// ===================================================================
// Author: Matt Kruse <matt@mattkruse.com>
// WWW: http://www.mattkruse.com/
//
// NOTICE: You may use this code for any purpose, commercial or
// private, without any further permission from the author. You may
// remove this notice from your final code if you wish, however it is
// appreciated by the author if at least my web site address is kept.
//
// You may *NOT* re-distribute this code in any way except through its
// use. That means, you can include it in your product, or your web
// site, or any other form where the code is actually being used. You
// may not put the plain javascript up on your site for download or
// include it in your javascript libraries for download.
// If you wish to share this code with others, please just point them
// to the URL instead.
// Please DO NOT link directly to my .js files from your site. Copy
// the files to your server and use them there. Thank you.
// ===================================================================

// HISTORY
// ------------------------------------------------------------------
// Feb 15, 2005: Documentation Fix
// March 31, 2004: First release
/*

DESCRIPTION: This library allows you to easily create select boxes whose
contents depend on the value in a parent select box. It supports default
options, preselected options, single or multiple-select lists, multiple
form fields referencing the same list structure, form resetting, and most
importantly, it's backwards-compatible way back to Netscape 4!

COMPATABILITY: Netscape 4+, IE, Opera >5 (O5 didn't support new Option()),
and should work on all other newer browsers.

USAGE:

  // Create a new object, passing in the fields that make up the dynamic set
  // of lists.
var dol = new DynamicOptionList("Field1","Child1","Child2");

  // Or, you can create it empty, and pass in sets of select objects later
var dol = new DynamicOptionList();
dol.addDependentFields("Field1","Child1","Child2");

  // Once you have the list object defined, you can additional sets of dependent
  // fields, too. These sets will act as separate groups of related fields, but
  // will all use the same options and data.
dol.addDependentOptions("Field1","Child2-1","Child2-2");

  // By default, the script will automatically find the form where your select
  // objects exist. But you can explicitly set it if you wish, either by form
  // name or index.
dol.setFormName("MyForm");
dol.setFormIndex(1);

  // Now define the options that will exist in sub-lists. This is done in a
  // very logical way - you say for an option in the parent, populate the child
  // with specific options. When selecting which parent option you're dealing
  // with, you can either select by its value or its display text. This command
  // says, for an option in the parent list that has value="Value1", if it is
  // selected then populate the child list with the given sub-options.
dol.forValue("Value1").addOptions("Suboption1","Suboption2","Suboption3");

  // And you can also say, for an option in the parent list that has display
  // text of "Text1", if it is selected then populate the child list with the
  // given sub-options.
dol.forText("Text1").addOptions("Suboption1","Suboption2","Suboption3");

  // For multi-level lists, you just continue the chain...
  // This says, if an option with value "Value1" is selected in the first list,
  // then an option with values "Value2" is selected in the second list, populate
  // the third list with these options.
dol.forValue("Value1").forValue("Value2").addOptions("1","2","3");

  // If the options you want to add should have different values and dislplay
  // text, you can do that
dol.forValue("Value1").addOptionsTextValue("Text2","Value2");

  // When an option is selected from the first list, and the options in the
  // second list are populated, you may want to have one of the options in the
  // child list be selected by default.
dol.forValue("Value1").setDefaultOptions("MyValue");

  // When the page first loads, you may set the values of the dependent select
  // lists to be selected by default. For example, when a user is editing an
  // existing record where they've already selected from the parent/child
  // relationships. This is different from the default option in that this
  // value is only selected when the page LOADS. If the user changes selections,
  // this will be lost.
dol.forField("Field1").setValues("MyPreselectedValue");

  // By default, if there are is no option which should be selected in the child
  // list, the code will automatically select the first option in the list. If
  // you want it to instead set selectedIndex = -1 (nothing selected - works in
  // most browsers but not all) than you can tell it to do that instead
dol.selectFirstOption = false;

// MODIFYING THE HTML
// If you are supporting Netscape 4.x browsers, you will need to insert a call to
// the library to populate options. This is because Netscape4 will not expand the
// size of the select box as new options are added, so you have to "pad" the list
// with blank options in order for it to work right.
// This is the ONLY change you should need to make to your HTML. To do this, just
// add a javascript block between your <select> </select> tags like this:

<select name="list1"><script>dol.printOptions("list1")</script></select>

// You only need to pass it the name of the select options that it should print
// options for.


NOTES:
 - There seems to be an issue with Netscape6, if you hit Reload on the page. It
   doesn't happen every time, and I can't figure out why it happens at all.

