/* This script and many more are available free online at
The JavaScript Source!! http://javascript.internet.com
Created by: Chris Crenshaw | http://www.creditcarddebtnegotiation.org/ */

// validation function
function isValid(entry, a, b) {
  if (isNaN(entry.value) || (entry.value==null) || (entry.value=="") || (entry.value < a) || (entry.value > b)) {
  alert("Invalid entry. Your min payment should be between " + a + " and " + b + ".")
	entry.focus()
  entry.select()
	return false
  }
	return true
}

function isValidEspanol(entry, a, b) {
  if (isNaN(entry.value) || (entry.value==null) || (entry.value=="") || (entry.value < a) || (entry.value > b)) {
  alert("Entrada no valida. Su pago minimo deberia ser de entre " + a + " y " + b + ".")
	entry.focus()
  entry.select()
	return false
  }
	return true
}

// clear results fields when input values changed
function clearCalcs(form) {
	form.num_months.value = ""
	form.total_pay.value = ""
	form.total_int.value = ""
}

function calculate(form) {
// send entries to validation function
// exit if not valid
	if (!isValid(form.balance, 0, 200000)) {  
		return false
	} else if (!isValid(form.interest, 0, 30)) {  
		return false
	} else {         
		var init_bal = eval(form.balance.value);
	}
	if (!isValid(form.mnth_pay, init_bal*.00, init_bal)) {
		return false
  } else {
	// variables used in calculation
	var cur_bal = init_bal;		// used in loop
	var interest = eval(form.interest.value/100);
	var mnth_pay = eval(form.mnth_pay.value);
	var fin_chg = 0;			// finance charge
	var num_mnths = 0;
	var tot_int = 0;
  }
	
  while (cur_bal > 0) {
    fin_chg = cur_bal*interest/12;
    cur_bal = cur_bal - mnth_pay + fin_chg;
    num_mnths++;
			if (num_mnths > 300) {
      	alert("We are interrupting this process to prevent a hang which may result with a very high balance, high interest rate and low monthly payment.\n\nTry entering a higher monthly payment amount." )
				form.mnth_pay.focus()
				form.mnth_pay.select()
				return
      }
    tot_int += fin_chg;
  }
	
// display result
	form.num_months.value = num_mnths;
	form.total_pay.value ="$" + round(init_bal + tot_int);
	form.total_int.value ="$" + round(tot_int);
   }

function calculateEspanol(form) {
// send entries to validation function
// exit if not valid
	if (!isValidEspanol(form.balance, 0, 200000)) {  
		return false
	} else if (!isValidEspanol(form.interest, 0, 30)) {  
		return false
	} else {         
		var init_bal = eval(form.balance.value);
	}
	if (!isValidEspanol(form.mnth_pay, init_bal*.00, init_bal)) {
		return false
  } else {
	// variables used in calculation
	var cur_bal = init_bal;		// used in loop
	var interest = eval(form.interest.value/100);
	var mnth_pay = eval(form.mnth_pay.value);
	var fin_chg = 0;			// finance charge
	var num_mnths = 0;
	var tot_int = 0;
  }
	
  while (cur_bal > 0) {
    fin_chg = cur_bal*interest/12;
    cur_bal = cur_bal - mnth_pay + fin_chg;
    num_mnths++;
			if (num_mnths > 300) {
      	alert("Estamos interrumpir este proceso para evitar un bloqueo que puede resultar con un saldo muy elevado, alta tasa de interes y pagos mensuales bajos. Prueba a introducir un mayor monto de pago mensual." )
				form.mnth_pay.focus()
				form.mnth_pay.select()
				return
      }
    tot_int += fin_chg;
  }
	
// display result
	form.num_months.value = num_mnths;
	form.total_pay.value ="$" + round(init_bal + tot_int);
	form.total_int.value ="$" + round(tot_int);
   }

// round to 2 decimal places
function round(x) {
	return Math.round(x*100)/100;
}