(function (global, factory) {
    typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
    typeof define === 'function' && define.amd ? define(factory) :
    (global.Recorder = factory());
}(this, (function () {
    var recorderWorker = function () {

        var recLength = 0,
            recBuffersL = [],
            recBuffersR = [],
            sampleRate;


        self.onmessage = function (e) {
            switch (e.data.command) {
                case 'init':
                    init(e.data.config);
                    break;
                case 'record':
                    record(e.data.buffer);
                    break;
                case 'exportWAV':
                    exportWAV(e.data.type);
                    break;
                case 'getBuffer':
                    getBuffer();
                    break;
                case 'clear':
                    clear();
                    break;
            }
        };

        function init(config) {
            sampleRate = config.sampleRate;
        }

        function record(inputBuffer) {
            recBuffersL.push(inputBuffer[0]);
            recBuffersR.push(inputBuffer[1]);
            recLength += inputBuffer[0].length;
        }

        function exportWAV(type) {
            var bufferL = mergeBuffers(recBuffersL, recLength);
            var bufferR = mergeBuffers(recBuffersR, recLength);
            var interleaved = interleave(bufferL, bufferR);
            var dataview = encodeWAV(interleaved);
            var audioBlob = new Blob([dataview], {type: type});

            self.postMessage({
                type: 'blob',
                data: audioBlob
            });
        }

        function getBuffer() {
            var buffers = [];
            buffers.push(mergeBuffers(recBuffersL, recLength));
            buffers.push(mergeBuffers(recBuffersR, recLength));
            self.postMessage({
                type: 'buffer',
                data: buffers
            });
        }

        function clear() {
            recLength = 0;
            recBuffersL = [];
            recBuffersR = [];
        }

        function mergeBuffers(recBuffers, recLength) {
            var result = new Float32Array(recLength);
            var offset = 0;
            for (var i = 0; i < recBuffers.length; i++) {
                result.set(recBuffers[i], offset);
                offset += recBuffers[i].length;
            }
            return result;
        }

        function interleave(inputL, inputR) {
            var length = inputL.length + inputR.length;
            var result = new Float32Array(length);

            var index = 0,
                inputIndex = 0;

            while (index < length) {
                result[index++] = inputL[inputIndex];
                result[index++] = inputR[inputIndex];
                inputIndex++;
            }
            return result;
        }

        function floatTo16BitPCM(output, offset, input) {
            for (var i = 0; i < input.length; i++, offset += 2) {
                var s = Math.max(-1, Math.min(1, input[i]));
                output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
            }
        }

        function writeString(view, offset, string) {
            for (var i = 0; i < string.length; i++) {
                view.setUint8(offset + i, string.charCodeAt(i));
            }
        }

        function encodeWAV(samples) {
            var buffer = new ArrayBuffer(44 + samples.length * 2);
            var view = new DataView(buffer);

            /* RIFF identifier */
            writeString(view, 0, 'RIFF');
            /* RIFF chunk length */
            view.setUint32(4, 36 + samples.length * 2, true);
            /* RIFF type */
            writeString(view, 8, 'WAVE');
            /* format chunk identifier */
            writeString(view, 12, 'fmt ');
            /* format chunk length */
            view.setUint32(16, 16, true);
            /* sample format (raw) */
            view.setUint16(20, 1, true);
            /* channel count */
            view.setUint16(22, 2, true);
            /* sample rate */
            view.setUint32(24, sampleRate, true);
            /* byte rate (sample rate * block align) */
            view.setUint32(28, sampleRate * 4, true);
            /* block align (channel count * bytes per sample) */
            view.setUint16(32, 4, true);
            /* bits per sample */
            view.setUint16(34, 16, true);
            /* data chunk identifier */
            writeString(view, 36, 'data');
            /* data chunk length */
            view.setUint32(40, samples.length * 2, true);

            floatTo16BitPCM(view, 44, samples);

            return view;
        }

    };

    var recorderWorkerStr = recorderWorker.toString()
        .replace(/^\s*function.*?\(\)\s*{/, '')
        .replace(/}\s*$/, '');

    // var WORKER_PATH = './recorderWorker.js';

    var Recorder = function(source, cfg){
      var config = cfg || {};
      var bufferLen = config.bufferLen || 4096;
      this.context = source.context;
      this.node = (this.context.createScriptProcessor ||
                   this.context.createJavaScriptNode).call(this.context,
                                                           bufferLen, 2, 2);
      var worker = new Worker((window.URL || window.webkitURL).createObjectURL(new Blob([recorderWorkerStr], {type:"text/javascript"})));
      worker.onmessage = function(e){
        if (e.data.type === 'blob') {
            currCallbackWithBlob(e.data.data);
        } else {
            currCallbackWithBuffer(e.data.data);
        }
      };

      worker.postMessage({
        command: 'init',
        config: {
          sampleRate: this.context.sampleRate
        }
      });
      var recording = false,
        currCallbackWithBuffer,
        currCallbackWithBlob;

      this.node.onaudioprocess = function(e){
        if (!recording) return;
        worker.postMessage({
          command: 'record',
          buffer: [
            e.inputBuffer.getChannelData(0),
            e.inputBuffer.getChannelData(1)
          ]
        });
      };

      this.configure = function(cfg){
        for (var prop in cfg){
          if (cfg.hasOwnProperty(prop)){
            config[prop] = cfg[prop];
          }
        }
      };

      this.record = function(){
        recording = true;
      };

      this.stop = function(){
        recording = false;
      };

      this.clear = function(){
        worker.postMessage({ command: 'clear' });
      };

      this.getBuffer = function(cb) {
        currCallbackWithBuffer = cb || config.callback;
        worker.postMessage({ command: 'getBuffer' });
      };

      this.exportWAV = function(cb, type){
        currCallbackWithBlob = cb || config.callback;
        type = type || config.type || 'audio/wav';
        if (!currCallbackWithBlob) throw new Error('Callback not set');
        worker.postMessage({
          command: 'exportWAV',
          type: type
        });
      };

      this.release = function() {
        this.stop();
        this.clear();
        this.configure = this.record = this.stop = this.clear = this.getBuffer = this.exportWAV = function () {};
        source.disconnect(this.node);
        this.node.onaudioprocess = null;
        this.node.disconnect();
        worker.terminate();
      };

      source.connect(this.node);
      this.node.connect(this.context.destination);    //this should not be necessary
    };

    Recorder.forceDownload = function(blob, filename){
      var url = (window.URL || window.webkitURL).createObjectURL(blob);
      var link = window.document.createElement('a');
      link.href = url;
      link.download = filename || 'output.wav';
      var click = document.createEvent("Event");
      click.initEvent("click", true, true);
      link.dispatchEvent(click);
    };

    var recorder = Recorder;

    return recorder;

})));