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

#include "content/browser/media/capture/desktop_capture_device.h"

#include <stddef.h>
#include <stdint.h>
#include <string.h>

#include <algorithm>
#include <memory>
#include <utility>

#include "base/check_op.h"
#include "base/command_line.h"
#include "base/compiler_specific.h"
#include "base/feature_list.h"
#include "base/functional/bind.h"
#include "base/location.h"
#include "base/memory/raw_ptr.h"
#include "base/message_loop/message_pump_type.h"
#include "base/metrics/histogram_macros.h"
#include "base/notreached.h"
#include "base/strings/string_number_conversions.h"
#include "base/synchronization/lock.h"
#include "base/task/single_thread_task_runner.h"
#include "base/threading/thread.h"
#include "base/threading/thread_restrictions.h"
#include "base/time/tick_clock.h"
#include "base/timer/timer.h"
#include "base/trace_event/trace_event.h"
#include "build/build_config.h"
#include "content/browser/media/capture/desktop_capture_device_uma_types.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/desktop_capture.h"
#include "content/public/browser/desktop_media_id.h"
#include "content/public/browser/device_service.h"
#include "content/public/common/content_switches.h"
#include "media/base/video_util.h"
#include "media/capture/content/capture_resolution_chooser.h"
#include "media/webrtc/webrtc_features.h"
#include "mojo/public/cpp/bindings/remote.h"
#include "services/device/public/mojom/wake_lock.mojom.h"
#include "services/device/public/mojom/wake_lock_provider.mojom.h"
#include "third_party/libyuv/include/libyuv/convert.h"
#include "third_party/libyuv/include/libyuv/scale.h"
#include "third_party/webrtc/modules/desktop_capture/cropped_desktop_frame.h"
#include "third_party/webrtc/modules/desktop_capture/cropping_window_capturer.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_and_cursor_composer.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_capture_options.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_capture_types.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_capturer.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
#include "third_party/webrtc/modules/desktop_capture/fake_desktop_capturer.h"
#include "third_party/webrtc/modules/desktop_capture/mouse_cursor_monitor.h"
#include "ui/gfx/icc_profile.h"

#if BUILDFLAG(IS_WIN)
#include "base/win/windows_version.h"
#endif

namespace content {

namespace {

// Maximum CPU time percentage of a single core that can be consumed for desktop
// capturing. This means that on systems where screen scraping is slow we may
// need to capture at frame rate lower than requested. This is necessary to keep
// UI responsive.
const int kDefaultMaximumCpuConsumptionPercentage = 50;

// Constant which sets the cutoff frequency in an an exponential moving average
// (EMA) filter used to calculate the current frame rate (in frames per second).
constexpr float kAlpha = 0.1;

const char* DesktopMediaTypeToString(DesktopMediaID::Type type) {
  switch (type) {
    case DesktopMediaID::TYPE_NONE:
      return "NONE";
    case DesktopMediaID::TYPE_SCREEN:
      return "SCREEN";
    case DesktopMediaID::TYPE_WINDOW:
      return "WINDOW";
    case DesktopMediaID::TYPE_WEB_CONTENTS:
      return "WEB_CONTENTS";
    default:
      return "UNKNOWN";
  }
}

webrtc::DesktopRect ComputeLetterboxRect(
    const webrtc::DesktopSize& max_size,
    const webrtc::DesktopSize& source_size) {
  gfx::Rect result = media::ComputeLetterboxRegion(
      gfx::Rect(0, 0, max_size.width(), max_size.height()),
      gfx::Size(source_size.width(), source_size.height()));
  return webrtc::DesktopRect::MakeLTRB(
      result.x(), result.y(), result.right(), result.bottom());
}

bool IsFrameUnpackedOrInverted(webrtc::DesktopFrame* frame) {
  return frame->stride() !=
      frame->size().width() * webrtc::DesktopFrame::kBytesPerPixel;
}

void BindWakeLockProvider(
    mojo::PendingReceiver<device::mojom::WakeLockProvider> receiver) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  GetDeviceService().BindWakeLockProvider(std::move(receiver));
}

void LogDesktopCaptureZeroHzIsActive(DesktopMediaID::Type capturer_type,
                                     bool zero_hz_is_active) {
  if (capturer_type == DesktopMediaID::TYPE_SCREEN) {
    UMA_HISTOGRAM_BOOLEAN("WebRTC.DesktopCapture.IsZeroHzActive.Screen",
                          zero_hz_is_active);
  } else {
    UMA_HISTOGRAM_BOOLEAN("WebRTC.DesktopCapture.IsZeroHzActive.Window",
                          zero_hz_is_active);
  }
}

void LogDesktopCaptureFrameIsRefresh(DesktopMediaID::Type capturer_type,
                                     bool is_refresh_frame) {
  if (capturer_type == DesktopMediaID::TYPE_SCREEN) {
    UMA_HISTOGRAM_BOOLEAN("WebRTC.DesktopCapture.FrameIsRefresh.Screen",
                          is_refresh_frame);
  } else {
    UMA_HISTOGRAM_BOOLEAN("WebRTC.DesktopCapture.FrameIsRefresh.Window",
                          is_refresh_frame);
  }
}

void LogDesktopCaptureFrameRate(DesktopMediaID::Type capturer_type,
                                int frame_rate_fps) {
  if (capturer_type == DesktopMediaID::TYPE_SCREEN) {
    UMA_HISTOGRAM_COUNTS_100("WebRTC.DesktopCapture.FrameRate.Screen",
                             frame_rate_fps);
  } else {
    UMA_HISTOGRAM_COUNTS_100("WebRTC.DesktopCapture.FrameRate.Window",
                             frame_rate_fps);
  }
}

void LogDesktopCaptureRequestRefreshRate(DesktopMediaID::Type capturer_type,
                                         int rrf_rate_fps) {
  if (capturer_type == DesktopMediaID::TYPE_SCREEN) {
    UMA_HISTOGRAM_COUNTS_100("WebRTC.DesktopCapture.RefreshRate.Screen",
                             rrf_rate_fps);
  } else {
    UMA_HISTOGRAM_COUNTS_100("WebRTC.DesktopCapture.RefreshRate.Window",
                             rrf_rate_fps);
  }
}

