// sherpa-onnx/csrc/wave-reader.cc
//
// Copyright (c)  2023  Xiaomi Corporation

#include "sherpa-onnx/csrc/wave-reader.h"

#include <cassert>
#include <fstream>
#include <utility>
#include <vector>

#include "sherpa-onnx/csrc/macros.h"

namespace sherpa_onnx {
namespace {
// see http://soundfile.sapp.org/doc/WaveFormat/
//
// Note: We assume little endian here
// TODO(fangjun): Support big endian
struct WaveHeader {
  // See
  // https://en.wikipedia.org/wiki/WAV#Metadata
  // and
  // https://www.robotplanet.dk/audio/wav_meta_data/riff_mci.pdf
  void SeekToDataChunk(std::istream &is) {
    //                              a t a d
    while (is && subchunk2_id != 0x61746164) {
      // const char *p = reinterpret_cast<const char *>(&subchunk2_id);
      // printf("Skip chunk (%x): %c%c%c%c of size: %d\n", subchunk2_id, p[0],
      //        p[1], p[2], p[3], subchunk2_size);
      is.seekg(subchunk2_size, std::istream::cur);
      is.read(reinterpret_cast<char *>(&subchunk2_id), sizeof(int32_t));
      is.read(reinterpret_cast<char *>(&subchunk2_size), sizeof(int32_t));
    }
  }

  int32_t chunk_id;
  int32_t chunk_size;
  int32_t format;
  int32_t subchunk1_id;
  int32_t subchunk1_size;
  int16_t audio_format;
  int16_t num_channels;
  int32_t sample_rate;
  int32_t byte_rate;
  int16_t block_align;
  int16_t bits_per_sample;
  int32_t subchunk2_id;    // a tag of this chunk
  int32_t subchunk2_size;  // size of subchunk2
};
static_assert(sizeof(WaveHeader) == 44);

// Read a wave file of mono-channel.
// Return its samples normalized to the range [-1, 1).
std::vector<float> ReadWaveImpl(std::istream &is, int32_t *sampling_rate,
                                bool *is_ok) {
  WaveHeader header{};
  is.read(reinterpret_cast<char *>(&header.chunk_id), sizeof(header.chunk_id));

  //                        F F I R
  if (header.chunk_id != 0x46464952) {
    SHERPA_ONNX_LOGE("Expected chunk_id RIFF. Given: 0x%08x\n",
                     header.chunk_id);
    *is_ok = false;
    return {};
  }

  is.read(reinterpret_cast<char *>(&header.chunk_size),
          sizeof(header.chunk_size));

  is.read(reinterpret_cast<char *>(&header.format), sizeof(header.format));

  //                      E V A W
  if (header.format != 0x45564157) {
    SHERPA_ONNX_LOGE("Expected format WAVE. Given: 0x%08x\n", header.format);
    *is_ok = false;
    return {};
  }

  is.read(reinterpret_cast<char *>(&header.subchunk1_id),
          sizeof(header.subchunk1_id));

  is.read(reinterpret_cast<char *>(&header.subchunk1_size),
          sizeof(header.subchunk1_size));

  if (header.subchunk1_id == 0x4b4e554a) {
    // skip junk padding
    is.seekg(header.subchunk1_size, std::istream::cur);

    is.read(reinterpret_cast<char *>(&header.subchunk1_id),
            sizeof(header.subchunk1_id));

    is.read(reinterpret_cast<char *>(&header.subchunk1_size),
            sizeof(header.subchunk1_size));
  }

  if (header.subchunk1_id != 0x20746d66) {
    SHERPA_ONNX_LOGE("Expected subchunk1_id 0x20746d66. Given: 0x%08x\n",
                     header.subchunk1_id);
    *is_ok = false;
    return {};
  }

