/*
   * EventSource polyfill version {{VERSION}}
   * Supported by sc AmvTek srl
   * :email: devel@amvtek.com
 */
;(function (global) {

    if (global.EventSource && !global._eventSourceImportPrefix){
        return;
    }

    var evsImportName = (global._eventSourceImportPrefix||'')+"EventSource";

    var EventSource = function (url, options) {

        if (!url || typeof url != 'string') {
            throw new SyntaxError('Not enough arguments');
        }

        this.URL = url;
        this.setOptions(options);
        var evs = this;
        setTimeout(function(){evs.poll()}, 0);
    };

    EventSource.prototype = {

        CONNECTING: 0,

        OPEN: 1,

        CLOSED: 2,

        defaultOptions: {

            loggingEnabled: false,

            loggingPrefix: "eventsource",

            interval: 500, // milliseconds

            bufferSizeLimit: 256*1024, // bytes

            silentTimeout: 300000, // milliseconds

            getArgs:{
                'evs_buffer_size_limit': 256*1024
            },

            xhrHeaders:{
                'Accept': 'text/event-stream',
                'Cache-Control': 'no-cache',
                'X-Requested-With': 'XMLHttpRequest'
            }
        },

        setOptions: function(options){

            var defaults = this.defaultOptions;
            var option;

            // set all default options...
            for (option in defaults){

                if ( defaults.hasOwnProperty(option) ){
                    this[option] = defaults[option];
                }
            }

            // override with what is in options
            for (option in options){

                if (option in defaults && options.hasOwnProperty(option)){
                    this[option] = options[option];
                }
            }

            // if getArgs option is enabled
            // ensure evs_buffer_size_limit corresponds to bufferSizeLimit
            if (this.getArgs && this.bufferSizeLimit) {

                this.getArgs['evs_buffer_size_limit'] = this.bufferSizeLimit;
            }

            // if console is not available, force loggingEnabled to false
            if (typeof console === "undefined" || typeof console.log === "undefined") {

                this.loggingEnabled = false;
            }
        },

        log: function(message) {

            if (this.loggingEnabled) {

                console.log("[" + this.loggingPrefix +"]:" + message)
            }
        },

        poll: function() {

            try {

                if (this.readyState == this.CLOSED) {
                    return;
                }

                this.cleanup();
                this.readyState = this.CONNECTING;
                this.cursor = 0;
                this.cache = '';
                this._xhr = new this.XHR(this);
                this.resetNoActivityTimer();

            }
            catch (e) {

                // in an attempt to silence the errors
                this.log('There were errors inside the pool try-catch');
                this.dispatchEvent('error', { type: 'error', data: e.message });
            }
        },

        pollAgain: function (interval) {

            // schedule poll to be called after interval milliseconds
            var evs = this;
            evs.readyState = evs.CONNECTING;
            evs.dispatchEvent('error', {
                type: 'error',
                data: "Reconnecting "
            });
            this._pollTimer = setTimeout(function(){evs.poll()}, interval||0);
        },


        cleanup: function() {

            this.log('evs cleaning up')

            if (this._pollTimer){
                clearInterval(this._pollTimer);
                this._pollTimer = null;
            }

            if (this._noActivityTimer){
                clearInterval(this._noActivityTimer);
                this._noActivityTimer = null;
            }

            if (this._xhr){
                this._xhr.abort();
                this._xhr = null;
            }
        },

        resetNoActivityTimer: function(){

            if (this.silentTimeout){

                if (this._noActivityTimer){
                    clearInterval(this._noActivityTimer);
                }
                var evs = this;
                this._noActivityTimer = setTimeout(
                        function(){ evs.log('Timeout! silentTImeout:'+evs.silentTimeout); evs.pollAgain(); },
                        this.silentTimeout
                        );
            }
        },

        close: function () {

            this.readyState = this.CLOSED;
            this.log('Closing connection. readyState: '+this.readyState);
            this.cleanup();
        },

        _onxhrdata: function() {

            var request = this._xhr;

            if (request.isReady() && !request.hasError() ) {
                // reset the timer, as we have activity
                this.resetNoActivityTimer();

                // move this EventSource to OPEN state...
                if (this.readyState == this.CONNECTING) {
                    this.readyState = this.OPEN;
                    this.dispatchEvent('open', { type: 'open' });
                }

                var buffer = request.getBuffer();

                if (buffer.length > this.bufferSizeLimit) {
                    this.log('buffer.length > this.bufferSizeLimit');
                    this.pollAgain();
                }

                if (this.cursor == 0 && buffer.length > 0){

                    // skip byte order mark \uFEFF character if it starts the stream
                    if (buffer.substring(0,1) == '\uFEFF'){
                        this.cursor = 1;
                    }
                }

                var lastMessageIndex = this.lastMessageIndex(buffer);
                if (lastMessageIndex[0] >= this.cursor){

                    var newcursor = lastMessageIndex[1];
                    var toparse = buffer.substring(this.cursor, newcursor);
                    this.parseStream(toparse);
                    this.cursor = newcursor;
                }

