Dates.ts

import DateConstants = require("./DateConstants");

/** Javascript 'Date' type conversion/manipulation
 */
module Dates {

    /** Get minutes of the day (0 - 1439) from a date. The date is in the current timezone.
     * @param date: the date to get the minute of the day from
     * @return the number of minutes that have elapsed since the last midnight of the timestamp
     */
    export function getDayMinutes(date: Date): number {
        return date.getHours() * 60 + date.getMinutes();
    }


    /** Convert a date to a string. The display date is in the current timezone. The format is 'mm/dd/yyyy'
     * @param date: the date to convert to a display date string
     * @param [separator='/']: optional separator such as '/' or '-' to separate the 'mm', 'dd', and 'yyyy' portions of the returned date string
     * @return the date represented by the timestamp in the format 'mm/dd/yyyy'
     */
    export function toDisplayDate(date: Date, separator: string = "/"): string {
        var d = date.getDate();
        var mon = date.getMonth() + 1;
        var y = date.getFullYear();
        return (mon <= 9 ? "0" + mon : "" + mon) + separator + (d <= 9 ? "0" + d : "" + d) + separator + y;
    }


    /** Convert a date to a date-time string. The display date-time is in the current timezone. The format is 'mm/dd/yyyy hh:mm am/pm'
     * @param date: the date to convert to a date-time string
     * @param [includingMidnight=false]: if true AND date is midnight, returns only the 'mm/dd/yyyy' portion of the date representation
     * @return the date-time representated by the timestamp in the format 'mm/dd/yyyy hh:mm am/pm'
     */
    export function toDisplayDateTime(date: Date, includingMidnight?: boolean): string {
        var hrs = date.getHours();
        var mins = date.getMinutes();
        if (!includingMidnight && hrs === 0 && mins === 0) {
            return Dates.toDisplayDate(date);
        }

        return Dates.toDisplayDate(date) + " " + Dates.toDisplayTime(date);
    }


    /** Convert a date to a time string. The display time is in the current timezone. The format is 'hh:mm am/pm'
     * @param date: the date to convert to a time string
     * @return the time representated by the timestamp in the format 'hh:mm am/pm'
     */
    export function toDisplayTime(date: Date): string {
        var hrs = date.getHours();
        var mins = date.getMinutes();
        var ampm = hrs < 12 ? DateConstants.AM_STRING : DateConstants.PM_STRING;
        hrs = hrs % 12;
        if (hrs === 0) {
            hrs = 12;
        }
        return (hrs <= 9 ? "0" + hrs : "" + hrs) + ":" + (mins <= 9 ? "0" + mins : "" + mins) + " " + ampm;
    }


    /** Calculates the number of days between 'dtLeft - dtRight'
     * @param [incrementAtMidnight=false]: if true, assumes dtRight's time is midnight and counts from dtRight's date
     * (i.e.if incrementAtMidnight == true then 2001-3-15 2:43 is the same day as 2001-3-15 19:39, even though the dates are more than 12 hours apart)
     */
    export function dayDiff(dtLeft: Date, dtRight: Date, incrementAtMidnight: boolean = false): number {
        var daysDiff = (<number>dtLeft.getTime() - <number>dtRight.getTime()) / DateConstants.MILLIS_PER_DAY;
        var dateDiff = (incrementAtMidnight ? Math.floor(daysDiff) : Math.round(daysDiff)); // TODO this does not handle leap years or non-gregorian calendar days
        return dateDiff;
    }

}

export = Dates;