 - If your select objects have onChange handlers in them, you'll need to manually
   add a call to the DynamicOptionList code to trigger the population of the child
   list. For example,

   <select onChange="yourfunction(); dol.change(this)">

*/
// Global objects to keep track of DynamicOptionList objects created on the page
var dynamicOptionListCount=0;
var dynamicOptionListObjects = new Array();

// Init call to setup lists after page load. One call to this function sets up all lists.
function initDynamicOptionLists() {
  // init each DynamicOptionList object
  for (var i=0; i<dynamicOptionListObjects.length; i++) {
    var dol = dynamicOptionListObjects[i];

    // Find the form associated with this list
    if (dol.formName!=null) {
      dol.form = document.forms[dol.formName];
    }
    else if (dol.formIndex!=null) {
      dol.form = document.forms[dol.formIndex];
    }
    else {
      // Form wasn't set manually, so go find it!
      // Search for the first form element name in the lists
      var name = dol.fieldNames[0][0];
      for (var f=0; f<document.forms.length; f++) {
        if (typeof(document.forms[f][name])!="undefined") {
          dol.form = document.forms[f];
          break;
        }
      }
      if (dol.form==null) {
        alert("ERROR: Couldn't find form element "+name+" in any form on the page! Init aborted"); return;
      }
    }

    // Form is found, now set the onchange attributes of each dependent select box
    for (var j=0; j<dol.fieldNames.length; j++) {
      // For each set of field names...
      for (var k=0; k<dol.fieldNames[j].length-1; k++) {
        // For each field in the set...
        var selObj = dol.form[dol.fieldNames[j][k]];
        if (typeof(selObj)=="undefined") { alert("Select box named "+dol.fieldNames[j][k]+" could not be found in the form. Init aborted"); return; }
        // Map the HTML options in the first select into the options we created
        if (k==0) {
          if (selObj.options!=null) {
            for (l=0; l<selObj.options.length; l++) {
              var sopt = selObj.options[l];
              var m = dol.findMatchingOptionInArray(dol.options,sopt.text,sopt.value,false);
              if (m!=null) {
                var reselectForNN6 = sopt.selected;
                var m2 = new Option(sopt.text, sopt.value, sopt.defaultSelected, sopt.selected);
                m2.selected = sopt.selected; // For some reason I need to do this to make NN4 happy
                m2.defaultSelected = sopt.defaultSelected;
                m2.DOLOption = m;
                selObj.options[l] = m2;
                selObj.options[l].selected = reselectForNN6; // Reselect this option for NN6 to be happy. Yuck.
              }
            }
          }
        }
        if (selObj.onchange==null) {
          // We only modify the onChange attribute if it's empty! Otherwise do it yourself in your source!
          selObj.onchange = new Function("dynamicOptionListObjects["+dol.index+"].change(this)");
        }
      }
    }
  }
  // Set the preselectd options on page load
  resetDynamicOptionLists();
}

// This function populates lists with the preselected values.
// It's pulled out into a separate function so it can be hooked into a 'reset' button on a form
// Optionally passed a form object which should be the only form reset
function resetDynamicOptionLists(theform) {
  // reset each DynamicOptionList object
  for (var i=0; i<dynamicOptionListObjects.length; i++) {
    var dol = dynamicOptionListObjects[i];
    if (typeof(theform)=="undefined" || theform==null || theform==dol.form) {
      for (var j=0; j<dol.fieldNames.length; j++) {
        dol.change(dol.form[dol.fieldNames[j][0]],true); // Second argument says to use preselected values rather than default values
      }
    }
  }
}

// An object to represent an Option() but just for data-holding
function DOLOption(text,value,defaultSelected,selected) {
  this.text = text;
  this.value = value;
  this.defaultSelected = defaultSelected;
  this.selected = selected;
  this.options = new Array(); // To hold sub-options
  return this;
}

// DynamicOptionList CONSTRUCTOR
function DynamicOptionList() {
  this.form = null;// The form this list belongs to
  this.options = new Array();// Holds the options of dependent lists
  this.longestString = new Array();// Longest string that is currently a potential option (for Netscape)
  this.numberOfOptions = new Array();// The total number of options that might be displayed, to build dummy options (for Netscape)
  this.currentNode = null;// The current node that has been selected with forValue() or forText()
  this.currentField = null;// The current field that is selected to be used for setValue()
  this.currentNodeDepth = 0;// How far down the tree the currentNode is
  this.fieldNames = new Array();// Lists of dependent fields which use this object
  this.formIndex = null;// The index of the form to associate with this list
  this.formName = null;// The name of the form to associate with this list
  this.fieldListIndexes = new Object();// Hold the field lists index where fields exist
  this.fieldIndexes = new Object();// Hold the index within the list where fields exist
  this.selectFirstOption = true;// Whether or not to select the first option by default if no options are default or preselected, otherwise set the selectedIndex = -1
  this.numberOfOptions = new Array();// Store the max number of options for a given option list
  this.longestString = new Array();// Store the longest possible string
  this.values = new Object(); // Will hold the preselected values for fields, by field name

