Please enter valid numbers in all fields.
';
if(dtiChart) dtiChart.destroy();
return;
}
const monthlyIncome = annualIncome / 12;
const totalExistingDebt = primaryMortgage + otherDebts;
const maxTotalDebtAllowed = monthlyIncome * (configData.maxDtiRatio / 100);
const availableForNewMortgage = maxTotalDebtAllowed - totalExistingDebt;
if (availableForNewMortgage <= 0) {
renderResults(0, 0);
updateChart(monthlyIncome, totalExistingDebt, 0);
return;
}
// Reverse mortgage calculation to find loan amount
const monthlyInterestRate = (configData.interestRate / 100) / 12;
const numberOfPayments = configData.loanTermYears * 12;
// Estimate P&I portion of the new mortgage payment
// Assuming T&I is roughly 25% of the PITI payment for estimation
const estimatedPrincipalAndInterest = availableForNewMortgage * 0.75;
const maxLoanAmount = estimatedPrincipalAndInterest * ( (Math.pow(1 + monthlyInterestRate, numberOfPayments) - 1) / (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) );
const affordableHomePrice = maxLoanAmount + downPayment;
const estimatedMonthlyPayment = availableForNewMortgage;
renderResults(affordableHomePrice, estimatedMonthlyPayment);
updateChart(monthlyIncome, totalExistingDebt, estimatedMonthlyPayment);
}
function renderResults(price, payment) {
resultsContent.innerHTML = `
Affordable Second Home Price
$${price.toLocaleString('en-US', {maximumFractionDigits: 0})}
Estimated Monthly Payment
$${payment.toLocaleString('en-US', {maximumFractionDigits: 0})}
(Principal, Interest, Taxes & Insurance)
`;
}
function updateChart(monthlyIncome, existingDebt, newMortgage) {
const ctx = document.getElementById('dtiChart').getContext('2d');
const totalDebt = existingDebt + newMortgage;
const dtiRatio = (totalDebt / monthlyIncome) * 100;
if (dtiChart) {
dtiChart.destroy();
}
dtiChart = new Chart(ctx, {
type: 'doughnut',
data: {
labels: ['Primary Home', 'New Second Home', 'Other Debts', 'Remaining Income'],
datasets: [{
data: [
document.getElementById('primary-mortgage').value,
newMortgage,
document.getElementById('other-debts').value,
monthlyIncome - totalDebt
],
backgroundColor: ['#0D47A1', '#FFC107', '#FF7043', '#CFD8DC'],
}]
},
options: {
responsive: true,
plugins: {
legend: { position: 'top' },
title: { display: true, text: `Total Debt-to-Income (DTI): ${dtiRatio.toFixed(1)}%` }
}
}
});
}
function renderConfig() {
configTbody.innerHTML = `
| Second Home Interest Rate | |
| Loan Term (years) | |
| Annual Property Tax Rate | |
| Annual Home Insurance Rate | |
| Max Debt-to-Income (DTI) Ratio | |
`;
}
window.updateConfig = function(element) {
const { prop } = element.dataset;
const value = parseFloat(element.value);
if (isNaN(value)) return;
configData[prop] = value;
calculateAffordability();
}
// --- TAB & NAVIGATION ---
window.openTab = function(evt, tabName) {
const tabContents = document.getElementsByClassName("tab-content");
Array.from(tabContents).forEach(tab => tab.style.display = "none");
const tabButtons = document.getElementsByClassName("tab-btn");
Array.from(tabButtons).forEach(btn => btn.classList.remove("active"));
document.getElementById(tabName).style.display = "block";
if (evt) {
evt.currentTarget.classList.add("active");
} else {
const btnToActivate = Array.from(tabButtons).find(btn => btn.getAttribute('onclick').includes(`'${tabName}'`));
if (btnToActivate) btnToActivate.classList.add("active");
}
updateNavButtons();
}
window.navigateTabs = function(direction) {
const tabs = Array.from(document.querySelectorAll('.tab-btn'));
const activeTabIndex = tabs.findIndex(tab => tab.classList.contains('active'));
let newIndex = (direction === 'next')
? (activeTabIndex + 1) % tabs.length
: (activeTabIndex - 1 + tabs.length) % tabs.length;
tabs[newIndex].click();
}
function updateNavButtons() {
const tabs = Array.from(document.querySelectorAll('.tab-btn'));
const activeTabIndex = tabs.findIndex(tab => tab.classList.contains('active'));
document.getElementById('prev-btn').style.visibility = activeTabIndex === 0 ? 'hidden' : 'visible';
document.getElementById('next-btn').style.visibility = activeTabIndex === tabs.length - 1 ? 'hidden' : 'visible';
}
// --- PDF DOWNLOAD ---
if(downloadPdfBtn) {
downloadPdfBtn.addEventListener('click', function() {
const { jsPDF } = window.jspdf;
const contentToDownload = document.getElementById('results-to-download');
if (!contentToDownload || !document.querySelector('.value')) {
console.warn("Please generate an estimate before downloading.");
return;
}
const originalButtonText = downloadPdfBtn.innerHTML;
downloadPdfBtn.innerHTML = 'Generating...';
downloadPdfBtn.disabled = true;
html2canvas(contentToDownload, { scale: 2, useCORS: true }).then(canvas => {
const imgData = canvas.toDataURL('image/png');
const pdf = new jsPDF({ orientation: 'p', unit: 'mm', format: 'a4' });
const pdfWidth = pdf.internal.pageSize.getWidth();
const imgProps = pdf.getImageProperties(imgData);
const imgHeight = (imgProps.height * pdfWidth) / imgProps.width;
pdf.addImage(imgData, 'PNG', 10, 10, pdfWidth - 20, imgHeight > 0 ? imgHeight - 20 : 0);
pdf.save('Second-Home-Affordability.pdf');
}).catch(err => {
console.error("Error generating PDF:", err);
}).finally(() => {
downloadPdfBtn.innerHTML = originalButtonText;
downloadPdfBtn.disabled = false;
});
});
}
// --- INITIALIZATION ---
function initializeTool() {
calculateAffordability();
renderConfig();
updateNavButtons();
}
initializeTool();
});