                // if request is finished, reopen the connection
                if (request.isDone()) {
                    this.log('request.isDone(). reopening the connection');
                    this.pollAgain(this.interval);
                }
            }
            else if (this.readyState !== this.CLOSED) {

                this.log('this.readyState !== this.CLOSED');
                this.pollAgain(this.interval);

                //MV: Unsure why an error was previously dispatched
            }
        },

        parseStream: function(chunk) {

            // normalize line separators (\r\n,\r,\n) to \n
            // remove white spaces that may precede \n
            chunk = this.cache + this.normalizeToLF(chunk);

            var events = chunk.split('\n\n');

            var i, j, eventType, datas, line, retry;

            for (i=0; i < (events.length - 1); i++) {

                eventType = 'message';
                datas = [];
                parts = events[i].split('\n');

                for (j=0; j < parts.length; j++) {

                    line = this.trimWhiteSpace(parts[j]);

                    if (line.indexOf('event') == 0) {

                        eventType = line.replace(/event:?\s*/, '');
                    }
                    else if (line.indexOf('retry') == 0) {

                        retry = parseInt(line.replace(/retry:?\s*/, ''));
                        if(!isNaN(retry)) {
                            this.interval = retry;
                        }
                    }
                    else if (line.indexOf('data') == 0) {

                        datas.push(line.replace(/data:?\s*/, ''));
                    }
                    else if (line.indexOf('id:') == 0) {

                        this.lastEventId = line.replace(/id:?\s*/, '');
                    }
                    else if (line.indexOf('id') == 0) { // this resets the id

                        this.lastEventId = null;
                    }
                }

                if (datas.length) {
                    // dispatch a new event
                    var event = new MessageEvent(eventType, datas.join('\n'), window.location.origin, this.lastEventId);
                    this.dispatchEvent(eventType, event);
                }
            }

            this.cache = events[events.length - 1];
        },

        dispatchEvent: function (type, event) {
            var handlers = this['_' + type + 'Handlers'];

            if (handlers) {

                for (var i = 0; i < handlers.length; i++) {
                    handlers[i].call(this, event);
                }
            }

            if (this['on' + type]) {
                this['on' + type].call(this, event);
            }

        },

        addEventListener: function (type, handler) {
            if (!this['_' + type + 'Handlers']) {
                this['_' + type + 'Handlers'] = [];
            }

            this['_' + type + 'Handlers'].push(handler);
        },

        removeEventListener: function (type, handler) {
            var handlers = this['_' + type + 'Handlers'];
            if (!handlers) {
                return;
            }
            for (var i = handlers.length - 1; i >= 0; --i) {
                if (handlers[i] === handler) {
                    handlers.splice(i, 1);
                    break;
                }
            }
        },

        _pollTimer: null,

        _noactivityTimer: null,

        _xhr: null,

        lastEventId: null,

        cache: '',

        cursor: 0,

        onerror: null,

        onmessage: null,

        onopen: null,

        readyState: 0,

        // ===================================================================
        // helpers functions
        // those are attached to prototype to ease reuse and testing...

        urlWithParams: function (baseURL, params) {

            var encodedArgs = [];

            if (params){

                var key, urlarg;
                var urlize = encodeURIComponent;

                for (key in params){
                    if (params.hasOwnProperty(key)) {
                        urlarg = urlize(key)+'='+urlize(params[key]);
                        encodedArgs.push(urlarg);
                    }
                }
            }

            if (encodedArgs.length > 0){

                if (baseURL.indexOf('?') == -1)
                    return baseURL + '?' + encodedArgs.join('&');
                return baseURL + '&' + encodedArgs.join('&');
            }
            return baseURL;
        },

        lastMessageIndex: function(text) {

            var ln2 =text.lastIndexOf('\n\n');
            var lr2 = text.lastIndexOf('\r\r');
            var lrln2 = text.lastIndexOf('\r\n\r\n');

            if (lrln2 > Math.max(ln2, lr2)) {
                return [lrln2, lrln2+4];
            }
            return [Math.max(ln2, lr2), Math.max(ln2, lr2) + 2]
        },

        trimWhiteSpace: function(str) {
            // to remove whitespaces left and right of string

            var reTrim = /^(\s|\u00A0)+|(\s|\u00A0)+$/g;
            return str.replace(reTrim, '');
        },

        normalizeToLF: function(str) {

            // replace \r and \r\n with \n
            return str.replace(/\r\n|\r/g, '\n');
        }

    };

    if (!isOldIE()){

        EventSource.isPolyfill = "XHR";