  // Method mappings
  this.forValue = DOL_forValue;
  this.forText = DOL_forText;
  this.forField = DOL_forField;
  this.forX = DOL_forX;
  this.addOptions = DOL_addOptions;
  this.addOptionsTextValue = DOL_addOptionsTextValue;
  this.setDefaultOptions = DOL_setDefaultOptions;
  this.setValues = DOL_setValues;
  this.setValue = DOL_setValues;
  this.setFormIndex = DOL_setFormIndex;
  this.setFormName = DOL_setFormName;
  this.printOptions = DOL_printOptions;
  this.addDependentFields = DOL_addDependentFields;
  this.change = DOL_change;
  this.child = DOL_child;
  this.selectChildOptions = DOL_selectChildOptions;
  this.populateChild = DOL_populateChild;
  this.change = DOL_change;
  this.addNewOptionToList = DOL_addNewOptionToList;
  this.findMatchingOptionInArray = DOL_findMatchingOptionInArray;

  // Optionally pass in the dependent field names
  if (arguments.length > 0) {
    // Process arguments and add dependency groups
    for (var i=0; i<arguments.length; i++) {
      this.fieldListIndexes[arguments[i].toString()] = this.fieldNames.length;
      this.fieldIndexes[arguments[i].toString()] = i;
    }
    this.fieldNames[this.fieldNames.length] = arguments;
  }

  // Add this object to the global array of dynamicoptionlist objects
  this.index = window.dynamicOptionListCount++;
  window["dynamicOptionListObjects"][this.index] = this;
}

// Given an array of Option objects, search for an existing option that matches value, text, or both
function DOL_findMatchingOptionInArray(a,text,value,exactMatchRequired) {
  if (a==null || typeof(a)=="undefined") { return null; }
  var value_match = null; // Whether or not a value has been matched
  var text_match = null; // Whether or not a text has been matched
  for (var i=0; i<a.length; i++) {
    var opt = a[i];
    // If both value and text match, return it right away
    if (opt.value==value && opt.text==text) { return opt; }
    if (!exactMatchRequired) {
      // If value matches, store it until we complete scanning the list
      if (value_match==null && value!=null && opt.value==value) {
        value_match = opt;
      }
      // If text matches, store it for later
      if (text_match==null && text!=null && opt.text==text) {
        text_match = opt;
      }
    }
  }
  return (value_match!=null)?value_match:text_match;
}

// Util function used by forValue and forText
function DOL_forX(s,type) {
  if (this.currentNode==null) { this.currentNodeDepth=0; }
  var useNode = (this.currentNode==null)?this:this.currentNode;
  var o = this.findMatchingOptionInArray(useNode["options"],(type=="text")?s:null,(type=="value")?s:null,false);
  if (o==null) {
    o = new DOLOption(null,null,false,false);
    o[type] = s;
    useNode.options[useNode.options.length] = o;
  }
  this.currentNode = o;
  this.currentNodeDepth++;
  return this;
}

// Set the portion of the list structure that is to be used by a later operation like addOptions
function DOL_forValue(s) { return this.forX(s,"value"); }

// Set the portion of the list structure that is to be used by a later operation like addOptions
function DOL_forText(s) { return this.forX(s,"text"); }

// Set the field to be used for setValue() calls
function DOL_forField(f) { this.currentField = f; return this; }

// Create and add an option to a list, avoiding duplicates
function DOL_addNewOptionToList(a, text, value, defaultSelected) {
  var o = new DOLOption(text,value,defaultSelected,false);
  // Add the option to the array
  if (a==null) { a = new Array(); }
  for (var i=0; i<a.length; i++) {
    if (a[i].text==o.text && a[i].value==o.value) {
      if (o.selected) {
        a[i].selected=true;
      }
      if (o.defaultSelected) {
        a[i].defaultSelected = true;
      }
      return a;
    }
  }
  a[a.length] = o;
}