#if BUILDFLAG(IS_WIN)
bool IsWgcEnabledForScreenCapture() {
  bool enabled =
      base::FeatureList::IsEnabled(features::kWebRtcAllowWgcScreenCapturer);
  if (enabled) {
    return true;
  }

  if (base::FeatureList::GetInstance() &&
      base::FeatureList::GetInstance()->IsFeatureOverridden(
          features::kWebRtcAllowWgcScreenCapturer.name)) {
    return enabled;
  }

  // Starting from WIN11 24H2 (build 26100), the Capture API returns empty
  // frame when the captured content is unchanged, helping to maintain
  // performance for 0Hz capture scenarios.
  enabled = (base::win::GetVersion() >= base::win::Version::WIN11_24H2);
  return enabled;
}

bool IsWgcZeroHzEnabledForScreenCapture() {
  bool enabled =
      base::FeatureList::IsEnabled(features::kWebRtcAllowWgcScreenZeroHz);
  if (enabled) {
    return true;
  }

  if (base::FeatureList::GetInstance() &&
      base::FeatureList::GetInstance()->IsFeatureOverridden(
          features::kWebRtcAllowWgcScreenZeroHz.name)) {
    return enabled;
  }
  return IsWgcEnabledForScreenCapture();
}
#endif  // BUILDFLAG(IS_WIN)

// Helper class which request that the system-global Windows timer interrupt
// frequency be raised at construction. The corresponding deactivation is done
// at destruction. How high the frequency is raised depends on the system's
// power state and possibly other options. Only supported on Windows.
class ScopedHighResolutionTimer {
 public:
#if !BUILDFLAG(IS_WIN)
  ScopedHighResolutionTimer() {}
#else
  ScopedHighResolutionTimer() {
    if (!base::Time::IsHighResolutionTimerInUse()) {
      enabled_ = base::Time::ActivateHighResolutionTimer(true);
    }
  }
  ~ScopedHighResolutionTimer() {
    if (enabled_) {
      base::Time::ActivateHighResolutionTimer(false);
    }
  }

 private:
  bool enabled_ = false;
#endif
};

}  // namespace

class DesktopCaptureDevice::Core : public webrtc::DesktopCapturer::Callback {
 public:
  Core(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
       std::unique_ptr<webrtc::DesktopCapturer> capturer,
       DesktopMediaID::Type type,
       bool zero_hertz_is_supported);

  Core(const Core&) = delete;
  Core& operator=(const Core&) = delete;

  ~Core() override;

  // Implementation of VideoCaptureDevice methods.
  void AllocateAndStart(const media::VideoCaptureParams& params,
                        std::unique_ptr<Client> client);
  // Executes a refresh capture, if conditions permit. Otherwise, schedules a
  // later retry. If a refresh was already pending, a new request is ignored.
  void RequestRefreshFrame();

  base::TimeDelta GetDelayBeforeNextRefreshAttempt() const;

  void SetNotificationWindowId(gfx::NativeViewId window_id);

  void SetMockTimeForTesting(
      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
      const base::TickClock* tick_clock);

  base::WeakPtr<Core> GetWeakPtr() { return weak_factory_.GetWeakPtr(); }

 private:
  // webrtc::DesktopCapturer::Callback interface.
  // A side-effect of this method is to schedule the next frame.
  void OnCaptureResult(
    webrtc::DesktopCapturer::Result result,
    std::unique_ptr<webrtc::DesktopFrame> frame) override;

  // Method that is scheduled on |task_runner_| to be called on regular interval
  // to capture a frame.
  void OnCaptureTimer();

  // Captures a frame. Upon completion, schedules the next frame. The frame type
  // is a refresh frame if `is_refresh_frame` is true and a default frame
  // otherwise. Sending refresh frames is expected to be a rare event since a
  // refresh request will be canceled by default capture events and they are
  // periodic.
  void CaptureFrame(bool is_refresh_frame);

  // Schedules a timer for the next call to |CaptureFrame|. This method assumes
  // that |CaptureFrame| has already been called at least once before.
  void ScheduleNextCaptureFrame();

  void RequestWakeLock();

  base::TimeTicks NowTicks() const;

  bool zero_hertz_is_supported() const { return zero_hertz_is_supported_; }

  // Requests high-resolution timers on Windows if not already active.
  // Created in AllocateAndStart() and destroyed in ~Core().
  std::unique_ptr<ScopedHighResolutionTimer> scoped_high_res_timer_;

  // Task runner used for capturing operations.
  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;

  // The underlying DesktopCapturer instance used to capture frames.
  std::unique_ptr<webrtc::DesktopCapturer> desktop_capturer_;

  // The device client which proxies device events to the controller. Accessed
  // on the task_runner_ thread.
  std::unique_ptr<Client> client_;

  // Requested video capture frame rate.
  float requested_frame_rate_;

  // Inverse of the requested frame rate.
  base::TimeDelta requested_frame_duration_;

  // Contains the actual (measured) frame rate using an exponential moving
  // average (EMA) filter. Uses a simple filter with 0.1 weight of the current
  // sample. Unit is in frames per second (fps).
  float frame_rate_;

