// payment-modal.js — ES Module für das Payment Recording Modal
// Ermöglicht: Auswahl mehrerer Rechnungen, Check/ACH, Deposit To Konto

// ============================================================
// State
// ============================================================
let bankAccounts = [];
let paymentMethods = [];
let selectedInvoices = [];  // Array of invoice objects
let isOpen = false;

// Cache QBO reference data (nur einmal laden)
let dataLoaded = false;

// ============================================================
// Load QBO Reference Data
// ============================================================

async function loadQboData() {
    if (dataLoaded) return;
    
    try {
        const [accRes, pmRes] = await Promise.all([
            fetch('/api/qbo/accounts'),
            fetch('/api/qbo/payment-methods')
        ]);
        
        if (accRes.ok) bankAccounts = await accRes.json();
        if (pmRes.ok) paymentMethods = await pmRes.json();
        
        dataLoaded = true;
    } catch (error) {
        console.error('Error loading QBO reference data:', error);
    }
}

// ============================================================
// Open / Close Modal
// ============================================================

export async function openPaymentModal(invoiceIds = []) {
    // Lade QBO-Daten falls noch nicht geschehen
    await loadQboData();
    
    // Lade die ausgewählten Rechnungen
    if (invoiceIds.length > 0) {
        selectedInvoices = [];
        for (const id of invoiceIds) {
            try {
                const res = await fetch(`/api/invoices/${id}`);
                const data = await res.json();
                if (data.invoice) {
                    selectedInvoices.push(data.invoice);
                }
            } catch (e) {
                console.error('Error loading invoice:', id, e);
            }
        }
    }
    
    renderModal();
    document.getElementById('payment-modal').classList.add('active');
    isOpen = true;
}

export function closePaymentModal() {
    const modal = document.getElementById('payment-modal');
    if (modal) modal.classList.remove('active');
    isOpen = false;
    selectedInvoices = [];
}

// ============================================================
// Add/Remove Invoices from selection
// ============================================================

export async function addInvoiceToPayment(invoiceId) {
    if (selectedInvoices.find(inv => inv.id === invoiceId)) return; // already selected
    
    try {
        const res = await fetch(`/api/invoices/${invoiceId}`);
        const data = await res.json();
        if (data.invoice) {
            // Validierung: Muss QBO-verknüpft sein
            if (!data.invoice.qbo_id) {
                alert('Diese Rechnung ist noch nicht in QBO. Bitte erst exportieren.');
                return;
            }
            // Validierung: Alle müssen zum selben Kunden gehören
            if (selectedInvoices.length > 0 && data.invoice.customer_id !== selectedInvoices[0].customer_id) {
                alert('Alle Rechnungen eines Payments müssen zum selben Kunden gehören.');
                return;
            }
            selectedInvoices.push(data.invoice);
            renderInvoiceList();
            updateTotal();
        }
    } catch (e) {
        console.error('Error adding invoice:', e);
    }
}

function removeInvoiceFromPayment(invoiceId) {
    selectedInvoices = selectedInvoices.filter(inv => inv.id !== invoiceId);
    renderInvoiceList();
    updateTotal();
}

// ============================================================
// Rendering
// ============================================================

function renderModal() {
    let modal = document.getElementById('payment-modal');
    
    if (!modal) {
        modal = document.createElement('div');
        modal.id = 'payment-modal';
        modal.className = 'modal-overlay';
        document.body.appendChild(modal);
    }

    const accountOptions = bankAccounts.map(acc => 
        `<option value="${acc.id}">${acc.name}</option>`
    ).join('');

    const methodOptions = paymentMethods
        .filter(pm => ['Check', 'ACH'].includes(pm.name) || pm.name.toLowerCase().includes('check') || pm.name.toLowerCase().includes('ach'))
        .map(pm => `<option value="${pm.id}">${pm.name}</option>`)
        .join('');
    