// Add sub-options to the currently-selected node, with the same text and value for each option
function DOL_addOptions() {
  if (this.currentNode==null) { this.currentNode = this; }
  if (this.currentNode["options"] == null) { this.currentNode["options"] = new Array(); }
  for (var i=0; i<arguments.length; i++) {
    var text = arguments[i];
    this.addNewOptionToList(this.currentNode.options,text,text,false);
    if (typeof(this.numberOfOptions[this.currentNodeDepth])=="undefined") {
      this.numberOfOptions[this.currentNodeDepth]=0;
    }
    if (this.currentNode.options.length > this.numberOfOptions[this.currentNodeDepth]) {
      this.numberOfOptions[this.currentNodeDepth] = this.currentNode.options.length;
    }
    if (typeof(this.longestString[this.currentNodeDepth])=="undefined" || (text.length > this.longestString[this.currentNodeDepth].length)) {
      this.longestString[this.currentNodeDepth] = text;
    }
  }
  this.currentNode = null;
  this.currentNodeDepth = 0;
}

// Add sub-options to the currently-selected node, specifying separate text and values for each option
function DOL_addOptionsTextValue() {
  if (this.currentNode==null) { this.currentNode = this; }
  if (this.currentNode["options"] == null) { this.currentNode["options"] = new Array(); }
  for (var i=0; i<arguments.length; i++) {
    var text = arguments[i++];
    var value = arguments[i];
    this.addNewOptionToList(this.currentNode.options,text,value,false);
    if (typeof(this.numberOfOptions[this.currentNodeDepth])=="undefined") {
      this.numberOfOptions[this.currentNodeDepth]=0;
    }
    if (this.currentNode.options.length > this.numberOfOptions[this.currentNodeDepth]) {
      this.numberOfOptions[this.currentNodeDepth] = this.currentNode.options.length;
    }
    if (typeof(this.longestString[this.currentNodeDepth])=="undefined" || (text.length > this.longestString[this.currentNodeDepth].length)) {
      this.longestString[this.currentNodeDepth] = text;
    }
  }
  this.currentNode = null;
  this.currentNodeDepth = 0;
}

// Find the first dependent list of a select box
// If it's the last list in a chain, return null because there are no children
function DOL_child(obj) {
  var listIndex = this.fieldListIndexes[obj.name];
  var index = this.fieldIndexes[obj.name];
  if (index < (this.fieldNames[listIndex].length-1)) {
    return this.form[this.fieldNames[listIndex][index+1]];
  }
  return null;
}

// Set the options which should be selected by default for a certain value in the parent
function DOL_setDefaultOptions() {
  if (this.currentNode==null) { this.currentNode = this; }
  for (var i=0; i<arguments.length; i++) {
    var o = this.findMatchingOptionInArray(this.currentNode.options,null,arguments[i],false);
    if (o!=null) {
      o.defaultSelected = true;
    }
  }
  this.currentNode = null;
}

// Set the options which should be selected when the page loads. This is different than the default value and ONLY applies when the page LOADS
function DOL_setValues() {
  if (this.currentField==null) {
    alert("Can't call setValues() without using forField() first!");
    return;
  }
  if (typeof(this.values[this.currentField])=="undefined") {
    this.values[this.currentField] = new Object();
  }
  for (var i=0; i<arguments.length; i++) {
    this.values[this.currentField][arguments[i]] = true;
  }
  this.currentField = null;
}

// Manually set the form for the object using an index
function DOL_setFormIndex(i) {
  this.formIndex = i;
}

// Manually set the form for the object using a form name
function DOL_setFormName(n) {
  this.formName = n;
}

// Print blank <option> objects for Netscape4, since it refuses to grow or shrink select boxes for new options
function DOL_printOptions(name) {
  // Only need to write out "dummy" options for Netscape4
    if ((navigator.appName == 'Netscape') && (parseInt(navigator.appVersion) <= 4)){
    var index = this.fieldIndexes[name];
    var ret = "";
    if (typeof(this.numberOfOptions[index])!="undefined") {
      for (var i=0; i<this.numberOfOptions[index]; i++) {
        ret += "<OPTION>";
      }
    }
    ret += "<OPTION>";
    if (typeof(this.longestString[index])!="undefined") {
      for (var i=0; i<this.longestString[index].length; i++) {
        ret += "_";
      }
    }
    document.writeln(ret);
  }
}

// Add a list of field names which use this option-mapping object.
// A single mapping object may be used by multiple sets of fields
function DOL_addDependentFields() {
  for (var i=0; i<arguments.length; i++) {
    this.fieldListIndexes[arguments[i].toString()] = this.fieldNames.length;
    this.fieldIndexes[arguments[i].toString()] = i;
  }
  this.fieldNames[this.fieldNames.length] = arguments;
}

