source: trunk/prototype/app/plugins/icalendar/jquery.icalendar.js @ 5341

/* http://keith-wood.name/icalendar.html
   iCalendar processing for jQuery v1.1.1.
   Written by Keith Wood (kbwood{at}iinet.com.au) October 2008.
   Dual licensed under the GPL (http://dev.jquery.com/browser/trunk/jquery/GPL-LICENSE.txt) and 
   MIT (http://dev.jquery.com/browser/trunk/jquery/MIT-LICENSE.txt) licenses. 
   Please attribute the author if you use it. */

(function($) { // Hide scope, no $ conflict

var PROP_NAME = 'icalendar';
var FLASH_ID = 'icalendar-flash-copy';

/* iCalendar sharing manager. */
function iCalendar() {
        this._defaults = {
                sites: [],  // List of site IDs to use, empty for all
                icons: 'icalendar.png', // Horizontal amalgamation of all site icons
                iconSize: 16,  // The size of the individual icons
                target: '_blank',  // The name of the target window for the iCalendar links
                compact: false,  // True if a compact presentation should be used, false for full
                popup: false,  // True to have it popup on demand, false to show always
                popupText: 'Send to my calendar...', // Text for the popup trigger
                tipPrefix: '',  // Additional text to show in the tool tip for each icon
                echoUrl: '',  // The URL to echo back iCalendar content, or blank for clipboard
                echoField: '', // The ID of a field to copy the iCalendar definition into, or blank for clipboard
                start: null,  // The start date/time of the event
                end: null,  // The end date/time of the event
                title: '',  // The title of the event
                summary: '',  // The summary of the event
                description: '',  // The description of the event
                location: '',  // The location of the event
                url: '',  // A URL with more information about the event
                contact: '',  // An e-mail address for further contact about the event
                recurrence: null, // Details about a recurring event, an object with attributes:
                        // dates (Date or Date[]) or times (Date or Date[]) or
                        // periods (Date[2] or Date[][2] or [][Date, string]) or
                        // freq (string - secondly, minutely, hourly, daily, weekly, monthly, yearly),
                        // interval (number), until (Date), count (number), weekStart (number),
                        // by (object or object[] - type (string - second, minute, day, monthday, yearday,
                        // weekno, month, setpos), values (number or number[] or string or string[]))
                // Confirmation message for clipboard copy
                copyConfirm: 'The event will be copied to your clipboard. Continue?',
                // Success message during clipboard copy
                copySucceeded: 'The event has been copied to your clipboard',
                // Failure message during clipboard copy
                copyFailed: 'Failed to copy the event to the clipboard\n',
                copyFlash: 'clipboard.swf', // The URL for the Flash clipboard copy module
                // Clipboard not supported message
                copyUnavailable: 'The clipboard is unavailable, please copy the event details from below:\n'
        };
        this._sites = {  // The definitions of the available iCalendar sites
                'google': {display: 'Google', icon: 0, override: null,
                        url: 'http://www.google.com/calendar/event?action=TEMPLATE' +
                        '&text={t}&dates={s}/{e}&details={d}&location={l}&sprop=website:{u}'},
                'icalendar': {display: 'iCalendar', icon: 1, override: null, url: 'echo'},
                'outlook': {display: 'Outlook', icon: 2, override: null, url: 'echo'},
                'yahoo': {display: 'Yahoo', icon: 3, override: yahooOverride,
                        url: 'http://calendar.yahoo.com/?v=60&view=d&type=20' +
                        '&title={t}&st={s}&dur={p}&desc={d}&in_loc={l}&url={u}&rpat={r}'}
        };
}

var FREQ_SETTINGS = [{method: 'Seconds', factor: 1},
        {method: 'Minutes', factor: 60}, {method: 'Hours', factor: 3600},
        {method: 'Date', factor: 86400}, {method: 'Month', factor: 1},
        {method: 'FullYear', factor: 12}, {method: 'Date', factor: 604800}];
var SE = 0;
var MI = 1;
var HR = 2;
var DY = 3;
var MO = 4;
var YR = 5;
var WK = 6;

$.extend(iCalendar.prototype, {
        /* Class name added to elements to indicate already configured with iCalendar. */
        markerClassName: 'hasICalendar',