  // NAudio uses 18
  // See https://github.com/naudio/NAudio/issues/1132
  if (header.subchunk1_size != 16 &&
      header.subchunk1_size != 18) {  // 16 for PCM
    SHERPA_ONNX_LOGE("Expected subchunk1_size 16. Given: %d\n",
                     header.subchunk1_size);
    *is_ok = false;
    return {};
  }

  is.read(reinterpret_cast<char *>(&header.audio_format),
          sizeof(header.audio_format));

  if (header.audio_format != 1) {  // 1 for PCM
    SHERPA_ONNX_LOGE("Expected audio_format 1. Given: %d\n",
                     header.audio_format);
    *is_ok = false;
    return {};
  }

  is.read(reinterpret_cast<char *>(&header.num_channels),
          sizeof(header.num_channels));

  if (header.num_channels != 1) {  // we support only single channel for now
    SHERPA_ONNX_LOGE("Expected single channel. Given: %d\n",
                     header.num_channels);
    *is_ok = false;
    return {};
  }

  is.read(reinterpret_cast<char *>(&header.sample_rate),
          sizeof(header.sample_rate));

  is.read(reinterpret_cast<char *>(&header.byte_rate),
          sizeof(header.byte_rate));

  is.read(reinterpret_cast<char *>(&header.block_align),
          sizeof(header.block_align));

  is.read(reinterpret_cast<char *>(&header.bits_per_sample),
          sizeof(header.bits_per_sample));

  if (header.byte_rate !=
      (header.sample_rate * header.num_channels * header.bits_per_sample / 8)) {
    SHERPA_ONNX_LOGE("Incorrect byte rate: %d. Expected: %d", header.byte_rate,
                     (header.sample_rate * header.num_channels *
                      header.bits_per_sample / 8));
    *is_ok = false;
    return {};
  }

  if (header.block_align !=
      (header.num_channels * header.bits_per_sample / 8)) {
    SHERPA_ONNX_LOGE("Incorrect block align: %d. Expected: %d\n",
                     header.block_align,
                     (header.num_channels * header.bits_per_sample / 8));
    *is_ok = false;
    return {};
  }

  if (header.bits_per_sample != 16) {  // we support only 16 bits per sample
    SHERPA_ONNX_LOGE("Expected bits_per_sample 16. Given: %d\n",
                     header.bits_per_sample);
    *is_ok = false;
    return {};
  }

  if (header.subchunk1_size == 18) {
    // this is for NAudio. It puts extra bytes after bits_per_sample
    // See
    // https://github.com/naudio/NAudio/blob/master/NAudio.Core/Wave/WaveFormats/WaveFormat.cs#L223

    int16_t extra_size = -1;
    is.read(reinterpret_cast<char *>(&extra_size), sizeof(int16_t));
    if (extra_size != 0) {
      SHERPA_ONNX_LOGE(
          "Extra size should be 0 for wave from NAudio. Current extra size "
          "%d\n",
          extra_size);
      *is_ok = false;
      return {};
    }
  }

  is.read(reinterpret_cast<char *>(&header.subchunk2_id),
          sizeof(header.subchunk2_id));

  is.read(reinterpret_cast<char *>(&header.subchunk2_size),
          sizeof(header.subchunk2_size));

  header.SeekToDataChunk(is);
  if (!is) {
    *is_ok = false;
    return {};
  }

  *sampling_rate = header.sample_rate;

  // header.subchunk2_size contains the number of bytes in the data.
  // As we assume each sample contains two bytes, so it is divided by 2 here
  std::vector<int16_t> samples(header.subchunk2_size / 2);

  is.read(reinterpret_cast<char *>(samples.data()), header.subchunk2_size);
  if (!is) {
    *is_ok = false;
    return {};
  }

  std::vector<float> ans(samples.size());
  for (int32_t i = 0; i != static_cast<int32_t>(ans.size()); ++i) {
    ans[i] = samples[i] / 32768.;
  }

  *is_ok = true;
  return ans;
}

}  // namespace

std::vector<float> ReadWave(const std::string &filename, int32_t *sampling_rate,
                            bool *is_ok) {
  std::ifstream is(filename, std::ifstream::binary);
  return ReadWave(is, sampling_rate, is_ok);
}

std::vector<float> ReadWave(std::istream &is, int32_t *sampling_rate,
                            bool *is_ok) {
  auto samples = ReadWaveImpl(is, sampling_rate, is_ok);
  return samples;
}

}  // namespace sherpa_onnx