var mpmetrics = {};
var mpt;
var mpt_total = 0, mpt_cap = 100; 

mpmetrics.init = function(token) {
    this.token = token;
    this.api_host = 'http://api.mixpanel.com';
    root = document.getRootElement();
    mpt = document.createElement("div");
    mpt.setStyle({height: '1px', width: '1px'});
    root.appendChild(mpt);
};

mpmetrics.get_unixtime = function() {
    return parseInt(new Date().getTime().toString().substring(0,10));
};

mpmetrics.jsonp_callback = function(response) {
    if (this.callback) { 
        this.callback(response); 
        this.callback = false; 
    }
};

mpmetrics.create_img = function(url) {
    var id = "mpt_img_" + mpt_total;
    var img = document.getElementById(id);
    if (img) {
        mpt.removeChild(img);
    }
    img = document.createElement("img");
    img.setSrc(url);
    img.setId(id);
    return img;
}

mpmetrics.http_build_query = function(formdata, arg_separator) {
    var key, use_val, use_key, i = 0, j=0, tmp_arr = [];

    if (!arg_separator) {
        arg_separator = '&';
    }

    for (key in formdata) {
        if (key) {
            use_val = formdata[key].toString();
            use_key = key;
            tmp_arr[i++] = use_key + '=' + use_val;
        }
    }
    return tmp_arr.join(arg_separator);
};

mpmetrics.send_request = function(url, data) {
    var callback = 'mpmetrics.jsonp_callback';
    mpt_total = mpt_total % mpt_cap;
    
    if (url.indexOf("?") > -1) {
        url += "&callback=";
    } else {
        url += "?callback=";
    }
    url += callback + "&";

    if (data) { url += this.http_build_query(data); }
    url += '&_=' + new Date().getTime().toString();
    
    var img = this.create_img(url);
    mpt.appendChild(img)
    mpt_total++;
};

mpmetrics.json_encode = function(mixed_val) {    
    var indent;
    var value = mixed_val;
    var i;

    var quote = function (string) {
        var escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
        var meta = {    // table of character substitutions
            '\b': '\\b',
            '\t': '\\t',
            '\n': '\\n',
            '\f': '\\f',
            '\r': '\\r',
            '"' : '\\"',
            '\\': '\\\\'
        };

        escapable.lastIndex = 0;
        return escapable.test(string) ?
        '"' + string.replace(escapable, function (a) {
            var c = meta[a];
            return typeof c === 'string' ? c :
            '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
        }) + '"' :
        '"' + string + '"';
    };

    var str = function(key, holder) {
        var gap = '';
        var indent = '    ';
        var i = 0;          // The loop counter.
        var k = '';          // The member key.
        var v = '';          // The member value.
        var length = 0;
        var mind = gap;
        var partial = [];
        var value = holder[key];

        // If the value has a toJSON method, call it to obtain a replacement value.
        if (value && typeof value === 'object' &&
            typeof value.toJSON === 'function') {
            value = value.toJSON(key);
        }
        
        // What happens next depends on the value's type.
        switch (typeof value) {
            case 'string':
                return quote(value);

            case 'number':
                // JSON numbers must be finite. Encode non-finite numbers as null.
                return isFinite(value) ? value.toString() : 'null';

            case 'boolean':
            case 'null':
                // If the value is a boolean or null, convert it to a string. Note:
                // typeof null does not produce 'null'. The case is included here in
                // the remote chance that this gets fixed someday.
            
                return value.toString();

            case 'object':
                // If the type is 'object', we might be dealing with an object or an array or
                // null.
                // Due to a specification blunder in ECMAScript, typeof null is 'object',
                // so watch out for that case.
                if (!value) {
                    return 'null';
                }

                // Make an array to hold the partial results of stringifying this object value.
                gap += indent;
                partial = [];
                // Iterate through all of the keys in the object.
                for (k in value) {
                    v = str(k, value);
                    if (v) {
                        partial.push(quote(k) + (gap ? ': ' : ':') + v);
                    }
                }

