function Reset()
{
     document.getElementById("affordableMonthlyPayment").value = "";
     document.getElementById("cash_trade").value = "";
     document.getElementById("rate").value = "";
     document.getElementById("cash_trade2").value = "";
     document.getElementById("rate2").value = "";
     document.getElementById("purchasingPower").value = "";
     document.getElementById("term").selectedIndex = 0;
     document.getElementById("term2").selectedIndex = 0;
}

function isNumber(inputStr) 
{
     for (var i=0; i<inputStr.length; i++)
     {
         var oneChar = inputStr.substring(i, i+1);
         if (oneChar < "0" || oneChar > "9") {
             return false; 
         }   
     }
     return true;
}

function Check(element)
{
     document.getElementById("purchasingPower").value = "";
     var inputStr = element.value;
     if (isNumber(inputStr)) {
         element.style.border = "#ccc solid 1px";
         calculateLoan();
     }
     else
     {
         element.style.border = "red solid 1px";
     }
}       



function calculateLoan()
{
     var trade     = parseInt(document.getElementById("cash_trade").value);

     var term      = parseInt(document.getElementById("term").options[document.getElementById("term").selectedIndex].value);
     var intrate   = parseInt(document.getElementById("rate").value) / 1200;
     var mounthly  = parseInt(document.getElementById("affordableMonthlyPayment").value);

     var loan = mounthly / (intrate / (1 - (Math.pow(1/(1 + intrate), term)))) + trade;
     //var loan = mounthly * (1 - (Math.pow(1/(1 + intrate), term))) / (intrate) + trade;

     if (!isNaN(parseInt(loan))) {
         document.getElementById("purchasingPower").value = Math.round(loan);
     }
     else document.getElementById("purchasingPower").value = 0;
}

function paymentCalcOpen(bl) {
     if (bl) document.getElementById("calculatorDiv").style.display = "block"
         else document.getElementById("calculatorDiv").style.display = "none";
}

function Check2(element)
{
     document.getElementById("resultSpan").value = "0";
     var inputStr = element.value;
     if (isNumber(inputStr)) {
         element.style.border = "#ccc solid 1px";
         calculateMonthly();
         
     }
     else
     {
         element.style.border = "red solid 1px";
     }
}

function calculateMonthly()
{   
     var trade     = parseInt(document.getElementById("cash_trade2").value);
     var loan      = parseInt(document.getElementById("loan").value);
     var term      = parseInt(document.getElementById("term2").options[document.getElementById("term2").selectedIndex].value);
     var intrate   = parseInt(document.getElementById("rate2").value) / 1200;

     var monthly = (loan - trade) * (intrate / (1 - (Math.pow(1/(1 + intrate), term))));
     //document.getElementById("resultSpan").value = intrate + '|' + trade + '|' + loan + '|' + term + '|' + monthly;
     if (monthly != null && !isNaN(monthly)) {
         document.getElementById("resultSpan").value = Math.round(monthly);
     }
     else document.getElementById("resultSpan").value = 0;
}