@php
    use App\Support\LoanCalculationMethod;
    $loanCalculationMethod = $loanCalculationMethod ?? LoanCalculationMethod::EQUAL_PRINCIPAL;
    $loanAnnualInterestRate = (float) ($loanAnnualInterestRate ?? 0);
@endphp
<script>
    (function () {
        var method = @json(LoanCalculationMethod::normalize($loanCalculationMethod));
        var annualRate = {{ json_encode($loanAnnualInterestRate) }};

        function computeMonthlyPayment(principal, months) {
            principal = parseFloat(principal);
            months = parseInt(months, 10);
            if (!principal || principal <= 0 || !months || months < 1) {
                return null;
            }
            if (method === @json(LoanCalculationMethod::AMORTIZATION) && annualRate > 0) {
                var r = annualRate / 100 / 12;
                var factor = Math.pow(1 + r, months);
                return Math.round((principal * (r * factor) / (factor - 1)) * 100) / 100;
            }
            return Math.round((principal / months) * 100) / 100;
        }

        window.fundLoanComputeMonthlyPayment = computeMonthlyPayment;

        var amountEl = document.getElementById(@json($amountInputId));
        var periodEl = document.getElementById(@json($periodInputId));
        var previewEl = document.getElementById(@json($previewInputId));

        if (!amountEl || !periodEl || !previewEl) {
            return;
        }

        function updatePreview() {
            var payment = computeMonthlyPayment(amountEl.value, periodEl.value);
            previewEl.value = payment !== null ? payment.toFixed(2) : '';
        }

        amountEl.addEventListener('input', updatePreview);
        amountEl.addEventListener('change', updatePreview);
        periodEl.addEventListener('input', updatePreview);
        periodEl.addEventListener('change', updatePreview);
        updatePreview();
    })();
</script>