/*
 * A Javascript date chooser.
 * Copyright (C) 2004 Baron Schwartz <baron at sequent dot org>
 * 
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA 02111-1307  USA
 */

Date.formatFunctions = {count:0};

Date.prototype.dateFormat = function(format) {
    if (Date.formatFunctions[format] == null) {
        Date.createNewFormat(format);
    }
    var func = Date.formatFunctions[format];
    return eval("this." + func + "();");
}

Date.createNewFormat = function(format) {
    var funcName = "format" + Date.formatFunctions.count++;
    Date.formatFunctions[format] = funcName;
    var code = "Date.prototype." + funcName + " = function(){return ";
    var special = false;
    var char = '';
    for (var i = 0; i < format.length; ++i) {
        char = format.charAt(i);
        if (!special && char == "\\") {
            special = true;
        }
        else if (special) {
            special = false;
            code += "'" + String.escape(char) + "' + ";
        }
        else {
            code += Date.getFormatCode(char);
        }
    }
    eval(code.substring(0, code.length - 3) + ";}");
}

Date.getFormatCode = function(character) {
    switch (character) {
    case "d":
        return "String.leftPad(this.getDate(), 2, '0') + ";
    case "D":
        return "Date.dayNames[this.getDay()].substring(0, 3) + ";
    case "j":
        return "this.getDate() + ";
    case "l":
        return "Date.dayNames[this.getDay()] + ";
    case "S":
        return "this.getSuffix() + ";
    case "w":
        return "this.getDay() + ";
    case "z":
        return "this.getDayOfYear() + ";
    case "W":
        return "this.getWeekOfYear() + ";
    case "F":
        return "Date.monthNames[this.getMonth()] + ";
    case "m":
        return "String.leftPad(this.getMonth() + 1, 2, '0') + ";
    case "M":
        return "Date.monthNames[this.getMonth()].substring(0, 3) + ";
    case "n":
        return "(this.getMonth() + 1) + ";
    case "t":
        return "this.getDaysInMonth() + ";
    case "L":
        return "(this.isLeapYear() ? 1 : 0) + ";
    case "Y":
        return "this.getFullYear() + ";
    case "y":
        return "('' + this.getFullYear()).substring(2, 4) + ";
    case "a":
        return "(this.getHours() < 12 ? 'am' : 'pm') + ";
    case "A":
        return "(this.getHours() < 12 ? 'AM' : 'PM') + ";
    case "g":
        return "((this.getHours() %12) ? this.getHours() % 12 : 12) + ";
    case "G":
        return "this.getHours() + ";
    case "h":
        return "String.leftPad((this.getHours() %12) ? this.getHours() % 12 : 12, 2, '0') + ";
    case "H":
        return "String.leftPad(this.getHours(), 2, '0') + ";
    case "i":
        return "String.leftPad(this.getMinutes(), 2, '0') + ";
    case "s":
        return "String.leftPad(this.getSeconds(), 2, '0') + ";
    case "O":
        return "this.getGMTOffset() + ";
    case "T":
        return "this.getTimezone() + ";
    case "Z":
        return "(this.getTimezoneOffset() * -60) + ";
    default:
        return "'" + String.escape(character) + "' + ";
    }
}

Date.prototype.getTimezone = function() {
    return this.toString().replace(
        /^.*? ([A-Z]{3}) [0-9]{4}.*$/, "$1").replace(
        /^.*?\(([A-Z])[a-z]+ ([A-Z])[a-z]+ ([A-Z])[a-z]+\)$/, "$1$2$3");
}

Date.prototype.getGMTOffset = function() {
    return (this.getTimezoneOffset() > 0 ? "-" : "+")
        + String.leftPad(Math.floor(this.getTimezoneOffset() / 60), 2, "0")
        + String.leftPad(this.getTimezoneOffset() % 60, 2, "0");
}

Date.prototype.getDayOfYear = function() {
    var num = 0;
    Date.daysInMonth[1] = this.isLeapYear() ? 29 : 28;
    for (var i = 0; i < this.getMonth(); ++i) {
        num += Date.daysInMonth[i];
    }
    return num + this.getDate() - 1;
}

Date.prototype.getWeekOfYear = function() {
    // Skip to Thursday of this week
    var now = this.getDayOfYear() + (4 - this.getDay());
    // Find the first Thursday of the year
    var jan1 = new Date(this.getFullYear(), 0, 1);
    var then = (7 - jan1.getDay() + 4);
    document.write(then);
    return String.leftPad(((now - then) / 7) + 1, 2, "0");
}

Date.prototype.isLeapYear = function() {
    var year = this.getFullYear();
    return ((year & 3) == 0 && (year % 100 || (year % 400 == 0 && year)));
}

Date.prototype.getFirstDayOfMonth = function() {
    var day = (this.getDay() - (this.getDate() - 1)) % 7;
    return (day < 0) ? (day + 7) : day;
}

Date.prototype.getLastDayOfMonth = function() {
    var day = (this.getDay() + (Date.daysInMonth[this.getMonth()] - this.getDate())) % 7;
    return (day < 0) ? (day + 7) : day;
}

Date.prototype.getDaysInMonth = function() {
    Date.daysInMonth[1] = this.isLeapYear() ? 29 : 28;
    return Date.daysInMonth[this.getMonth()];
}

Date.prototype.getSuffix = function() {
    switch (this.getDate()) {
        case 1:
        case 21:
        case 31:
            return "st";
        case 2:
        case 22:
            return "nd";
        case 3:
        case 23:
            return "rd";
        default:
            return "th";
    }
}

String.escape = function(string) {
    return string.replace(/('|\\)/g, "\\$1");
}

String.leftPad = function (val, size, char) {
    var result = new String(val);
    if (char == null) {
        char = " ";
    }
    while (result.length < size) {
        result = char + result;
    }
    return result;
}

Date.daysInMonth = [31,28,31,30,31,30,31,31,30,31,30,31];
Date.monthNames =
   ["January",
    "February",
    "March",
    "April",
    "May",
    "June",
    "July",
    "August",
    "September",
    "October",
    "November",
    "December"];
Date.dayNames =
   ["Sunday",
    "Monday",
    "Tuesday",
    "Wednesday",
    "Thursday",
    "Friday",
    "Saturday"];
Date.patterns = {
    ISO8601LongPattern:"Y-m-d H:i:s",
    ISO8601ShortPattern:"Y-m-d",
    ShortDatePattern: "n/j/Y",
    LongDatePattern: "l, F d, Y",
    FullDateTimePattern: "l, F d, Y g:i:s A",
    MonthDayPattern: "F d",
    ShortTimePattern: "g:i A",
    LongTimePattern: "g:i:s A",
    SortableDateTimePattern: "Y-m-d\\TH:i:s",
    UniversalSortableDateTimePattern: "Y-m-d H:i:sO",
    YearMonthPattern: "F, Y"};

Date.parseIsoDate = function(dateString) {
    var result = new Date();
    var re = /^(\d\d\d\d)-(\d\d)-(\d\d)( (\d\d):(\d\d):(\d\d))?$/;
    var match = dateString.match(re);
    if (match != null) {
        if (match[5] != null && match[5] != '') {
            result = new Date(
                parseInt(match[1], 10),
                parseInt(match[2], 10) - 1,
                parseInt(match[3], 10),
                parseInt(match[5], 10),
                parseInt(match[6], 10),
                parseInt(match[7], 10));
        }
        else {
            result = new Date(
                parseInt(match[1], 10),
                parseInt(match[2], 10) - 1,
                parseInt(match[3], 10));
        }
    }
    return result;
}