// Basic dynamic HTML / DOM methods

var isNav4, isNav6, isIE4;

/*
 * Browser version snooper; determines your browser
 * (Navigator 4, Navigator 6, or Internet Explorer 4/5)
 */
function setBrowser()
{
    if (navigator.appVersion.charAt(0) == "4")
    {
        if (navigator.appName.indexOf("Explorer") >= 0)
        {
            isIE4 = true;
        }
        else
        {
            isNav4 = true;
        }
    }
    else if (navigator.appVersion.charAt(0) > "4")
    {
        isNav6 = true;
    }
        
}

/*
 *
 * Given a selector string, return a style object
 * by searching through stylesheets. Return null if
 * none found
 *
 */
function getStyleBySelector( selector )
{
    if (!isNav6)
    {
        return null;
    }
    var sheetList = document.styleSheets;
    var ruleList;
    var i, j;

    /* look through stylesheets in reverse order that
       they appear in the document */
    for (i=sheetList.length-1; i >= 0; i--)
    {
        ruleList = sheetList[i].cssRules;
        for (j=0; j<ruleList.length; j++)
        {
            if (ruleList[j].type == CSSRule.STYLE_RULE &&
                ruleList[j].selectorText == selector)
            {
                return ruleList[j].style;
            }   
        }
    }
    return null;
}

/*
 *
 * Given an id and a property (as strings), return
 * the given property of that id.  Navigator 6 will
 * first look for the property in a tag; if not found,
 * it will look through the stylesheet.
 *
 * Note: do not precede the id with a # -- it will be
 * appended when searching the stylesheets
 *
 */
function getIdProperty( id, property )
{
    if (isNav6)
    {
        var styleObject = document.getElementById( id );
        if (styleObject != null)
        {
            styleObject = styleObject.style;
            if (styleObject[property])
            {
                return styleObject[ property ];
            }
        }
        styleObject = getStyleBySelector( "#" + id );
        return (styleObject != null) ?
            styleObject[property] :
            null;
    }
    else if (isNav4)
    {
        return document[id][property];
    }
    else if (isIE4)
    {
        return document.all[id].style[property];
    }
}





/*
 *
 * Given an id and a property (as strings), set
 * the given property of that id to the value provided.
 *
 * The property is set directly on the tag, not in the
 * stylesheet.
 *
 */
function setIdProperty( id, property, value )
{
    if (isNav6)
    {
        var styleObject = document.getElementById( id );
        if (styleObject != null)
        {
            styleObject = styleObject.style;
            styleObject[ property ] = value;
        }
    }
    else if (isNav4)
    {
        // document.layers[tab].visibility = 'hidden';
        // document.layers[id].property = value;
        
        if (property == "visibility")
          document.layers["main"].document.layers[id].visibility = value;
    }
    else if (isIE4)
    {
         document.all[id].style[property] = value;
    }
}

/*
 *
 * Move a given id.  If additive is true,
 * then move it by xValue dots horizontally and
 * yValue units vertically.  If additive is
 * false, then move it to (xValue, yValue)
 *
 * Note: do not precede the id with a # -- it will be
 * appended when searching the stylesheets
 *
 * Note also: length units are preserved in Navigator 6
 * and Internet Explorer. That is, if left is 2cm and
 * top is 3cm, and you move to (4, 5), the left will
 * become 4cm and the top 5cm.
 *
 */
/*  function generic_move( id, xValue, yValue, additive )
{
    var left = getIdProperty(id, "left");
    var top = getIdProperty(id, "top");
    var leftMatch, topMatch;

    if (isNav4)
    {
        leftMatch = new Array( 0, left, "");
        topMatch = new Array( 0, top, "");
    }
    else if (isNav6 || isIE4 )
    {
        var splitexp = /([-0-9.]+)(\w+)/;
        leftMatch = splitexp.exec( left );
        topMatch = splitexp.exec( top );
        if (leftMatch == null || topMatch == null)
        {
            leftMatch = new Array(0, 0, "px");
            topMatch = new Array(0, 0, "px");
        }
    }
    left = ((additive) ? parseFloat( leftMatch[1] ) : 0) + xValue;
    top = ((additive) ? parseFloat( topMatch[1] ) : 0) + yValue;
    setIdProperty( id, "left", left + leftMatch[2] );
    setIdProperty( id, "top", top + topMatch[2] );
}

*/


/*
 *
 * Return a division's document
 * 
 */
function getDocument( divName )
{
    var doc;

    if (isNav4)
    {
        doc = window.document[divName].document;
    }
    else if (isNav6)
    {
        doc = document;
    }
    else if (isIE4)
    {
        doc = document;
    }
    return doc;
}




/* Find out if we're using Gecko, and if so, what version */
function geckoGetRv()
{
  if (navigator.product != 'Gecko')
  {
    return -1;
  }
  var rvValue = 0;
  var ua      = navigator.userAgent.toLowerCase();
  var rvStart = ua.indexOf('rv:');
  var rvEnd   = ua.indexOf(')', rvStart);
  var rv      = ua.substring(rvStart+3, rvEnd);
  var rvParts = rv.split('.');
  var exp     = 1;

  for (var i = 0; i < rvParts.length; i++)
  {
    var val = parseInt(rvParts[i]);
    rvValue += val / exp;
    exp *= 100;
  }

  return rvValue;
}