export function downloadWAVTemplate (audioBuffer) {
  var channelData = []
  var totalLength = 0
  var channelLength = 0
 
  for (var i = 0; i < audioBuffer.numberOfChannels; i++) {
    channelData.push(audioBuffer.getChannelData(i))
    totalLength += channelData[i].length
    if (i === 0) channelLength = channelData[i].length
  }
 
  // interleaved
  const interleaved = new Float32Array(totalLength)
 
  for (
    let src = 0, dst = 0;
    src < channelLength;
    src++, dst += audioBuffer.numberOfChannels
  ) {
    for (var j = 0; j < audioBuffer.numberOfChannels; j++) {
      interleaved[dst + j] = channelData[j][src]
    }
    // interleaved[dst] = left[src];
    // interleaved[dst + 1] = right[src];
  }
 
  // get WAV file bytes and audio params of your audio source
  const wavBytes = getWavBytes(interleaved.buffer, {
    isFloat: true, // floating point or 16-bit integer
    numChannels: audioBuffer.numberOfChannels,
    sampleRate: 48000,
  })
  const wav = new Blob([wavBytes], { type: 'audio/wav' })
  const downloadLink = document.createElement('a')
  downloadLink.href = URL.createObjectURL(wav)
  downloadLink.setAttribute('download', 'my-audio.wav')
  downloadLink.click()
}
 
// Returns Uint8Array of WAV bytes
function getWavBytes (buffer, options) {
  const type = options.isFloat ? Float32Array : Uint16Array
  const numFrames = buffer.byteLength / type.BYTES_PER_ELEMENT
 
  const headerBytes = getWavHeader(Object.assign({}, options, { numFrames }))
  const wavBytes = new Uint8Array(headerBytes.length + buffer.byteLength)
 
  // prepend header, then add pcmBytes
  wavBytes.set(headerBytes, 0)
  wavBytes.set(new Uint8Array(buffer), headerBytes.length)
 
  return wavBytes
}
 
// adapted from https://gist.github.com/also/900023
// returns Uint8Array of WAV header bytes
function getWavHeader (options) {
  const numFrames = options.numFrames
  const numChannels = options.numChannels || 2
  const sampleRate = options.sampleRate || 44100
  const bytesPerSample = options.isFloat ? 4 : 2
  const format = options.isFloat ? 3 : 1
 
  const blockAlign = numChannels * bytesPerSample
  const byteRate = sampleRate * blockAlign
  const dataSize = numFrames * blockAlign
 
  const buffer = new ArrayBuffer(44)
  const dv = new DataView(buffer)
 
  let p = 0
 
  function writeString (s) {
    for (let i = 0; i < s.length; i++) {
      dv.setUint8(p + i, s.charCodeAt(i))
    }
    p += s.length
  }
 
  function writeUint32 (d) {
    dv.setUint32(p, d, true)
    p += 4
  }
 
  function writeUint16 (d) {
    dv.setUint16(p, d, true)
    p += 2
  }
 
  writeString('RIFF') // ChunkID
  writeUint32(dataSize + 36) // ChunkSize
  writeString('WAVE') // Format
  writeString('fmt ') // Subchunk1ID
  writeUint32(16) // Subchunk1Size
  writeUint16(format) // AudioFormat https://i.stack.imgur.com/BuSmb.png
  writeUint16(numChannels) // NumChannels
  writeUint32(sampleRate) // SampleRate
  writeUint32(byteRate) // ByteRate
  writeUint16(blockAlign) // BlockAlign
  writeUint16(bytesPerSample * 8) // BitsPerSample
  writeString('data') // Subchunk2ID
  writeUint32(dataSize) // Subchunk2Size
 
  return new Uint8Array(buffer)
}