/**
 * Calendar Script
 * Creates a calendar widget which can be used to select the date more easily than using just a text box
 *
 * Original: http://www.openjs.com/scripts/ui/calendar/
 * Modified: http://svn.yourcmc.ru/viewvc.py/vitaphoto/js/{util.js,calendar.js,calendar.css}
 * (uses addListener() and getOffset() from util.js)
 * License: MIT-like, http://www.openjs.com/license.php
 *
 * Example:
 * <input type="text" name="date" id="date" />
 * <script type="text/javascript">
 *     Calendar.set("date");
 * </script>
 */
var Calendar = {
	month_names: ["Январь","Февраль","Март","Апрель","Май","Июнь","Июлья","Август","Сентябрь","Октябрь","Ноябрь","Декабрь"],
	weekdays: ["Пн","Вт","Ср","Чт","Пт","Сб","Вс"],
	sunday: 6,
	month_days: [31,28,31,30,31,30,31,31,30,31,30,31],
	// Get today's date - year, month, day and date
	today: new Date(),
	format: 'Y-m-d', // either d.m.Y or Y-m-d, other formats are not supported
	opt: {},
	data: [],
	addedListener: false,

	//Functions
	/// Used to create HTML in a optimized way.
	wrt:function(txt) {
		this.data.push(txt);
	},

	/// Called when the user clicks on a date in the calendar.
	selectDate:function(year,month,day) {
		var ths = _calendar_active_instance;
		var i = document.getElementById(ths.opt["input"]);
		var t = i.value.split(/\s+/, 2)[1]||'';
		if (t)
			t = ' '+t;
		i.value = (ths.format == 'Y-m-d' ? year + '-' + month + '-' + day : day + '.' + month + '.' + year) + t;
		ths.hideCalendar();
	},

	/// Creates a calendar with the date given in the argument as the selected date.
	makeCalendar:function(year, month, day) {
		year = parseInt(year);
		month= parseInt(month);
		day	 = parseInt(day);

		//Display the table
		var next_month = month+1;
		var next_month_year = year;
		if(next_month>=12) {
			next_month = 0;
			next_month_year++;
		}

		var previous_month = month-1;
		var previous_month_year = year;
		if(previous_month<0) {
			previous_month = 11;
			previous_month_year--;
		}

		this.wrt("<table>");
		this.wrt("<tr><th><a href='javascript:Calendar.makeCalendar("+(previous_month_year)+","+(previous_month)+");' title='"+this.month_names[previous_month]+" "+(previous_month_year)+"'>&lt;</a></th>");
		this.wrt("<th colspan='5' class='calendar-title'><select name='calendar-month' class='calendar-month' onChange='Calendar.makeCalendar("+year+",this.value);'>");
		for(var i in this.month_names) {
			this.wrt("<option value='"+i+"'");
			if(i == month) this.wrt(" selected='selected'");
			this.wrt(">"+this.month_names[i]+"</option>");
		}
		this.wrt("</select>");
		this.wrt("<select name='calendar-year' class='calendar-year' onChange='Calendar.makeCalendar(this.value, "+month+");'>");
		var current_year = this.today.getYear();
		if(current_year < 1900) current_year += 1900;

		for(var i=current_year-70; i<current_year+10; i++) {
			this.wrt("<option value='"+i+"'")
			if(i == year) this.wrt(" selected='selected'");
			this.wrt(">"+i+"</option>");
		}
		this.wrt("</select></th>");
		this.wrt("<th><a href='javascript:Calendar.makeCalendar("+(next_month_year)+","+(next_month)+");' title='"+this.month_names[next_month]+" "+(next_month_year)+"'>&gt;</a></th></tr>");
		this.wrt("<tr class='header'>");
		for (var weekday = 0; weekday < 7; weekday++)
			this.wrt("<td>"+this.weekdays[weekday]+"</td>");
		this.wrt("</tr>");

		// Get the first day of this month
		var first_day = new Date(year,month,1);
		var start_day = (first_day.getDay()+Calendar.sunday)%7;

		var d = 1;
		var flag = 0;

		// Leap year support
		if (year % 4 == 0)
			this.month_days[1] = 29;
		else
			this.month_days[1] = 28;

		var days_in_this_month = this.month_days[month];

		// Create the calender
		var yea = this.today.getYear();
		if (yea < 1900)
			yea += 1900;
		var all_diff = (year - yea) || (month - this.today.getMonth());
		for (var i = 0; i <= 5; i++)
		{
			if (w >= days_in_this_month)
				break;
			this.wrt("<tr>");
			for (var j = 0; j < 7; j++)
			{
				if (d > days_in_this_month)
					flag = 0; // If the days has overshooted the number of days in this month, stop writing
				else if (j >= start_day && !flag)
					flag = 1; // If the first day of this month has come, start the date writing

				if (flag)
				{
					var w = d, mon = month+1;
					if (w < 10)
						w = "0" + w;
					if (mon < 10)
						mon = "0" + mon;