  // Contains the measured request-refresh rate using an exponential moving
  // average (EMA) filter. Uses a simple filter with 0.1 weight of the current
  // sample. Unit is in frames per second (fps).
  float rrf_rate_;

  // Records time of last call to CaptureFrame.
  base::TimeTicks capture_start_time_;

  // Size of frame most recently captured from the source.
  webrtc::DesktopSize last_frame_size_;

  // DesktopFrame into which captured frames are down-scaled and/or letterboxed,
  // depending upon the caller's requested capture capabilities. If frames can
  // be returned to the caller directly then this is NULL.
  // TODO(https://crbug.com/1444340): should NOT be used to store frames
  // received from the underlying capturer since it can cause cursor flickering
  // if the frame is a DesktopFrameWithCursor. The output frame is black when
  // |output_frame_is_black_| is set. This can happen when a minimized window
  // is shared.
  std::unique_ptr<webrtc::DesktopFrame> output_frame_;

  // True when the |output_frame_->data()| contains only zeros. Tracking this is
  // an optimization to avoid re-clearing |output_frame_| during stretches where
  // we are only sending black frames.
  bool output_frame_is_black_ = false;

  bool output_is_i420_ = false;
  // Used for conversion to I420 before scaling.
  std::vector<uint8_t> temp_buffer_;

  // Determines the size of frames to deliver to the |client_|.
  media::CaptureResolutionChooser resolution_chooser_;

  raw_ptr<const base::TickClock> tick_clock_ = nullptr;

  // Timer used to capture the frame.
  std::unique_ptr<base::OneShotTimer> capture_timer_;

  // See above description of kDefaultMaximumCpuConsumptionPercentage.
  int max_cpu_consumption_percentage_;

  // True when waiting for |desktop_capturer_| to capture current frame.
  bool capture_in_progress_ = false;

  // True when waiting for |desktop_capturer_| to capture current frame as a
  // response to refresh frame request.
  bool refresh_in_progress_ = false;

  // True if the first capture call has returned. Used to log the first capture
  // result.
  bool first_capture_returned_ = false;

  // True if the first capture permanent error has been logged. Used to log the
  // first capture permanent error.
  bool first_permanent_error_logged = false;

  // The type of the capturer.
  DesktopMediaID::Type capturer_type_;

  // True if we support dropping captured frames where the updated region
  // contains no change since last captured frame. To support this 0Hz mode,
  // the utilized capturer implementation must updates the
  // |DesktopFrame::updated_region()| desktop region for each captured frame.
  const bool zero_hertz_is_supported_;

  // The system time when we receive the first frame.
  base::TimeTicks first_ref_time_;

  // The time when Core::CaptureFrame() is called. Used to derive the delta
  // time since last call. The delta time then drives the frame-rate filter
  // which results in an average capture frame rate in `frame_rate_`.
  base::TimeTicks last_capture_time_;

  // The time when Core::RequestRefreshFrame() is called. Used to derive the
  // delta time since last call. The delta time then drives the refresh-rate
  // filter which results in an average refresh rate in `rrf_rate_`.
  base::TimeTicks last_rrf_time_;

  std::unique_ptr<webrtc::BasicDesktopFrame> black_frame_;

  // TODO(jiayl): Remove wake_lock_ when there is an API to keep the
  // screen from sleeping for the drive-by web.
  mojo::Remote<device::mojom::WakeLock> wake_lock_;

  base::WeakPtrFactory<Core> weak_factory_{this};
};

DesktopCaptureDevice::Core::Core(
    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
    std::unique_ptr<webrtc::DesktopCapturer> capturer,
    DesktopMediaID::Type type,
    bool zero_hertz_is_supported)
    : task_runner_(task_runner),
      desktop_capturer_(std::move(capturer)),
      capture_timer_(new base::OneShotTimer()),
      max_cpu_consumption_percentage_(kDefaultMaximumCpuConsumptionPercentage),
      capture_in_progress_(false),
      first_capture_returned_(false),
      first_permanent_error_logged(false),
      capturer_type_(type),
      zero_hertz_is_supported_(zero_hertz_is_supported) {}

DesktopCaptureDevice::Core::~Core() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  client_.reset();
  output_frame_.reset();
  last_frame_size_.set(0, 0);
  desktop_capturer_.reset();
}

void DesktopCaptureDevice::Core::AllocateAndStart(
    const media::VideoCaptureParams& params,
    std::unique_ptr<Client> client) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_GT(params.requested_format.frame_size.GetArea(), 0);
  DCHECK_GT(params.requested_format.frame_rate, 0);
  DCHECK(desktop_capturer_);
  DCHECK(client);
  DCHECK(!client_);

  scoped_high_res_timer_ = std::make_unique<ScopedHighResolutionTimer>();
  client_ = std::move(client);
  requested_frame_rate_ = params.requested_format.frame_rate;
  frame_rate_ = requested_frame_rate_;
  rrf_rate_ = 0;
  requested_frame_duration_ = base::Microseconds(static_cast<int64_t>(
      static_cast<double>(base::Time::kMicrosecondsPerSecond) /
          requested_frame_rate_ +
      0.5 /* round to nearest int */));

  // Pass the min/max resolution and fixed aspect ratio settings from |params|
  // to the CaptureResolutionChooser.
  const auto constraints = params.SuggestConstraints();
  resolution_chooser_.SetConstraints(constraints.min_frame_size,
                                     constraints.max_frame_size,
                                     constraints.fixed_aspect_ratio);
  VLOG(1) << __func__ << " (requested_frame_rate=" << requested_frame_rate_
          << ", max_frame_size=" << constraints.max_frame_size.ToString()
          << ", requested_frame_duration="
          << requested_frame_duration_.InMilliseconds()
          << ", max_cpu_consumption_percentage="
          << max_cpu_consumption_percentage_ << ")";

