/**
* TextAreaExpander plugin for jQuery
* v1.0
* Expands or contracts a textarea height depending on the
* quatity of content entered by the user in the box.
*
* By Craig Buckler, Optimalworks.net
*
* As featured on SitePoint.com:
* http://www.sitepoint.com/blogs/2009/07/29/build-auto-expanding-textarea-1/
*
* Please use as you wish at your own risk.
*/

/**
* Usage:
*
* From JavaScript, use:
*     $(<node>).TextAreaExpander(<minHeight>, <maxHeight>);
*     where:
*       <node> is the DOM node selector, e.g. "textarea"
*       <minHeight> is the minimum textarea height in pixels (optional)
*       <maxHeight> is the maximum textarea height in pixels (optional)
*
* Alternatively, in you HTML:
*     Assign a class of "expand" to any <textarea> tag.
*     e.g. <textarea name="textarea1" rows="3" cols="40" class="expand"></textarea>
*
*     Or assign a class of "expandMIN-MAX" to set the <textarea> minimum and maximum height.
*     e.g. <textarea name="textarea1" rows="3" cols="40" class="expand50-200"></textarea>
*     The textarea will use an appropriate height between 50 and 200 pixels.
*/

(function($) {

    // jQuery plugin definition
    $.fn.TextAreaExpander = function(minHeight, maxHeight) {

        var hCheck = !($.browser.msie || $.browser.opera);

        // resize a textarea
        function ResizeTextarea(e) {

            // event or initialize element?
            e = e.target || e;

            // find content length and box width
            var vlen = e.value.length, ewidth = e.offsetWidth;
            if (vlen != e.valLength || ewidth != e.boxWidth) {

                if (hCheck && (vlen < e.valLength || ewidth != e.boxWidth)) e.style.height = "0px";
                var h = Math.max(e.expandMin, Math.min(e.scrollHeight, e.expandMax));

                e.style.overflow = (e.scrollHeight > h ? "auto" : "hidden");
                e.style.height = h + "px";

                e.valLength = vlen;
                e.boxWidth = ewidth;
            }

            return true;
        };

        // initialize
        this.each(function() {

            // is a textarea?
            if (this.nodeName.toLowerCase() != "textarea") return;

            // set height restrictions
            var p = this.className.match(/expand(\d+)\-*(\d+)*/i);
            this.expandMin = minHeight || (p ? parseInt('0' + p[1], 10) : 0);
            this.expandMax = maxHeight || (p ? parseInt('0' + p[2], 10) : 99999);

            // initial resize
            ResizeTextarea(this);

            // zero vertical padding and add events
            if (!this.Initialized) {
                this.Initialized = true;
                $(this).css("padding-top", 0).css("padding-bottom", 0);
                $(this).bind("keyup", ResizeTextarea).bind("focus", ResizeTextarea);
            }
        });

        return this;
    };

})(jQuery);