/**
*	@name							Elastic
*	@descripton						Elastic is jQuery plugin that grow and shrink your textareas automatically
*	@version						1.6.10
*	@requires						jQuery 1.2.6+
*
*	@author							Jan Jarfalk
*	@author-email					jan.jarfalk@unwrongest.com
*	@author-website					http://www.unwrongest.com
*
*	@licence						MIT License - http://www.opensource.org/licenses/mit-license.php
*/

(function (jQuery) {
	jQuery.fn.extend({
		elastic: function () {

			//	We will create a div clone of the textarea
			//	by copying these attributes from the textarea to the div.
			var mimics = [
				'paddingTop',
				'paddingRight',
				'paddingBottom',
				'paddingLeft',
				'font-size',
				'lineHeight',
				'fontFamily',
				'width',
				'fontWeight',
				'border-top-width',
				'border-right-width',
				'border-bottom-width',
				'border-left-width',
				'borderTopStyle',
				'borderTopColor',
				'borderRightStyle',
				'borderRightColor',
				'borderBottomStyle',
				'borderBottomColor',
				'borderLeftStyle',
				'borderLeftColor'
				];

			return this.each(function () {

				// Elastic only works on textareas
				if (this.type !== 'textarea') {
					return false;
				}

				var $textarea = jQuery(this),
				$twin = jQuery('<div />').css({ 'position': 'absolute', 'display': 'none', 'word-wrap': 'break-word' }),
				lineHeight = parseInt($textarea.css('line-height'), 10) || parseInt($textarea.css('font-size'), '10'),
				minheight = parseInt($textarea.css('height'), 10) || lineHeight * 3,
				maxheight = parseInt($textarea.css('max-height'), 10) || Number.MAX_VALUE,
				goalheight = 0;

				// Opera returns max-height of -1 if not set
				if (maxheight < 0) { maxheight = Number.MAX_VALUE; }

				// Append the twin to the DOM
				// We are going to meassure the height of this, not the textarea.
				$twin.appendTo($textarea.parent());

				// Copy the essential styles (mimics) from the textarea to the twin
				for (i in mimics) {
					$twin.css(mimics[i].toString(), $textarea.css(mimics[i].toString()));
				}

				// Sets a given height and overflow state on the textarea
				function setHeightAndOverflow(height, overflow) {
					var curratedHeight = Math.floor(parseInt(height, 10));
					if ($textarea.height() !== curratedHeight) {
						$textarea.css({ 'height': curratedHeight + 'px', 'overflow': overflow });
					}
				}

				// This function will update the height of the textarea if necessary 
				function update(forced) {
					// Update the width of the twin. (solution for textareas with widths in percent)
					curatedWidth = Math.floor(parseInt($textarea.width(), 10));
					if ($twin.width() !== curatedWidth) {
						$twin.css({ 'width': curatedWidth + 'px' });
					}

					// Get curated content from the textarea.
					var textareaContent = $textarea.val().replace(/&/g, '&amp;').replace(/ {2}/g, '&nbsp;').replace(/<|>/g, '&gt;').replace(/\n/g, '<br />');

					// Compare curated content with curated twin.
					var twinContent = $twin.html().replace(/<br>/ig, '<br />');

					if (forced || textareaContent + '&nbsp;' !== twinContent) {

						// Add an extra white space so new rows are added when you are at the end of a row.
						$twin.html(textareaContent + '&nbsp;');

						// Change textarea height if twin plus the height of one line differs more than 3 pixel from textarea height
						if (Math.abs($twin.height() + lineHeight - $textarea.height()) > 3) {

							var goalheight = $twin.height() + lineHeight;
							if (goalheight >= maxheight) {
								setHeightAndOverflow(maxheight, 'auto');
							} else if (goalheight <= minheight) {
								setHeightAndOverflow(minheight, 'hidden');
							} else {
								setHeightAndOverflow(goalheight, 'hidden');
							}

						}

					}

				}

				// Hide scrollbars
				$textarea.css({ 'overflow': 'hidden' });

				// Update textarea size on keyup, change, cut and paste
				$textarea.bind('keyup change cut paste update', update);

				// Update width of twin if browser or textarea is resized (solution for textareas with widths in percent)
				$(window).bind('resize', update);

				// Compact textarea on blur
				$textarea.bind('blur', function () {
					if ($twin.height() < maxheight) {
						if ($twin.height() > minheight) {
							$textarea.height($twin.height());
						} else {
							$textarea.height(minheight);
						}
					}
				});

				// Run update once when elastic is initialized
				update();

			});

		}
	});
})(jQuery);