//driver function
function getValues() {
  //get  values the user entered
  let userLoan = document.getElementById("userLoan").value;
  let userTerm = document.getElementById("userTerm").value;
  let userRate = document.getElementById("userRate").value;

  //parse int
  let loan = parseInt(userLoan);
  let term = parseInt(userTerm);
  let rate = parseFloat(userRate);

  if (Number.isNaN(loan) || Number.isNaN(term) || Number.isNaN(rate)) {
    // one of the inputs is wrong
    let errorMsg = "Please only use numbers for:
";

    Swal.fire({
      backdrop: false,
      title: "Error!",
      html: errorMsg,
    });
  }
  let payments = generatePayments(loan, term, rate);
  displayPayments(payments);
  displayMonthPayment(loan, term, rate);
}

const numberFormatter = Intl.NumberFormat("en-US", {
  style: "currency",
  currency: "USD",
  minimumFractionDigits: 2,
});

function generatePayments(loan, term, rate) {
  //what are the imputs for this function?
  //what are the calculations?

  let totalmonthly =
    (loan * (rate / 1200)) / (1 - Math.pow(1 + rate / 1200, -term));

  //should return array of payment objects(JSON?)
  let payments = [];
  for (let index = 0; index < term; index++) {
    let previousBal = loan;
    if (index != 0) {
      previousBal = payments[index - 1].balance;
    }
    let interestPay = (previousBal * rate) / 1200;
    let princPay = totalmonthly - interestPay;
    let remainingBal = previousBal - princPay;
    let totalInterest = interestPay;
    if (index != 0) {
      totalInterest += payments[index - 1].totalInterest;
    }

    let monthPay = {
      month: index + 1,
      payment: totalmonthly,
      principal: princPay,
      interest: interestPay,
      totalInterest: totalInterest,
      balance: remainingBal,
    };
    payments.push(monthPay);
  }
  return payments;
}

function displayMonthPayment(loan, term, rate) {
  const numberFormatter = Intl.NumberFormat("en-US", {
    style: "currency",
    currency: "USD",
    minimumFractionDigits: 2,
    //2000.5 => $2000.50
  });

  let totalmonthly =
    (loan * (rate / 1200)) / (1 - Math.pow(1 + rate / 1200, -term));
  let remainingBal = loan;
  let interestPay = (remainingBal * rate) / 1200;
  let totalInterest = (rate / 100) * loan;
  let princPay = totalmonthly - interestPay;
  let cost = loan + totalInterest;

  let viewPayment = document.getElementById("totalMonthlyPayment");
  let viewPrincipal = document.getElementById("totalPrincipal");
  let viewInterest = document.getElementById("totalInterest");
  let viewTotalCost = document.getElementById("totalCost");

  viewPayment.innerHTML = numberFormatter.format(totalmonthly);
  viewPrincipal.innerHTML = numberFormatter.format(princPay);
  viewInterest.innerHTML = numberFormatter.format(totalInterest);
  viewTotalCost.innerHTML = numberFormatter.format(cost);
}

function displayPayments(payments) { 
  let body = document.getElementById("body");

  body.innerHTML = "";

  payments.forEach((element) => {
    let node = document.importNode(tempData.content, true);
    let item = node.querySelectorAll("td");

    item[0].textContent = element.month;
    item[1].textContent = numberFormatter.format(element.payment);
    item[2].textContent = numberFormatter.format(element.principal);
    item[3].textContent = numberFormatter.format(element.interest);
    item[4].textContent = numberFormatter.format(element.interest);
    item[5].textContent = numberFormatter.format(element.balance);
    body.appendChild(node);
  });
}