        // EventSource will send request using XMLHttpRequest
        EventSource.prototype.XHR = function(evs) {

            request = new XMLHttpRequest();
            this._request = request;
            evs._xhr = this;

            // set handlers
            request.onreadystatechange = function(){
                if (request.readyState > 1 && evs.readyState != evs.CLOSED) {
                    if (request.status == 200 || (request.status>=300 && request.status<400)){
                        evs._onxhrdata();
                    }
                    else {
                        request._failed = true;
                        evs.readyState = evs.CLOSED;
                        evs.dispatchEvent('error', {
                            type: 'error',
                            data: "The server responded with "+request.status
                        });
                        evs.close();
                    }
                }
            };

            request.onprogress = function () {
            };

            request.open('GET', evs.urlWithParams(evs.URL, evs.getArgs), true);

            var headers = evs.xhrHeaders; // maybe null
            for (var header in headers) {
                if (headers.hasOwnProperty(header)){
                    request.setRequestHeader(header, headers[header]);
                }
            }
            if (evs.lastEventId) {
                request.setRequestHeader('Last-Event-Id', evs.lastEventId);
            }

            request.send();
        };

        EventSource.prototype.XHR.prototype = {

            useXDomainRequest: false,

            _request: null,

            _failed: false, // true if we have had errors...

            isReady: function() {


                return this._request.readyState >= 2;
            },

            isDone: function() {

                return (this._request.readyState == 4);
            },

            hasError: function() {

                return (this._failed || (this._request.status >= 400));
            },

            getBuffer: function() {

                var rv = '';
                try {
                    rv = this._request.responseText || '';
                }
                catch (e){}
                return rv;
            },

            abort: function() {

                if ( this._request ) {
                    this._request.abort();
                }
            }
        };
    }
    else {

	EventSource.isPolyfill = "IE_8-9";

        // patch EventSource defaultOptions
        var defaults = EventSource.prototype.defaultOptions;
        defaults.xhrHeaders = null; // no headers will be sent
        defaults.getArgs['evs_preamble'] = 2048 + 8;

        // EventSource will send request using Internet Explorer XDomainRequest
        EventSource.prototype.XHR = function(evs) {

            request = new XDomainRequest();
            this._request = request;

            // set handlers
            request.onprogress = function(){
                request._ready = true;
                evs._onxhrdata();
            };

            request.onload = function(){
                this._loaded = true;
                evs._onxhrdata();
            };

            request.onerror = function(){
                this._failed = true;
                evs.readyState = evs.CLOSED;
                evs.dispatchEvent('error', {
                    type: 'error',
                    data: "XDomainRequest error"
                });
            };

            request.ontimeout = function(){
                this._failed = true;
                evs.readyState = evs.CLOSED;
                evs.dispatchEvent('error', {
                    type: 'error',
                    data: "XDomainRequest timed out"
                });
            };

            // XDomainRequest does not allow setting custom headers
            // If EventSource has enabled the use of GET arguments
            // we add parameters to URL so that server can adapt the stream...
            var reqGetArgs = {};
            if (evs.getArgs) {

                // copy evs.getArgs in reqGetArgs
                var defaultArgs = evs.getArgs;
                    for (var key in defaultArgs) {
                        if (defaultArgs.hasOwnProperty(key)){
                            reqGetArgs[key] = defaultArgs[key];
                        }
                    }
                if (evs.lastEventId){
                    reqGetArgs['evs_last_event_id'] = evs.lastEventId;
                }
            }
            // send the request

            request.open('GET', evs.urlWithParams(evs.URL,reqGetArgs));
            request.send();
        };

        EventSource.prototype.XHR.prototype = {

            useXDomainRequest: true,

            _request: null,

            _ready: false, // true when progress events are dispatched

            _loaded: false, // true when request has been loaded

            _failed: false, // true if when request is in error

            isReady: function() {

                return this._request._ready;
            },

            isDone: function() {

                return this._request._loaded;
            },

            hasError: function() {

                return this._request._failed;
            },

            getBuffer: function() {

                var rv = '';
                try {
                    rv = this._request.responseText || '';
                }
                catch (e){}
                return rv;
            },

            abort: function() {

                if ( this._request){
                    this._request.abort();
                }
            }
        };
    }

    function MessageEvent(type, data, origin, lastEventId) {

        this.bubbles = false;
        this.cancelBubble = false;
        this.cancelable = false;
        this.data = data || null;
        this.origin = origin || '';
        this.lastEventId = lastEventId || '';
        this.type = type || 'message';
    }

    function isOldIE () {

        //return true if we are in IE8 or IE9
        return (window.XDomainRequest && (window.XMLHttpRequest && new XMLHttpRequest().responseType === undefined)) ? true : false;
    }

    global[evsImportName] = EventSource;
})(this);