        /* Override the default settings for all iCalendar instances.
           @param  settings  (object) the new settings to use as defaults
           @return void */
        setDefaults: function(settings) {
                extendRemove(this._defaults, settings || {});
                return this;
        },

        /* Add a new iCalendar site to the list.
           @param  id        (string) the ID of the new site
           @param  display   (string) the display name for this site
           @param  icon      (url) the location of an icon for this site (16x16), or
                             (number) the index of the icon within the combined image
           @param  url       (url) the submission URL for this site
                             with {t} marking where the event title should be inserted,
                             {s} indicating the event start date/time insertion point,
                             {e} indicating the event end date/time insertion point,
                             {p} indicating the event period (duration) insertion point,
                             {d} indicating the event description insertion point,
                             {l} indicating the event location insertion point,
                             {u} indicating the event URL insertion point,
                             {c} indicating the event contact insertion point,
                             {r} indicating the event recurrence insertion point
           @param  override  (function, optional) a function to override default settings
           @return void */
        addSite: function(id, display, icon, url, override) {
                this._sites[id] = {display: display, icon: icon, override: override, url: url};
                return this;
        },

        /* Return the list of defined sites.
           @return  object[] - indexed by site id (string), each object contains
                    display (string) the display name,
                    icon    (string) the location of the icon, or
                            (number) the icon's index in the combined image
                    url     (string) the submission URL for the site */
        getSites: function() {
                return this._sites;
        },

        /* Attach the iCalendar widget to a div. */
        _attachICalendar: function(target, settings) {
                target = $(target);
                if (target.hasClass(this.markerClassName)) {
                        return;
                }
                target.addClass(this.markerClassName);
                this._updateICalendar(target, settings);
        },

        /* Reconfigure the settings for an iCalendar div. */
        _changeICalendar: function(target, settings) {
                target = $(target);
                if (!target.hasClass(this.markerClassName)) {
                        return;
                }
                this._updateICalendar(target, settings);
        },

        /* Construct the requested iCalendar links. */
        _updateICalendar: function(target, settings) {
                settings = extendRemove($.extend({}, this._defaults,
                        $.data(target[0], PROP_NAME) || {}), settings);
                $.data(target[0], PROP_NAME, settings);
                var sites = settings.sites || this._defaults.sites;
                if (sites.length == 0) { // default to all sites
                        $.each(this._sites, function(id) {
                                sites[sites.length] = id;
                        });
                }
                var addSite = function(site, calId) {
                        var inserts = {t: encodeURIComponent(settings.title),
                                d: encodeURIComponent(settings.description),
                                s: $.icalendar.formatDateTime(settings.start),
                                e: $.icalendar.formatDateTime(settings.end),
                                p: $.icalendar.calculateDuration(settings.start, settings.end),
                                l: encodeURIComponent(settings.location),
                                u: encodeURIComponent(settings.url),
                                c: encodeURIComponent(settings.contact),
                                r: makeRecurrence(settings.recurrence)};
                        if (site.override) {
                                site.override.apply(target, [inserts, settings]);
                        }
                        var url = site.url;
                        $.each(inserts, function(n, v) {
                                var re = new RegExp('\\{' + n + '\\}', 'g');
                                url = url.replace(re, v);
                        });
                        var url = (site.url == 'echo' ? '#' : url);
                        var item = $('<li></li>');
                        var anchor = $('<a href="' + url + '" title="' + settings.tipPrefix + site.display + '"' +
                                (site.url == 'echo' ? '' : ' target="' + settings._target + '"') + '></a>');
                        if (site.url == 'echo') {
                                anchor.click(function() {
                                        return $.icalendar._echo(target[0], calId);
                                });
                        }
                        var html = '';
                        if (site.icon != null) {
                                if (typeof site.icon == 'number') {
                                        html += '<span style="background: ' +
                                                'transparent url(' + settings.icons + ') no-repeat -' +
                                                (site.icon * settings.iconSize) + 'px 0px;' +
                                                ($.browser.mozilla && $.browser.version < '1.9' ?
                                                ' padding-left: ' + settings.iconSize + 'px; padding-bottom: ' +
                                                Math.max(0, (settings.iconSize / 2) - 5) + 'px;' : '') + '"></span>';
                                }
                                else {
                                        html += '<img src="' + site.icon + '"' +
                                                (($.browser.mozilla && $.browser.version < '1.9') ||
                                                ($.browser.msie && $.browser.version < '7.0') ?
                                                ' style="vertical-align: bottom;"' :
                                                ($.browser.msie ? ' style="vertical-align: middle;"' :
                                                ($.browser.opera || $.browser.safari ?
                                                ' style="vertical-align: baseline;"' : ''))) + '/>';
                                }
                                html += (settings.compact ? '' : '&#xa0;');
                        }
                        anchor.html(html + (settings.compact ? '' : site.display));
                        item.append(anchor);
                        return item;
                };
                var list = $('<ul class="icalendar_list' +
                        (settings.compact ? ' icalendar_compact' : '') + '"></ul>');
                var allSites = this._sites;
                $.each(sites, function(index, id) {
                        list.append(addSite(allSites[id], id));
                });
                target.empty().append(list);
                if (settings.popup) {
                        list.before('<span class="icalendar_popup_text">' +
                                settings.popupText + '</span>').
                                wrap('<div class="icalendar_popup"></div>');
                        target.click(function() {
                                var target = $(this);
                                var offset = target.offset();
                                $('.icalendar_popup', target).css('left', offset.left).
                                        css('top', offset.top + target.outerHeight()).toggle();
                        });
                }
        },

