/**
 * @author Zane DeBusk, John Howland
 * 
 */

Event.observe(window, 'load', function() {
	var calculator = $("calc-form");
	
	if ($("loanamt")) {
		Event.observe("loanamt", 'click', function() {
			$("loanamt").clear();
		});
	}
	
	if ($("loanterm")) {
		Event.observe("loanterm", 'click', function(){
			$("loanterm").clear();
		});
	}
	
	if ($("intrate")) {
		Event.observe("intrate", 'click', function(){
			$("intrate").clear();
		});
	}
	
	if ($("clear-button")) {
		Event.observe("clear-button", 'click', function(e){
			clearForm();
			Event.stop(e);
		});
	}
	
	if ($("calc-form")) {
		Event.observe("calc-form", 'submit', function(e){
			mortgage();
			Event.stop(e);
		});
	}
	
	function mortgage() {
		if ($F("loanamt") != "" && $F("loanterm") != "" && $F("intrate") != "") {
			var amount = $F("loanamt");
			var term = $F("loanterm") * 12;
			var interest = $F("intrate") / 1200;
			
			if (parseFloat(amount) && parseFloat(term) && parseFloat(interest)) {
				var x =(amount*(interest/(1-Math.pow((1+interest),-term))));
				var n = Math.pow(10, !2 ? 2 : 2);
				var payment = Math.round(x*n) / n;
				payment = payment.toString();
				$("payment").update(":   $" + payment);
			} else {
				$("calc-error").update("Please enter only numbers for payment calculations.");
				$("calc-error").show();
			}
		} else {
			$("calc-error").update("Please fill in each field to perform a payment calculation.");
			$("calc-error").show();
		}
	}
		
	function clearForm() {
		calculator.reset();
		$("calc-error").hide();
		$("payment").update("");
	}
});