var Locations = {
	countryChanged : function(select) {
		var countryId = select.options[select.selectedIndex].value;

		if (countryId != '') {
			Locations.populate(countryId, document.getElementById('region'));
			Locations.disable(document.getElementById('town'));
		}

		Locations.setLocation();
	},

	regionChanged : function(select) {
		var regionId = select.options[select.selectedIndex].value;

		if (regionId != '') {
			Locations.populate(regionId, document.getElementById('town'));
		}

		Locations.setLocation();
	},

	townChanged : function(select) {
		Locations.setLocation();
	},

	disable : function(target) {
		target.options.length = 0;
		addOption(target, 'No Preference', '');
		target.setAttribute('disabled', 'disabled');
	},

	populate : function(parentId, target) {
		target.options.length = 0;
		target.setAttribute('disabled', 'disabled');

		var request = new Request.JSON({
			url: '/locations.js?parent_id=' + parentId,
			method: 'get',
			onComplete: function(json) {
				target.removeAttribute('disabled');
				addOption(target, 'No Preference', '');

				for (var i = 0; i < json.length; i++) {
					addOption(target, json[i][1], json[i][0]);
				}
			}
		}).send();
	},

	getHandle : function(name) {
		return name.toLowerCase().replace(' ', '-');
	},

	setLocation : function() {
		var location = document.getElementById('location');

		var country = document.getElementById('country');
		location.value = Locations.getHandle(country.options[country.selectedIndex].text);

		var region = document.getElementById('region');
		if (region.selectedIndex > 0) {
			location.value = Locations.getHandle(region.options[region.selectedIndex].text);
		}

		var town = document.getElementById('town');
		if (town.selectedIndex > 0) {
			location.value = Locations.getHandle(town.options[town.selectedIndex].text);
		}
	}
}

function setCountryAndRegion(location) {
	for (var i = 0; i < locations.length; i++) {
		// check for match on country
		if (String(locations[i][1]).toLowerCase() == location) {
			setListValue('country', location);

		// check for region, and work backwards to update its country
		} else if (String(locations[i][0]).toLowerCase() == location) {
			setListValue('country', locations[i][1]);
			setListValue('region', location);
		}
	}
}

function setListValue(id, value) {
	var list = document.getElementById(id);

	for (var i = 0; i < list.options.length; i++) {
		if (list.options[i].value.toLowerCase() == String(value).toLowerCase())
		{
			list.options.selectedIndex = i;
			list.onchange();

			break;
		}
	}
}

function countryChanged(selectedOption) {
	var list = document.getElementById('region');

	document.getElementById('location').value = selectedOption.value;
	
	// clear existing options by removing the 0 index until
	// there's no more, if we for loop the options the array
	// is changed as we loop so it fails to remove all items.
	while (list.options.length > 0)
		list.options[0] = null;

	addOption(list, 'No Preference', '');

	if (selectedOption.value == '') {
		list.disabled = true;
		document.getElementById('location').value = '';
	} else {
		if (list.disabled)
			list.disabled = false;

		// loop regions and find ones belonging to selected country,
		// adding them to the list
		for (var i = 0; i < locations.length; i++) {
			if (locations[i][1] == selectedOption.text)
				addOption(list, locations[i][0], locations[i][0].toLowerCase());
		}
	}
}

function regionChanged(selectedOption) {
	// if the region has been set to no preference, set location to the selected country
	if (selectedOption.value == '') {
		country = document.getElementById('country');
		document.getElementById('location').value = country.options[country.selectedIndex].value;
	} else {
		document.getElementById('location').value = selectedOption.value;
	}
}

function addOption(list, text, value) {
	var option = document.createElement('option');
	option.innerHTML = text;
	option.value = value;

	list.appendChild(option);
}