        /* Remove the iCalendar widget from a div. */
        _destroyICalendar: function(target) {
                target = $(target);
                if (!target.hasClass(this.markerClassName)) {
                        return;
                }
                target.removeClass(this.markerClassName).empty();
                $.removeData(target[0], PROP_NAME);
        },

        /* Echo the iCalendar text back to the user either as a
           downloadable file or via the clipboard.
           @param  target  (element) the owning division
           @param  calId  (string) the ID of the site to send the calendar to */
        _echo: function(target, calId) {
                var settings = $.data(target, PROP_NAME);
                var event = makeICalendar(settings);
                if (settings.echoUrl) {
                        window.location.href = settings.echoUrl + '?content=' + escape(event);
                }
                else if (settings.echoField) {
                        $(settings.echoField).val(event);
                }
                else if (!settings.copyFlash) {
                        alert(settings.copyUnavailable + event);
                }
                else if (confirm(settings.copyConfirm)) {
                        var error = '';
                        if (error = copyViaFlash(event, settings.copyFlash)) {
                                alert(settings.copyFailed + error);
                                }
                                else {
                                alert(settings.copySucceeded);
                                }
                        }
                return false; // Don't follow link
        },
        
        /* Ensure a string has at least two digits.
           @param  value  (number) the number to convert
           @return  (string) the string equivalent */
        _ensureTwo: function(value) {
                return (value < 10 ? '0' : '') + value;
        },

        /* Format a date for iCalendar: yyyymmdd.
           @param  date   (Date) the date to format
           @return  (string) the formatted date */
        formatDate: function(date, local) {
                return (!date ? '' : '' + date.getFullYear() +
                        this._ensureTwo(date.getMonth() + 1) + this._ensureTwo(date.getDate()));
        },

        /* Format a date/time for iCalendar: yyyymmddThhmmss[Z].
           @param  dateTime  (Date) the date/time to format
           @param  local     (boolean) true if this should be a local date/time
           @return  (string) the formatted date/time */
        formatDateTime: function(dateTime, local) {
                return (!dateTime ? '' : (local ?
                        '' + dateTime.getFullYear() + this._ensureTwo(dateTime.getMonth() + 1) +
                        this._ensureTwo(dateTime.getDate()) + 'T' + this._ensureTwo(dateTime.getHours()) +
                        this._ensureTwo(dateTime.getMinutes()) + this._ensureTwo(dateTime.getSeconds()) :
                        '' + dateTime.getUTCFullYear() + this._ensureTwo(dateTime.getUTCMonth() + 1) +
                        this._ensureTwo(dateTime.getUTCDate()) + 'T' + this._ensureTwo(dateTime.getUTCHours()) +
                        this._ensureTwo(dateTime.getUTCMinutes()) + this._ensureTwo(dateTime.getUTCSeconds()) + 'Z'));
        },

