// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <utility>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/threading/sequenced_task_runner_handle.h"
#include "media/base/decoder_buffer.h"
#include "media/base/fallback_video_decoder.h"
#include "media/base/video_decoder_config.h"

namespace media {

FallbackVideoDecoder::FallbackVideoDecoder(
    std::unique_ptr<VideoDecoder> preferred,
    std::unique_ptr<VideoDecoder> fallback)
    : preferred_decoder_(std::move(preferred)),
      fallback_decoder_(std::move(fallback)) {}

void FallbackVideoDecoder::Initialize(const VideoDecoderConfig& config,
                                      bool low_delay,
                                      CdmContext* cdm_context,
                                      InitCB init_cb,
                                      const OutputCB& output_cb,
                                      const WaitingCB& waiting_cb) {
  // If we've already fallen back, just reinitialize the selected decoder.
  if (selected_decoder_ && did_fallback_) {
    selected_decoder_->Initialize(config, low_delay, cdm_context,
                                  std::move(init_cb), output_cb, waiting_cb);
    return;
  }

  InitCB fallback_initialize_cb =
      base::BindOnce(&FallbackVideoDecoder::FallbackInitialize,
                     weak_factory_.GetWeakPtr(), config, low_delay, cdm_context,
                     std::move(init_cb), output_cb, waiting_cb);

  preferred_decoder_->Initialize(config, low_delay, cdm_context,
                                 std::move(fallback_initialize_cb), output_cb,
                                 waiting_cb);
}

void FallbackVideoDecoder::FallbackInitialize(const VideoDecoderConfig& config,
                                              bool low_delay,
                                              CdmContext* cdm_context,
                                              InitCB init_cb,
                                              const OutputCB& output_cb,
                                              const WaitingCB& waiting_cb,
                                              Status status) {
  // The preferred decoder was successfully initialized.
  if (status.is_ok()) {
    selected_decoder_ = preferred_decoder_.get();
    std::move(init_cb).Run(OkStatus());
    return;
  }

  did_fallback_ = true;
  // Post destruction of |preferred_decoder_| so that we don't destroy the
  // object during the callback.  DeleteSoon doesn't handle custom deleters, so
  // we post a do-nothing task instead.
  base::SequencedTaskRunnerHandle::Get()->PostTask(
      FROM_HERE,
      base::BindOnce(base::DoNothing::Once<std::unique_ptr<VideoDecoder>>(),
                     std::move(preferred_decoder_)));
  selected_decoder_ = fallback_decoder_.get();
  fallback_decoder_->Initialize(config, low_delay, cdm_context,
                                std::move(init_cb), output_cb, waiting_cb);
}

void FallbackVideoDecoder::Decode(scoped_refptr<DecoderBuffer> buffer,
                                  DecodeCB decode_cb) {
  DCHECK(selected_decoder_);
  selected_decoder_->Decode(std::move(buffer), std::move(decode_cb));
}

void FallbackVideoDecoder::Reset(base::OnceClosure reset_cb) {
  DCHECK(selected_decoder_);
  selected_decoder_->Reset(std::move(reset_cb));
}

bool FallbackVideoDecoder::NeedsBitstreamConversion() const {
  DCHECK(selected_decoder_);
  return selected_decoder_->NeedsBitstreamConversion();
}

bool FallbackVideoDecoder::CanReadWithoutStalling() const {
  DCHECK(selected_decoder_);
  return selected_decoder_->CanReadWithoutStalling();
}

int FallbackVideoDecoder::GetMaxDecodeRequests() const {
  DCHECK(selected_decoder_);
  return selected_decoder_->GetMaxDecodeRequests();
}

std::string FallbackVideoDecoder::GetDisplayName() const {
  // MojoVideoDecoder always identifies itself as such, and never asks for the
  // name of the underlying decoder.
  NOTREACHED();
  return "FallbackVideoDecoder";
}

FallbackVideoDecoder::~FallbackVideoDecoder() = default;

}  // namespace media