/**
 * AAC demuxer
 */
import {logger} from '../utils/logger';
import ID3 from '../demux/id3';
import {ErrorTypes, ErrorDetails} from '../errors';

 class AACDemuxer {

  constructor(observer,remuxerClass) {
    this.observer = observer;
    this.remuxerClass = remuxerClass;
    this.remuxer = new this.remuxerClass(observer);
    this._aacTrack = {type: 'audio', id :-1, sequenceNumber: 0, samples : [], len : 0};
  }

  static probe(data) {
    // check if data contains ID3 timestamp and ADTS sync worc
    var id3 = new ID3(data), adtsStartOffset,len;
    if(id3.hasTimeStamp) {
      // look for ADTS header (0xFFFx)
      for (adtsStartOffset = id3.length, len = data.length; adtsStartOffset < len - 1; adtsStartOffset++) {
        if ((data[adtsStartOffset] === 0xff) && (data[adtsStartOffset+1] & 0xf0) === 0xf0) {
          //logger.log('ADTS sync word found !');
          return true;
        }
      }
    }
    return false;
  }


  // feed incoming data to the front of the parsing pipeline
  push(data, audioCodec, videoCodec, timeOffset, cc, level, sn, duration) {
    var id3 = new ID3(data), adtsStartOffset,len, track = this._aacTrack, pts = id3.timeStamp, config, nbSamples,adtsFrameSize,adtsHeaderLen,stamp,aacSample;
    // look for ADTS header (0xFFFx)
    for (adtsStartOffset = id3.length, len = data.length; adtsStartOffset < len - 1; adtsStartOffset++) {
      if ((data[adtsStartOffset] === 0xff) && (data[adtsStartOffset+1] & 0xf0) === 0xf0) {
        break;
      }
    }

    if (!track.audiosamplerate) {
      config = this._ADTStoAudioConfig(data, adtsStartOffset, audioCodec);
      track.config = config.config;
      track.audiosamplerate = config.samplerate;
      track.channelCount = config.channelCount;
      track.codec = config.codec;
      track.timescale = this.remuxer.timescale;
      track.duration = this.remuxer.timescale * duration;
      logger.log(`parsed codec:${track.codec},rate:${config.samplerate},nb channel:${config.channelCount}`);
    }
    nbSamples = 0;
    while ((adtsStartOffset + 5) < len) {
      // retrieve frame size
      adtsFrameSize = ((data[adtsStartOffset + 3] & 0x03) << 11);
      // byte 4
      adtsFrameSize |= (data[adtsStartOffset + 4] << 3);
      // byte 5
      adtsFrameSize |= ((data[adtsStartOffset + 5] & 0xE0) >>> 5);
      adtsHeaderLen = (!!(data[adtsStartOffset + 1] & 0x01) ? 7 : 9);
      adtsFrameSize -= adtsHeaderLen;
      stamp = Math.round(90*pts + nbSamples * 1024 * 90000 / track.audiosamplerate);
      //stamp = pes.pts;
      //console.log('AAC frame, offset/length/pts:' + (adtsStartOffset+7) + '/' + adtsFrameSize + '/' + stamp.toFixed(0));
      if ((adtsFrameSize > 0) && ((adtsStartOffset + adtsHeaderLen + adtsFrameSize) <= len)) {
        aacSample = {unit: data.subarray(adtsStartOffset + adtsHeaderLen, adtsStartOffset + adtsHeaderLen + adtsFrameSize), pts: stamp, dts: stamp};
        track.samples.push(aacSample);
        track.len += adtsFrameSize;
        adtsStartOffset += adtsFrameSize + adtsHeaderLen;
        nbSamples++;
        // look for ADTS header (0xFFFx)
        for ( ; adtsStartOffset < (len - 1); adtsStartOffset++) {
          if ((data[adtsStartOffset] === 0xff) && ((data[adtsStartOffset + 1] & 0xf0) === 0xf0)) {
            break;
          }
        }
      } else {
        break;
      }
    }
    this.remuxer.remux(this._aacTrack,{samples : []}, {samples : []}, timeOffset);
  }

