/* date.js - Custom Date methods
 * addDays
 * addWeeks
 * addYears
 * addMonths
 * addMonthsTrunc
 * copy
 * daysBetween
 * getCDay
 * getDayName
 * getDayOfYear
 * getCMonth
 * getMonthName
 * getWeekDays
 * addBizDays
 * lastDay
 * monthsBetween
 * yearsBetween
 * getAge
 * sameDayEachWeek
 */

Date.prototype.DAYNAMES = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
Date.prototype.MONTHNAMES = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
Date.prototype.msPERMIN = 1000 * 60;
Date.prototype.msPERDAY = 1000 * 60 * 60 * 24;

Date.prototype.addBizDays = function(d) {
    /* Adds the necessary number of days
     * to the date to include the required
     * weekdays.
     */
    var day = this.getDay();    //day of week number 0 through 6
    var wkEnd = 0;              //number of weekends needed
    var m = d % 5;              //number of weekdays for partial week

    if (d < 0) {
        wkEnd = Math.ceil(d/5); //Yields a negative number of weekends

        switch (day) {
        case 6:
            //If staring day is Sat. one less weekend needed
            if (m == 0 && wkEnd < 0) wkEnd++;
            break;
        case 0:
            if (m == 0) d++; //decrease - part of weekend
            else d--;        //increase - part of weekend
            break;
        default:
            if (m <= -day) wkEnd--; //add weekend if not enough days to cover
        }
    }
    else if (d > 0) {
        wkEnd = Math.floor(d/5);

        switch (day) {
        case 6:
            /* If staring day is Sat and
             * no partial week one less day needed
             * if partial week one more day needed
             */
            if (m == 0) d--;
            else d++;
            break;
        case 0:
            if (m == 0 && wkEnd > 0) wkEnd--;
            break;
        default:
            if (5 - day < m) wkEnd++;
        }
    }

    d += wkEnd * 2; //Add weekends to weekdays needed

    this.addDays(d);
};
Date.prototype.addDays = function(d) {
        /* Adds the number of days to the date */
        this.setDate( this.getDate() + d );
    };
Date.prototype.addWeeks = function(w) {
        /* Adds the number of weeks to the date */
        this.setDate(this.getDate() + (w * 7) );
    };
Date.prototype.addMonths = function(m) {
        /* Adds the number of months to date
         * If starting with a day that is
         * greater than the number of days
         * in the new month the new date is
         * in the next month
         */
        this.setMonth(this.getMonth() + m);
    };
	Date.prototype.subtractMonths = function(m) {
        /* Adds the number of months to date
         * If starting with a day that is
         * greater than the number of days
         * in the new month the new date is
         * in the next month
         */
        this.setMonth(this.getMonth() - m);
    };
Date.prototype.addMonthsTrunc = function(m) {
        /* Adds the number of months to date,
         * but unlike addMonths this method
         * truncates extra days at end of month
         * when the start day of month is greater
         * than the number of days in the target
         * ending month (js overflows into the following month)
         */
         var d = this.getDate();
         this.setMonth(this.getMonth() + m);

         /* Adjust when original month has more days then new month and overflows */
         if (this.getDate() < d)
             this.setDate(0);
    };
Date.prototype.addYears = function(y) {
        /* Adds the number of years to date
         * If adding to 2/29 and result is not
         * a leap year the day is set to 28
         */
        var m = this.getMonth();
        this.setFullYear(this.getFullYear() + y);

        //Adjust for leap years
        if (m < this.getMonth()) {
            this.setDate(0);
        }
    };
Date.prototype.copy = function () {
        /* Creates a copy of date by value
         * Normal assignment only creates
         * a reference to the date, whereas
         * this creates a new date object
         */
        return Date(this.getTime());
    };
Date.prototype.daysBetween = function(d) {
        /*Returns number of days between two dates
        * including the last day, but not the first.
        *
        * This is value can be added
        * to one date get the other date.
        */
	     if (! d instanceof Date) {
	        try {
					d = new Date(d);
				} catch (e) {
					return null;
				}
			}
					
			var c = this.getTime();
			var n = d.getTime();

