/**
* jQMinMax     http://davecardwell.co.uk/javascript/jquery/plugins/jquery-minmax/
*
* @author      Dave Cardwell <http://davecardwell.co.uk/>
* @version     0.1
*
* @projectDescription  Add min-/max- height & width support.
*
* Built on the shoulders of giants:
*   * John Resig      - http://jquery.com/
*
*
* Copyright (c) 2006 Dave Cardwell, licensed under the MIT License:
*   * http://www.opensource.org/licenses/mit-license.php
*/


new function() {
    $.minmax = {
        active: false,
        native: false
    };


    $(document).ready(function() {
        // Create a div to test for native minmax support.
        var test = document.createElement('div');
        $(test).css({
            'width': '1px',
            'min-width': '2px'
        });
        $('body').append(test);

        // In compliant browsers, the min-width of 2px should overwrite the
        // width of 1px.
        $.minmax.native = (test.offsetWidth && test.offsetWidth == 2);

        // Tidy up.
        $(test).remove();

        // Go no further if minmax is supported natively.
        if ($.minmax.native)
            return;


        // Use jQMinMax.
        $.minmax.active = true;
        // Set up the minmax jQuery expressions.
        $.minmax.expressions();


        // Use the plugin on all elements where a min/max CSS style is set.
        $('*').minmax();
    });



    /**
    * Set up the minmax jQuery expressions.
    *
    * @example $.minmax.expressions();
    *
    * @name $.minmax.expressions
    * @cat  jQMinMax
    */
    $.minmax.expressions = function() {
        // p for 'properties'.
        var p = new Array('min-width', 'min-height',
                           'max-width', 'max-height');

        // This will hold the components of an uber selector for grabbing
        // anything with a minmax value.
        var minmax = new Array();

        for (var i = 0; i < p.length; i++) {
            // Build the expression.
            var expr = "$.css(a,'" + p[i] + "')!='0px'&&"
                     + "$.css(a,'" + p[i] + "')!='auto'&&"
                     + "$.css(a,'" + p[i] + "')!=window.undefined";

            // max-width / max-height can also have the value 'none'.
            if (p[i].charAt(2) == 'x')
                expr += "&&$.css(a,'" + p[i] + "')!='none'";

            // Add the expression to jQuery.
            $.expr[':'][p[i]] = expr;

            // Add the expression to the ':minmax' expression.
            minmax[i] = '(' + expr + ')';
        }

        // Build and add the ':minmax' expression.
        $.expr[':']['minmax'] = minmax.join('||');
    };



    /**
    * Check the given elements for height/width values that fall outside
    * their min/max constraints and update them appropriately.
    *
    * @example $('#foo').minmax();
    *
    * @name $.fn.minmax();
    * @cat  jQMinMax
    */
    $.fn.minmax = function() {
        return $(this).each(function() {
            // Get the min/max constraints of the current element.
            var constraint = {
                'min-width': calculate(this, 'min-width'),
                'max-width': calculate(this, 'max-width'),
                'min-height': calculate(this, 'min-height'),
                'max-height': calculate(this, 'max-height')
            };

            // Determine its current width and height.
            var width = this.offsetWidth;
            var height = this.offsetHeight;

            var newWidth = width;
            var newHeight = height;


            // If the element is wider than its max-width...
            if (constraint['max-width'] != window.undefined
             && newWidth > constraint['max-width'])
                newWidth = constraint['max-width'];

            // If the element is/is now thinner than its min-width...
            if (constraint['min-width'] != window.undefined
             && newWidth < constraint['min-width'])
                newWidth = constraint['min-width'];

            // If the element is taller than its max-height...
            if (constraint['max-height'] != window.undefined
             && newHeight > constraint['max-height'])
                newHeight = constraint['max-height'];

            // If the element is/is now shorter than its min-height...
            if (constraint['min-height'] != window.undefined
             && newHeight < constraint['min-height'])
                newHeight = constraint['min-height'];


            // Update the proportions of the current element as required.
            if (newWidth != width)
                $(this).css('width', newWidth);
            if (newHeight != height)
                $(this).css('height', newHeight);
        });
    };



    // Calculate the computed numeric value of a CSS length value.
    function calculate(obj, p) {
        var raw = $(obj).css(p);

        // Nothing in, nothing out.
        if (raw == window.undefined || raw == 'auto')
            return window.undefined;

        var result;

        // Is it a percentage value?
        result = raw.match(/^\+?(\d*(?:\.\d+)?)%$/);
        if (result) {
            return Math.round(
                Number(
                    (
                        /width$/.test(p) ? $(obj).parent().get(0).offsetWidth
                                         : $(obj).parent().get(0).offsetHeight
                    )
                    * result[1]
                    / 100
                )
            );
        }


        // Is it a straight pixel value?
        result = raw.match(/^\+?(\d*(?:\.\d+)?)(?:px)?$/);
        if (result) {
            return Number(result[1]);
        }


        // Garbage in, nothing out.
        return window.undefined;
    }
} ();