DateInput = (function($) { // Localise the $ function

	DateInput.DEFAULT_OPTS = {
		month_names: ["一月", "二月", "三月", "四月", "五月", "六月", "七月", "八月", "九月", "十月", "十一月", "十二月"],
		short_month_names: ["一", "二", "三", "四", "五", "六", "七", "八", "九", "十", "十一", "十二"],
		short_day_names: ["日", "一", "二", "三", "四", "五", "六"],
		start_of_week: 0
	};

	function DateInput(el, opts) {
		if (typeof(opts) != "object") opts = {};
		$.extend(this, DateInput.DEFAULT_OPTS, opts);
		this.input = $(el);
		this.bindMethodsToObj("show", "hide", "hideIfClickOutside", "keydownHandler", "selectDate");
		this.build();
		this.selectDate();
		this.hide();
	};
	DateInput.prototype = {
		build: function() {
			var monthNav = $('
' + '«' + '  ' + '»' + '
');
			this.monthNameSpan = $(".month_name", monthNav);
			$(".prev", monthNav).click(this.bindToObj(function() {
				this.moveMonthBy(-1);
			}));
			$(".next", monthNav).click(this.bindToObj(function() {
				this.moveMonthBy(1);
			}));
			var yearNav = $('
' + '«' + '  ' + '»' + '
');
			this.yearNameSpan = $(".year_name", yearNav);
			$(".prev", yearNav).click(this.bindToObj(function() {
				this.moveMonthBy(-12);
			}));
			$(".next", yearNav).click(this.bindToObj(function() {
				this.moveMonthBy(12);
			}));
			var nav = $('
').append(monthNav, yearNav);
			var tableShell = "";
			$(this.adjustDays(this.short_day_names)).each(function() {
				tableShell += "";
			});
			tableShell += "
" + this + "
";
			this.dateSelector = this.rootLayers = $('
').append(nav, tableShell).insertAfter(this.input);
			if (/MSIE 6/.test(navigator.userAgent)) {
				this.ieframe = $('').insertBefore(this.dateSelector);
				this.rootLayers = this.rootLayers.add(this.ieframe);
				$(".buttonx", nav).mouseover(function() {
					$(this).addClass("hover")
				});
				$(".buttonx", nav).mouseout(function() {
					$(this).removeClass("hover")
				});
			};
			this.tbody = $("tbody", this.dateSelector);
			this.input.change(this.bindToObj(function() {
				this.selectDate();
			}));
			this.selectDate();
		},
		selectMonth: function(date) {
			var newMonth = new Date(date.getFullYear(), date.getMonth(), 1);
			if (!this.currentMonth || !(this.currentMonth.getFullYear() == newMonth.getFullYear() && this.currentMonth.getMonth() == newMonth.getMonth())) {
				this.currentMonth = newMonth;
				var rangeStart = this.rangeStart(date),
					rangeEnd = this.rangeEnd(date);
				var numDays = this.daysBetween(rangeStart, rangeEnd);
				var dayCells = "";
				for (var i = 0; i <= numDays; i++) {
					var currentDay = new Date(rangeStart.getFullYear(), rangeStart.getMonth(), rangeStart.getDate() + i, 12, 00);
					if (this.isFirstDayOfWeek(currentDay)) dayCells += "";
					if (currentDay.getMonth() == date.getMonth()) {
						dayCells += '' + currentDay.getDate() + '';
					} else {
						dayCells += '' + currentDay.getDate() + '';
					}; if (this.isLastDayOfWeek(currentDay)) dayCells += "";
				};
				this.tbody.empty().append(dayCells);
				this.monthNameSpan.empty().append(this.monthName(date));
				this.yearNameSpan.empty().append(this.currentMonth.getFullYear());
				$(".selectable_day", this.tbody).click(this.bindToObj(function(event) {
					this.changeInput($(event.target).attr("date"));
				}));
				$("td[date='" + this.dateToString(new Date()) + "']", this.tbody).addClass("today");
				$("td.selectable_day", this.tbody).mouseover(function() {
					$(this).addClass("hover")
				});
				$("td.selectable_day", this.tbody).mouseout(function() {
					$(this).removeClass("hover")
				});
			};
			$('.selected', this.tbody).removeClass("selected");
			$('td[date="' + this.selectedDateString + '"]', this.tbody).addClass("selected");
		},
		selectDate: function(date) {
			if (typeof(date) == "undefined") {
				date = this.stringToDate(this.input.val());
			};
			if (!date) date = new Date();
			this.selectedDate = date;
			this.selectedDateString = this.dateToString(this.selectedDate);
			this.selectMonth(this.selectedDate);
		},
		changeInput: function(dateString) {
			this.input.val(dateString).change();
			this.hide();
		},
		show: function() {
			this.rootLayers.css("display", "block");
			$([window, document.body]).click(this.hideIfClickOutside);
			this.input.unbind("focus", this.show);
			$(document.body).keydown(this.keydownHandler);
			this.setPosition();
		},
		hide: function() {
			this.rootLayers.css("display", "none");
			$([window, document.body]).unbind("click", this.hideIfClickOutside);
			this.input.focus(this.show);
			$(document.body).unbind("keydown", this.keydownHandler);
		},
		hideIfClickOutside: function(event) {
			if (event.target != this.input[0] && !this.insideSelector(event)) {
				this.hide();
