/*
 *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "test/frame_generator_capturer.h"

#include <algorithm>
#include <cmath>
#include <cstddef>
#include <memory>
#include <optional>
#include <utility>

#include "api/task_queue/task_queue_base.h"
#include "api/task_queue/task_queue_factory.h"
#include "api/test/frame_generator_interface.h"
#include "api/units/time_delta.h"
#include "api/video/color_space.h"
#include "api/video/video_frame.h"
#include "api/video/video_rotation.h"
#include "api/video/video_sink_interface.h"
#include "api/video/video_source_interface.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/task_utils/repeating_task.h"
#include "system_wrappers/include/clock.h"
#include "test/frame_utils.h"
#include "test/test_video_capturer.h"

namespace webrtc {
namespace test {

FrameGeneratorCapturer::FrameGeneratorCapturer(
    Clock* clock,
    std::unique_ptr<FrameGeneratorInterface> frame_generator,
    int target_fps,
    TaskQueueFactory& task_queue_factory,
    bool allow_zero_hertz)
    : clock_(clock),
      sending_(true),
      sink_wants_observer_(nullptr),
      frame_generator_(std::move(frame_generator)),
      source_fps_(target_fps),
      target_capture_fps_(target_fps),
      allow_zero_hertz_(allow_zero_hertz),
      task_queue_(task_queue_factory.CreateTaskQueue(
          "FrameGenCapQ",
          TaskQueueFactory::Priority::HIGH)) {
  RTC_DCHECK(frame_generator_);
  RTC_DCHECK_GT(target_fps, 0);
}

FrameGeneratorCapturer::~FrameGeneratorCapturer() {
  Stop();
  // Deconstruct first as tasks in the TaskQueue access other fields of the
  // instance of this class.
  task_queue_ = nullptr;
}

void FrameGeneratorCapturer::SetFakeRotation(VideoRotation rotation) {
  MutexLock lock(&lock_);
  fake_rotation_ = rotation;
}

void FrameGeneratorCapturer::SetFakeColorSpace(
    std::optional<ColorSpace> color_space) {
  MutexLock lock(&lock_);
  fake_color_space_ = color_space;
}

bool FrameGeneratorCapturer::Init() {
  // This check is added because frame_generator_ might be file based and should
  // not crash because a file moved.
  if (frame_generator_ == nullptr)
    return false;

  frame_task_ = RepeatingTaskHandle::DelayedStart(
      task_queue_.get(),
      TimeDelta::Seconds(1) / GetCurrentConfiguredFramerate(),
      [this] {
        InsertFrame();
        return TimeDelta::Seconds(1) / GetCurrentConfiguredFramerate();
      },
      TaskQueueBase::DelayPrecision::kHigh);
  return true;
}

void FrameGeneratorCapturer::InsertFrame() {
  MutexLock lock(&lock_);
  if (sending_) {
    int decimation =
        std::round(static_cast<double>(source_fps_) / target_capture_fps_);
    for (int i = 1; i < decimation; ++i) {
      frame_generator_->SkipNextFrame();
    }

    FrameGeneratorInterface::VideoFrameData frame_data =
        frame_generator_->NextFrame();
    if (allow_zero_hertz_) {
      // Skip frames that are identical to the previous one but still send at
      // least one frame every second.
      if (number_of_frames_skipped_ < target_capture_fps_ - 1 &&
          test::FrameBufsEqual(last_frame_captured_, frame_data.buffer)) {
        ++number_of_frames_skipped_;
        return;
      }
      number_of_frames_skipped_ = 0;
    }
    last_frame_captured_ = frame_data.buffer;
    TestVideoCapturer::OnFrame(
        VideoFrame::Builder()
            .set_video_frame_buffer(frame_data.buffer)
            .set_rotation(fake_rotation_)
            .set_timestamp_us(clock_->TimeInMicroseconds())
            .set_update_rect(frame_data.update_rect)
            .set_color_space(fake_color_space_)
            .build());
  }
}

std::optional<FrameGeneratorCapturer::Resolution>
FrameGeneratorCapturer::GetResolution() const {
  FrameGeneratorInterface::Resolution resolution =
      frame_generator_->GetResolution();
  return Resolution{.width = static_cast<int>(resolution.width),
                    .height = static_cast<int>(resolution.height)};
}

