/*
 *  Copyright (c) 2019 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/pc/e2e/analyzer/video/default_encoded_image_id_injector.h"

#include <cstddef>

#include "absl/memory/memory.h"
#include "api/video/encoded_image.h"
#include "rtc_base/checks.h"

namespace webrtc {
namespace test {
namespace {

// The amount on which encoded image buffer will be expanded to inject frame id.
// This is 2 bytes for uint16_t frame id itself and 4 bytes for original length
// of the buffer.
constexpr int kEncodedImageBufferExpansion = 6;
constexpr size_t kInitialBufferSize = 2 * 1024;
// Count of coding entities for which buffers pools will be added on
// construction.
constexpr int kPreInitCodingEntitiesCount = 2;
constexpr size_t kBuffersPoolPerCodingEntity = 256;

}  // namespace

DefaultEncodedImageIdInjector::DefaultEncodedImageIdInjector() {
  for (size_t i = 0;
       i < kPreInitCodingEntitiesCount * kBuffersPoolPerCodingEntity; ++i) {
    bufs_pool_.push_back(
        absl::make_unique<std::vector<uint8_t>>(kInitialBufferSize));
  }
}
DefaultEncodedImageIdInjector::~DefaultEncodedImageIdInjector() = default;

EncodedImage DefaultEncodedImageIdInjector::InjectId(uint16_t id,
                                                     const EncodedImage& source,
                                                     int coding_entity_id) {
  ExtendIfRequired(coding_entity_id);

  EncodedImage out = source;
  std::vector<uint8_t>* buffer = NextBuffer();
  if (buffer->size() < source.size() + kEncodedImageBufferExpansion) {
    buffer->resize(source.size() + kEncodedImageBufferExpansion);
  }
  out.set_buffer(buffer->data(), buffer->size());
  out.set_size(source.size() + kEncodedImageBufferExpansion);
  memcpy(&out.data()[kEncodedImageBufferExpansion], source.data(),
         source.size());
  out.data()[0] = id & 0x00ff;
  out.data()[1] = (id & 0xff00) >> 8;
  out.data()[2] = source.size() & 0x00ff;
  out.data()[3] = (source.size() & 0xff00) >> 8;
  out.data()[4] = (source.size() & 0xff00) >> 16;
  out.data()[5] = (source.size() & 0xff00) >> 24;
  return out;
}

EncodedImageWithId DefaultEncodedImageIdInjector::ExtractId(
    const EncodedImage& source,
    int coding_entity_id) {
  ExtendIfRequired(coding_entity_id);

  EncodedImage out = source;
  std::vector<uint8_t>* buffer = NextBuffer();
  if (buffer->size() < source.capacity() - kEncodedImageBufferExpansion) {
    buffer->resize(source.capacity() - kEncodedImageBufferExpansion);
  }
  out.set_buffer(buffer->data(), buffer->size());

  size_t source_pos = 0;
  size_t out_pos = 0;
  absl::optional<uint16_t> id = absl::nullopt;
  while (source_pos < source.size()) {
    RTC_CHECK_LE(source_pos + kEncodedImageBufferExpansion, source.size());
    uint16_t next_id =
        source.data()[source_pos] + (source.data()[source_pos + 1] << 8);
    RTC_CHECK(!id || id.value() == next_id)
        << "Different frames encoded into single encoded image: " << id.value()
        << " vs " << next_id;
    id = next_id;
    uint32_t length = source.data()[source_pos + 2] +
                      (source.data()[source_pos + 3] << 8) +
                      (source.data()[source_pos + 3] << 16) +
                      (source.data()[source_pos + 3] << 24);
    RTC_CHECK_LE(source_pos + kEncodedImageBufferExpansion + length,
                 source.size());
    memcpy(&out.data()[out_pos],
           &source.data()[source_pos + kEncodedImageBufferExpansion], length);
    source_pos += length + kEncodedImageBufferExpansion;
    out_pos += length;
  }
  out.set_size(out_pos);

  return EncodedImageWithId{id.value(), out};
}

void DefaultEncodedImageIdInjector::ExtendIfRequired(int coding_entity_id) {
  rtc::CritScope crit(&lock_);
  if (coding_entities_.find(coding_entity_id) != coding_entities_.end()) {
    // This entity is already known for this injector, so buffers are allocated.
    return;
  }

  // New coding entity. We need allocate extra buffers for this encoder/decoder
  // We will put them into front of the queue to use them first.
  coding_entities_.insert(coding_entity_id);
  if (coding_entities_.size() <= kPreInitCodingEntitiesCount) {
    // Buffers for the first kPreInitCodingEntitiesCount coding entities were
    // allocated during construction.
    return;
  }
  for (size_t i = 0; i < kBuffersPoolPerCodingEntity; ++i) {
    bufs_pool_.push_front(
        absl::make_unique<std::vector<uint8_t>>(kInitialBufferSize));
  }
}

std::vector<uint8_t>* DefaultEncodedImageIdInjector::NextBuffer() {
  rtc::CritScope crit(&lock_);
  // Get buffer from the front of the queue, return it to the caller and
  // put in the back
  std::vector<uint8_t>* out = bufs_pool_.front().get();
  bufs_pool_.push_back(std::move(bufs_pool_.front()));
  bufs_pool_.pop_front();
  return out;
}

}  // namespace test
}  // namespace webrtc