@extends('layouts.app')

@section('title', 'New Sale Agreement')

@section('content')
<div class="d-flex align-items-center mb-4">
    <a href="{{ route('sales.index') }}" class="btn btn-outline-secondary me-3"><i class="bi bi-arrow-left"></i></a>
    <h1 class="h3 mb-0"><i class="bi bi-file-earmark-plus me-2"></i>New Sale Agreement</h1>
</div>

<div class="card">
    <div class="card-body">
        <form method="POST" action="{{ route('sales.store') }}" id="saleForm">
            @csrf

            <div class="row g-3">
                {{-- Booking Selection --}}
                <div class="col-md-6">
                    <label for="booking_id" class="form-label fw-semibold">Booking <span class="text-danger">*</span></label>
                    <select name="booking_id" id="booking_id" class="form-select @error('booking_id') is-invalid @enderror" required>
                        <option value="">Select Booking</option>
                        @foreach ($bookings as $b)
                            <option value="{{ $b->id }}"
                                data-flat-price="{{ $b->flat->flat_price ?? 0 }}"
                                data-booking-amount="{{ $b->booking_amount ?? 0 }}"
                                {{ ($booking?->id == $b->id || old('booking_id') == $b->id) ? 'selected' : '' }}>
                                #{{ $b->id }} — {{ $b->customer->name }} — Flat {{ $b->flat->flat_number }}
                            </option>
                        @endforeach
                    </select>
                    @error('booking_id') <div class="invalid-feedback">{{ $message }}</div> @enderror
                </div>

                {{-- Agreement Date --}}
                <div class="col-md-3">
                    <label for="agreement_date" class="form-label fw-semibold">Agreement Date <span class="text-danger">*</span></label>
                    <input type="date" name="agreement_date" id="agreement_date"
                        class="form-control @error('agreement_date') is-invalid @enderror"
                        value="{{ old('agreement_date', date('Y-m-d')) }}" required>
                    @error('agreement_date') <div class="invalid-feedback">{{ $message }}</div> @enderror
                </div>

                {{-- Handover Date --}}
                <div class="col-md-3">
                    <label for="handover_date" class="form-label">Expected Handover</label>
                    <input type="date" name="handover_date" id="handover_date"
                        class="form-control @error('handover_date') is-invalid @enderror"
                        value="{{ old('handover_date') }}">
                    @error('handover_date') <div class="invalid-feedback">{{ $message }}</div> @enderror
                </div>

                <hr>
                <h6 class="text-muted">Pricing</h6>

                {{-- Total Flat Price --}}
                <div class="col-md-4">
                    <label for="total_flat_price" class="form-label fw-semibold">Total Flat Price (৳) <span class="text-danger">*</span></label>
                    <input type="number" name="total_flat_price" id="total_flat_price" step="0.01" min="0"
                        class="form-control @error('total_flat_price') is-invalid @enderror"
                        value="{{ old('total_flat_price', $booking?->flat?->flat_price) }}" required>
                    @error('total_flat_price') <div class="invalid-feedback">{{ $message }}</div> @enderror
                </div>

                {{-- Discount --}}
                <div class="col-md-4">
                    <label for="discount" class="form-label">Discount (৳)</label>
                    <input type="number" name="discount" id="discount" step="0.01" min="0"
                        class="form-control @error('discount') is-invalid @enderror"
                        value="{{ old('discount', 0) }}">
                    @error('discount') <div class="invalid-feedback">{{ $message }}</div> @enderror
                </div>

                {{-- Parking/Utility Charge --}}
                <div class="col-md-4">
                    <label for="parking_utility_charge" class="form-label">Parking / Utility Charge (৳)</label>
                    <input type="number" name="parking_utility_charge" id="parking_utility_charge" step="0.01" min="0"
                        class="form-control @error('parking_utility_charge') is-invalid @enderror"
                        value="{{ old('parking_utility_charge', 0) }}">
                    @error('parking_utility_charge') <div class="invalid-feedback">{{ $message }}</div> @enderror
                </div>

