export default function AudioRecorder(stream, config) {
  config = config || {};
  config.sampleBits = config.sampleBits || 16;   //采样数位 8, 16
  config.sampleRate = config.sampleRate || 16000;  //采样率16khz
 
  var context = new (window.webkitAudioContext || window.AudioContext)();
  var audioInput = context.createMediaStreamSource(stream);
  var createScript = context.createScriptProcessor || context.createJavaScriptNode;
  var recorder = createScript.apply(context, [4096, 1, 1]);
 
  var audioData = {
    size: 0     //录音文件长度
    , buffer: []   //录音缓存
    , inputSampleRate: 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
      var data = new Float32Array(this.size);
      var offset = 0;
      for (var i = 0; i < this.buffer.length; i++) {
        data.set(this.buffer[i], offset);
        offset += this.buffer[i].length;
      }
      //压缩
      var compression = parseInt(this.inputSampleRate / this.outputSampleRate);
      var length = data.length / compression;
      var result = new Float32Array(length);
      var index = 0, j = 0;
      while (index < length) {
        result[index] = data[j];
        j += compression;
        index++;
      }
      return result;
    }
    , encodeWAV: function () {
      var sampleRate = Math.min(this.inputSampleRate, this.outputSampleRate);
      var sampleBits = Math.min(this.inputSampleBits, this.oututSampleBits);
      var bytes = this.compress();
      var dataLength = bytes.length * (sampleBits / 8);
      var buffer = new ArrayBuffer(44 + dataLength);
      var data = new DataView(buffer);
 
      var channelCount = 1;//单声道
      var offset = 0;
 
      var writeString = function (str) {
        for (var 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 (var i = 0; i < bytes.length; i++, offset++) {
          var s = Math.max(-1, Math.min(1, bytes[i]));
          var val = s < 0 ? s * 0x8000 : s * 0x7FFF;
          val = parseInt(255 / (65535 / (val + 32768)));
          data.setInt8(offset, val, true);
        }
      } else {
        for (var i = 0; i < bytes.length; i++, offset += 2) {
          var 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
  this.start = function () {
    audioInput.connect(recorder);
    recorder.connect(context.destination);
  }
 
  //停止
  this.stop = function () {
    stream.getTracks().forEach(function(track) {
      track.stop();
    });
    recorder.disconnect();
  }
 
  //获取音频文件
  this.getBlob = function () {
    this.stop();
    return audioData.encodeWAV();
  }
 
  //回放
  this.play = function (audio) {
   var blob=this.getBlob();
   // saveAs(blob, "F:/3.wav");
   audio.src = window.URL.createObjectURL(this.getBlob());
  }
 
  //上传
  this.upload = function () {
   return this.getBlob()
  }
 
  //音频采集
  recorder.onaudioprocess = function (e) {
    audioData.input(e.inputBuffer.getChannelData(0));
    //record(e.inputBuffer.getChannelData(0));
  }
 
}