export default class Recorder {
  constructor(stream, config) {
    //兼容
    window.URL = window.URL || window.webkitURL
    navigator.getUserMedia =
      navigator.getUserMedia ||
      navigator.webkitGetUserMedia ||
      navigator.mozGetUserMedia ||
      navigator.msGetUserMedia

    config = config || {}
    config.sampleBits = config.sampleBits || 16 //采样数位 8, 16
    config.sampleRate = config.sampleRate || 8000 //采样率(1/6 44100)

    this.context = new (window.webkitAudioContext || window.AudioContext)()
    this.audioInput = this.context.createMediaStreamSource(stream)
    this.createScript =
      this.context.createScriptProcessor || this.context.createJavaScriptNode
    this.recorder = this.createScript.apply(this.context, [4096, 1, 1])

    this.audioData = {
      size: 0, //录音文件长度
      buffer: [], //录音缓存
      inputSampleRate: this.context.sampleRate, //输入采样率
      inputSampleBits: 16, //输入采样数位 8, 16
      outputSampleRate: config.sampleRate, //输出采样率
      oututSampleBits: config.sampleBits, //输出采样数位 8, 16
      input: function(data) {
        this.buffer.push(new Float32Array(data))
        this.size += data.length
      },
      compress: function() {
        //合并压缩
        //合并
        let data = new Float32Array(this.size)
        let offset = 0
        for (let i = 0; i < this.buffer.length; i++) {
          data.set(this.buffer[i], offset)
          offset += this.buffer[i].length
        }
        //压缩
        let compression = parseInt(this.inputSampleRate / this.outputSampleRate)
        let length = data.length / compression
        let result = new Float32Array(length)
        let index = 0,
          j = 0
        while (index < length) {
          result[index] = data[j]
          j += compression
          index++
        }
        return result
      },
      encodeWAV: function() {
        let sampleRate = Math.min(this.inputSampleRate, this.outputSampleRate)
        let sampleBits = Math.min(this.inputSampleBits, this.oututSampleBits)
        let bytes = this.compress()
        let dataLength = bytes.length * (sampleBits / 8)
        let buffer = new ArrayBuffer(44 + dataLength)
        let data = new DataView(buffer)

        let channelCount = 1 //单声道
        let offset = 0

        let writeString = function(str) {
          for (let i = 0; i < str.length; i++) {
            data.setUint8(offset + i, str.charCodeAt(i))
          }
        }

        // 资源交换文件标识符
        writeString('RIFF')
        offset += 4
        // 下个地址开始到文件尾总字节数,即文件大小-8
        data.setUint32(offset, 36 + dataLength, true)
        offset += 4
        // WAV文件标志
        writeString('WAVE')
        offset += 4
        // 波形格式标志
        writeString('fmt ')
        offset += 4
        // 过滤字节,一般为 0x10 = 16
        data.setUint32(offset, 16, true)
        offset += 4
        // 格式类别 (PCM形式采样数据)
        data.setUint16(offset, 1, true)
        offset += 2
        // 通道数
        data.setUint16(offset, channelCount, true)
        offset += 2
        // 采样率,每秒样本数,表示每个通道的播放速度
        data.setUint32(offset, sampleRate, true)
        offset += 4
        // 波形数据传输率 (每秒平均字节数) 单声道×每秒数据位数×每样本数据位/8
        data.setUint32(
          offset,
          channelCount * sampleRate * (sampleBits / 8),
          true
        )
        offset += 4
        // 快数据调整数 采样一次占用字节数 单声道×每样本的数据位数/8
        data.setUint16(offset, channelCount * (sampleBits / 8), true)
        offset += 2
        // 每样本数据位数
        data.setUint16(offset, sampleBits, true)
        offset += 2
        // 数据标识符
        writeString('data')
        offset += 4
        // 采样数据总数,即数据总大小-44
        data.setUint32(offset, dataLength, true)
        offset += 4
        // 写入采样数据
        if (sampleBits === 8) {
          for (let i = 0; i < bytes.length; i++, offset++) {
            let s = Math.max(-1, Math.min(1, bytes[i]))
            let val = s < 0 ? s * 0x8000 : s * 0x7fff
            val = parseInt(255 / (65535 / (val + 32768)))
            data.setInt8(offset, val, true)
          }
        } else {
          for (let i = 0; i < bytes.length; i++, offset += 2) {
            let s = Math.max(-1, Math.min(1, bytes[i]))
            data.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7fff, true)
          }
        }
        return new Blob([data], {
          type: 'audio/wav',
        })
      },
    }
  }

  //开始录音
  start() {
    this.audioInput.connect(this.recorder)
    this.recorder.connect(this.context.destination)

    //音频采集
    let self = this
    this.recorder.onaudioprocess = function(e) {
      self.audioData.input(e.inputBuffer.getChannelData(0))
    }
  }

  //停止
  stop() {
    this.recorder.disconnect()
  }

  //获取音频文件
  getBlob() {
    this.stop()
    return this.audioData.encodeWAV()
  }

  //回放
  play(audio) {
    audio.src = window.URL.createObjectURL(this.getBlob())
  }

  //清理缓存的录音数据
  clear(audio) {
    this.audioData.buffer = []
    this.audioData.size = 0
    audio.src = ''
  }

  static checkError(e) {
    const { name } = e
    let errorMsg = ''
    switch (name) {
      case 'AbortError':
        errorMsg = '录音设备无法被使用'
        break
      case 'NotAllowedError':
        errorMsg = '用户已禁止网页调用录音设备'
        break
      case 'PermissionDeniedError':
        errorMsg = '用户已禁止网页调用录音设备'
        break // 用户拒绝
      case 'NotFoundError':
        errorMsg = '录音设备未找到'
        break
      case 'DevicesNotFoundError':
        errorMsg = '录音设备未找到'
        break
      case 'NotReadableError':
        errorMsg = '录音设备无法使用'
        break
      case 'NotSupportedError':
        errorMsg = '不支持录音功能'
        break
      case 'MandatoryUnsatisfiedError':
        errorMsg = '无法发现指定的硬件设备'
        break
      default:
        errorMsg = '录音调用错误'
        break
    }
    return {
      error: errorMsg,
    }
  }

  static get(callback, config) {
    if (callback) {
      if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
        navigator.mediaDevices
          .getUserMedia({
            audio: true,
            video: false,
          })
          .then(stream => {
            let rec = new Recorder(stream, config)
            callback(rec)
          })
          .catch(e => {
            callback(Recorder.checkError(e))
          })
      } else {
        navigator
          .getUserMedia({
            audio: true,
            video: false,
          })
          .then(stream => {
            let rec = new Recorder(stream, config)
            callback(rec)
          })
          .catch(e => {
            // Recorder.checkError(e)
            callback(Recorder.checkError(e))
          })
      }
    }
  }
}