  DCHECK(!wake_lock_);
  RequestWakeLock();

  desktop_capturer_->Start(this);
  // Assume it will be always started successfully for now.
  client_->OnStarted();

  CaptureFrame(/*is_refresh_frame=*/false);
}

void DesktopCaptureDevice::Core::RequestRefreshFrame() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  TRACE_EVENT0("webrtc", __func__);
  VLOG(2) << __func__;

  if (!client_) {
    return;
  }

  const base::TimeTicks now = NowTicks();
  if (last_rrf_time_.is_null()) {
    last_rrf_time_ = now;
  } else {
    const base::TimeDelta delta_ms = now - last_rrf_time_;
    // We use an exponential moving average (EMA) filter to calculate the
    // current RRF frame rate (in frames per second).
    const float input_frame_rate_fps = (1000.0 / delta_ms.InMillisecondsF());
    rrf_rate_ = kAlpha * input_frame_rate_fps + (1.0 - kAlpha) * rrf_rate_;
    last_rrf_time_ = now;
    VLOG(2) << " rrf_delta_ms=" << delta_ms.InMillisecondsF()
            << ", rrf_rate=" << frame_rate_ << " [fps]";
    const int rrf_rate_fps = base::saturated_cast<int>(frame_rate_ + 0.5);
    LogDesktopCaptureRequestRefreshRate(capturer_type_, rrf_rate_fps);
  }

  if (!capture_in_progress_) {
    CaptureFrame(/*is_refresh_frame=*/true);
  }
}

void DesktopCaptureDevice::Core::SetNotificationWindowId(
    gfx::NativeViewId window_id) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(window_id);
  desktop_capturer_->SetExcludedWindow(window_id);
}

void DesktopCaptureDevice::Core::SetMockTimeForTesting(
    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
    const base::TickClock* tick_clock) {
  tick_clock_ = tick_clock;
  capture_timer_ = std::make_unique<base::OneShotTimer>(tick_clock_);
  capture_timer_->SetTaskRunner(task_runner);
}

void DesktopCaptureDevice::Core::OnCaptureResult(
    webrtc::DesktopCapturer::Result result,
    std::unique_ptr<webrtc::DesktopFrame> frame) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(client_);
  DCHECK(capture_in_progress_ || refresh_in_progress_);
  capture_in_progress_ = false;
  const bool frame_is_refresh = refresh_in_progress_;
  refresh_in_progress_ = false;
  TRACE_EVENT1("webrtc", __func__, "frame_is_refresh", frame_is_refresh);

  bool success = result == webrtc::DesktopCapturer::Result::SUCCESS;

  if (!first_capture_returned_) {
    first_capture_returned_ = true;
    if (capturer_type_ == DesktopMediaID::TYPE_SCREEN) {
      IncrementDesktopCaptureCounter(success ? FIRST_SCREEN_CAPTURE_SUCCEEDED
                                             : FIRST_SCREEN_CAPTURE_FAILED);
    } else {
      IncrementDesktopCaptureCounter(success ? FIRST_WINDOW_CAPTURE_SUCCEEDED
                                             : FIRST_WINDOW_CAPTURE_FAILED);
    }
  }

  if (!success) {
    VLOG(2) << __func__ << " [ERROR]";
    if (result == webrtc::DesktopCapturer::Result::ERROR_PERMANENT) {
      if (!first_permanent_error_logged) {
        first_permanent_error_logged = true;
        if (capturer_type_ == DesktopMediaID::TYPE_SCREEN) {
          IncrementDesktopCaptureCounter(SCREEN_CAPTURER_PERMANENT_ERROR);
        } else {
          IncrementDesktopCaptureCounter(WINDOW_CAPTURER_PERMANENT_ERROR);
        }
      }
      client_->OnError(media::VideoCaptureError::
                           kDesktopCaptureDeviceWebrtcDesktopCapturerHasFailed,
                       FROM_HERE, "The desktop capturer has failed.");
      return;
    }
    // Continue capturing frames in the temporary error case.
    ScheduleNextCaptureFrame();
    return;
  }
  DCHECK(frame);

  // Continue capturing frames when there are no changes in updated regions
  // since the last captured frame but don't send the same frame again to the
  // client. Checking `first_ref_time_` ensures that at least one frame has been
  // captured before 0Hz can be activated. The zero-hertz mode is disabled if
  // the captured frame is a refresh frame to guarantee that the client actually
  // receives a new frame when explicitly asking for it.
  // |zero_hertz_is_supported()| can be false in combination with capturers that
  // do not support the 0Hz mode, e.g. Windows capturers using the WGC API.
  const bool zero_hertz_is_active =
      zero_hertz_is_supported() && !first_ref_time_.is_null() &&
      !frame_is_refresh && frame->updated_region().is_empty();
  VLOG(2) << __func__ << " [SUCCESS]" << (frame_is_refresh ? "[RRF]" : "")
          << (zero_hertz_is_active ? "[0Hz]" : "");
  if (zero_hertz_is_supported()) {
    LogDesktopCaptureZeroHzIsActive(capturer_type_, zero_hertz_is_active);
  }
  if (zero_hertz_is_active) {
    ScheduleNextCaptureFrame();
    return;
  }