        /* Calculate the duration between two date/times.
           @param  start  (Date) the starting date/time
           @param  end    (Date) the ending date/time
           @return  (string) the formatted duration or blank if invalid parameters */
        calculateDuration: function(start, end) {
                if (!start || !end) {
                        return '';
                }
                var seconds = Math.abs(end.getTime() - start.getTime()) / 1000;
                var days = Math.floor(seconds / 86400);
                seconds -= days * 86400;
                var hours = Math.floor(seconds / 3600);
                seconds -= hours * 3600;
                var minutes = Math.floor(seconds / 60);
                seconds -= minutes * 60;
                return (start.getTime() > end.getTime() ? '-' : '') +
                        'P' + (days > 0 ? days + 'D' : '') +
                        (hours || minutes || seconds ? 'T' + hours + 'H' : '') +
                        (minutes || seconds ? minutes + 'M' : '') + (seconds ? seconds + 'S' : '');
        },

        /* Calculate the end date/time given a start and a duration.
           @param  start     (Date) the starting date/time
           @param  duration  (string) the description of the duration
           @return  (Date) the ending date/time
           @throws  error if an invalid duration is found */
        addDuration: function(start, duration) {
                if (!duration) {
                        return start;
                }
                var end = new Date(start.getTime());
                var matches = DURATION.exec(duration);
                if (!matches) {
                        throw 'Invalid duration';
                }
                if (matches[2] && (matches[3] || matches[5] || matches[6] || matches[7])) {
                        throw 'Invalid duration - week must be on its own'; // Week must be on its own
                }
                if (!matches[4] && (matches[5] || matches[6] || matches[7])) {
                        throw 'Invalid duration - missing time marker'; // Missing T with hours/minutes/seconds
                }
                var sign = (matches[1] == '-' ? -1 : +1);
                var apply = function(value, factor, method) {
                        value = parseInt(value);
                        if (!isNaN(value)) {
                                end['setUTC' + method](end['getUTC' + method]() + sign * value * factor);
                        }
                };
                if (matches[2]) {
                        apply(matches[2], 7, 'Date');
                }
                else {
                        apply(matches[3], 1, 'Date');
                        apply(matches[5], 1, 'Hours');
                        apply(matches[6], 1, 'Minutes');
                        apply(matches[7], 1, 'Seconds');
                }
                return end;
        },

        /* Parse the iCalendar data into a JavaScript object model.
           @param  content  (string) the original iCalendar data
           @return  (object) the iCalendar JavaScript model
           @throws  errors if the iCalendar structure is incorrect */
        parse: function(content) {
                var cal = {};
                var timezones = {};
                var lines = unfoldLines(content);
                parseGroup(lines, 0, cal, timezones);
                if (!cal.vcalendar) {
                        throw 'Invalid iCalendar data';
                }
                return cal.vcalendar;
        },

        /* Calculate the week of the year for a given date
           according to the ISO 8601 definition.
           @param  date       (Date) the date to calculate the week for
           @param  weekStart  (number) the day on which a week starts:
                              0 = Sun, 1 = Mon, ... (optional, defaults to 1)
           @return  (number) the week for these parameters (1-53) */
        getWeekOfYear: function(date, weekStart) {
                return getWeekOfYear(date, weekStart);
        },

        _parseParams: function(owner, params) {
                return parseParams(owner, params);
        }
});

/* jQuery extend now ignores nulls! */
function extendRemove(target, props) {
        $.extend(target, props);
        for (var name in props) {
                if (props[name] == null) {
                        target[name] = null;
                }
        }
        return target;
}

/* Attach the iCalendar functionality to a jQuery selection.
   @param  command  (string) the command to run (optional, default 'attach')
   @param  options  (object) the new settings to use for these iCalendar instances
   @return  (jQuery object) jQuery for chaining further calls */
$.fn.icalendar = function(options) {
        var otherArgs = Array.prototype.slice.call(arguments, 1);
        return this.each(function() {
                if (typeof options == 'string') {
                        $.icalendar['_' + options + 'ICalendar'].
                                apply($.icalendar, [this].concat(otherArgs));
                }
                else {
                        $.icalendar._attachICalendar(this, options || {});
                }
        });
};

