source: Dev/trunk/src/client/dojo/date.js @ 485

define(["./has", "./_base/lang"], function(has, lang){
// module:
//              dojo/date

var date = {
        // summary:
        //              Date manipulation utilities
};

date.getDaysInMonth = function(/*Date*/dateObject){
        // summary:
        //              Returns the number of days in the month used by dateObject
        var month = dateObject.getMonth();
        var days = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
        if(month == 1 && date.isLeapYear(dateObject)){ return 29; } // Number
        return days[month]; // Number
};

date.isLeapYear = function(/*Date*/dateObject){
        // summary:
        //              Determines if the year of the dateObject is a leap year
        // description:
        //              Leap years are years with an additional day YYYY-02-29, where the
        //              year number is a multiple of four with the following exception: If
        //              a year is a multiple of 100, then it is only a leap year if it is
        //              also a multiple of 400. For example, 1900 was not a leap year, but
        //              2000 is one.

        var year = dateObject.getFullYear();
        return !(year%400) || (!(year%4) && !!(year%100)); // Boolean
};

// FIXME: This is not localized
date.getTimezoneName = function(/*Date*/dateObject){
        // summary:
        //              Get the user's time zone as provided by the browser
        // dateObject:
        //              Needed because the timezone may vary with time (daylight savings)
        // description:
        //              Try to get time zone info from toString or toLocaleString method of
        //              the Date object -- UTC offset is not a time zone.  See
        //              http://www.twinsun.com/tz/tz-link.htm Note: results may be
        //              inconsistent across browsers.

        var str = dateObject.toString(); // Start looking in toString
        var tz = ''; // The result -- return empty string if nothing found
        var match;

        // First look for something in parentheses -- fast lookup, no regex
        var pos = str.indexOf('(');
        if(pos > -1){
                tz = str.substring(++pos, str.indexOf(')'));
        }else{
                // If at first you don't succeed ...
                // If IE knows about the TZ, it appears before the year
                // Capital letters or slash before a 4-digit year
                // at the end of string
                var pat = /([A-Z\/]+) \d{4}$/;
                if((match = str.match(pat))){
                        tz = match[1];
                }else{
                // Some browsers (e.g. Safari) glue the TZ on the end
                // of toLocaleString instead of putting it in toString
                        str = dateObject.toLocaleString();
                        // Capital letters or slash -- end of string,
                        // after space
                        pat = / ([A-Z\/]+)$/;
                        if((match = str.match(pat))){
                                tz = match[1];
                        }
                }
        }

        // Make sure it doesn't somehow end up return AM or PM
        return (tz == 'AM' || tz == 'PM') ? '' : tz; // String
};

// Utility methods to do arithmetic calculations with Dates

date.compare = function(/*Date*/date1, /*Date?*/date2, /*String?*/portion){
        // summary:
        //              Compare two date objects by date, time, or both.
        // description:
        //              Returns 0 if equal, positive if a > b, else negative.
        // date1:
        //              Date object
        // date2:
        //              Date object.  If not specified, the current Date is used.
        // portion:
        //              A string indicating the "date" or "time" portion of a Date object.
        //              Compares both "date" and "time" by default.  One of the following:
        //              "date", "time", "datetime"

        // Extra step required in copy for IE - see #3112
        date1 = new Date(+date1);
        date2 = new Date(+(date2 || new Date()));

        if(portion == "date"){
                // Ignore times and compare dates.
                date1.setHours(0, 0, 0, 0);
                date2.setHours(0, 0, 0, 0);
        }else if(portion == "time"){
                // Ignore dates and compare times.
                date1.setFullYear(0, 0, 0);
                date2.setFullYear(0, 0, 0);
        }

        if(date1 > date2){ return 1; } // int
        if(date1 < date2){ return -1; } // int
        return 0; // int
};

date.add = function(/*Date*/date, /*String*/interval, /*int*/amount){
        // summary:
        //              Add to a Date in intervals of different size, from milliseconds to years
        // date: Date
        //              Date object to start with
        // interval:
        //              A string representing the interval.  One of the following:
        //              "year", "month", "day", "hour", "minute", "second",
        //              "millisecond", "quarter", "week", "weekday"
        // amount:
        //              How much to add to the date.

        var sum = new Date(+date); // convert to Number before copying to accomodate IE (#3112)
        var fixOvershoot = false;
        var property = "Date";

        switch(interval){
                case "day":
                        break;
                case "weekday":
                        //i18n FIXME: assumes Saturday/Sunday weekend, but this is not always true.  see dojo/cldr/supplemental