                {{-- Net Payable (computed, read-only display) --}}
                <div class="col-md-4">
                    <label class="form-label fw-semibold">Net Payable (৳)</label>
                    <input type="text" id="net_payable_display" class="form-control bg-light fw-bold" readonly>
                    <div class="form-text">= Total - Discount + Parking/Utility</div>
                </div>

                <hr>
                <h6 class="text-muted">Payment Breakdown</h6>

                {{-- Down Payment --}}
                <div class="col-md-3">
                    <label for="down_payment" class="form-label fw-semibold">Down Payment (৳)</label>
                    <input type="number" name="down_payment" id="down_payment" step="0.01" min="0"
                        class="form-control @error('down_payment') is-invalid @enderror"
                        value="{{ old('down_payment', $defaultDownPayment) }}">
                    @error('down_payment') <div class="invalid-feedback">{{ $message }}</div> @enderror
                    <div class="form-text" id="downPaymentHint">
                        Includes initial booking amount
                        @if($defaultDownPayment > 0)
                            <span class="text-primary fw-semibold">(min ৳{{ number_format($defaultDownPayment, 2) }})</span>
                        @endif
                    </div>
                </div>

                {{-- Total Installments --}}
                <div class="col-md-3">
                    <label for="total_installments" class="form-label fw-semibold">No. of Installments <span class="text-danger">*</span></label>
                    <input type="number" name="total_installments" id="total_installments" min="0"
                        class="form-control @error('total_installments') is-invalid @enderror"
                        value="{{ old('total_installments', 0) }}" required>
                    @error('total_installments') <div class="invalid-feedback">{{ $message }}</div> @enderror
                </div>

                {{-- Installment Amount --}}
                <div class="col-md-3">
                    <label for="installment_amount" class="form-label fw-semibold">Per Installment (৳)</label>
                    <input type="number" name="installment_amount" id="installment_amount" step="0.01" min="0"
                        class="form-control @error('installment_amount') is-invalid @enderror"
                        value="{{ old('installment_amount', 0) }}">
                    @error('installment_amount') <div class="invalid-feedback">{{ $message }}</div> @enderror
                    {{-- Rounding-safe info block --}}
                    <div id="installmentInfo" class="mt-1 small"></div>
                </div>

                {{-- Validation Check Display --}}
                <div class="col-md-3">
                    <label class="form-label">Schedule Validation</label>
                    <div id="breakdownCheck" class="form-control bg-light text-center">—</div>
                    <div class="form-text" id="breakdownDetail">Down + Schedule = Net</div>
                </div>

                {{-- Start Date --}}
                <div class="col-md-4">
                    <label for="installment_start_date" class="form-label">Installment Start Date</label>
                    <input type="date" name="installment_start_date" id="installment_start_date"
                        class="form-control @error('installment_start_date') is-invalid @enderror"
                        value="{{ old('installment_start_date') }}">
                    @error('installment_start_date') <div class="invalid-feedback">{{ $message }}</div> @enderror
                </div>

                {{-- Frequency --}}
                <div class="col-md-4">
                    <label for="installment_frequency" class="form-label">Frequency</label>
                    <select name="installment_frequency" id="installment_frequency" class="form-select">
                        <option value="monthly" {{ old('installment_frequency') === 'monthly' ? 'selected' : '' }}>Monthly</option>
                        <option value="quarterly" {{ old('installment_frequency') === 'quarterly' ? 'selected' : '' }}>Quarterly</option>
                        <option value="half_yearly" {{ old('installment_frequency') === 'half_yearly' ? 'selected' : '' }}>Half Yearly</option>
                        <option value="yearly" {{ old('installment_frequency') === 'yearly' ? 'selected' : '' }}>Yearly</option>
                    </select>
                </div>