			};
		},
		insideSelector: function(event) {
			var offset = this.dateSelector.position();
			offset.right = offset.left + this.dateSelector.outerWidth();
			offset.bottom = offset.top + this.dateSelector.outerHeight();
			return event.pageY < offset.bottom && event.pageY > offset.top && event.pageX < offset.right && event.pageX > offset.left;
		},
		keydownHandler: function(event) {
			switch (event.keyCode) {
				case 9:
				case 27:
					this.hide();
					return;
					break;
				case 13:
					this.changeInput(this.selectedDateString);
					break;
				case 33:
					this.moveDateMonthBy(event.ctrlKey ? -12 : -1);
					break;
				case 34:
					this.moveDateMonthBy(event.ctrlKey ? 12 : 1);
					break;
				case 38:
					this.moveDateBy(-7);
					break;
				case 40:
					this.moveDateBy(7);
					break;
				case 37:
					this.moveDateBy(-1);
					break;
				case 39:
					this.moveDateBy(1);
					break;
				default:
					return;
			}
			event.preventDefault();
		},
		stringToDate: function(string) {
			var matches;
			if (matches = string.match(/^(\d{1,2}) ([^\s]+) (\d{4,4})$/)) {
				return new Date(matches[3], this.shortMonthNum(matches[2]), matches[1], 12, 00);
			} else {
				return null;
			};
		},
		dateToString: function(date) {
			var month = (date.getMonth() + 1).toString();
			var dom = date.getDate().toString();
			if (month.length == 1) month = "0" + month;
			if (dom.length == 1) dom = "0" + dom;
			return date.getFullYear() + "-" + month + "-" + dom;
		},
		setPosition: function() {
			var offset = this.input.offset();
			this.rootLayers.css({
				top: offset.top + this.input.outerHeight(),
				left: offset.left
			});
			if (this.ieframe) {
				this.ieframe.css({
					width: this.dateSelector.outerWidth(),
					height: this.dateSelector.outerHeight()
				});
			};
		},
		moveDateBy: function(amount) {
			var newDate = new Date(this.selectedDate.getFullYear(), this.selectedDate.getMonth(), this.selectedDate.getDate() + amount);
			this.selectDate(newDate);
		},
		moveDateMonthBy: function(amount) {
			var newDate = new Date(this.selectedDate.getFullYear(), this.selectedDate.getMonth() + amount, this.selectedDate.getDate());
			if (newDate.getMonth() == this.selectedDate.getMonth() + amount + 1) {
				newDate.setDate(0);
			};
			this.selectDate(newDate);
		},
		moveMonthBy: function(amount) {
			var newMonth = new Date(this.currentMonth.getFullYear(), this.currentMonth.getMonth() + amount, this.currentMonth.getDate());
			this.selectMonth(newMonth);
		},
		monthName: function(date) {
			return this.month_names[date.getMonth()];
		},
		bindToObj: function(fn) {
			var self = this;
			return function() {
				return fn.apply(self, arguments)
			};
		},
		bindMethodsToObj: function() {
			for (var i = 0; i < arguments.length; i++) {
				this[arguments[i]] = this.bindToObj(this[arguments[i]]);
			};
		},
		indexFor: function(array, value) {
			for (var i = 0; i < array.length; i++) {
				if (value == array[i]) return i;
			};
		},
		monthNum: function(month_name) {
			return this.indexFor(this.month_names, month_name);
		},
		shortMonthNum: function(month_name) {
			return this.indexFor(this.short_month_names, month_name);
		},
		shortDayNum: function(day_name) {
			return this.indexFor(this.short_day_names, day_name);
		},
		daysBetween: function(start, end) {
			start = Date.UTC(start.getFullYear(), start.getMonth(), start.getDate());
			end = Date.UTC(end.getFullYear(), end.getMonth(), end.getDate());
			return (end - start) / 86400000;
		},
		changeDayTo: function(dayOfWeek, date, direction) {
			var difference = direction * (Math.abs(date.getDay() - dayOfWeek - (direction * 7)) % 7);
			return new Date(date.getFullYear(), date.getMonth(), date.getDate() + difference);
		},
		rangeStart: function(date) {
			return this.changeDayTo(this.start_of_week, new Date(date.getFullYear(), date.getMonth()), -1);
		},
		rangeEnd: function(date) {
			return this.changeDayTo((this.start_of_week - 1) % 7, new Date(date.getFullYear(), date.getMonth() + 1, 0), 1);
		},
		isFirstDayOfWeek: function(date) {
			return date.getDay() == this.start_of_week;
		},
		isLastDayOfWeek: function(date) {
			return date.getDay() == (this.start_of_week - 1) % 7;
		},
		adjustDays: function(days) {
			var newDays = [];
			for (var i = 0; i < days.length; i++) {
				newDays[i] = days[(i + this.start_of_week) % 7];
			};
			return newDays;
		}
	};
	$.fn.date_input = function(opts) {
		return this.each(function() {
			new DateInput(this, opts);
		});
	};
	$.date_input = {
		initialize: function(opts) {
			$("input.date_input").date_input(opts);
		}
	};

	return DateInput;
})(jQuery); // End localisation of the $ function