// Autosize 1.13 - jQuery plugin for textareas
// (c) 2012 Jack Moore - jacklmoore.com
// license: www.opensource.org/licenses/mit-license.php

(function ($) {
	var
	defaults = {
		className: 'autosizejs',
		append: "",
		callback: false
	},
	hidden = 'hidden',
	borderBox = 'border-box',
	lineHeight = 'lineHeight',
	copy = '<textarea tabindex="-1" style="position:absolute; top:-9999px; left:-9999px; right:auto; bottom:auto; -moz-box-sizing:content-box; -webkit-box-sizing:content-box; box-sizing:content-box; word-wrap:break-word; height:0 !important; min-height:0 !important; overflow:hidden;"/>',
	// line-height is omitted because IE7/IE8 doesn't return the correct value.
	copyStyle = [
		'fontFamily',
		'fontSize',
		'fontWeight',
		'fontStyle',
		'letterSpacing',
		'textTransform',
		'wordSpacing',
		'textIndent'
	],
	oninput = 'oninput',
	onpropertychange = 'onpropertychange',
	test = $(copy)[0];

	// For testing support in old FireFox
	test.setAttribute(oninput, "return");

	if ($.isFunction(test[oninput]) || onpropertychange in test) {

		// test that line-height can be accurately copied to avoid
		// incorrect value reporting in old IE and old Opera
		$(test).css(lineHeight, '99px');
		if ($(test).css(lineHeight) === '99px') {
			copyStyle.push(lineHeight);
		}

		$.fn.autosize = function (options) {
			options = $.extend({}, defaults, options || {});

			return this.each(function () {
				var
				ta = this,
				$ta = $(ta),
				mirror,
				minHeight = $ta.height(),
				maxHeight = parseInt($ta.css('maxHeight'), 10),
				active,
				i = copyStyle.length,
				resize,
				boxOffset = 0,
				value = ta.value,
				callback = $.isFunction(options.callback);

				if ($ta.css('box-sizing') === borderBox || $ta.css('-moz-box-sizing') === borderBox || $ta.css('-webkit-box-sizing') === borderBox){
					boxOffset = $ta.outerHeight() - $ta.height();
				}

				if ($ta.data('mirror') || $ta.data('ismirror')) {
					// if autosize has already been applied, exit.
					// if autosize is being applied to a mirror element, exit.
					return;
				} else {
					mirror = $(copy).data('ismirror', true).addClass(options.className)[0];

					resize = $ta.css('resize') === 'none' ? 'none' : 'horizontal';

					$ta.data('mirror', $(mirror)).css({
						overflow: hidden,
						overflowY: hidden,
						wordWrap: 'break-word',
						resize: resize
					});
				}

				// Opera returns '-1px' when max-height is set to 'none'.
				maxHeight = maxHeight && maxHeight > 0 ? maxHeight : 9e4;

				// Using mainly bare JS in this function because it is going
				// to fire very often while typing, and needs to very efficient.
				function adjust() {
					var height, overflow, original;

					// the active flag keeps IE from tripping all over itself.  Otherwise
					// actions in the adjust function will cause IE to call adjust again.
					if (!active) {
						active = true;
						mirror.value = ta.value + options.append;
						mirror.style.overflowY = ta.style.overflowY;
						original = parseInt(ta.style.height,10);

						// Update the width in case the original textarea width has changed
						mirror.style.width = $ta.css('width');

						// Needed for IE to reliably return the correct scrollHeight
						mirror.scrollTop = 0;

						// Set a very high value for scrollTop to be sure the
						// mirror is scrolled all the way to the bottom.
						mirror.scrollTop = 9e4;

						height = mirror.scrollTop;
						overflow = hidden;
						if (height > maxHeight) {
							height = maxHeight;
							overflow = 'scroll';
						} else if (height < minHeight) {
							height = minHeight;
						}
						height += boxOffset;
						ta.style.overflowY = overflow;

						if (original !== height) {
							ta.style.height = height + 'px';
							if (callback) {
								options.callback.call(ta);
							}
						}
						
						// This small timeout gives IE a chance to draw it's scrollbar
						// before adjust can be run again (prevents an infinite loop).
						setTimeout(function () {
							active = false;
						}, 1);
					}
				}

				// mirror is a duplicate textarea located off-screen that
				// is automatically updated to contain the same text as the
				// original textarea.  mirror always has a height of 0.
				// This gives a cross-browser supported way getting the actual
				// height of the text, through the scrollTop property.
				while (i--) {
					mirror.style[copyStyle[i]] = $ta.css(copyStyle[i]);
				}

				$('body').append(mirror);

				if (onpropertychange in ta) {
					if (oninput in ta) {
						// Detects IE9.  IE9 does not fire onpropertychange or oninput for deletions,
						// so binding to onkeyup to catch most of those occassions.  There is no way that I
						// know of to detect something like 'cut' in IE9.
						ta[oninput] = ta.onkeyup = adjust;
					} else {
						// IE7 / IE8
						ta[onpropertychange] = adjust;
					}
				} else {
					// Modern Browsers
					ta[oninput] = adjust;

					// The textarea overflow is now hidden.  But Chrome doesn't reflow the text after the scrollbars are removed.
					// This is a hack to get Chrome to reflow it's text.
					ta.value = '';
					ta.value = value;
				}

				$(window).resize(adjust);

				// Allow for manual triggering if needed.
				$ta.bind('autosize', adjust);

				// Call adjust in case the textarea already contains text.
				adjust();
			});
		};
	} else {
		// Makes no changes for older browsers (FireFox3- and Safari4-)
		$.fn.autosize = function (callback) {
			return this;
		};
	}

}(window.jQuery || window.Zepto));