                {{-- Terms --}}
                <div class="col-md-12">
                    <label for="terms" class="form-label">Terms & Conditions</label>
                    <textarea name="terms" id="terms" rows="3" class="form-control"
                        placeholder="Sale agreement terms...">{{ old('terms') }}</textarea>
                </div>
            </div>

            <hr>
            <button type="submit" class="btn btn-primary" id="submitBtn">
                <i class="bi bi-check-circle me-1"></i> Create Sale Agreement
            </button>
        </form>
    </div>
</div>
@endsection

@push('scripts')
<script>
document.addEventListener('DOMContentLoaded', function() {
    const bookingSelect = document.getElementById('booking_id');
    const downPaymentEl = document.getElementById('down_payment');
    const totalPriceEl  = document.getElementById('total_flat_price');
    const discountEl    = document.getElementById('discount');
    const parkingEl     = document.getElementById('parking_utility_charge');
    const countEl       = document.getElementById('total_installments');
    const perInstEl     = document.getElementById('installment_amount');
    const netDisplay    = document.getElementById('net_payable_display');
    const checkEl       = document.getElementById('breakdownCheck');
    const detailEl      = document.getElementById('breakdownDetail');
    const infoEl        = document.getElementById('installmentInfo');
    const saleForm      = document.getElementById('saleForm');

    // Track whether user has manually edited per-installment
    let userEditedPerInst = false;

    // ═════════════════════════════════════════════════════════
    //  Paisa helpers — all arithmetic in integer paisa (×100)
    //  to eliminate IEEE-754 floating-point rounding errors.
    // ═════════════════════════════════════════════════════════
    function toPaisa(bdt) {
        // Use string-based parsing to avoid float * 100 drift
        const str = String(bdt || '0').trim();
        const num = parseFloat(str);
        if (isNaN(num)) return 0;
        return Math.round(num * 100);
    }

    function fmtBDT(paisa) {
        return (paisa / 100).toLocaleString('en-US', {
            minimumFractionDigits: 2,
            maximumFractionDigits: 2
        });
    }

    function fmtInput(paisa) {
        return (paisa / 100).toFixed(2);
    }

    // ═════════════════════════════════════════════════════════
    //  Event listeners — recalculate on any pricing field change
    // ═════════════════════════════════════════════════════════
    const pricingFields = [
        'total_flat_price', 'discount', 'parking_utility_charge',
        'down_payment', 'total_installments'
    ];

    pricingFields.forEach(function(fieldId) {
        const el = document.getElementById(fieldId);
        if (!el) return;
        el.addEventListener('input', function() {
            // Any pricing/count change resets user override so we auto-recalc
            userEditedPerInst = false;
            recalculate();
        });
    });

    // If user manually types a Per Installment value, respect it
    perInstEl.addEventListener('input', function() {
        userEditedPerInst = true;
        recalculate();
    });

    // ═════════════════════════════════════════════════════════
    //  Booking change: pre-fill pricing from selected booking
    // ═════════════════════════════════════════════════════════
    bookingSelect.addEventListener('change', function() {
        const opt = this.options[this.selectedIndex];
        if (!opt || !opt.value) {
            downPaymentEl.value = 0;
            downPaymentEl.min   = 0;
            totalPriceEl.value  = '';
            updateMinHint(0);
            userEditedPerInst = false;
            recalculate();
            return;
        }

        const bookingAmount = parseFloat(opt.dataset.bookingAmount) || 0;
        const flatPrice     = parseFloat(opt.dataset.flatPrice) || 0;

        downPaymentEl.value = bookingAmount;
        downPaymentEl.min   = bookingAmount;
        totalPriceEl.value  = flatPrice;

        updateMinHint(bookingAmount);
        userEditedPerInst = false;
        recalculate();
    });

    function updateMinHint(amount) {
        const hintEl = document.getElementById('downPaymentHint');
        if (!hintEl) return;
        if (amount > 0) {
            hintEl.innerHTML =
                'Includes initial booking amount ' +
                '<span class="text-primary fw-semibold">(min ৳' +
                Number(amount).toLocaleString('en-US', { minimumFractionDigits: 2 }) +
                ')</span>';
        } else {
            hintEl.textContent = 'Includes initial booking amount';
        }
    }

