/*
 * Copyright (C) 2019 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <android-base/macros.h>
#include <audio_utils/primitives.h>
#include <audio_utils/sndfile.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <math.h>
#include <media/AudioBufferProvider.h>
#include <media/AudioResampler.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
#include <utils/Vector.h>

#include <memory>

using namespace android;

const int MAX_FRAMES = 10;
const int MIN_FREQ = 1e3;
const int MAX_FREQ = 100e3;

const AudioResampler::src_quality qualities[] = {
    AudioResampler::DEFAULT_QUALITY,
    AudioResampler::LOW_QUALITY,
    AudioResampler::MED_QUALITY,
    AudioResampler::HIGH_QUALITY,
    AudioResampler::VERY_HIGH_QUALITY,
    AudioResampler::DYN_LOW_QUALITY,
    AudioResampler::DYN_MED_QUALITY,
    AudioResampler::DYN_HIGH_QUALITY,
};

class Provider : public AudioBufferProvider {
  const void* mAddr;        // base address
  const size_t mNumFrames;  // total frames
  const size_t mFrameSize;  // size of each frame in bytes
  size_t mNextFrame;        // index of next frame to provide
  size_t mUnrel;            // number of frames not yet released
 public:
  Provider(const void* addr, size_t frames, size_t frameSize)
      : mAddr(addr),
        mNumFrames(frames),
        mFrameSize(frameSize),
        mNextFrame(0),
        mUnrel(0) {}
  status_t getNextBuffer(Buffer* buffer) override {
    if (buffer->frameCount > mNumFrames - mNextFrame) {
      buffer->frameCount = mNumFrames - mNextFrame;
    }
    mUnrel = buffer->frameCount;
    if (buffer->frameCount > 0) {
      buffer->raw = (char*)mAddr + mFrameSize * mNextFrame;
      return NO_ERROR;
    } else {
      buffer->raw = nullptr;
      return NOT_ENOUGH_DATA;
    }
  }
  virtual void releaseBuffer(Buffer* buffer) {
    if (buffer->frameCount > mUnrel) {
      mNextFrame += mUnrel;
      mUnrel = 0;
    } else {
      mNextFrame += buffer->frameCount;
      mUnrel -= buffer->frameCount;
    }
    buffer->frameCount = 0;
    buffer->raw = nullptr;
  }
  void reset() { mNextFrame = 0; }
};

audio_format_t chooseFormat(AudioResampler::src_quality quality,
                            uint8_t input_byte) {
  switch (quality) {
    case AudioResampler::DYN_LOW_QUALITY:
    case AudioResampler::DYN_MED_QUALITY:
    case AudioResampler::DYN_HIGH_QUALITY:
      if (input_byte % 2) {
        return AUDIO_FORMAT_PCM_FLOAT;
      }
      FALLTHROUGH_INTENDED;
    default:
      return AUDIO_FORMAT_PCM_16_BIT;
  }
}

int parseValue(const uint8_t* src, int index, void* dst, size_t size) {
  memcpy(dst, &src[index], size);
  return size;
}

bool validFreq(int freq) { return freq > MIN_FREQ && freq < MAX_FREQ; }

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
  int input_freq = 0;
  int output_freq = 0;
  int input_channels = 0;

  float left_volume = 0;
  float right_volume = 0;

  size_t metadata_size = 2 + 3 * sizeof(int) + 2 * sizeof(float);
  if (size < metadata_size) {
    // not enough data to set options
    return 0;
  }

  AudioResampler::src_quality quality = qualities[data[0] % 8];
  audio_format_t format = chooseFormat(quality, data[1]);

  int index = 2;

  index += parseValue(data, index, &input_freq, sizeof(int));
  index += parseValue(data, index, &output_freq, sizeof(int));
  index += parseValue(data, index, &input_channels, sizeof(int));

  index += parseValue(data, index, &left_volume, sizeof(float));
  index += parseValue(data, index, &right_volume, sizeof(float));

  if (!validFreq(input_freq) || !validFreq(output_freq)) {
    // sampling frequencies must be reasonable
    return 0;
  }

  if (input_channels < 1 ||
      input_channels > (quality < AudioResampler::DYN_LOW_QUALITY ? 2 : 8)) {
    // invalid number of input channels
    return 0;
  }

  size_t single_channel_size =
      format == AUDIO_FORMAT_PCM_FLOAT ? sizeof(float) : sizeof(int16_t);
  size_t input_frame_size = single_channel_size * input_channels;
  size_t input_size = size - metadata_size;
  uint8_t input_data[input_size];
  memcpy(input_data, &data[metadata_size], input_size);

  size_t input_frames = input_size / input_frame_size;
  if (input_frames > MAX_FRAMES) {
    return 0;
  }

  Provider provider(input_data, input_frames, input_frame_size);

  std::unique_ptr<AudioResampler> resampler(
      AudioResampler::create(format, input_channels, output_freq, quality));

  resampler->setSampleRate(input_freq);
  resampler->setVolume(left_volume, right_volume);

  // output is at least stereo samples
  int output_channels = input_channels > 2 ? input_channels : 2;
  size_t output_frame_size = output_channels * sizeof(int32_t);
  size_t output_frames = (input_frames * output_freq) / input_freq;
  size_t output_size = output_frames * output_frame_size;

  uint8_t output_data[output_size];
  for (size_t i = 0; i < output_frames; i++) {
    memset(output_data, 0, output_size);
    resampler->resample((int*)output_data, i, &provider);
  }

  return 0;
}