					// Is it today?
					var class_name = '';

					var diff = all_diff || (d - this.today.getDate());
					if (diff < 0)
						class_name = ' past';
					else if (!diff)
						class_name = ' today';
					else
						class_name = ' future';

					if (day == d)
						class_name += ' selected';

					class_name += " " + this.weekdays[j].toLowerCase();

					this.wrt("<td class='days"+class_name+"'><a href='javascript:Calendar.selectDate(\""+year+"\",\""+mon+"\",\""+w+"\")'>"+w+"</a></td>");
					d++;
				}
				else
				{
					this.wrt("<td class='days'>&nbsp;</td>");
				}
			}
			this.wrt("</tr>");
		}
		this.wrt("</table>");
		this.wrt("<input type='button' value='Закрыть' class='calendar-cancel' onclick='Calendar.hideCalendar();' />");

		document.getElementById(this.opt['calendar']).innerHTML = this.data.join("");
		this.data = [];
	},

	/// Display the calendar - if a date exists in the input box, that will be selected in the calendar.
	showCalendar: function() {
		var input = document.getElementById(this.opt['input']);

		//Position the div in the correct location...
		var div = document.getElementById(this.opt['calendar']);
		var xy = getOffset(input);
		var width = input.clientWidth||input.offsetWidth;
		div.style.left=(xy.left+width+10)+"px";
		div.style.top=xy.top+"px";

		// Show the calendar with the date in the input as the selected date
		var existing_date = new Date();
		var date_in_input = input.value.replace(/\s+.*$/, ''); //Remove time
		if(date_in_input) {
			// date format is HARDCODE
			var selected_date = false;
			var date_parts = date_in_input.split("-");
			if(date_parts.length == 3) {
				// Y-m-d
				date_parts[1]--; //Month starts with 0
				selected_date = new Date(date_parts[0], date_parts[1], date_parts[2]);
			} else if (date_parts.length == 1) {
				date_parts = date_in_input.split('.');
				if (date_parts.length == 3) {
					// d.m.Y
					date_parts[1]--; //Month starts with 0
					selected_date = new Date(date_parts[2], date_parts[1], date_parts[0]);
				}
			}
			if(selected_date && !isNaN(selected_date.getYear())) { //Valid date.
				existing_date = selected_date;
			}
		}

		var the_year = existing_date.getYear();
		if(the_year < 1900) the_year += 1900;
		this.makeCalendar(the_year, existing_date.getMonth(), existing_date.getDate());
		document.getElementById(this.opt['calendar']).style.display = "block";
		_calendar_active_instance = this;

		if (!Calendar.addedListener)
		{
			addListener(div, "mousedown", function(ev) {
				ev = ev || window.event;
				if (ev.stopPropagation)
					ev.stopPropagation();
				else
					ev.cancelBubble = true;
				return true;
			});
			addListener(document, "mousedown", function() { Calendar.hideCalendar(); });
			Calendar.addedListener = true;
		}
	},

	/// Hides the currently show calendar.
	hideCalendar: function(instance) {
		var active_calendar_id = "";
		if(instance) active_calendar_id = instance.opt['calendar'];
		else if(!_calendar_active_instance) return;
		else active_calendar_id = _calendar_active_instance.opt['calendar'];

		if(active_calendar_id) document.getElementById(active_calendar_id).style.display = "none";
		_calendar_active_instance = null;
	},

	/// Setup a text input box to be a calendar box.
	set: function(input_id) {
		var input = document.getElementById(input_id);
		if(!input) return; //If the input field is not there, exit.

		if(!this.opt['calendar']) this.init();

		var ths = this;
		addListener(input, 'focus', function(ev) {
			ths.opt['input'] = this.id;
			ths.showCalendar();
		});
	},

	/// Will be called once when the first input is set.
	init: function() {
		if(!this.opt['calendar'] || !document.getElementById(this.opt['calendar'])) {
			var div = document.createElement('div');
			if(!this.opt['calendar']) this.opt['calendar'] = 'calender_div_'+ Math.round(Math.random() * 100);

			div.setAttribute('id',this.opt['calendar']);
			div.className="calendar-box";

			document.getElementsByTagName("body")[0].insertBefore(div,document.getElementsByTagName("body")[0].firstChild);
		}
	}
}