    // ═════════════════════════════════════════════════════════
    //  CORE: Paisa-based recalculation  (PRD AC-1.2 RND-03)
    //
    //  All arithmetic uses integer paisa so that:
    //    target_paisa = net_paisa − down_paisa
    //    base_paisa   = floor(target_paisa / count)
    //    remainder    = target_paisa − (base_paisa × count)
    //    last_inst    = base_paisa + remainder
    //    ⇒ down + base×(n−1) + last = net   EXACTLY
    // ═════════════════════════════════════════════════════════
    function recalculate() {
        // 1) Net payable in paisa
        const pricePaisa = toPaisa(totalPriceEl.value);
        const discPaisa  = toPaisa(discountEl.value);
        const parkPaisa  = toPaisa(parkingEl.value);
        const netPaisa   = pricePaisa - discPaisa + parkPaisa;

        netDisplay.value = '৳ ' + fmtBDT(netPaisa);

        // 2) Down payment & count
        const downPaisa = toPaisa(downPaymentEl.value);
        const count     = parseInt(countEl.value) || 0;

        // 3) What installments must collectively cover
        const targetPaisa = Math.max(0, netPaisa - downPaisa);

        // ──────────────────────────────────────────────
        //  4) Auto-calculate Per Installment
        // ──────────────────────────────────────────────
        if (!userEditedPerInst && count > 0 && targetPaisa > 0) {
            const basePaisa = Math.floor(targetPaisa / count);
            perInstEl.value = fmtInput(basePaisa);
        } else if (!userEditedPerInst && (count === 0 || targetPaisa <= 0)) {
            perInstEl.value = '0.00';
        }

        // 5) Read back the (possibly user-overridden) per-installment value
        const perInstPaisa = toPaisa(perInstEl.value);

        // ──────────────────────────────────────────────
        //  6) Compute schedule totals in paisa
        //     Last installment absorbs rounding remainder
        // ──────────────────────────────────────────────
        let scheduleSum    = 0;
        let lastInstPaisa  = 0;
        let adjustmentPaisa = 0;    // difference between last and base

        if (count > 0 && perInstPaisa > 0 && targetPaisa > 0) {
            const baseTotal = perInstPaisa * (count - 1);
            lastInstPaisa   = targetPaisa - baseTotal;
            adjustmentPaisa = lastInstPaisa - perInstPaisa;
            scheduleSum     = downPaisa + baseTotal + lastInstPaisa;
        } else if (count === 0) {
            scheduleSum = downPaisa;
        }

        // ──────────────────────────────────────────────
        //  7) Info block under Per Installment
        // ──────────────────────────────────────────────
        if (infoEl) {
            if (count > 0 && perInstPaisa > 0 && targetPaisa > 0) {
                if (adjustmentPaisa !== 0) {
                    const sign = adjustmentPaisa > 0 ? '+' : '';
                    infoEl.innerHTML =
                        '<div class="p-2 rounded bg-info-subtle border border-info-subtle">' +
                            '<div class="d-flex justify-content-between">' +
                                '<span>Auto: <strong>৳' + fmtBDT(perInstPaisa) + '</strong> × ' + (count - 1) + '</span>' +
                                '<span class="text-muted">|</span>' +
                                '<span>Last: <strong>৳' + fmtBDT(lastInstPaisa) + '</strong></span>' +
                            '</div>' +
                            '<div class="text-muted mt-1" style="font-size:.8rem">' +
                                '<i class="bi bi-info-circle me-1"></i>' +
                                'Last installment adjusted by <strong>' + sign + '৳' + fmtBDT(Math.abs(adjustmentPaisa)) + '</strong> to match net payable exactly' +
                            '</div>' +
                        '</div>';
                } else {
                    infoEl.innerHTML =
                        '<span class="text-success">' +
                        '<i class="bi bi-check-circle me-1"></i>All ' + count + ' installments equal: ৳' + fmtBDT(perInstPaisa) +
                        '</span>';
                }
            } else {
                infoEl.innerHTML = '';
            }
        }

