/*
 * EasyApplet solves three important problems when deploying Java applets in
 * hetergeneous environments:
 *
 * (1) Eliminates "Click to Activate" message in Internet Explorer.
 *     See: http://en.wikipedia.org/wiki/Eolas
 * 
 * (2) Enables the minimum JRE version required to run an applet to be set, and
 *     uses the browser's own built-in mechanism for installing plugins to
 *     install the correct JVM, if needed.
 *
 * (3) Uses the standards-compliant <object> tag, which replaces the deprecated
 *     <applet> tag in HTML 4.
 *
 * Usage: easyApplet.run({attr1:val1, attr2:val2, ...},
 *                       {param1:val1, param2:val2, ...},
 *                       minimumVersion, fallbackContent);
 */
var easyApplet = {
  run: function(attributes, parameters, minimumVersion, fallbackContent){    
    if (easyApplet.isIE()){
      easyApplet.openTagIE(attributes)
    }
    else{
      easyApplet.openTagStandard(minimumVersion || '1.4.2');
    }
    
    easyApplet.writeAttributes(attributes);
    easyApplet.writeParameters(parameters);
    document.write(fallbackContent || 'This content requires Java.');
    document.write('</object>');
  },
  
  /*
   * Creates the opening object tag for standards-compliant browsers. Requests the minumum JRE version
   * specified with minimumVersion.
   */
  openTagStandard: function(minimumVersion){
    document.write('<object type="application/x-java-applet;version=' + minimumVersion + '"');
  },
  
  /*
   * Creates the opening object tag for IE using classid and codebase attributes.
   * If these attributes are not set, EasyApplet will request that the applet be run
   * with the latest installed JRE, or JDK 1.4, whichever is higher. For more information, see:
   *
   * http://java.sun.com/javase/6/webnotes/family-clsid.html
   * http://java.sun.com/javase/6/docs/technotes/guides/deployment/deployment-guide/autodl-files.html
   */
  openTagIE: function(attributes){
    var classid = attributes['classid'] || "clsid:8AD9C840-044E-11D1-B3E9-00805F499D93"; //use latest installed JRE; 
    var codebase = attributes['codebase'] || "http://java.sun.com/products/plugin/autodl/jinstall-1_4-windows-i586.cab#Version=1,4,0,0"; //download JRE 1.4 if suitable JRE not found;
    
    document.write('<object classid="' + classid + '" codebase=' + codebase + '"');
  },
  
  writeAttributes: function(attributes){
    for (attribute in attributes){
      document.write(" ");
      document.write(attribute + "='" + attributes[attribute] + "'");
    }
    
    document.write('>');
  },
  
  writeParameters: function(parameters){
    for (parameter in parameters){
      document.write("<param name=" + parameter + " value='" + parameters[parameter] + "'>");
    }
  },
  
  isIE: function(){
    if (navigator == null) return false;
    
    return navigator.userAgent.match(/MSIE/) != null;
  }
}