// lightness can vary upwards from about 110
var baseLightness = 125;
var maxAge = 100;

/**
 * Converts an HSL color value to RGB. Conversion formula
 * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
 * Assumes h, s, and l are contained in the set [0, 1] and
 * returns r, g, and b in the set [0, 255].
 *
 * @param   Number  h       The hue
 * @param   Number  s       The saturation
 * @param   Number  l       The lightness
 * @return  Array           The RGB representation
 */
function hslToRgb(h, s, l){
    var r, g, b;

    if(s == 0){
        r = g = b = l; // achromatic
    }else{
        function hue2rgb(p, q, t){
            if(t < 0) t += 1;
            if(t > 1) t -= 1;
            if(t < 1/6) return p + (q - p) * 6 * t;
            if(t < 1/2) return q;
            if(t < 2/3) return p + (q - p) * (2/3 - t) * 6;
            return p;
        }

        var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
        var p = 2 * l - q;
        r = hue2rgb(p, q, h + 1/3);
        g = hue2rgb(p, q, h);
        b = hue2rgb(p, q, h - 1/3);
    }

    return [r * 255, g * 255, b * 255];
}


log = function(message) {
    return; // remove this line to allow logging to Firebug
    if ($.browser.mozilla)
        if (window.console) {
            console.debug(message);
        } else {
            // alert(message);
        }
};


function getColorCode (n) {
    log ("Days old: " + n);

    if (n > maxAge)
        n = maxAge;
    
    var dark = baseLightness + ((255 - baseLightness) / maxAge) * (maxAge - n);
    // Modify the 30 and 254 to vary the colour - the default is a nice orange
    var array = hslToRgb(30/255, 254/255, dark / 255);
    return "rgb(" + parseInt(array[0]) + "," + parseInt(array[1]) + "," + parseInt(array[2]) + ")";
}

var months = new Array();
months['Jan'] = 0;
months['Feb'] = 1;
months['Mar'] = 2;
months['Apr'] = 3;
months['May'] = 4;
months['Jun'] = 5;
months['Jul'] = 6;
months['Aug'] = 7;
months['Sep'] = 8;
months['Oct'] = 9;
months['Nov'] = 10;
months['Dec'] = 11;
var one_day = 1000*60*60*24;

$(document).ready(function() {

    var today = new Date();
    $("table.tableBorder").each (function () {
        var dueDateCol = $("td.colHeaderLink :contains('Due')", this).parent();
        var colIndex = $("td.colHeaderLink", this).index(dueDateCol);
        if (colIndex > -1) {
            $('tr', this).each(function() {
                var dueDateStr = $(this).find("td").eq(colIndex - 1).text();
                if (dueDateStr && dueDateStr.indexOf("/") > -1) {
                    var splitDate = dueDateStr.split("/");

                    // create a new date parsing the date string - not Y2k compliant!
                    var dueDate = new Date (20 + splitDate[2], months[splitDate[1]], splitDate[0]);
                    var daysOverdue = parseInt((today - dueDate)/one_day);
                    if (dueDate - today < 0) {
                        $(this).css({'background-color': getColorCode(daysOverdue)});
                    }
                    else {
                        $(this).css({'background-color': '#FFFFFF'});
                    }
                }
            });
        }
    });
});