunEngine(shell.get(), std::move(configuration));

  ASSERT_FALSE(IsAnimatorRunning(shell.get()));

  // teardown.
  DestroyShell(std::move(shell), std::move(task_runners));
  ASSERT_FALSE(DartVMRef::IsInstanceRunning());
}

TEST_F(ShellTest, AnimatorDoesNotNotifyIdleBeforeRender) {
  FakeAnimatorDelegate delegate;
  TaskRunners task_runners = {
      "test",
      CreateNewThread(),  // platform
      CreateNewThread(),  // raster
      CreateNewThread(),  // ui
      CreateNewThread()   // io
  };

  auto clock = std::make_shared<ShellTestVsyncClock>();
  fml::AutoResetWaitableEvent latch;
  std::shared_ptr<Animator> animator;

  auto flush_vsync_task = [&] {
    fml::AutoResetWaitableEvent ui_latch;
    task_runners.GetUITaskRunner()->PostTask([&] { ui_latch.Signal(); });
    do {
      clock->SimulateVSync();
    } while (ui_latch.WaitWithTimeout(fml::TimeDelta::FromMilliseconds(1)));
    latch.Signal();
  };

  // Create the animator on the UI task runner.
  task_runners.GetUITaskRunner()->PostTask([&] {
    auto vsync_waiter = static_cast<std::unique_ptr<VsyncWaiter>>(
        std::make_unique<ShellTestVsyncWaiter>(task_runners, clock));
    animator = std::make_unique<Animator>(delegate, task_runners,
                                          std::move(vsync_waiter));
    latch.Signal();
  });
  latch.Wait();

  // Validate it has not notified idle and start it. This will request a frame.
  task_runners.GetUITaskRunner()->PostTask([&] {
    ASSERT_FALSE(delegate.notify_idle_called_);
    animator->Start();
    // Immediately request a frame saying it can reuse the last layer tree to
    // avoid more calls to BeginFrame by the animator.
    animator->RequestFrame(false);
    task_runners.GetPlatformTaskRunner()->PostTask(flush_vsync_task);
  });
  latch.Wait();
  ASSERT_FALSE(delegate.notify_idle_called_);

  // Validate it has not notified idle and try to render.
  task_runners.GetUITaskRunner()->PostDelayedTask(
      [&] {
        ASSERT_FALSE(delegate.notify_idle_called_);
        auto layer_tree =
            std::make_unique<LayerTree>(SkISize::Make(600, 800), 1.0);
        animator->Render(std::move(layer_tree));
        task_runners.GetPlatformTaskRunner()->PostTask(flush_vsync_task);
      },
      // See kNotifyIdleTaskWaitTime in animator.cc.
      fml::TimeDelta::FromMilliseconds(60));
  latch.Wait();

  // Still hasn't notified idle because there has been no frame request.
  task_runners.GetUITaskRunner()->PostTask([&] {
    ASSERT_FALSE(delegate.notify_idle_called_);
    // False to avoid getting cals to BeginFrame that will request more frames
    // before we are ready.
    animator->RequestFrame(false);
    task_runners.GetPlatformTaskRunner()->PostTask(flush_vsync_task);
  });
  latch.Wait();

  // Now it should notify idle. Make sure it is destroyed on the UI thread.
  ASSERT_TRUE(delegate.notify_idle_called_);

  // Stop and do one more flush so we can safely clean up on the UI thread.
  animator->Stop();
  task_runners.GetPlatformTaskRunner()->PostTask(flush_vsync_task);
  latch.Wait();

  task_runners.GetUITaskRunner()->PostTask([&] {
    animator.reset();
    latch.Signal();
  });
  latch.Wait();
}

}  // namespace testing
}  // namespace flutter