(function() {

    /**
    * IntervalCalendar is an extension of the CalendarGroup designed specifically
    * for the selection of an interval of dates.
    *
    * @namespace YAHOO.example.calendar
    * @module calendar
    * @since 2.5.2
    * @requires yahoo, dom, event, calendar
    */

    /**
    * IntervalCalendar is an extension of the CalendarGroup designed specifically
    * for the selection of an interval of dates, as opposed to a single date or
    * an arbitrary collection of dates.
    * <p>
    * <b>Note:</b> When using IntervalCalendar, dates should not be selected or
    * deselected using the 'selected' configuration property or any of the
    * CalendarGroup select/deselect methods. Doing so will corrupt the internal
    * state of the control. Instead, use the provided methods setInterval and
    * resetInterval.
    * </p>
    * <p>
    * Similarly, when handling select/deselect/etc. events, do not use the
    * dates passed in the arguments to attempt to keep track of the currently
    * selected interval. Instead, use getInterval.
    * </p>
    *
    * @namespace YAHOO.example.calendar
    * @class IntervalCalendar
    * @extends YAHOO.widget.CalendarGroup
    * @constructor
    * @param {String | HTMLElement} container The id of, or reference to, an HTML DIV element which will contain the control.
    * @param {Object} cfg optional The initial configuration options for the control.
    */
    function IntervalCalendar(container, cfg) {
        /**
        * The interval state, which counts the number of interval endpoints that have
        * been selected (0 to 2).
        * 
        * @private
        * @type Number
        */
        this._iState = 1;

        // Must be a multi-select CalendarGroup
        cfg = cfg || {};
        cfg.multi_select = true;

        // Call parent constructor
        IntervalCalendar.superclass.constructor.call(this, container, cfg);

        // Subscribe internal event handlers
        this.beforeSelectEvent.subscribe(this._intervalOnBeforeSelect, this, true);
        this.selectEvent.subscribe(this._intervalOnSelect, this, true);
        this.beforeDeselectEvent.subscribe(this._intervalOnBeforeDeselect, this, true);
        this.deselectEvent.subscribe(this._intervalOnDeselect, this, true);
    }

    /**
    * Default configuration parameters.
    * 
    * @property IntervalCalendar._DEFAULT_CONFIG
    * @final
    * @static
    * @private
    * @type Object
    */
    IntervalCalendar._DEFAULT_CONFIG = YAHOO.widget.CalendarGroup._DEFAULT_CONFIG;

    YAHOO.lang.extend(IntervalCalendar, YAHOO.widget.CalendarGroup, {

        /**
        * Returns a string representation of a date which takes into account
        * relevant localization settings and is suitable for use with
        * YAHOO.widget.CalendarGroup and YAHOO.widget.Calendar methods.
        * 
        * @method _dateString
        * @private
        * @param {Date} d The JavaScript Date object of which to obtain a string representation.
        * @return {String} The string representation of the JavaScript Date object.
        */
        _dateString : function(d) {
            var a = [];
            a[this.cfg.getProperty(IntervalCalendar._DEFAULT_CONFIG.MDY_MONTH_POSITION.key)-1] = (d.getMonth() + 1);
            a[this.cfg.getProperty(IntervalCalendar._DEFAULT_CONFIG.MDY_DAY_POSITION.key)-1] = d.getDate();
            a[this.cfg.getProperty(IntervalCalendar._DEFAULT_CONFIG.MDY_YEAR_POSITION.key)-1] = d.getFullYear();
            var s = this.cfg.getProperty(IntervalCalendar._DEFAULT_CONFIG.DATE_FIELD_DELIMITER.key);
            return a.join(s);
        },

        /**
        * Given a lower and upper date, returns a string representing the interval
        * of dates between and including them, which takes into account relevant
        * localization settings and is suitable for use with
        * YAHOO.widget.CalendarGroup and YAHOO.widget.Calendar methods.
        * <p>
        * <b>Note:</b> No internal checking is done to ensure that the lower date
        * is in fact less than or equal to the upper date.
        * </p>
        * 
        * @method _dateIntervalString
        * @private
        * @param {Date} l The lower date of the interval, as a JavaScript Date object.
        * @param {Date} u The upper date of the interval, as a JavaScript Date object.
        * @return {String} The string representing the interval of dates between and
        *                   including the lower and upper dates.
        */
        _dateIntervalString : function(l, u) {
            var s = this.cfg.getProperty(IntervalCalendar._DEFAULT_CONFIG.DATE_RANGE_DELIMITER.key);
            return (this._dateString(l)
                    + s + this._dateString(u));
        },

