/* This script and many more are available free online at
The JavaScript Source :: http://javascript.internet.com
Created by: Brian McAllister :: http://www.frequency-decoder.com/

Further information on this script can be located on the
  author's Web site: http://www.frequency-decoder.com/

This script is distributed under a 
  "Attribution-NonCommercial-ShareAlike 2.0" license

You are free:
  1. to copy, distribute, display, and perform the work.
  2. to make derivative works.

Under the following conditions:

  1. Attribution: You must attribute the work in the manner
       specified by the author or licensor.
  2. Noncommercial: You may not use this work for commercial purposes.
  3. Share Alike*: If you alter, transform, or build upon this work,
       you may distribute the resulting work only under a   license identical to this one.
*/

var checkBoxMaster = {
  butCnt: 0,

  checkOrUncheckAll: function() {
    // Step 1: Get the checkbox group name from the button classname
    var cname = this.className;
    cname = cname.replace(/uncheckall/,"");
    cname = cname.replace(/checkall/,"");
    cname = cname.replace(' ','');

    // Step 2: Find the form element
    var form = this.parentNode;
    while(form.nodeName.toLowerCase() != "form") {
      if(!form.parentNode) break;
      form = form.parentNode;
    };

    if(form.nodeName.toLowerCase() == 'form') {
      var checkboxs = form.getElementsByTagName('input');
      // Step 3: Loop through all the checkboxs and check/uncheck the ones whose name matches the name located in Step 1.
      for(var i = 0, inp; inp = checkboxs[i]; i++) if(inp.type.toLowerCase() == 'checkbox' && inp.name.indexOf(cname) == 0) inp.checked = (this.className.search('uncheckall') == -1);
    };
  },

  createButtons: function(form, classname) {
    // Get all of the forms child divs
    var placeholder = form.getElementsByTagName('div');
    var elem = form;

    // Try to find the button placeholder div
    for(var i = 0, ph; ph = placeholder[i]; i++) {
      if(ph.className && ph.className.search('button-placeholder-'+classname) != -1) {
        elem = ph;
        break;
      };
    };

    // Button 1 - check all
    var but1 = document.createElement('input');
    but1.type = "button";
    but1.className = "checkall " + classname;
    but1.name = "button" + checkBoxMaster.butCnt++;
    but1.value = "Check All";
    but1.onclick = checkBoxMaster.checkOrUncheckAll;

    // Button 2 - uncheck all
    var but2 = document.createElement('input');
    but2.type = "button";
    but2.className = "uncheckall " + classname;
    but2.name = "button" + checkBoxMaster.butCnt++;
    but2.value = "Uncheck All";
    but2.onclick = checkBoxMaster.checkOrUncheckAll;

    // DOM inject
    elem.appendChild(but1);
    elem.appendChild(but2);
  },

  init: function() {
    // Get all the forms
    var forms = document.getElementsByTagName('form');

    // Loop through the forms
    for(var i = 0, form; form = forms[i]; i++) {

      // Make sure the form has at least one required classname
      if(!form.className || form.className.search(/fdCheckbox-[^\s]+/) == -1) continue;

      // Get all child input tags
      var inplist = form.getElementsByTagName('input');

      // Create an array of relevant classnames
      var cboxnames = form.className.match(/fdCheckbox-[^\s]+/g);

      // Loop through the classname array
      for(var k = 0, cname; cname = cboxnames[k]; k++) {

        // Get the name of the checkbox group by removing the string "fdCheckbox-" from the current classname
        cname = cname.replace("fdCheckbox-","");

        // Initiate the checkbox counter
        var cbox = 0;

        // Loop through all the inputs
        for(var j = 0, inp; inp = inplist[j]; j++) {
          // If the input is of type checkbox and has the correct name and is not disabled then increment the counter
          if(inp.type=='checkbox' && inp.disabled == false && inp.name.indexOf(cname) == 0) cbox++;
        }
        // If two or more checkboxs have been located then create the buttons (it would be daft to create the buttons for a single checkbox)
        if(cbox > 1) checkBoxMaster.createButtons(form, cname);
      }
    };
  }
};



// Multiple onload function created by: Simon Willison
// http://simonwillison.net/2004/May/26/addLoadEvent/
function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

addLoadEvent(function() {
  checkBoxMaster.init();
});