                        // Divide the increment time span into weekspans plus leftover days
                        // e.g., 8 days is one 5-day weekspan / and two leftover days
                        // Can't have zero leftover days, so numbers divisible by 5 get
                        // a days value of 5, and the remaining days make up the number of weeks
                        var days, weeks;
                        var mod = amount % 5;
                        if(!mod){
                                days = (amount > 0) ? 5 : -5;
                                weeks = (amount > 0) ? ((amount-5)/5) : ((amount+5)/5);
                        }else{
                                days = mod;
                                weeks = parseInt(amount/5);
                        }
                        // Get weekday value for orig date param
                        var strt = date.getDay();
                        // Orig date is Sat / positive incrementer
                        // Jump over Sun
                        var adj = 0;
                        if(strt == 6 && amount > 0){
                                adj = 1;
                        }else if(strt == 0 && amount < 0){
                        // Orig date is Sun / negative incrementer
                        // Jump back over Sat
                                adj = -1;
                        }
                        // Get weekday val for the new date
                        var trgt = strt + days;
                        // New date is on Sat or Sun
                        if(trgt == 0 || trgt == 6){
                                adj = (amount > 0) ? 2 : -2;
                        }
                        // Increment by number of weeks plus leftover days plus
                        // weekend adjustments
                        amount = (7 * weeks) + days + adj;
                        break;
                case "year":
                        property = "FullYear";
                        // Keep increment/decrement from 2/29 out of March
                        fixOvershoot = true;
                        break;
                case "week":
                        amount *= 7;
                        break;
                case "quarter":
                        // Naive quarter is just three months
                        amount *= 3;
                        // fallthrough...
                case "month":
                        // Reset to last day of month if you overshoot
                        fixOvershoot = true;
                        property = "Month";
                        break;
//              case "hour":
//              case "minute":
//              case "second":
//              case "millisecond":
                default:
                        property = "UTC"+interval.charAt(0).toUpperCase() + interval.substring(1) + "s";
        }

        if(property){
                sum["set"+property](sum["get"+property]()+amount);
        }

        if(fixOvershoot && (sum.getDate() < date.getDate())){
                sum.setDate(0);
        }

        return sum; // Date
};

date.difference = function(/*Date*/date1, /*Date?*/date2, /*String?*/interval){
        // summary:
        //              Get the difference in a specific unit of time (e.g., number of
        //              months, weeks, days, etc.) between two dates, rounded to the
        //              nearest integer.
        // date1:
        //              Date object
        // date2:
        //              Date object.  If not specified, the current Date is used.
        // interval:
        //              A string representing the interval.  One of the following:
        //              "year", "month", "day", "hour", "minute", "second",
        //              "millisecond", "quarter", "week", "weekday"
        //
        //              Defaults to "day".

        date2 = date2 || new Date();
        interval = interval || "day";
        var yearDiff = date2.getFullYear() - date1.getFullYear();
        var delta = 1; // Integer return value

        switch(interval){
                case "quarter":
                        var m1 = date1.getMonth();
                        var m2 = date2.getMonth();
                        // Figure out which quarter the months are in
                        var q1 = Math.floor(m1/3) + 1;
                        var q2 = Math.floor(m2/3) + 1;
                        // Add quarters for any year difference between the dates
                        q2 += (yearDiff * 4);
                        delta = q2 - q1;
                        break;
                case "weekday":
                        var days = Math.round(date.difference(date1, date2, "day"));
                        var weeks = parseInt(date.difference(date1, date2, "week"));
                        var mod = days % 7;

                        // Even number of weeks
                        if(mod == 0){
                                days = weeks*5;
                        }else{
                                // Weeks plus spare change (< 7 days)
                                var adj = 0;
                                var aDay = date1.getDay();
                                var bDay = date2.getDay();

                                weeks = parseInt(days/7);
                                mod = days % 7;
                                // Mark the date advanced by the number of
                                // round weeks (may be zero)
                                var dtMark = new Date(date1);
                                dtMark.setDate(dtMark.getDate()+(weeks*7));
                                var dayMark = dtMark.getDay();

                                // Spare change days -- 6 or less
                                if(days > 0){
                                        switch(true){
                                                // Range starts on Sat
                                                case aDay == 6:
                                                        adj = -1;
                                                        break;
                                                // Range starts on Sun
                                                case aDay == 0:
                                                        adj = 0;
                                                        break;
                                                // Range ends on Sat
                                                case bDay == 6:
                                                        adj = -1;
                                                        break;
                                                // Range ends on Sun
                                                case bDay == 0:
                                                        adj = -2;
                                                        break;
                                                // Range contains weekend
                                                case (dayMark + mod) > 5:
                                                        adj = -2;
                                        }
                                }else if(days < 0){
                                        switch(true){
                                                // Range starts on Sat
                                                case aDay == 6:
                                                        adj = 0;
                                                        break;
                                                // Range starts on Sun
                                                case aDay == 0:
                                                        adj = 1;
                                                        break;
                                                // Range ends on Sat
                                                case bDay == 6:
                                                        adj = 2;
                                                        break;
                                                // Range ends on Sun
                                                case bDay == 0:
                                                        adj = 1;
                                                        break;
                                                // Range contains weekend
                                                case (dayMark + mod) < 0:
                                                        adj = 2;
                                        }
                                }
                                days += adj;
                                days -= (weeks*2);
                        }
                        delta = days;
                        break;
                case "year":
                        delta = yearDiff;
                        break;
                case "month":
                        delta = (date2.getMonth() - date1.getMonth()) + (yearDiff * 12);
                        break;
                case "week":
                        // Truncate instead of rounding
                        // Don't use Math.floor -- value may be negative
                        delta = parseInt(date.difference(date1, date2, "day")/7);
                        break;
                case "day":
                        delta /= 24;
                        // fallthrough
                case "hour":
                        delta /= 60;
                        // fallthrough
                case "minute":
                        delta /= 60;
                        // fallthrough
                case "second":
                        delta /= 1000;
                        // fallthrough
                case "millisecond":
                        delta *= date2.getTime() - date1.getTime();
        }

        // Round for fractional values and DST leaps
        return Math.round(delta); // Number (integer)
};

// Don't use setObject() because it may overwrite dojo/date/stamp (if that has already been loaded)
has("extend-dojo") && lang.mixin(lang.getObject("dojo.date", true), date);

return date;
});