                // Join all of the member texts together, separated with commas,
                // and wrap them in braces.
                v = partial.length === 0 ? '{}' :
                gap ? '{' + partial.join(',') + '' +
                mind + '}' : '{' + partial.join(',') + '}';
                gap = mind;
                return v;
        }
    };

    // Make a fake root object containing our value under the key of ''.
    // Return the result of stringifying the value.
    return str('', {
        '': value
    });
};

mpmetrics.utf8_encode = function (string) {
    string = (string+'').replace(/\r\n/g, "\n").replace(/\r/g, "\n");

    var utftext = "";
    var start, end;
    var stringl = 0;

    start = end = 0;
    stringl = string.length;
    for (var n = 0; n < stringl; n++) {
        var c1 = string.charCodeAt(n);
        var enc = null;

        if (c1 < 128) {
            end++;
        } else if((c1 > 127) && (c1 < 2048)) {
            enc = String.fromCharCode((c1 >> 6) | 192) + String.fromCharCode((c1 & 63) | 128);
        } else {
            enc = String.fromCharCode((c1 >> 12) | 224) + String.fromCharCode(((c1 >> 6) & 63) | 128) + String.fromCharCode((c1 & 63) | 128);
        }
        if (enc !== null) {
            if (end > start) {
                utftext += string.substring(start, end);
            }
            utftext += enc;
            start = end = n+1;
        }
    }

    if (end > start) {
        utftext += string.substring(start, string.length);
    }

    return utftext;
};

mpmetrics.base64_encode = function(data) {        
    var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    var o1, o2, o3, h1, h2, h3, h4, bits, i = 0, ac = 0, enc="", tmp_arr = [];

    if (!data) {
        return data;
    }

    data = this.utf8_encode(data+'');
    
    do { // pack three octets into four hexets
        o1 = data.charCodeAt(i++);
        o2 = data.charCodeAt(i++);
        o3 = data.charCodeAt(i++);

        bits = o1<<16 | o2<<8 | o3;

        h1 = bits>>18 & 0x3f;
        h2 = bits>>12 & 0x3f;
        h3 = bits>>6 & 0x3f;
        h4 = bits & 0x3f;

        // use hexets to index into b64, and append result to encoded string
        tmp_arr[ac++] = b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);
    } while (i < data.length);
    
    enc = tmp_arr.join('');
    
    switch( data.length % 3 ){
        case 1:
            enc = enc.slice(0, -2) + '==';
        break;
        case 2:
            enc = enc.slice(0, -1) + '=';
        break;
    }

    return enc;
};

mpmetrics.track = function(event, properties, callback) {
    //  Usage: mpmetrics.track('event', {'property1':'value1', 'gender':'male'});
    if (!properties){
        properties = {};
    }
    if (callback) { this.callback = callback; }
    
    properties.time = this.get_unixtime();
    properties.token = this.token;
    
    var data = {
        'event' : event,
        'properties' : properties
    };
    
    encoded_data = this.base64_encode(this.json_encode(data)); // Security by obscurity
    this.send_request(
        this.api_host + '/track/', 
        {
            'data' : encoded_data, 
            'ip' : 1,
            'img' : 1
        }
    );
    
};

mpmetrics.track_funnel = function(funnel, step, goal, properties, callback) {
    /*
    @funnel: Name of this funnel
    @step: integer, starting with 1
    @goal: name for this step
    Usage: mpmetrics.track_funnel('registration', 1, 'splash_page', {'gender': 'male', 'referer': 'Twitter'});
    */
    if (! properties) { properties = {}; }
    
    properties.funnel = funnel;
    properties.step = parseInt(step);
    properties.goal = goal;
    
    mpmetrics.track('mp_funnel', properties, callback);
};

mpmetrics.log = function(data, callback) {
    /*  Deprecated, do not use.
        Use mpmetrics.track() instead */
    if (! data.project) { data.project = this.token; }
    if (data.project && data.category) {
        this.callback = callback;
        data.ip = 1;
        data.img = 1;
        this.send_request(this.api_host + "/log/", data);
    }
};