/*
 * jQuery Keyboard Navigation Plugin - Current
 *   http://www.amountaintop.com/projects/keynav/
 *
 * To use, download this file to your server, save as keynav.js,
 * and add this HTML into the <head>...</head> of your web page:
 *   <script type="text/javascript" src="keynav.js"></script>
 *
 * Copyright (c) 2006 Mike Hostetler <http://www.amountaintop.com/>
 * Licensed under the MIT License:
 *   http://www.opensource.org/licenses/mit-license.php
 */
$.keynav = new Object();

$.fn.keynav = function (onClass,offClass) {
    //Initialization
    var kn = $.keynav;
    if(!kn.init) {
        kn.el = new Array();

        $(document).keydown(function(e) {
            var key = 0;
            if (e == null) {
                key = event.keyCode;
            } else { // mozilla
                key = e.which;
            }
            switch(key) {
                case 37:
                   // $.keynav.goLeft();
                    break;
                case 38:
                    $.keynav.goUp();
                    return false;
                    break;
                case 39:
                   // $.keynav.goRight();
                    break;
                case 40:
                    $.keynav.goDown();
                    return false;
                    break;
                case 13:
                  //  $.keynav.activate();
                    break;
            }
        });
        kn.init = true;
    }

    return this.each(function() {
        $.keynav.reg(this,onClass,offClass);
    });
}
$.fn.keynav_sethover = function(onClass,offClass) {
    return this.each(function() {
        this.onClass = onClass;
        this.offClass = offClass;
    });
}

$.keynav.reset = function() {
    var kn = $.keynav;
    kn.el = new Array();
}

$.keynav.reg = function(e,onClass,offClass) {
    var kn = $.keynav;
    e.pos = $.keynav.getPos(e);
    e.onClass = onClass;
    e.offClass = offClass;
    e.onmouseover = function (e) {
        $.keynav.setActive(this);
    };
    kn.el.push(e);
}
$.keynav.setActive = function(e) {
    var kn = $.keynav;
    var cur = $.keynav.getCurrent();
    $(cur).trigger('blur');
    for(var i=0;i<kn.el.length;i++) {
        var tmp = kn.el[i];
        $(tmp).removeClass(tmp.onClass).addClass(tmp.offClass);
    }
    $(e).removeClass(e.offClass).addClass(e.onClass);
    $(e).trigger('focus');
    kn.currentEl = e;
}
$.keynav.getCurrent = function () {
    var kn = $.keynav;
    if(kn.currentEl) {
        var cur = kn.currentEl;
    }
    else {
        var cur = kn.el[0];
    }
    return cur;
}
$.keynav.quad = function(cur,fQuad) {
    var kn = $.keynav;
    var quad = Array();
    for(i=0;i<kn.el.length;i++) {
        var el = kn.el[i];
        if(cur == el) continue;
        if(fQuad((cur.pos.cx - el.pos.cx),(cur.pos.cy - el.pos.cy)))
            quad.push(el);
    }
    return quad;
}
$.keynav.activateClosest = function(cur,quad) {
    var closest;
    var od = 1000000;
    var nd = 0;
    var found = false;
    for(i=0;i<quad.length;i++) {
        var e = quad[i];
        nd = Math.sqrt(Math.pow(cur.pos.cx-e.pos.cx,2)+Math.pow(cur.pos.cy-e.pos.cy,2));
        if(nd < od) {
            closest = e;
            od = nd;
            found = true;
        }
    }
    if(found)
        $.keynav.setActive(closest);
}
$.keynav.goLeft = function () {
    var cur = $.keynav.getCurrent();
    var quad = $.keynav.quad(cur,function (dx,dy) { 
        if((dy >= 0) && (Math.abs(dx) - dy) <= 0)
            return true;	
        else
            return false;
    });
    $.keynav.activateClosest(cur,quad);
}
$.keynav.goRight = function () {
    var cur = $.keynav.getCurrent();
    var quad = $.keynav.quad(cur,function (dx,dy) { 
        if((dy <= 0) && (Math.abs(dx) + dy) <= 0)
            return true;	
        else
            return false;
    });
    $.keynav.activateClosest(cur,quad);
}

$.keynav.goUp = function () {
    var cur = $.keynav.getCurrent();
    var quad = $.keynav.quad(cur,function (dx,dy) { 
        if((dx >= 0) && (Math.abs(dy) - dx) <= 0)
            return true;	
        else
            return false;
    });
    $.keynav.activateClosest(cur,quad);
}

$.keynav.goDown = function () {
    var cur = $.keynav.getCurrent();
    var quad = $.keynav.quad(cur,function (dx,dy) { 
        if((dx <= 0) && (Math.abs(dy) + dx) <= 0)
            return true;	
        else
            return false;
    });
    $.keynav.activateClosest(cur,quad);
    
}

$.keynav.activate = function () {
    var kn = $.keynav;
    $(kn.currentEl).trigger('click');
}

/**
   * This function was taken from Stefan's exellent interface plugin
   * http://www.eyecon.ro/interface/
   * 
   * I included it in this library's namespace because the functions aren't
   * quite the same.
   */
$.keynav.getPos = function (e)
{
    var l = 0;
    var t  = 0;
    var w = $.intval($.css(e,'width'));
    var h = $.intval($.css(e,'height'));
    while (e.offsetParent){
        l += e.offsetLeft + (e.currentStyle?$.intval(e.currentStyle.borderLeftWidth):0);
        t += e.offsetTop  + (e.currentStyle?$.intval(e.currentStyle.borderTopWidth):0);
        e = e.offsetParent;
    }
    l += e.offsetLeft + (e.currentStyle?$.intval(e.currentStyle.borderLeftWidth):0);
    t += e.offsetTop  + (e.currentStyle?$.intval(e.currentStyle.borderTopWidth):0);
    var cx = Math.round(t+(h/2));
    var cy = Math.round(l+(w/2));
    return {
        x:l, 
        y:t, 
        w:w, 
        h:h, 
        cx:cx, 
        cy:cy
    };
};

/**
   * This function was taken from Stefan's exellent interface plugin
   * http://www.eyecon.ro/interface/
   */
$.intval = function (v)
{
    v = parseInt(v);
    return isNaN(v) ? 0 : v;
};