/* Initialise the iCalendar functionality. */
$.icalendar = new iCalendar(); // singleton instance

/* Override some substitution values for Yahoo.
   @param  inserts   (object) current values (updated)
   @param  settings  (object) current instance settings */
function yahooOverride(inserts, settings) {
        var twoDigits = function(value) {
                return (value < 10 ? '0' : '') + value;
        };
        var dur = (settings.end ? (settings.end.getTime() - settings.start.getTime()) / 60000 : 0);
        inserts.p = (dur ? twoDigits(Math.floor(dur / 60)) + '' + twoDigits(dur % 60) : ''); // hhmm
        if (inserts.r) {
                var byDay = (settings.recurrence.by && settings.recurrence.by[0].type == 'day' ?
                        settings.recurrence.by[0].values.join('').toLowerCase() : '');
                var freq = {daily: 'dy', weekly: 'wk', monthly: 'mh', yearly: 'yr'}[settings.recurrence.freq];
                inserts.r = (byDay || freq ? twoDigits(settings.recurrence.interval || 1) + (byDay || freq) : '');
        }
}

/* Construct an iCalendar with an event object.
   @param  event  (object) the event details
   @return  (string) the iCalendar definition */
function makeICalendar(event) {
        var limit75 = function(text) {
                var out = '';
                while (text.length > 75) {
                        out += text.substr(0, 75) + '\n';
                        text = ' ' + text.substr(75);
                }
                out += text;
                return out;
        };
        return 'BEGIN:VCALENDAR\n' +
                'VERSION:2.0\n' +
                'PRODID:jquery.icalendar\n' +
                'METHOD:PUBLISH\n' +
                'BEGIN:VEVENT\n' +
                'UID:' + new Date().getTime() + '@' +
                (window.location.href.replace(/^[^\/]*\/\/([^\/]*)\/.*$/, '$1') || 'localhost') + '\n' +
                'DTSTAMP:' + $.icalendar.formatDateTime(new Date()) + '\n' +
                (event.url ? limit75('URL:' + event.url) + '\n' : '') +
                (event.contact ? limit75('MAILTO:' + event.contact) + '\n' : '') +
                limit75('TITLE:' + event.title) + '\n' +
                'DTSTART:' + $.icalendar.formatDateTime(event.start) + '\n' +
                'DTEND:' + $.icalendar.formatDateTime(event.end) + '\n' +
                (event.summary ? limit75('SUMMARY:' + event.summary) + '\n' : '') +
                (event.description ? limit75('DESCRIPTION:' + event.description) + '\n' : '') +
                (event.location ? limit75('LOCATION:' + event.location) + '\n' : '') +
                (event.recurrence ? makeRecurrence(event.recurrence) + '\n' : '') +
                'END:VEVENT\n' +
                'END:VCALENDAR';
}

/* Construct an iCalendar recurrence definition.
   @param  recur  (object) the recurrence details
   @return  (string) the iCalendar definition */
function makeRecurrence(recur) {
        if (!recur) {
        return '';
        }
        var def = '';
        if (recur.dates) {
                def = 'RDATE;VALUE=DATE:';
                if (!isArray(recur.dates)) {
                        recur.dates = [recur.dates];
                }
                for (var i = 0; i < recur.dates.length; i++) {
                        def += (i > 0 ? ',' : '') + $.icalendar.formatDate(recur.dates[i]);
                }
        }
        else if (recur.times) {
                def = 'RDATE;VALUE=DATE-TIME:';
                if (!isArray(recur.times)) {
                        recur.times = [recur.times];
                }
                for (var i = 0; i < recur.times.length; i++) {
                        def += (i > 0 ? ',' : '') + $.icalendar.formatDateTime(recur.times[i]);
                }
        }
        else if (recur.periods) {
                def = 'RDATE;VALUE=PERIOD:';
                if (!isArray(recur.periods[0])) {
                        recur.periods = [recur.periods];
                }
                for (var i = 0; i < recur.periods.length; i++) {
                        def += (i > 0 ? ',' : '') + $.icalendar.formatDateTime(recur.periods[i][0]) +
                                '/' + (recur.periods[i][1].constructor != Date ? recur.periods[i][1] :
                                $.icalendar.formatDateTime(recur.periods[i][1]));
                }
        }
        else {
                def = 'RRULE:FREQ=' + (recur.freq || 'daily').toUpperCase() +
                        (recur.interval ? ';INTERVAL=' + recur.interval : '') +
                        (recur.until ? ';UNTIL=' + $.icalendar.formatDateTime(recur.until) :
                        (recur.count ? ';COUNT=' + recur.count : '')) +
                        (recur.weekStart != null ? ';WKST=' +
                        ['SU', 'MO', 'TU', 'WE', 'TH', 'FR', 'SA'][recur.weekStart] : '');
                if (recur.by) {
                        if (!isArray(recur.by)) {
                                recur.by = [recur.by];
                        }
                        for (var i = 0; i < recur.by.length; i++) {
                                if (!isArray(recur.by[i].values)) {
                                        recur.by[i].values = [recur.by[i].values];
                                }
                                def += ';BY' + recur.by[i].type.toUpperCase() + '=' +
                                        recur.by[i].values.join(',');
                        }
                }
        }
        return def;
}

