var adjustFontCurrentSize = 0;
var adjustFontDefaultSize = 0;
var adjustFontMinSize = -1;
var adjustFontMaxSize = 2;

function setActiveStyleSheet(title) {
  var i, a, main;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title")) {
      a.disabled = true;
      if(a.getAttribute("title") == title) a.disabled = false;
    }
  }
}

function getActiveStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title") && !a.disabled) return a.getAttribute("title");
  }
  return null;
}

function getPreferredStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1
       && a.getAttribute("rel").indexOf("alt") == -1
       && a.getAttribute("title")
       ) return a.getAttribute("title");
  }
  return null;
}

function adjustFontLoadPage()
{
	adjustFontCurrentSize = adjustFontCheckSize(getCookie('currentFontSize'));
	
	if (adjustFontCurrentSize != adjustFontDefaultSize)
		adjustFontSize(adjustFontCurrentSize);
}

function adjustFontCheckSize(size)
{
	if (isNaN(parseFloat(size))) {
		size = adjustFontDefaultSize;
	}
	else if (size > adjustFontMaxSize) {
		size = adjustFontMaxSize;
	}
	else if (size < adjustFontMinSize) {
		size = adjustFontMinSize;
	}
	
	return size;
}

function adjustFontSizeIncrement(increment)
{
	adjustFontSize(adjustFontCheckSize(parseFloat(adjustFontCurrentSize) + increment));
}

function adjustFontSize(size)
{
	setActiveStyleSheet('adjustFont' + size);

	adjustFontCurrentSize = size;
	setCookie('currentFontSize', adjustFontCurrentSize, false, '/');
}

// call LoadPage function to select the appropriate font right away
window.onload = adjustFontLoadPage;


/**
 * Read the JavaScript cookies tutorial at:
 *   http://www.netspade.com/articles/javascript/cookies.xml
 */

/**
 * Sets a Cookie with the given name and value.
 *
 * name       Name of the cookie
 * value      Value of the cookie
 * [expires]  Expiration date of the cookie (default: end of current session)
 * [path]     Path where the cookie is valid (default: path of calling document)
 * [domain]   Domain where the cookie is valid
 *              (default: domain of calling document)
 * [secure]   Boolean value indicating if the cookie transmission requires a
 *              secure transmission
 */
function setCookie(name, value, expires, path, domain, secure)
{
    document.cookie= name + "=" + escape(value) +
        ((expires) ? "; expires=" + expires.toGMTString() : "") +
        ((path) ? "; path=" + path : "") +
        ((domain) ? "; domain=" + domain : "") +
        ((secure) ? "; secure" : "");
}

/**
 * Gets the value of the specified cookie.
 *
 * name  Name of the desired cookie.
 *
 * Returns a string containing value of specified cookie,
 *   or null if cookie does not exist.
 */
function getCookie(name)
{
    var dc = document.cookie;
    var prefix = name + "=";
    var begin = dc.indexOf("; " + prefix);
    if (begin == -1)
    {
        begin = dc.indexOf(prefix);
        if (begin != 0) return null;
    }
    else
    {
        begin += 2;
    }
    var end = document.cookie.indexOf(";", begin);
    if (end == -1)
    {
        end = dc.length;
    }
    return unescape(dc.substring(begin + prefix.length, end));
}

/**
 * Deletes the specified cookie.
 *
 * name      name of the cookie
 * [path]    path of the cookie (must be same as path used to create cookie)
 * [domain]  domain of the cookie (must be same as domain used to create cookie)
 */
function deleteCookie(name, path, domain)
{
    if (getCookie(name))
    {
        document.cookie = name + "=" + 
            ((path) ? "; path=" + path : "") +
            ((domain) ? "; domain=" + domain : "") +
            "; expires=Thu, 01-Jan-70 00:00:01 GMT";
    }
}