// Textarea Autoresize
// http://james.padolsey.com/javascript/jquery-plugin-autoresize/

(function($) {
	$.fn.autoResize = function(options) {
		// Just some abstracted details,
		// to make plugin users happy:
		var settings = $.extend( {
			onResize : function() {},

			animate : true,
			animateDuration : 150,
			animateCallback : function() {},

			extraSpace : 20,
			limit : 1000
		}, options);

		// Only textarea's auto-resize:
		this
			.filter('textarea')
			.each(function() {
				// Get rid of scrollbars and disable WebKit resizing:
				var textarea = $(this).css( {
					resize : 'none',
					'overflow-y' : 'hidden'
				}),

				// Cache original height, for use later:
				origHeight = textarea.height(),

				// Need clone of textarea, hidden off screen:
				clone = (function() {
					// Properties which may effect space taken up by
					// chracters:
					var props = [ 'height', 'width', 'lineHeight', 'textDecoration', 'letterSpacing' ], propOb = {};
					// Create object of styles to apply:
					$.each(props, function(i, prop) {
						propOb[prop] = textarea.css(prop);
					});

					// Clone the actual textarea removing unique
					// properties
					// and insert before original textarea:
					return textarea.clone().removeAttr('id').removeAttr('name').css({
						position : 'absolute',
						top : 0,
						left : -9999
					}).css(propOb).attr('tabIndex', '-1').insertBefore(textarea);
				})(),

				lastScrollTop = null, updateSize = function() {
					// Prepare the clone:
					clone.height(0).val($(this).val()).scrollTop(10000);
					// Find the height of text:
					var scrollTop = Math.max(clone.scrollTop(), origHeight) + settings.extraSpace, toChange = $(this).add(clone);
					// Don't do anything if scrollTip hasen't changed:
					if (lastScrollTop === scrollTop) {
						return;
					}

					lastScrollTop = scrollTop;
					// Check for limit:
					if (scrollTop >= settings.limit) {
						$(this).css('overflow-y', '');

						return;
					}
					// Fire off callback:
					settings.onResize.call(this);
					// Either animate or directly apply height:
					settings.animate && textarea.css('display') === 'block' ? toChange.stop().animate({
						height : scrollTop
					}, settings.animateDuration, settings.animateCallback) : toChange.height(scrollTop);
				};
				
				// Bind namespaced handlers to appropriate events:
				textarea.unbind('.dynSiz').bind('keyup.dynSiz', updateSize).bind('keydown.dynSiz', updateSize).bind('change.dynSiz', updateSize);
			});

		// Chain:
		return this;
	};
})(jQuery);