/*
 *  Copyright (c) 2016 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 "media/engine/videoencodersoftwarefallbackwrapper.h"

#include <cstdio>
#include <utility>

#include "media/base/h264_profile_level_id.h"
#include "modules/video_coding/include/video_error_codes.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/timeutils.h"
#include "system_wrappers/include/field_trial.h"

namespace webrtc {
namespace {
const char kVp8ForceFallbackEncoderFieldTrial[] =
    "WebRTC-VP8-Forced-Fallback-Encoder-v2";

bool EnableForcedFallback() {
  return field_trial::IsEnabled(kVp8ForceFallbackEncoderFieldTrial);
}

bool IsForcedFallbackPossible(const VideoCodec& codec_settings) {
  return codec_settings.codecType == kVideoCodecVP8 &&
         codec_settings.numberOfSimulcastStreams <= 1 &&
         codec_settings.VP8().numberOfTemporalLayers == 1;
}

void GetForcedFallbackParamsFromFieldTrialGroup(int* param_min_pixels,
                                                int* param_max_pixels,
                                                int minimum_max_pixels) {
  RTC_DCHECK(param_min_pixels);
  RTC_DCHECK(param_max_pixels);
  std::string group =
      webrtc::field_trial::FindFullName(kVp8ForceFallbackEncoderFieldTrial);
  if (group.empty())
    return;

  int min_pixels;
  int max_pixels;
  int min_bps;
  if (sscanf(group.c_str(), "Enabled-%d,%d,%d", &min_pixels, &max_pixels,
             &min_bps) != 3) {
    RTC_LOG(LS_WARNING)
        << "Invalid number of forced fallback parameters provided.";
    return;
  }
  if (min_pixels <= 0 || max_pixels < minimum_max_pixels ||
      max_pixels < min_pixels || min_bps <= 0) {
    RTC_LOG(LS_WARNING) << "Invalid forced fallback parameter value provided.";
    return;
  }
  *param_min_pixels = min_pixels;
  *param_max_pixels = max_pixels;
}
}  // namespace

VideoEncoderSoftwareFallbackWrapper::VideoEncoderSoftwareFallbackWrapper(
    std::unique_ptr<webrtc::VideoEncoder> sw_encoder,
    std::unique_ptr<webrtc::VideoEncoder> hw_encoder)
    : number_of_cores_(0),
      max_payload_size_(0),
      rates_set_(false),
      framerate_(0),
      channel_parameters_set_(false),
      packet_loss_(0),
      rtt_(0),
      use_fallback_encoder_(false),
      encoder_(std::move(hw_encoder)),
      fallback_encoder_(std::move(sw_encoder)),
      callback_(nullptr),
      forced_fallback_possible_(EnableForcedFallback()) {
  if (forced_fallback_possible_) {
    GetForcedFallbackParamsFromFieldTrialGroup(
        &forced_fallback_.min_pixels_, &forced_fallback_.max_pixels_,
        encoder_->GetScalingSettings().min_pixels_per_frame -
            1);  // No HW below.
  }
}
VideoEncoderSoftwareFallbackWrapper::~VideoEncoderSoftwareFallbackWrapper() =
    default;

bool VideoEncoderSoftwareFallbackWrapper::InitFallbackEncoder() {
  RTC_LOG(LS_WARNING) << "Encoder falling back to software encoding.";

  const int ret = fallback_encoder_->InitEncode(
      &codec_settings_, number_of_cores_, max_payload_size_);
  use_fallback_encoder_ = (ret == WEBRTC_VIDEO_CODEC_OK);
  if (!use_fallback_encoder_) {
    RTC_LOG(LS_ERROR) << "Failed to initialize software-encoder fallback.";
    fallback_encoder_->Release();
    return false;
  }
  // Replay callback, rates, and channel parameters.
  if (callback_)
    fallback_encoder_->RegisterEncodeCompleteCallback(callback_);
  if (rates_set_)
    fallback_encoder_->SetRateAllocation(bitrate_allocation_, framerate_);
  if (channel_parameters_set_)
    fallback_encoder_->SetChannelParameters(packet_loss_, rtt_);

  // Since we're switching to the fallback encoder, Release the real encoder. It
  // may be re-initialized via InitEncode later, and it will continue to get
  // Set calls for rates and channel parameters in the meantime.
  encoder_->Release();
  return true;
}

int32_t VideoEncoderSoftwareFallbackWrapper::InitEncode(
    const VideoCodec* codec_settings,
    int32_t number_of_cores,
    size_t max_payload_size) {
  // Store settings, in case we need to dynamically switch to the fallback
  // encoder after a failed Encode call.
  codec_settings_ = *codec_settings;
  number_of_cores_ = number_of_cores;
  max_payload_size_ = max_payload_size;
  // Clear stored rate/channel parameters.
  rates_set_ = false;
  channel_parameters_set_ = false;
  ValidateSettingsForForcedFallback();

  // Try to reinit forced software codec if it is in use.
  if (TryReInitForcedFallbackEncoder()) {
    return WEBRTC_VIDEO_CODEC_OK;
  }
  // Try to init forced software codec if it should be used.
  if (TryInitForcedFallbackEncoder()) {
    return WEBRTC_VIDEO_CODEC_OK;
  }
  forced_fallback_.active_ = false;

  int32_t ret =
      encoder_->InitEncode(codec_settings, number_of_cores, max_payload_size);
  if (ret == WEBRTC_VIDEO_CODEC_OK) {
    if (use_fallback_encoder_) {
      RTC_LOG(LS_WARNING)
          << "InitEncode OK, no longer using the software fallback encoder.";
      fallback_encoder_->Release();
      use_fallback_encoder_ = false;
    }
    if (callback_)
      encoder_->RegisterEncodeCompleteCallback(callback_);
    return ret;
  }
  // Try to instantiate software codec.
  if (InitFallbackEncoder()) {
    return WEBRTC_VIDEO_CODEC_OK;
  }
  // Software encoder failed, use original return code.
  return ret;
}