/* Copy the given text to the system clipboard via Flash.
   @param  text  (string) the text to copy
   @param  url   (string) the URL for the Flash clipboard copy module
   @return  (string) '' if successful, error message if not */
function copyViaFlash(text, url) {
        $('#' + FLASH_ID).remove();
        try {
                $('body').append('<div id="' + FLASH_ID + '"><embed src="' + url +
                '" FlashVars="clipboard=' + encodeURIComponent(text) +
                '" width="0" height="0" type="application/x-shockwave-flash"></embed></div>');
                return '';
        }
        catch(e) {
                return e;
        }
}

/* Pattern for folded lines: start with a whitespace character */
var FOLDED = /^\s(.*)$/;
/* Pattern for an individual entry: name:value */
var ENTRY = /^([A-Za-z0-9-]+)((?:;[A-Za-z0-9-]+=(?:"[^"]+"|[^";:,]+)(?:,(?:"[^"]+"|[^";:,]+))*)*):(.*)$/;
/* Pattern for an individual parameter: name=value[,value] */
var PARAM = /;([A-Za-z0-9-]+)=((?:"[^"]+"|[^";:,]+)(?:,(?:"[^"]+"|[^";:,]+))*)/g;
/* Pattern for an individual parameter value: value | "value" */
var PARAM_VALUE = /,?("[^"]+"|[^";:,]+)/g;
/* Pattern for a date only field: yyyymmdd */
var DATEONLY = /^(\d{4})(\d\d)(\d\d)$/;
/* Pattern for a date/time field: yyyymmddThhmmss[Z] */
var DATETIME = /^(\d{4})(\d\d)(\d\d)T(\d\d)(\d\d)(\d\d)(Z?)$/;
/* Pattern for a date/time range field: yyyymmddThhmmss[Z]/yyyymmddThhmmss[Z] */
var DATETIME_RANGE = /^(\d{4})(\d\d)(\d\d)T(\d\d)(\d\d)(\d\d)(Z?)\/(\d{4})(\d\d)(\d\d)T(\d\d)(\d\d)(\d\d)(Z?)$/;
/* Pattern for a timezone offset field: +hhmm */
var TZ_OFFSET = /^([+-])(\d\d)(\d\d)$/;
/* Pattern for a duration: [+-]PnnW or [+-]PnnDTnnHnnMnnS */
var DURATION = /^([+-])?P(\d+W)?(\d+D)?(T)?(\d+H)?(\d+M)?(\d+S)?$/;
/* Reserved names not suitable for attrbiute names. */
var RESERVED_NAMES = ['class'];

/* iCalendar lines are split so the max length is no more than 75.
   Split lines start with a whitespace character.
   @param  content  (string) the original iCalendar data
   @return  (string[]) the restored iCalendar data */
function unfoldLines(content) {
        var lines = content.replace(/\r\n/g, '\n').split('\n');
        for (var i = lines.length - 1; i > 0; i--) {
                var matches = FOLDED.exec(lines[i]);
                if (matches) {
                        lines[i - 1] += matches[1];
                        lines[i] = '';
                }
        }
        return $.map(lines, function(line, i) { // Remove blank lines
                return (line ? line : null);
        });
}