			c = Math.floor(c/this.msPERDAY);
			n = Math.floor(n/this.msPERDAY);
         return n - c;
    };
Date.prototype.getCDay = function() {
        //Returns first 3 letters in day name
        return this.getDayName().slice(0,3);
    };
Date.prototype.getDayName = function() {
        //Returns full name of day
        return this.DAYNAMES[this.getDay()];
    };
Date.prototype.getDayOfYear = function() {
        //Returns day of year 1 through 365 or 366
        var start = new Date(this.getFullYear(), 0, 0);
        return this.daysBetween(start) * -1;
    };
Date.prototype.getCMonth = function() {
        //Returns first 3 letters in month name
        return this.getMonthName().slice(0, 3);
    }
Date.prototype.getMonthName = function() {
        //Returns full name of month
        return this.MONTHNAMES[this.getMonth()];
    };
Date.prototype.getWeekDays = function(d) {
        /*Returns number of weekdays between two dates
        * including the last day, but not the first,
        * if either is a weekday.
        *
        * This is the value that can be added
        * to one date to get the other date
        * (although because you can use dates
        * that are weekends, adding back,
        * which only returns weekdays, may
        * return a different date than original.
        */
        var wkEnds = 0, days = 0;
        var s = 0, e = 0;

        days = Math.abs(this.daysBetween(d));

        if (days) {
            wkEnds = Math.floor(days/7);

            s = (d < this) ? d.getDay() : this.getDay() ;
            e = (d < this) ? this.getDay() : d.getDay();

            if (s != 6 && s > e) wkEnds++;
            if (s != e && (s == 6 || e == 6) ) days--;

            days -= (wkEnds * 2);
        }
        return days;
    };
Date.prototype.lastday = function() {
        //returns number of days in month
        var d = new Date(this.getFullYear(), this.getMonth() + 1, 0);
        return d.getDate();
    };
Date.prototype.monthsBetween = function(d) {
        //returns months between dates
        var d1 = this.getFullYear() * 12 + this.getMonth() + 1;
        var d2 = d.getFullYear() * 12 + d.getMonth() + 1;
        return d2 - d1;
    };
Date.prototype.monthsBetween2 = function(d) {
    /* partial month */
	var sDate,eDate;
	var lastday = this.lastday();

	if (lastday > d.lastday())
		lastday = d.lastday();
	
	if (this <=  d){
		sDate = this;
		eDate = d;
	} else {
		sDate = d;
		eDate = this;
	}

	var fromDay = sDate.getDate();
	if (fromDay > lastday)
		fromDay = lastday;

	var toDay = eDate.getDate();
	if (toDay > lastday)
		toDay = lastday;
	
	var diff = toDay - fromDay;
	var percentExtra = 1 + diff/30;

	var d1 = this.getFullYear() * 12 + this.getMonth() + 1;
	var d2 = d.getFullYear() * 12 + d.getMonth();

	return (d2 - d1) + (percentExtra).toFixed(2) * 1;
}

Date.prototype.yearsBetween = function(d) {
        //returns years and fraction between dates
        var months = this.monthsBetween(d);
        var years = months/12;
        if (Number.prototype.toFixed)
            return (years%1) ? years.toFixed(2) : years.toFixed(0);
        else
            return (years%1) ? Math.round(years * 100)/100 : Math.round(years);
    };
Date.prototype.getAge = function() {
        var d = new Date();
        return (this.yearsBetween(d));
    };
Date.prototype.sameDayEachWeek = function (d, date) {
        /* Returns array of dates of same day each week in range */
        var aDays = new Array();
        var eDate, nextDate, adj;
        if (this > date) {
            eDate = this;
            nextDate = new Date(date.getTime());
        } else {
            eDate = date;
            nextDate = new Date(this.getTime());
        }
        adj = (d - nextDate.getDay() + 7) %7;
        nextDate.setDate(nextDate.getDate() + adj);

        while (nextDate < eDate) {
            aDays[aDays.length] = new Date(nextDate.getTime() );
            nextDate.setDate(nextDate.getDate() + 7);
        }
        return aDays
    };
/* Add built-in method to earlier browsers*/
if (!Date.prototype.toDateString) {
    Date.prototype.toDateString = function() {
            return this.toString().replace(/\d\d:\d\d:\d\d\s\w{2,3}\s/, '');
        };
}
if (!Date.prototype.toLocaleDateString) {
    Date.prototype.toLocaleDateString = function() {
            return (this.getMonth() + 1) + "/" + this.getDate() + "/" + this.getFullYear();
        };
}