// Called when a parent select box is changed. It populates its direct child, then calls change on the child object to continue the population.
function DOL_change(obj, usePreselected) {
  if (usePreselected==null || typeof(usePreselected)=="undefined") { usePreselected = false; }
  var changedListIndex = this.fieldListIndexes[obj.name];
  var changedIndex = this.fieldIndexes[obj.name];
  var child = this.child(obj);
  if (child == null) { return; } // No child, no need to continue
  if (obj.type == "select-one") {
    // Treat single-select differently so we don't have to scan the entire select list, which could potentially speed things up
    if (child.options!=null) {
      child.options.length=0; // Erase all the options from the child so we can re-populate
    }
    if (obj.options!=null && obj.options.length>0 && obj.selectedIndex>=0) {
      var o = obj.options[obj.selectedIndex];
      this.populateChild(o.DOLOption,child,usePreselected);
      this.selectChildOptions(child,usePreselected);
    }
  }
  else if (obj.type == "select-multiple") {
    // For each selected value in the parent, find the options to fill in for this list
    // Loop through the child list and keep track of options that are currently selected
    var currentlySelectedOptions = new Array();
    if (!usePreselected) {
      for (var i=0; i<child.options.length; i++) {
        var co = child.options[i];
        if (co.selected) {
          this.addNewOptionToList(currentlySelectedOptions, co.text, co.value, co.defaultSelected);
        }
      }
    }
    child.options.length=0;
    if (obj.options!=null) {
      var obj_o = obj.options;
      // For each selected option in the parent...
      for (var i=0; i<obj_o.length; i++) {
        if (obj_o[i].selected) {
          // if option is selected, add its children to the list
           this.populateChild(obj_o[i].DOLOption,child,usePreselected);
        }
      }
      // Now go through and re-select any options which were selected before
      var atLeastOneSelected = false;
      if (!usePreselected) {
        for (var i=0; i<child.options.length; i++) {
          var m = this.findMatchingOptionInArray(currentlySelectedOptions,child.options[i].text,child.options[i].value,true);
          if (m!=null) {
            child.options[i].selected = true;
            atLeastOneSelected = true;
          }
        }
      }
      if (!atLeastOneSelected) {
        this.selectChildOptions(child,usePreselected);
      }
    }
  }
  // Change all the way down the chain
  this.change(child,usePreselected);
  child.disabled=(child.options.length==0);
}
function DOL_populateChild(dolOption,childSelectObj,usePreselected) {
  // If this opton has sub-options, populate the child list with them
  if (dolOption!=null && dolOption.options!=null) {
    for (var j=0; j<dolOption.options.length; j++) {
      var srcOpt = dolOption.options[j];
      if (childSelectObj.options==null) { childSelectObj.options = new Array(); }
      // Put option into select list
      var duplicate = false;
      var preSelectedExists = false;
      for (var k=0; k<childSelectObj.options.length; k++) {
        var csi = childSelectObj.options[k];
        if (csi.text==srcOpt.text && csi.value==srcOpt.value) {
          duplicate = true;
          break;
        }
      }
      if (!duplicate) {
        var newopt = new Option(srcOpt.text, srcOpt.value, false, false);
        newopt.selected = false; // Again, we have to do these two statements for NN4 to work
        newopt.defaultSelected = false;
        newopt.DOLOption = srcOpt;
        childSelectObj.options[childSelectObj.options.length] = newopt;
      }
    }
  }
}

// Once a child select is populated, go back over it to select options which should be selected
function DOL_selectChildOptions(obj,usePreselected) {
  // Look to see if any options are preselected=true. If so, then set then selected if usePreselected=true, otherwise set defaults
  var values = this.values[obj.name];
  var preselectedExists = false;
  if (usePreselected && values!=null && typeof(values)!="undefined") {
    for (var i=0; i<obj.options.length; i++) {
      var v = obj.options[i].value;
      if (v!=null && values[v]!=null && typeof(values[v])!="undefined") {
        preselectedExists = true;
        break;
      }
    }
  }
  // Go back over all the options to do the selection
  var atLeastOneSelected = false;
  for (var i=0; i<obj.options.length; i++) {
    var o = obj.options[i];
    if (preselectedExists && o.value!=null && values[o.value]!=null && typeof(values[o.value])!="undefined") {
      o.selected = true;
      atLeastOneSelected = true;
    }
    else if (!preselectedExists && o.DOLOption!=null && o.DOLOption.defaultSelected) {
      o.selected = true;
      atLeastOneSelected = true;
    }
    else {
      o.selected = false;
    }
  }
  // If nothing else was selected, select the first one by default
  if (this.selectFirstOption && !atLeastOneSelected && obj.options.length>0) {
    obj.options[0].selected = true;
  }
  else if (!atLeastOneSelected &&  obj.type=="select-one") {
    obj.selectedIndex = -1;
  }
}