/* Parse a group in the file, delimited by BEGIN:xxx and END:xxx.
   Recurse if an embedded group encountered.
   @param  lines      (string[]) the iCalendar data
   @param  index      (number) the current position within the data
   @param  owner      (object) the current owner for the new group
   @param  timezones  (object) collection of defined timezones
   @return  (number) the updated position after processing this group
   @throws  errors if group structure is incorrect */
function parseGroup(lines, index, owner, timezones) {
        if (index >= lines.length || lines[index].indexOf('BEGIN:') != 0) {
                throw 'Missing group start';
        }
        var group = {};
        var name = lines[index].substr(6);
        addEntry(owner, name.toLowerCase(), group);
        index++;
        while (index < lines.length && lines[index].indexOf('END:') != 0) {
                if (lines[index].indexOf('BEGIN:') == 0) { // Recurse for embedded group
                        index = parseGroup(lines, index, group, timezones);
                }
                else {
                        var entry = parseEntry(lines[index]);
                        addEntry(group, entry._name, (entry._simple ? entry._value : entry));
                }
                index++;
        }
        if (name == 'VTIMEZONE') { // Save timezone offset
                var matches = TZ_OFFSET.exec(group.standard.tzoffsetto);
                if (matches) {
                        timezones[group.tzid] = (matches[1] == '-' ? -1 : +1) *
                                (parseInt(matches[2], 10) * 60 + parseInt(matches[3], 10));
                }
        }
        else {
                for (var name2 in group) {
                        resolveTimezones(group[name2], timezones);
                }
        }
        if (lines[index] != 'END:' + name) {
                throw 'Missing group end ' + name;
        }
        return index;
}

/* Resolve timezone references for dates.
   @param  value  (any) the current value to check - updated if appropriate
   @param  timezones  (object) collection of defined timezones */
function resolveTimezones(value, timezones) {
        if (!value) {
                return;
        }
        if (value.tzid && value._value) {
                var offset = timezones[value.tzid];
                var offsetDate = function(date, tzid) {
                        date.setMinutes(date.getMinutes() - offset);
                        date._type = tzid;
                };
                if (isArray(value._value)) {
                        for (var i = 0; i < value._value.length; i++) {
                                offsetDate(value._value[i], value.tzid);
                        }
                }
                else if (value._value.start && value._value.end) {
                        offsetDate(value._value.start, value.tzid);
                        offsetDate(value._value.end, value.tzid);
                }
                else {
                        offsetDate(value._value, value.tzid);
                }
        }
        else if (isArray(value)) {
                for (var i = 0; i < value.length; i++) {
                        resolveTimezones(value[i], timezones);
                }
        }
}

/* Add a new entry to an object, making multiple entries into an array.
   @param  owner  (object) the owning object for the new entry
   @param  name   (string) the name of the new entry
   @param  value  (string or object) the new entry value */
function addEntry(owner, name, value) {
        if (typeof value == 'string') {
                value = value.replace(/\\n/g, '\n');
        }
        if ($.inArray(name, RESERVED_NAMES) > -1) {
                name += '_';
        }
        if (owner[name]) { // Turn multiple values into an array
                if (!isArray(owner[name]) || owner['_' + name + 'IsArray']) {
                        owner[name] = [owner[name]];
                }
                owner[name][owner[name].length] = value;
                if (owner['_' + name + 'IsArray']) {
                        owner['_' + name + 'IsArray'] = undefined;
                }
        }
        else {
                owner[name] = value;
                if (isArray(value)) {
                        owner['_' + name + 'IsArray'] = true;
                }
        }
}

/* Parse an individual entry.
   The format is: <name>[;<param>=<pvalue>]...:<value>
   @param  line  (string) the line to parse
   @return  (object) the parsed entry with _name and _value
            attributes, _simple to indicate whether or not
            other parameters, and other parameters as necessary */
function parseEntry(line) {
        var entry = {};
        var matches = ENTRY.exec(line);
        if (!matches) {
                throw 'Missing entry name: ' + line;
        }
        entry._name = matches[1].toLowerCase();
        entry._value = checkDate(matches[3]);
        entry._simple = true;
        parseParams(entry, matches[2]);
        return entry;
}