        // ──────────────────────────────────────────────
        //  8) Validation badge
        // ──────────────────────────────────────────────
        if (netPaisa > 0 && count > 0) {
            if (scheduleSum === netPaisa && lastInstPaisa > 0) {
                checkEl.textContent = '✅ Match';
                checkEl.className   = 'form-control bg-success-subtle text-success fw-bold text-center';
                detailEl.innerHTML  =
                    '৳' + fmtBDT(downPaisa) +
                    ' + (' + (count - 1) + ' × ৳' + fmtBDT(perInstPaisa) +
                    ') + ৳' + fmtBDT(lastInstPaisa) +
                    ' = <strong>৳' + fmtBDT(netPaisa) + '</strong>';
            } else if (lastInstPaisa <= 0 && count > 0) {
                checkEl.textContent = '⚠️ Invalid';
                checkEl.className   = 'form-control bg-warning-subtle text-warning fw-bold text-center';
                detailEl.textContent = 'Down payment too large or per-installment too high';
            } else {
                const diff = scheduleSum - netPaisa;
                checkEl.textContent = '❌ Off by ৳' + fmtBDT(Math.abs(diff));
                checkEl.className   = 'form-control bg-danger-subtle text-danger fw-bold text-center';
                detailEl.textContent =
                    'Down + Schedule = ৳' + fmtBDT(scheduleSum) +
                    ' vs Net = ৳' + fmtBDT(netPaisa);
            }
        } else if (netPaisa > 0 && count === 0) {
            if (downPaisa === netPaisa) {
                checkEl.textContent = '✅ Full Cash';
                checkEl.className   = 'form-control bg-success-subtle text-success fw-bold text-center';
                detailEl.textContent = 'Down payment covers full net payable';
            } else {
                checkEl.textContent = '❌ Down ≠ Net';
                checkEl.className   = 'form-control bg-danger-subtle text-danger fw-bold text-center';
                detailEl.textContent = '0 installments: down payment must equal net payable';
            }
        } else {
            checkEl.textContent = '—';
            checkEl.className   = 'form-control bg-light text-center';
            detailEl.textContent = 'Down + Schedule = Net';
        }
    }

    // ═════════════════════════════════════════════════════════
    //  Form Submit — re-sync installment_amount to the
    //  auto-calculated base BEFORE posting, so the backend
    //  receives a clean base value it can reproduce exactly.
    // ═════════════════════════════════════════════════════════
    saleForm.addEventListener('submit', function(e) {
        const count = parseInt(countEl.value) || 0;
        if (count <= 0) return; // full-cash, nothing to sync

        const netPaisa    = toPaisa(totalPriceEl.value) - toPaisa(discountEl.value) + toPaisa(parkingEl.value);
        const downPaisa   = toPaisa(downPaymentEl.value);
        const targetPaisa = Math.max(0, netPaisa - downPaisa);

        if (targetPaisa <= 0) return;

        // Always submit the floor-based per-installment so backend schedule matches
        const basePaisa = Math.floor(targetPaisa / count);
        perInstEl.value = fmtInput(basePaisa);
    });

    // ═════════════════════════════════════════════════════════
    //  Initial state on page load
    // ═════════════════════════════════════════════════════════
    const initialSelected = bookingSelect.options[bookingSelect.selectedIndex];
    if (initialSelected && initialSelected.value) {
        const initialBookingAmount = parseFloat(initialSelected.dataset.bookingAmount) || 0;
        downPaymentEl.min = initialBookingAmount;
    }

    // Fire initial calculation
    recalculate();
});
</script>
@endpush