  // If the frame size has changed, drop the output frame (if any), and
  // determine the new output size.
  if (!last_frame_size_.equals(frame->size())) {
    output_frame_.reset();
    resolution_chooser_.SetSourceSize(
        gfx::Size(frame->size().width(), frame->size().height()));
    last_frame_size_ = frame->size();
  }
  // Align to 2x2 pixel boundaries, as required by OnIncomingCapturedData() so
  // it can convert the frame to I420 format.
  webrtc::DesktopSize output_size(
      resolution_chooser_.capture_size().width() & ~1,
      resolution_chooser_.capture_size().height() & ~1);
  if (output_size.is_empty()) {
    // Even RESOLUTION_POLICY_ANY_WITHIN_LIMIT is used, a non-empty size should
    // be guaranteed.
    output_size.set(2, 2);
  }
  VLOG(2) << __func__ << " [output_size=(" << output_size.width() << "x"
          << output_size.height() << ")]";

  size_t output_bytes = output_size.width() * output_size.height() *
                        webrtc::DesktopFrame::kBytesPerPixel;
  const uint8_t* output_data = nullptr;

  if (frame->size().width() <= 1 || frame->size().height() <= 1) {
    // On OSX We receive a 1x1 frame when the shared window is minimized. It
    // cannot be subsampled to I420 and will be dropped downstream. So we
    // replace it with a black frame to avoid the video appearing frozen at the
    // last frame.
    if (!output_frame_ || !output_frame_->size().equals(output_size)) {
      // The new frame will be black by default.
      output_frame_ = std::make_unique<webrtc::BasicDesktopFrame>(output_size);
      output_frame_is_black_ = true;
    }
    if (!output_frame_is_black_) {
      output_frame_->SetFrameDataToBlack();
      output_frame_is_black_ = true;
    }
  } else {
    // Scaling frame with odd dimensions to even dimensions will cause
    // blurring. See https://crbug.com/737278.
    // Since chromium always requests frames to be with even dimensions,
    // i.e. for I420 format and video codec, always cropping captured frame
    // to even dimensions.
    const int32_t frame_width = frame->size().width();
    const int32_t frame_height = frame->size().height();
    // TODO(braveyao): remove the check once |CreateCroppedDesktopFrame| can
    // do this check internally.
    if (frame_width & 1 || frame_height & 1) {
      frame = webrtc::CreateCroppedDesktopFrame(
          std::move(frame),
          webrtc::DesktopRect::MakeWH(frame_width & ~1, frame_height & ~1));
    }
    DCHECK(frame);
    DCHECK(!frame->size().is_empty());

    output_is_i420_ = false;

    if (!frame->size().equals(output_size)) {
      VLOG(2) << "  Downscaling: frame->size=(" << frame->size().width() << "x"
              << frame->size().height() << ")";
      // Down-scale and/or letterbox to the target format if the frame does
      // not match the output size.

      // Allocate a buffer of the correct size to scale the frame into.
      // |output_frame_| is cleared whenever the output size changes, so we
      // don't need to worry about clearing out stale pixel data in
      // letterboxed areas.
      if (!output_frame_) {
        output_frame_ =
            std::make_unique<webrtc::BasicDesktopFrame>(output_size);
      }
      DCHECK(output_frame_->size().equals(output_size));

      const int temp_width_y = frame->size().width();
      const int temp_height_y = frame->size().height();
      const int temp_plane_size_y = temp_width_y * temp_height_y;

      // In I420, U and V planes have half the resolution.
      const int temp_width_uv = temp_width_y / 2;
      const int temp_height_uv = temp_height_y / 2;
      const int temp_plane_size_uv = temp_width_uv * temp_height_uv;

      const size_t i420_buffer_size =
          temp_plane_size_y + 2 * temp_plane_size_uv;
      if (temp_buffer_.size() < i420_buffer_size) {
        temp_buffer_.resize(i420_buffer_size);
      }

      // SAFETY: libyuv interface requires raw pointers.
      // temp_buffer_ is allocated to be enough to store I420 frame.
      uint8_t* temp_buffer_y = temp_buffer_.data();
      uint8_t* temp_buffer_u =
          UNSAFE_BUFFERS(temp_buffer_y + temp_plane_size_y);
      uint8_t* temp_buffer_v =
          UNSAFE_BUFFERS(temp_buffer_u + temp_plane_size_uv);

      const int temp_stride_y = temp_width_y;
      const int temp_stride_u = temp_width_uv;
      const int temp_stride_v = temp_width_uv;

      libyuv::ARGBToI420(frame->data(), frame->stride(), temp_buffer_y,
                         temp_stride_y, temp_buffer_u, temp_stride_u,
                         temp_buffer_v, temp_stride_v, frame->size().width(),
                         frame->size().height());

      webrtc::DesktopRect output_rect =
          ComputeLetterboxRect(output_size, frame->size());

      // output_rect for I420 format must start and end at even offsets
      // because of UV planes subsampling.
      if ((output_rect.top() & 1) || (output_rect.left() & 1)) {
        output_rect.Translate(-(output_rect.left() & 1),
                              -(output_rect.top() & 1));
      }
      if ((output_rect.bottom() & 1) || (output_rect.right() & 1)) {
        output_rect.Extend(0, 0, output_rect.right() & 1,
                           output_rect.bottom() & 1);
      }

      CHECK_LE(output_rect.right(), output_size.width());
      CHECK_LE(output_rect.bottom(), output_size.height());

      const int output_width_y = output_size.width();
      const int output_height_y = output_size.height();
      const int output_plane_size_y = output_width_y * output_height_y;

      const int output_width_uv = output_width_y / 2;
      const int output_height_uv = output_height_y / 2;
      const int output_plane_size_uv = output_width_uv * output_height_uv;

      // Offsets of the top-left pixel for the output rect inside each plane.
      const int offset_y =
          output_rect.left() + output_rect.top() * output_width_y;
      // UV planes have half the resolution, so coordinates are also halved.
      const int offset_uv =
          output_rect.left() / 2 + (output_rect.top() / 2) * output_width_uv;

      uint8_t* output_data_base = output_frame_->data();

