var VCAL_DATETIME_FORMAT = "YMMDD[T]HHmmss"; //20160216T130500
var UID_FORMAT = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx';
var NEW_LINE = "\r\n";
var productID = window.title;

function VMeta() {
    this.properties = new Map();
    this.children = [];
    this.tag = "VMETA";
}
VMeta.formatDate = function (aMoment) {
    'use strict';
    return aMoment.format(VCAL_DATETIME_FORMAT);
};
VMeta.generateUID = function () {
    'use strict';
    return UID_FORMAT.replace(/[xy]/g, function (c) {
        var r = Math.random() * 16 | 0,
            v = c == 'x' ? r : (r & 0x3 | 0x8);
        return v.toString(16);
    });
};
VMeta.prototype.set = function (key, value) {
    'use strict';
    this.properties.set(key, value);
};
VMeta.prototype.get = function (key) {
    'use strict';
    this.properties.get(key);
};
VMeta.prototype.add = function (child) {
    'use strict';
    this.children.push(child);
};
VMeta.prototype.mapToString = function () {
    'use strict';
    var output = "";
    this.properties.forEach(function (value, key, map) {
        output += (NEW_LINE + key + ":" + value);
    });
    return output;
};
VMeta.prototype.childrenToString = function () {
    'use strict';
    var output = "";
    this.children.forEach(function (child) {
        output += (NEW_LINE + child.toString());
    });
    return output;
};
VMeta.prototype.toString = function () {
    'use strict';
    var output = "BEGIN:" + this.tag;
    output += this.mapToString();
    output += this.childrenToString();
    output += (NEW_LINE + "END:" + this.tag);
    return output;
};

function VCalendar(calendarName) {
    'use strict';
    VMeta.call(this);
    this.add(VTimeZone.Berlin());
    this.tag = "VCALENDAR";
    this.set('X-WR-CALNAME', calendarName);
    this.set('VERSION', '2.0');
    this.set('PRODID', productID);
    this.set('METHOD', "PUBLISH");
    this.set('X-WR-TIMEZONE', "Europe/Berlin");
    this.set('CALSCALE', "GREGORIAN");
};
VCalendar.prototype = Object.create(VMeta.prototype);
VCalendar.prototype.constructor = VCalendar;

function VEvent(timezoneName, startMoment, endMoment, title, description) {
    VMeta.call(this);
    this.tag = "VEVENT";

    this.set('DTSTART;TZID=' + timezoneName, VMeta.formatDate(startMoment));
    this.set('DTEND;TZID=' + timezoneName, VMeta.formatDate(endMoment));
    this.set('DTSTAMP', VMeta.formatDate(moment()) + "Z");
    this.set('UID', VMeta.generateUID());
    this.set('SUMMARY', title);
    this.set('DESCRIPTION', description);
    this.set('CLASS', "PUBLIC");
    this.set('TRANSP', "OPAQUE");
    this.set('STATUS', "CONFIRMED");
    this.set('ORGANIZER', "");
}
VEvent.prototype = Object.create(VMeta.prototype);
VEvent.prototype.constructor = VEvent;

function VTimeZone() {
    VMeta.call(this);
    this.tag = "VTIMEZONE";
}
VTimeZone.prototype = Object.create(VMeta.prototype);
VTimeZone.prototype.constructor = VTimeZone;
VTimeZone.Berlin = function () {
    var tz = new VTimeZone();
    tz.children = [VTimeDef.MESZ(), VTimeDef.MEZ()];
    tz.set("TZID", "Europe/Berlin");
    return tz;
}

function VTimeDef(name) {
    VMeta.call(this);
    this.tag = name;
}
VTimeDef.prototype = Object.create(VMeta.prototype);
VTimeDef.prototype.constructor = VTimeDef;
VTimeDef.MESZ = function () {
    var timedef = new VTimeDef("DAYLIGHT");
    timedef.set("TZOFFSETFROM", "+0100");
    timedef.set("RRULE", "FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU");
    timedef.set("DTSTART", "19819329T020000");
    timedef.set("TZNAME", "MESZ");
    timedef.set("TZOFFSETTO", "+0200");
    return timedef;
}
VTimeDef.MEZ = function () {
    var timedef = new VTimeDef("STANDARD");
    timedef.set("TZOFFSETFROM", "+0200");
    timedef.set("RRULE", "FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU");
    timedef.set("DTSTART", "19961027T030000");
    timedef.set("TZNAME", "MEZ");
    timedef.set("TZOFFSETTO", "+0100");
    return timedef;
}