// Author: Matt Kruse <matt@mattkruse.com>
// WWW: http://www.mattkruse.com/ 


function DynamicOptionList() {
	if (arguments.length < 2) { alert("Not enough arguments in DynamicOptionList()"); }
	
	this.target = arguments[0];
	
	this.dependencies = new Array();
	for (var i=1; i<arguments.length; i++) {
		this.dependencies[this.dependencies.length] = arguments[i];
		}
	this.form = null;	
	this.dependentValues = new Object();	
	this.defaultValues = new Object();	
	this.options = new Object();	
	this.delimiter = "|";	
	this.longestString = "";	
	this.numberOfOptions = 0;	
	this.addOptions = DynamicOptionList_addOptions;
	this.populate = DynamicOptionList_populate;
	this.setDelimiter = DynamicOptionList_setDelimiter;
	this.setDefaultOption = DynamicOptionList_setDefaultOption;
	this.printOptions = DynamicOptionList_printOptions;
	this.init = DynamicOptionList_init;
	}

function DynamicOptionList_setDelimiter(val) {
	this.delimiter = val;
	}


function DynamicOptionList_setDefaultOption(condition, val) {
	this.defaultValues[condition] = val;
	}


function DynamicOptionList_init(theform) {
	this.form = theform;
	this.populate();
	}


function DynamicOptionList_addOptions(dependentValue) {
	if (typeof this.options[dependentValue] != "object") { this.options[dependentValue] = new Array(); }
	for (var i=1; i<arguments.length; i+=2) {
		
		if (arguments[i].length > this.longestString.length) {
			this.longestString = arguments[i];
			}
		this.numberOfOptions++;
		this.options[dependentValue][this.options[dependentValue].length] = arguments[i];
		this.options[dependentValue][this.options[dependentValue].length] = arguments[i+1];
		}
	}


function DynamicOptionList_printOptions() {
    if ((navigator.appName == 'Netscape') && (parseInt(navigator.appVersion) <= 4)){
		var ret = "";
		for (var i=0; i<this.numberOfOptions; i++) { 
			ret += "<OPTION>";
			}
		ret += "<OPTION>"
		for (var i=0; i<this.longestString.length; i++) {
			ret += "_";
			}
		document.writeln(ret);
		}
	}


function DynamicOptionList_populate() {
	var theform = this.form;
	var i,j,obj,obj2;
	this.dependentValues = new Object;
	var dependentValuesInitialized = false;
	for (i=0; i<this.dependencies.length;i++) {
		var sel = theform[this.dependencies[i]];
		var selName = sel.name;
		if (!dependentValuesInitialized) {
			dependentValuesInitialized = true;
			for (j=0; j<sel.options.length; j++) {
				if (sel.options[j].selected) {
					this.dependentValues[sel.options[j].value] = true;
					}
				}
			}
		
		else {
			var tmpList = new Object();
			var newList = new Object();
			for (j=0; j<sel.options.length; j++) {
				if (sel.options[j].selected) {
					tmpList[sel.options[j].value] = true;
					}
				}
			for (obj in this.dependentValues) {
				for (obj2 in tmpList) {
					newList[obj + this.delimiter + obj2] = true;
					}
				}
			this.dependentValues = newList;
			}
		}

	var targetSel = theform[this.target];
		
	
	var targetSelected = new Object();
	for (i=0; i<targetSel.options.length; i++) {
		if (targetSel.options[i].selected) {
			targetSelected[targetSel.options[i].value] = true;
			}
		}

	targetSel.options.length = 0; // Clear all target options
		
	for (i in this.dependentValues) {
		if (typeof this.options[i] == "object") {
			var o = this.options[i];
			for (j=0; j<o.length; j+=2) {
				var text = o[j];
				var val = o[j+1];
				targetSel.options[targetSel.options.length] = new Option(text, val, false, false);
				if (this.defaultValues[i] == val) {
					targetSelected[val] = true;
					}
				}
			}
		}
	targetSel.selectedIndex=-1;
	
	
	for (i=0; i<targetSel.options.length; i++) {
		if (targetSelected[targetSel.options[i].value] != null && targetSelected[targetSel.options[i].value]==true) {
			targetSel.options[i].selected = true;
			}
		}
	}