      // SAFETY: libyuv interface requires raw pointers.
      // output_frame_ is big enough to store ARGB frame and I420
      // is smaller.
      uint8_t* output_y = UNSAFE_BUFFERS(output_data_base + offset_y);
      uint8_t* output_u =
          UNSAFE_BUFFERS(output_data_base + output_plane_size_y + offset_uv);
      uint8_t* output_v =
          UNSAFE_BUFFERS(output_data_base + output_plane_size_y +
                         output_plane_size_uv + offset_uv);

      const int output_stride_y = output_width_y;
      const int output_stride_u = output_width_uv;
      const int output_stride_v = output_width_uv;

      libyuv::I420Scale(temp_buffer_y, temp_stride_y, temp_buffer_u,
                        temp_stride_u, temp_buffer_v, temp_stride_v,
                        frame->size().width(), frame->size().height(), output_y,
                        output_stride_y, output_u, output_stride_u, output_v,
                        output_stride_v, output_rect.width(),
                        output_rect.height(), libyuv::kFilterBox);
      output_is_i420_ = true;

      output_data = output_frame_->data();
      output_frame_is_black_ = false;
    } else if (IsFrameUnpackedOrInverted(frame.get())) {
      // If |frame| is not packed top-to-bottom then create a packed
      // top-to-bottom copy. This is required if the frame is inverted (see
      // crbug.com/306876), or if |frame| is cropped form a larger frame (see
      // crbug.com/437740).
      if (!output_frame_) {
        output_frame_ =
            std::make_unique<webrtc::BasicDesktopFrame>(output_size);
      }
      output_frame_->CopyPixelsFrom(
          *frame, webrtc::DesktopVector(),
          webrtc::DesktopRect::MakeSize(frame->size()));
      output_data = output_frame_->data();
      output_frame_is_black_ = false;
    } else {
      // If the captured frame matches the output size, we can return the pixel
      // data directly.
      output_data = frame->data();
      output_frame_is_black_ = false;
    }
  }

  gfx::ColorSpace frame_color_space;
  if (!frame->icc_profile().empty()) {
    gfx::ICCProfile icc_profile = gfx::ICCProfile::FromData(
        frame->icc_profile().data(), frame->icc_profile().size());
    frame_color_space = icc_profile.GetColorSpace();
    if (output_is_i420_) {
      // Conversion ARGB->I420 will switch the color space.
      frame_color_space = frame_color_space.GetWithMatrixAndRange(
          gfx::ColorSpace::MatrixID::SMPTE170M,
          gfx::ColorSpace::RangeID::LIMITED);
    }
  }

  base::TimeTicks now = NowTicks();
  if (first_ref_time_.is_null())
    first_ref_time_ = now;

  // This passes the information to the frame metadata for screen and non-chrome
  // window captures.
  media::VideoFrameMetadata metadata;
  metadata.source_size =
      gfx::Size(frame->size().width(), frame->size().height());
  metadata.device_scale_factor = frame->device_scale_factor();

  client_->OnIncomingCapturedData(
      output_data, output_bytes,
      media::VideoCaptureFormat(
          gfx::Size(output_size.width(), output_size.height()),
          requested_frame_rate_,
          output_is_i420_ ? media::PIXEL_FORMAT_I420
                          : media::PIXEL_FORMAT_ARGB),
      frame_color_space, 0 /* clockwise_rotation */, false /* flip_y */, now,
      now - first_ref_time_, /*capture_begin_timestamp=*/std::nullopt,
      metadata);

  ScheduleNextCaptureFrame();
}

void DesktopCaptureDevice::Core::OnCaptureTimer() {
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (!client_)
    return;

  CaptureFrame(/*is_refresh_frame=*/false);
}

void DesktopCaptureDevice::Core::CaptureFrame(bool is_refresh_frame) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(!capture_in_progress_);
  TRACE_EVENT1("webrtc", __func__, "is_refresh_frame", is_refresh_frame);
  VLOG(2) << __func__ << "(is_refresh_frame=" << is_refresh_frame << ")";
  LogDesktopCaptureFrameIsRefresh(capturer_type_, is_refresh_frame);

  capture_start_time_ = NowTicks();

  if (!is_refresh_frame) {
    capture_in_progress_ = true;
  } else {
    refresh_in_progress_ = true;
  }

  // Track the average frame rate for the default capture path. Frame rate for
  // request refresh frames is tracked separately by calls to
  // RequestRefreshFrame (see `rrf_rate_`);
  if (!is_refresh_frame) {
    if (last_capture_time_.is_null()) {
      last_capture_time_ = capture_start_time_;
    } else {
      const base::TimeDelta delta_ms = capture_start_time_ - last_capture_time_;
      // We use an exponential moving average (EMA) filter to calculate the
      // current frame rate (in frames per second). The filter has the following
      // difference (time-domain) equation:
      //   y[i]=α⋅x[i]+(1-α)⋅y[i−1]
      // where
      //   y is the output, [i] denotes the sample number, x is the input, and α
      //   is a constant which sets the cutoff frequency (a value between 0 and
      //   1 where 1 corresponds to "no filtering").
      // A value of α=0.1 results in a suitable amount of smoothing.
      const float input_frame_rate_fps = (1000.0 / delta_ms.InMillisecondsF());
      frame_rate_ =
          kAlpha * input_frame_rate_fps + (1.0 - kAlpha) * frame_rate_;
      last_capture_time_ = capture_start_time_;
      VLOG(2) << " delta_ms=" << delta_ms.InMillisecondsF()
              << ", frame_rate=" << frame_rate_ << " [fps]";
      const int frame_rate_fps = base::saturated_cast<int>(frame_rate_ + 0.5);
      LogDesktopCaptureFrameRate(capturer_type_, frame_rate_fps);
    }
  }

  desktop_capturer_->CaptureFrame();
}

void DesktopCaptureDevice::Core::ScheduleNextCaptureFrame() {
  // Make sure CaptureFrame() was called at least once before.
  DCHECK(!capture_start_time_.is_null());

  base::TimeDelta last_capture_duration = NowTicks() - capture_start_time_;
  VLOG(2) << __func__ << " [last_capture_duration="
          << last_capture_duration.InMilliseconds() << "]";