  _ADTStoAudioConfig(data, offset, audioCodec) {
    var adtsObjectType, // :int
        adtsSampleingIndex, // :int
        adtsExtensionSampleingIndex, // :int
        adtsChanelConfig, // :int
        config,
        userAgent = navigator.userAgent.toLowerCase(),
        adtsSampleingRates = [
            96000, 88200,
            64000, 48000,
            44100, 32000,
            24000, 22050,
            16000, 12000,
            11025, 8000,
            7350];
    // byte 2
    adtsObjectType = ((data[offset + 2] & 0xC0) >>> 6) + 1;
    adtsSampleingIndex = ((data[offset + 2] & 0x3C) >>> 2);
    if(adtsSampleingIndex > adtsSampleingRates.length-1) {
      this.observer.trigger(Event.ERROR, {type: ErrorTypes.MEDIA_ERROR, details: ErrorDetails.FRAG_PARSING_ERROR, fatal: true, reason: `invalid ADTS sampling index:${adtsSampleingIndex}`});
      return;
    }
    adtsChanelConfig = ((data[offset + 2] & 0x01) << 2);
    // byte 3
    adtsChanelConfig |= ((data[offset + 3] & 0xC0) >>> 6);
    logger.log(`manifest codec:${audioCodec},ADTS data:type:${adtsObjectType},sampleingIndex:${adtsSampleingIndex}[${adtsSampleingRates[adtsSampleingIndex]}Hz],channelConfig:${adtsChanelConfig}`);
    // firefox: freq less than 24kHz = AAC SBR (HE-AAC)
    if (userAgent.indexOf('firefox') !== -1) {
      if (adtsSampleingIndex >= 6) {
        adtsObjectType = 5;
        config = new Array(4);
        // HE-AAC uses SBR (Spectral Band Replication) , high frequencies are constructed from low frequencies
        // there is a factor 2 between frame sample rate and output sample rate
        // multiply frequency by 2 (see table below, equivalent to substract 3)
        adtsExtensionSampleingIndex = adtsSampleingIndex - 3;
      } else {
        adtsObjectType = 2;
        config = new Array(2);
        adtsExtensionSampleingIndex = adtsSampleingIndex;
      }
      // Android : always use AAC
    } else if (userAgent.indexOf('android') !== -1) {
      adtsObjectType = 2;
      config = new Array(2);
      adtsExtensionSampleingIndex = adtsSampleingIndex;
    } else {
      /*  for other browsers (chrome ...)
          always force audio type to be HE-AAC SBR, as some browsers do not support audio codec switch properly (like Chrome ...)
      */
      adtsObjectType = 5;
      config = new Array(4);
      // if (manifest codec is HE-AAC) OR (manifest codec not specified AND frequency less than 24kHz)
      if ((audioCodec && audioCodec.indexOf('mp4a.40.5') !== -1) || (!audioCodec && adtsSampleingIndex >= 6)) {
        // HE-AAC uses SBR (Spectral Band Replication) , high frequencies are constructed from low frequencies
        // there is a factor 2 between frame sample rate and output sample rate
        // multiply frequency by 2 (see table below, equivalent to substract 3)
        adtsExtensionSampleingIndex = adtsSampleingIndex - 3;
      } else {
        // if (manifest codec is AAC) AND (frequency less than 24kHz OR nb channel is 1)
        if (audioCodec && audioCodec.indexOf('mp4a.40.2') !== -1 && (adtsSampleingIndex >= 6 || adtsChanelConfig === 1)) {
          adtsObjectType = 2;
          config = new Array(2);
        }
        adtsExtensionSampleingIndex = adtsSampleingIndex;
      }
    }
    /* refer to http://wiki.multimedia.cx/index.php?title=MPEG-4_Audio#Audio_Specific_Config
        ISO 14496-3 (AAC).pdf - Table 1.13 — Syntax of AudioSpecificConfig()
      Audio Profile / Audio Object Type
      0: Null
      1: AAC Main
      2: AAC LC (Low Complexity)
      3: AAC SSR (Scalable Sample Rate)
      4: AAC LTP (Long Term Prediction)
      5: SBR (Spectral Band Replication)
      6: AAC Scalable
     sampling freq
      0: 96000 Hz
      1: 88200 Hz
      2: 64000 Hz
      3: 48000 Hz
      4: 44100 Hz
      5: 32000 Hz
      6: 24000 Hz
      7: 22050 Hz
      8: 16000 Hz
      9: 12000 Hz
      10: 11025 Hz
      11: 8000 Hz
      12: 7350 Hz
      13: Reserved
      14: Reserved
      15: frequency is written explictly
      Channel Configurations
      These are the channel configurations:
      0: Defined in AOT Specifc Config
      1: 1 channel: front-center
      2: 2 channels: front-left, front-right
    */
    // audioObjectType = profile => profile, the MPEG-4 Audio Object Type minus 1
    config[0] = adtsObjectType << 3;
    // samplingFrequencyIndex
    config[0] |= (adtsSampleingIndex & 0x0E) >> 1;
    config[1] |= (adtsSampleingIndex & 0x01) << 7;
    // channelConfiguration
    config[1] |= adtsChanelConfig << 3;
    if (adtsObjectType === 5) {
      // adtsExtensionSampleingIndex
      config[1] |= (adtsExtensionSampleingIndex & 0x0E) >> 1;
      config[2] = (adtsExtensionSampleingIndex & 0x01) << 7;
      // adtsObjectType (force to 2, chrome is checking that object type is less than 5 ???
      //    https://chromium.googlesource.com/chromium/src.git/+/master/media/formats/mp4/aac.cc
      config[2] |= 2 << 2;
      config[3] = 0;
    }
    return {config: config, samplerate: adtsSampleingRates[adtsSampleingIndex], channelCount: adtsChanelConfig, codec: ('mp4a.40.' + adtsObjectType)};
  }

  destroy() {
  }

}

export default AACDemuxer;