/* Parse parameters for an individual entry.
   The format is: <param>=<pvalue>[;...]
   @param  owner   (object) the owning object for the parameters,
                   updated with parameters as attributes, and
                                   _simple to indicate whether or not other parameters
   @param  params  (string or string[]) the parameters to parse */
function parseParams(owner, params) {
        var param = PARAM.exec(params);
        while (param) {
                var values = [];
                var value = PARAM_VALUE.exec(param[2]);
                while (value) {
                        values.push(checkDate(value[1].replace(/^"(.*)"$/, '$1')));
                        value = PARAM_VALUE.exec(param[2]);
                }
                owner[param[1].toLowerCase()] = (values.length > 1 ? values : values[0]);
                owner._simple = false;
                param = PARAM.exec(params);
        }
}

/* Convert a value into a Date object or array of Date objects if appropriate.
   @param  value  (string) the value to check
   @return  (string or Date) the converted value (if appropriate) */
function checkDate(value) {
        var matches = DATETIME.exec(value);
        if (matches) {
                return makeDate(matches);
        }
        matches = DATETIME_RANGE.exec(value);
        if (matches) {
                return {start: makeDate(matches), end: makeDate(matches.slice(7))};
        }
        matches = DATEONLY.exec(value);
        if (matches) {
                return makeDate(matches.concat([0, 0, 0, '']));
        }
        return value;
}

/* Create a date value from matches on a string.
   @param  matches  (string[]) the component parts of the date
   @return  (Date) the corresponding date */
function makeDate(matches) {
        var date = new Date(matches[1], matches[2] - 1, matches[3],
                matches[4], matches[5], matches[6]);
        date._type = (matches[7] ? 'UTC' : 'float');
        return utcDate(date);
}

/* Standardise a date to UTC.
   @param  date  (Date) the date to standardise
   @return  (Date) the equivalent UTC date */
function utcDate(date) {
        date.setMinutes(date.getMinutes() - date.getTimezoneOffset());
        return date;
}

/* Calculate the week of the year for a given date
   according to the ISO 8601 definition.
   @param  date       (Date) the date to calculate the week for
   @param  weekStart  (number) the day on which a week starts:
                      0 = Sun, 1 = Mon, ... (optional, defaults to 1)
   @return  (number) the week for these parameters (1-53) */
function getWeekOfYear(date, weekStart) {
        weekStart = (weekStart || weekStart == 0 ? weekStart : 1);
        var checkDate = new Date(date.getFullYear(), date.getMonth(), date.getDate(),
                (date.getTimezoneOffset() / -60));
        var firstDay = new Date(checkDate.getFullYear(), 1 - 1, 4); // First week always contains 4 Jan
        var firstDOW = firstDay.getDay(); // Day of week: Sun = 0, Mon = 1, ...
        firstDay.setDate(4 + weekStart - firstDOW - (weekStart > firstDOW ? 7 : 0)); // Preceding week start
        if (checkDate < firstDay) { // Adjust first three days in year if necessary
                checkDate.setDate(checkDate.getDate() - 3); // Generate for previous year
                return getWeekOfYear(checkDate, weekStart);
        } else if (checkDate > new Date(checkDate.getFullYear(), 12 - 1, 28)) { // Check last three days in year
                var firstDay2 = new Date(checkDate.getFullYear() + 1, 1 - 1, 4); // Find first week in next year
                firstDOW = firstDay2.getDay();
                firstDay2.setDate(4 + weekStart - firstDOW - (weekStart > firstDOW ? 7 : 0));
                if (checkDate >= firstDay2) { // Adjust if necessary
                        return 1;
                }
        }
        return Math.floor(((checkDate - firstDay) /
                (FREQ_SETTINGS[DY].factor * 1000)) / 7) + 1; // Weeks to given date
}

/* Determine whether an object is an array.
   @param  a  (object) the object to test
   @return  (boolean) true if it is an array, or false if not */
function isArray(a) {
        return (a && a.constructor == Array);
}

})(jQuery);