  // Limit frame-rate to reduce CPU consumption.
  base::TimeDelta capture_period =
      std::max((last_capture_duration * 100) / max_cpu_consumption_percentage_,
               requested_frame_duration_);
  VLOG(2) << "  capture_period=" << capture_period.InMilliseconds();
  VLOG(2) << "  timer(dT="
          << (capture_period - last_capture_duration).InMilliseconds() << ")";

  // Schedule a task for the next frame.
  capture_timer_->Start(FROM_HERE, capture_period - last_capture_duration, this,
                        &Core::OnCaptureTimer);
}

void DesktopCaptureDevice::Core::RequestWakeLock() {
  mojo::Remote<device::mojom::WakeLockProvider> wake_lock_provider;
  auto receiver = wake_lock_provider.BindNewPipeAndPassReceiver();
  // TODO(crbug.com/41377723): Fix DesktopCaptureDeviceTest and remove
  // this conditional.
  if (BrowserThread::IsThreadInitialized(BrowserThread::UI)) {
    GetUIThreadTaskRunner({})->PostTask(
        FROM_HERE, base::BindOnce(&BindWakeLockProvider, std::move(receiver)));
  }

  wake_lock_provider->GetWakeLockWithoutContext(
      device::mojom::WakeLockType::kPreventDisplaySleep,
      device::mojom::WakeLockReason::kOther, "Native desktop capture",
      wake_lock_.BindNewPipeAndPassReceiver());

  wake_lock_->RequestWakeLock();
}

base::TimeTicks DesktopCaptureDevice::Core::NowTicks() const {
  return tick_clock_ ? tick_clock_->NowTicks() : base::TimeTicks::Now();
}

// static
std::unique_ptr<media::VideoCaptureDevice> DesktopCaptureDevice::Create(
    const DesktopMediaID& source) {
  CHECK(source.type == DesktopMediaID::TYPE_WINDOW ||
        source.type == DesktopMediaID::TYPE_SCREEN);

  VLOG(1) << __func__ << "(source=" << source.ToString() << ")";
  auto options = desktop_capture::CreateDesktopCaptureOptions();
  std::unique_ptr<webrtc::DesktopCapturer> capturer;
  std::unique_ptr<media::VideoCaptureDevice> result;

#if BUILDFLAG(IS_WIN)
  options.set_allow_cropping_window_capturer(true);

  // We prefer to allow the WGC and DXGI capturers to embed the cursor when
  // possible. The DXGI implementation uses this switch in combination with
  // internal checks for support of if it is possible to embed the cursor.
  // Note that, very few graphical adapters support embedding the cursor into
  // the captured frame in combination with DXGI; hence most cursors will be
  // added separately by a desktop and cursor composer even if this option is
  // set to true. GDI does not use this option.
  options.set_prefer_cursor_embedded(true);

  if (IsWgcEnabledForScreenCapture()) {
    options.set_allow_wgc_screen_capturer(true);

    // 0Hz support is by default disabled for WGC but it can be enabled using
    // the `kWebRtcAllowWgcZeroHz` feature flag. When enabled, the WGC capturer
    // will compare the pixel values of the new frame and the previous frame and
    // update the DesktopRegion part of the frame to reflect if the content has
    // changed or not. DesktopFrame::updated_region() will be empty if nothing
    // has changed and contain one (damage) region corresponding to the complete
    // screen or window being captured if any change is detected.
    if (source.type == DesktopMediaID::TYPE_SCREEN) {
      options.set_allow_wgc_zero_hertz(IsWgcZeroHzEnabledForScreenCapture());
    }
  }
  if (base::FeatureList::IsEnabled(features::kWebRtcAllowWgcWindowCapturer)) {
    options.set_allow_wgc_window_capturer(true);
    if (source.type == DesktopMediaID::TYPE_WINDOW) {
      options.set_allow_wgc_zero_hertz(
          base::FeatureList::IsEnabled(features::kWebRtcAllowWgcWindowZeroHz));
    }
  }

  options.set_wgc_require_border(
      base::FeatureList::IsEnabled(features::kWebRtcWgcRequireBorder));

  VLOG(1) << "DesktopCaptureOptions: options={prefer_cursor_embedded: "
          << options.prefer_cursor_embedded() << ", allow_wgc_screen_capturer: "
          << options.allow_wgc_screen_capturer()
          << ", allow_wgc_window_capturer: "
          << options.allow_wgc_window_capturer()
          << ", allow_wgc_zero_hertz: " << options.allow_wgc_zero_hertz()
          << ", wgc_require_border: " << options.wgc_require_border() << "}";
#endif