void FrameGeneratorCapturer::Start() {
  {
    MutexLock lock(&lock_);
    sending_ = true;
  }
  if (!frame_task_.Running()) {
    frame_task_ = RepeatingTaskHandle::Start(
        task_queue_.get(),
        [this] {
          InsertFrame();
          return TimeDelta::Seconds(1) / GetCurrentConfiguredFramerate();
        },
        TaskQueueBase::DelayPrecision::kHigh);
  }
}

void FrameGeneratorCapturer::Stop() {
  MutexLock lock(&lock_);
  sending_ = false;
}

void FrameGeneratorCapturer::ChangeResolution(size_t width, size_t height) {
  MutexLock lock(&lock_);
  frame_generator_->ChangeResolution(width, height);
}

void FrameGeneratorCapturer::ChangeFramerate(int target_framerate) {
  MutexLock lock(&lock_);
  RTC_CHECK(target_capture_fps_ > 0);
  if (target_framerate > source_fps_)
    RTC_LOG(LS_WARNING) << "Target framerate clamped from " << target_framerate
                        << " to " << source_fps_;
  if (source_fps_ % target_capture_fps_ != 0) {
    int decimation =
        std::round(static_cast<double>(source_fps_) / target_capture_fps_);
    int effective_rate = target_capture_fps_ / decimation;
    RTC_LOG(LS_WARNING) << "Target framerate, " << target_framerate
                        << ", is an uneven fraction of the source rate, "
                        << source_fps_
                        << ". The framerate will be :" << effective_rate;
  }
  target_capture_fps_ = std::min(source_fps_, target_framerate);
}

int FrameGeneratorCapturer::GetFrameWidth() const {
  return static_cast<int>(frame_generator_->GetResolution().width);
}

int FrameGeneratorCapturer::GetFrameHeight() const {
  return static_cast<int>(frame_generator_->GetResolution().height);
}

void FrameGeneratorCapturer::OnOutputFormatRequest(
    int width,
    int height,
    const std::optional<int>& max_fps) {
  TestVideoCapturer::OnOutputFormatRequest(width, height, max_fps);
}

void FrameGeneratorCapturer::SetSinkWantsObserver(SinkWantsObserver* observer) {
  MutexLock lock(&lock_);
  RTC_DCHECK(!sink_wants_observer_);
  sink_wants_observer_ = observer;
}

void FrameGeneratorCapturer::AddOrUpdateSink(
    VideoSinkInterface<VideoFrame>* sink,
    const VideoSinkWants& wants) {
  TestVideoCapturer::AddOrUpdateSink(sink, wants);
  {
    MutexLock lock(&lock_);
    if (sink_wants_observer_) {
      // Tests need to observe unmodified sink wants.
      sink_wants_observer_->OnSinkWantsChanged(sink, wants);
    }
  }
  ChangeFramerate(GetSinkWants().max_framerate_fps);
}

void FrameGeneratorCapturer::RemoveSink(VideoSinkInterface<VideoFrame>* sink) {
  TestVideoCapturer::RemoveSink(sink);
  ChangeFramerate(GetSinkWants().max_framerate_fps);
}

void FrameGeneratorCapturer::RequestRefreshFrame() {
  MutexLock lock(&lock_);
  if (sending_ && last_frame_captured_ != nullptr) {
    TestVideoCapturer::OnFrame(
        VideoFrame::Builder()
            .set_video_frame_buffer(last_frame_captured_)
            .set_rotation(fake_rotation_)
            .set_timestamp_us(clock_->TimeInMicroseconds())
            .set_color_space(fake_color_space_)
            .build());
  }
}

void FrameGeneratorCapturer::ForceFrame() {
  // One-time non-repeating task,
  task_queue_->PostTask([this] { InsertFrame(); });
}

int FrameGeneratorCapturer::GetCurrentConfiguredFramerate() {
  MutexLock lock(&lock_);
  return target_capture_fps_;
}

}  // namespace test
}  // namespace webrtc