/*
 * jQuery DateSelect Plugin v0.1
 *
 * Date Select - create a set of month, day, year selects with the days appearing in the days select limited
 * by the month and year (i.e. handle days in month and leap years) and insert into the matched element(s). 
 *
 * Any element can be used as the parent element. Fieldset is a semantically sound choice.
 *
 * Usage:
 *     <fieldset id="dateOfBirth" />
 * 	   $("#dateOfBirth").dateselect();
 *
 * Optionally specify the names (and ids = names) for each select:
 *     $("#dateOfBirth").dateselect(
 *     {
 *          dateName: dateOfBirthDay
 *          monthName: dateOfBirthMonth
 *          yearName: dateOfBirthYear
 *     });
 *
 * Copyright (c) 2007 Justin Knoll
 *
 */

jQuery.fn.dateselect = function(settings)
{
	settings = jQuery.extend(
	{
		dateName: "date",
		monthName: "month",
		yearName: "year",
		minYear: 1900,
		maxYear: 2020		
	}, settings);
	
	var dateSelect = document.createElement("select");
	var yearSelect = document.createElement("select");
	var monthSelect = document.createElement("select");
	
	var today = new Date();
		
	return this.each(function()
	{
		var parentNode = this;

		monthSelect.name = settings["monthName"]
		for (var i=0; i <= 11; i++)
		{
			var option = document.createElement("option");
			option.value=i;
			
			// The year and date in the call to Date's constructor below are arbitrary;
			// we're just getting the month label.
			var dateLabel = new Date(1900, i, 1).toString().split(" ")[1];
			option.innerHTML = dateLabel;
			option.selected = (i == today.getMonth());
			
			monthSelect.appendChild(option);
		} 
  		this.appendChild(monthSelect);

		appendSelect(dateSelect, settings["dateName"], 1, 31, today.getDate());
		appendSelect(yearSelect, settings["yearName"], settings["minYear"], settings["maxYear"], today.getFullYear());

		$([monthSelect, yearSelect]).change(setDateSelectOptions);
		
		function appendSelect(selectNode, name, min, max, selectedIndex)
		{
			selectNode.name = name;
			selectNode.id = name;
			optionFill(selectNode, min, max, selectedIndex);
	  		parentNode.appendChild(selectNode);
		};
		
		function optionFill(selectNode, min, max, newSelectedValue)
		{
			var selectedValue = selectNode.selectedIndex == -1 ? newSelectedValue : selectNode.options[selectNode.selectedIndex].value;
			$(selectNode).empty();
			for (var i=min; i <= max; i++)
			{
				var option = document.createElement("option");
				option.value=i;
				option.innerHTML=i;
				option.selected = (i == selectedValue);
				selectNode.appendChild(option);
			}
		};

		function getDaysInMonth(month, year)
		{
			month = parseInt(month) + 1;
			var date = new Date(year, month, 1);
			// Subtract one day's worth of milliseconds
			date -= 1000 * 60 * 60 * 24;
			return new Date(date).getDate();
		};

		function setDateSelectOptions()
		{
			optionFill(dateSelect, 1, getDaysInMonth(monthSelect.value, yearSelect.value));
		};
	});
};