  // For browser tests, to create a fake desktop capturer.
  if (source.id == DesktopMediaID::kFakeId) {
    capturer = std::make_unique<webrtc::FakeDesktopCapturer>();
    result.reset(new DesktopCaptureDevice(std::move(capturer), source.type));
    return result;
  }

  switch (source.type) {
    case DesktopMediaID::TYPE_SCREEN: {
      std::unique_ptr<webrtc::DesktopCapturer> screen_capturer(
          webrtc::DesktopCapturer::CreateScreenCapturer(options));
      if (screen_capturer && screen_capturer->SelectSource(source.id)) {
        capturer = std::make_unique<webrtc::DesktopAndCursorComposer>(
            std::move(screen_capturer), options);
        IncrementDesktopCaptureCounter(SCREEN_CAPTURER_CREATED);
        IncrementDesktopCaptureCounter(
            source.audio_share ? SCREEN_CAPTURER_CREATED_WITH_AUDIO
                               : SCREEN_CAPTURER_CREATED_WITHOUT_AUDIO);
      }
      break;
    }

    case DesktopMediaID::TYPE_WINDOW: {
      std::unique_ptr<webrtc::DesktopCapturer> window_capturer =
          webrtc::DesktopCapturer::CreateWindowCapturer(options);
      if (window_capturer && window_capturer->SelectSource(source.id)) {
        capturer = std::make_unique<webrtc::DesktopAndCursorComposer>(
            std::move(window_capturer), options);
        IncrementDesktopCaptureCounter(WINDOW_CAPTURER_CREATED);
      }
      break;
    }

    default: {
      NOTREACHED();
    }
  }

  if (capturer)
    result.reset(new DesktopCaptureDevice(std::move(capturer), source.type));

  return result;
}

DesktopCaptureDevice::~DesktopCaptureDevice() {
  // There is an edge case that `StopAndDeAllocate()` is not called before
  // destruction, which might happen during shutdown (can't repro it though).
  // It calls `StopAndDeAllocate()` here in order to ensure `core_` is deleted
  // on the `desktopCaptureThread`.
  StopAndDeAllocate();
}

void DesktopCaptureDevice::AllocateAndStart(
    const media::VideoCaptureParams& params,
    std::unique_ptr<Client> client) {
  thread_.task_runner()->PostTask(
      FROM_HERE, base::BindOnce(&Core::AllocateAndStart, core_->GetWeakPtr(),
                                params, std::move(client)));
}

void DesktopCaptureDevice::StopAndDeAllocate() {
  if (core_) {
    // This thread should mostly be an idle observer. Stopping it should be
    // fast.
    base::ScopedAllowBaseSyncPrimitivesOutsideBlockingScope allow_thread_join;
    thread_.task_runner()->DeleteSoon(FROM_HERE, core_.release());
    thread_.Stop();
  }
}

void DesktopCaptureDevice::RequestRefreshFrame() {
  // Refresh request shall have no effect after the capturer has been stopped.
  if (!core_) {
    return;
  }
  thread_.task_runner()->PostTask(
      FROM_HERE,
      base::BindOnce(&Core::RequestRefreshFrame, core_->GetWeakPtr()));
}

void DesktopCaptureDevice::SetNotificationWindowId(
    gfx::NativeViewId window_id) {
  // This may be called after the capturer has been stopped.
  if (!core_)
    return;
  thread_.task_runner()->PostTask(
      FROM_HERE, base::BindOnce(&Core::SetNotificationWindowId,
                                core_->GetWeakPtr(), window_id));
}

DesktopCaptureDevice::DesktopCaptureDevice(
    std::unique_ptr<webrtc::DesktopCapturer> capturer,
    DesktopMediaID::Type type)
    : thread_("desktopCaptureThread") {
  DVLOG(1) << __func__ << "(type=" << DesktopMediaTypeToString(type) << ")";
#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_MAC)
  // On Windows/OSX the thread must be a UI thread.
  base::MessagePumpType thread_type = base::MessagePumpType::UI;
#else
  base::MessagePumpType thread_type = base::MessagePumpType::DEFAULT;
#endif
  bool zero_hertz_is_supported = true;
#if BUILDFLAG(IS_WIN)
  const bool wgc_screen_zero_hertz = IsWgcZeroHzEnabledForScreenCapture();
  const bool wgc_window_zero_hertz =
      base::FeatureList::IsEnabled(features::kWebRtcAllowWgcWindowZeroHz);
  const bool wgc_screen_capturer = IsWgcEnabledForScreenCapture();
  const bool wgc_window_capturer =
      base::FeatureList::IsEnabled(features::kWebRtcAllowWgcWindowCapturer);
  if (!wgc_window_capturer && !wgc_screen_capturer) {
    zero_hertz_is_supported = true;
  } else if (!wgc_window_capturer && wgc_screen_capturer) {
    zero_hertz_is_supported =
        (type == DesktopMediaID::TYPE_SCREEN) ? wgc_screen_zero_hertz : true;
  } else if (wgc_window_capturer && !wgc_screen_capturer) {
    zero_hertz_is_supported =
        (type == DesktopMediaID::TYPE_WINDOW) ? wgc_window_zero_hertz : true;
  } else {
    if (type == DesktopMediaID::TYPE_SCREEN) {
      zero_hertz_is_supported = wgc_screen_zero_hertz;
    } else if (type == DesktopMediaID::TYPE_WINDOW) {
      zero_hertz_is_supported = wgc_window_zero_hertz;
    } else {
      zero_hertz_is_supported = false;
    }
  }
  VLOG(1) << __func__ << " [zero_hertz_is_supported=" << zero_hertz_is_supported
          << "]";
#endif

  thread_.StartWithOptions(base::Thread::Options(thread_type, 0));

  core_ = std::make_unique<Core>(thread_.task_runner(), std::move(capturer),
                                 type, zero_hertz_is_supported);
}

void DesktopCaptureDevice::SetMockTimeForTesting(
    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
    const base::TickClock* tick_clock) {
  core_->SetMockTimeForTesting(task_runner, tick_clock);  // IN-TEST
}

}  // namespace content