        /**
        * Returns the lower and upper dates of the currently selected interval, if an
        * interval is selected.
        * 
        * @method getInterval
        * @return {Array} An empty array if no interval is selected; otherwise an array
        *                 consisting of two JavaScript Date objects, the first being the
        *                 lower date of the interval and the second being the upper date.
        */
        getInterval : function() {
            // Get selected dates
            var dates = this.getSelectedDates();
            if(dates.length > 0) {
                // Return lower and upper date in array
                var l = dates[0];
                var u = dates[dates.length - 1];
                return [l, u];
            }
            else {
                // No dates selected, return empty array
                return [];
            }
        },

        /**
        * Sets the currently selected interval by specifying the lower and upper
        * dates of the interval (in either order).
        * <p>
        * <b>Note:</b> The render method must be called after setting the interval
        * for any changes to be seen.
        * </p>
        * 
        * @method setInterval
        * @param {Date} d1 A JavaScript Date object.
        * @param {Date} d2 A JavaScript Date object.
        */
        setInterval : function(d1, d2) {
            // Determine lower and upper dates
            var b = (d1 <= d2);
            var l = b ? d1 : d2;
            var u = b ? d2 : d1;
            // Update configuration
            this.cfg.setProperty('selected', this._dateIntervalString(l, u), false);
            this._iState = 2;
        },

        /**
        * Resets the currently selected interval.
        * <p>
        * <b>Note:</b> The render method must be called after resetting the interval
        * for any changes to be seen.
        * </p>
        * 
        * @method resetInterval
        */
        resetInterval : function() {
            // Update configuration
            this.cfg.setProperty('selected', [], false);
            this._iState = 0;
        },

        /**
        * Handles beforeSelect event.
        * 
        * @method _intervalOnBeforeSelect
        * @private
        */
        _intervalOnBeforeSelect : function(t,a,o) {
            // Update interval state
            this._iState = (this._iState + 1) % 3;
            if(this._iState == 0) {
                // If starting over with upcoming selection, first deselect all
                this.deselectAll();
                this._iState++;
            }
        },

        /**
        * Handles selectEvent event.
        * 
        * @method _intervalOnSelect
        * @private
        */
        _intervalOnSelect : function(t,a,o) {
            // Get selected dates
            var dates = this.getSelectedDates();
            if(dates.length > 1) {
                /* If more than one date is selected, ensure that the entire interval
                    between and including them is selected */
                var l = dates[0];
                var u = dates[dates.length - 1];
                this.cfg.setProperty('selected', this._dateIntervalString(l, u), false);
            }
            // Render changes
            this.render();
        },

        /**
        * Handles beforeDeselect event.
        * 
        * @method _intervalOnBeforeDeselect
        * @private
        */
        _intervalOnBeforeDeselect : function(t,a,o) {
            if(this._iState != 0) {
                /* If part of an interval is already selected, then swallow up
                    this event because it is superfluous (see _intervalOnDeselect) */
                return false;
            }
        },

        /**
        * Handles deselectEvent event.
        *
        * @method _intervalOnDeselect
        * @private
        */
        _intervalOnDeselect : function(t,a,o) {
            if(this._iState != 0) {
                // If part of an interval is already selected, then first deselect all
                this._iState = 0;
                this.deselectAll();

                // Get individual date deselected and page containing it
                var d = a[0][0];
                var date = YAHOO.widget.DateMath.getDate(d[0], d[1] - 1, d[2]);
                var page = this.getCalendarPage(date);
                if(page) {
                    // Now (re)select the individual date
                    page.beforeSelectEvent.fire();
                    this.cfg.setProperty('selected', this._dateString(date), false);
                    page.selectEvent.fire([d]);
                }
                // Swallow up since we called deselectAll above
                return false;
            }
        }
    });

    YAHOO.namespace("example.calendar");
    YAHOO.example.calendar.IntervalCalendar = IntervalCalendar;
})();

YAHOO.util.Event.onDOMReady(function() {

    var inTxt = YAHOO.util.Dom.get("in"),
        outTxt = YAHOO.util.Dom.get("out"),
        inDate, outDate, interval;

    inTxt.value = "";
    outTxt.value = "";

    var cal = new YAHOO.example.calendar.IntervalCalendar("cal1Container", {pages:1});

    cal.selectEvent.subscribe(function() {
        interval = this.getInterval();

        if (interval.length == 2) {
            inDate = interval[0];
            inTxt.value = (inDate.getMonth() + 1) + "/" + inDate.getDate() + "/" + inDate.getFullYear();

            if (interval[0].getTime() != interval[1].getTime()) {
                outDate = interval[1];
                outTxt.value = (outDate.getMonth() + 1) + "/" + outDate.getDate() + "/" + outDate.getFullYear();
            } else {
                outTxt.value = "";
            }
        }
    }, cal, true);
    
    cal.render();
});