int32_t VideoEncoderSoftwareFallbackWrapper::RegisterEncodeCompleteCallback(
    EncodedImageCallback* callback) {
  callback_ = callback;
  int32_t ret = encoder_->RegisterEncodeCompleteCallback(callback);
  if (use_fallback_encoder_)
    return fallback_encoder_->RegisterEncodeCompleteCallback(callback);
  return ret;
}

int32_t VideoEncoderSoftwareFallbackWrapper::Release() {
  return use_fallback_encoder_ ? fallback_encoder_->Release()
                               : encoder_->Release();
}

int32_t VideoEncoderSoftwareFallbackWrapper::Encode(
    const VideoFrame& frame,
    const CodecSpecificInfo* codec_specific_info,
    const std::vector<FrameType>* frame_types) {
  if (use_fallback_encoder_)
    return fallback_encoder_->Encode(frame, codec_specific_info, frame_types);
  int32_t ret = encoder_->Encode(frame, codec_specific_info, frame_types);
  // If requested, try a software fallback.
  bool fallback_requested = (ret == WEBRTC_VIDEO_CODEC_FALLBACK_SOFTWARE);
  if (fallback_requested && InitFallbackEncoder()) {
    // Start using the fallback with this frame.
    return fallback_encoder_->Encode(frame, codec_specific_info, frame_types);
  }
  return ret;
}

int32_t VideoEncoderSoftwareFallbackWrapper::SetChannelParameters(
    uint32_t packet_loss,
    int64_t rtt) {
  channel_parameters_set_ = true;
  packet_loss_ = packet_loss;
  rtt_ = rtt;
  int32_t ret = encoder_->SetChannelParameters(packet_loss, rtt);
  if (use_fallback_encoder_)
    return fallback_encoder_->SetChannelParameters(packet_loss, rtt);
  return ret;
}

int32_t VideoEncoderSoftwareFallbackWrapper::SetRateAllocation(
    const VideoBitrateAllocation& bitrate_allocation,
    uint32_t framerate) {
  rates_set_ = true;
  bitrate_allocation_ = bitrate_allocation;
  framerate_ = framerate;
  int32_t ret = encoder_->SetRateAllocation(bitrate_allocation_, framerate);
  if (use_fallback_encoder_)
    return fallback_encoder_->SetRateAllocation(bitrate_allocation_, framerate);
  return ret;
}

bool VideoEncoderSoftwareFallbackWrapper::SupportsNativeHandle() const {
  return use_fallback_encoder_ ? fallback_encoder_->SupportsNativeHandle()
                               : encoder_->SupportsNativeHandle();
}

VideoEncoder::ScalingSettings
VideoEncoderSoftwareFallbackWrapper::GetScalingSettings() const {
  if (forced_fallback_possible_) {
    const auto settings = forced_fallback_.active_
                              ? fallback_encoder_->GetScalingSettings()
                              : encoder_->GetScalingSettings();
    return settings.thresholds
               ? VideoEncoder::ScalingSettings(settings.thresholds->low,
                                               settings.thresholds->high,
                                               forced_fallback_.min_pixels_)
               : VideoEncoder::ScalingSettings::kOff;
  }
  return encoder_->GetScalingSettings();
}

const char* VideoEncoderSoftwareFallbackWrapper::ImplementationName() const {
  return use_fallback_encoder_ ? fallback_encoder_->ImplementationName()
                               : encoder_->ImplementationName();
}

bool VideoEncoderSoftwareFallbackWrapper::IsForcedFallbackActive() const {
  return (forced_fallback_possible_ && use_fallback_encoder_ &&
          forced_fallback_.active_);
}

bool VideoEncoderSoftwareFallbackWrapper::TryInitForcedFallbackEncoder() {
  if (!forced_fallback_possible_ || use_fallback_encoder_) {
    return false;
  }
  // Fallback not active.
  if (!forced_fallback_.IsValid(codec_settings_)) {
    return false;
  }
  // Settings valid, try to instantiate software codec.
  RTC_LOG(LS_INFO) << "Request forced SW encoder fallback: "
                   << codec_settings_.width << "x" << codec_settings_.height;
  if (!InitFallbackEncoder()) {
    return false;
  }
  forced_fallback_.active_ = true;
  return true;
}

bool VideoEncoderSoftwareFallbackWrapper::TryReInitForcedFallbackEncoder() {
  if (!IsForcedFallbackActive()) {
    return false;
  }
  // Forced fallback active.
  if (!forced_fallback_.IsValid(codec_settings_)) {
    RTC_LOG(LS_INFO) << "Stop forced SW encoder fallback, max pixels exceeded.";
    return false;
  }
  // Settings valid, reinitialize the forced fallback encoder.
  if (fallback_encoder_->InitEncode(&codec_settings_, number_of_cores_,
                                    max_payload_size_) !=
      WEBRTC_VIDEO_CODEC_OK) {
    RTC_LOG(LS_ERROR) << "Failed to init forced SW encoder fallback.";
    return false;
  }
  return true;
}

void VideoEncoderSoftwareFallbackWrapper::ValidateSettingsForForcedFallback() {
  if (!forced_fallback_possible_)
    return;

  if (!IsForcedFallbackPossible(codec_settings_)) {
    if (IsForcedFallbackActive()) {
      fallback_encoder_->Release();
      use_fallback_encoder_ = false;
    }
    RTC_LOG(LS_INFO) << "Disable forced_fallback_possible_ due to settings.";
    forced_fallback_possible_ = false;
  }
}

}  // namespace webrtc