/* eslint-disable */
/*
 * H264 NAL Slicer
 */
import Event from '../events';
import EventHandler from '../event-handler';
import H264Demuxer from '../demux/h264-demuxer';

class SlicesReader extends EventHandler {

    constructor(wfs, config = null) {
        super(wfs, Event.H264_DATA_PARSING);

        this.config = this.wfs.config || config;
        this.h264Demuxer = new H264Demuxer(wfs);
        this.wfs = wfs;
        this.lastBuf = null;
        this.nals = [];
    }

    destroy() {
        this.lastBuf = null;
        this.nals = [];
        EventHandler.prototype.destroy.call(this);
    }

    _read(buffer) {
        var typedAr = null;
        this.nals = [];
        if (!buffer || buffer.byteLength < 1) return;
        if (this.lastBuf) {
            typedAr = new Uint8Array(buffer.byteLength + this.lastBuf.length);
            typedAr.set(this.lastBuf);
            typedAr.set(new Uint8Array(buffer), this.lastBuf.length);
        } else {
            typedAr = new Uint8Array(buffer);
        }
        var lastNalEndPos = 0;
        var b1 = -1; // byte before one
        var b2 = -2; // byte before two
        var nalStartPos = new Array();
        for (var i = 0; i < typedAr.length; i += 2) {
            var b_0 = typedAr[i];
            var b_1 = typedAr[i + 1];
            if (b1 == 0 && b_0 == 0 && b_1 == 0) {
                nalStartPos.push(i - 1);
            } else if (b_1 == 1 && b_0 == 0 && b1 == 0 && b2 == 0) {
                nalStartPos.push(i - 2);
            }
            b2 = b_0;
            b1 = b_1;
        }
        if (nalStartPos.length > 1) {
            for (var i = 0; i < nalStartPos.length - 1; ++i) {
                this.nals.push(typedAr.subarray(nalStartPos[i], nalStartPos[i + 1] + 1));
                lastNalEndPos = nalStartPos[i + 1];
            }
        } else {
            lastNalEndPos = nalStartPos[0];
        }
        if (lastNalEndPos != 0 && lastNalEndPos < typedAr.length) {
            this.lastBuf = typedAr.subarray(lastNalEndPos);
        } else {
            if ( !! !this.lastBuf) {
                this.lastBuf = typedAr;
            }
            var _newBuf = new Uint8Array(this.lastBuf.length + buffer.byteLength);
            _newBuf.set(this.lastBuf);
            _newBuf.set(new Uint8Array(buffer), this.lastBuf.length);
            this.lastBuf = _newBuf;
        }
    }

  onH264DataParsing(event) {
    this._read(event.data);
    var $this = this;
    this.nals.forEach(function(nal) {
      $this.wfs.trigger(Event.H264_DATA_PARSED, {
        data: nal
      });
    });
  }
}

export default SlicesReader;