    // Falls keine Filter-Treffer, alle anzeigen
    const allMethodOptions = paymentMethods.map(pm => 
        `<option value="${pm.id}">${pm.name}</option>`
    ).join('');

    const today = new Date().toISOString().split('T')[0];

    modal.innerHTML = `
        <div class="modal-content" style="max-width: 700px;">
            <div class="flex justify-between items-center mb-6">
                <h2 class="text-2xl font-bold text-gray-800">💰 Record Payment</h2>
                <button onclick="window.paymentModal.close()" class="text-gray-400 hover:text-gray-600">
                    <svg class="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                        <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12" />
                    </svg>
                </button>
            </div>

            <!-- Selected Invoices -->
            <div class="mb-6">
                <label class="block text-sm font-medium text-gray-700 mb-2">Invoices to pay</label>
                <div id="payment-invoice-list" class="border border-gray-200 rounded-lg max-h-48 overflow-y-auto">
                    <!-- Wird dynamisch gefüllt -->
                </div>
                <div class="mt-2 flex items-center gap-2">
                    <input type="number" id="payment-add-invoice-id" placeholder="Invoice ID hinzufügen..." 
                           class="flex-1 px-3 py-1.5 border border-gray-300 rounded-md text-sm">
                    <button onclick="window.paymentModal.addById()" 
                            class="px-3 py-1.5 bg-blue-600 text-white rounded-md text-sm hover:bg-blue-700">
                        + Add
                    </button>
                </div>
            </div>

            <!-- Payment Details -->
            <div class="grid grid-cols-2 gap-4 mb-6">
                <div>
                    <label class="block text-sm font-medium text-gray-700 mb-1">Payment Date</label>
                    <input type="date" id="payment-date" value="${today}"
                           class="w-full px-3 py-2 border border-gray-300 rounded-md focus:ring-blue-500 focus:border-blue-500">
                </div>
                <div>
                    <label class="block text-sm font-medium text-gray-700 mb-1">Reference # (Check / ACH)</label>
                    <input type="text" id="payment-reference" placeholder="Check # or ACH ref"
                           class="w-full px-3 py-2 border border-gray-300 rounded-md focus:ring-blue-500 focus:border-blue-500">
                </div>
                <div>
                    <label class="block text-sm font-medium text-gray-700 mb-1">Payment Method</label>
                    <select id="payment-method" 
                            class="w-full px-3 py-2 border border-gray-300 rounded-md bg-white focus:ring-blue-500 focus:border-blue-500">
                        ${methodOptions || allMethodOptions}
                    </select>
                </div>
                <div>
                    <label class="block text-sm font-medium text-gray-700 mb-1">Deposit To</label>
                    <select id="payment-deposit-to" 
                            class="w-full px-3 py-2 border border-gray-300 rounded-md bg-white focus:ring-blue-500 focus:border-blue-500">
                        ${accountOptions}
                    </select>
                </div>
            </div>

            <!-- Total -->
            <div class="bg-gray-50 p-4 rounded-lg mb-6">
                <div class="flex justify-between items-center">
                    <span class="text-lg font-bold text-gray-700">Total Payment:</span>
                    <span id="payment-total" class="text-2xl font-bold text-blue-600">$0.00</span>
                </div>
            </div>

            <!-- Actions -->
            <div class="flex justify-end space-x-3">
                <button onclick="window.paymentModal.close()" 
                        class="px-6 py-2 bg-gray-200 text-gray-700 rounded-md hover:bg-gray-300">
                    Cancel
                </button>
                <button onclick="window.paymentModal.submit()" id="payment-submit-btn"
                        class="px-6 py-2 bg-green-600 text-white rounded-md hover:bg-green-700 font-semibold">
                    💰 Record Payment in QBO
                </button>
            </div>
        </div>
    `;

    renderInvoiceList();
    updateTotal();
}

function renderInvoiceList() {
    const container = document.getElementById('payment-invoice-list');
    if (!container) return;

    if (selectedInvoices.length === 0) {
        container.innerHTML = `<div class="p-4 text-center text-gray-400 text-sm">Keine Rechnungen ausgewählt</div>`;
        return;
    }

    container.innerHTML = selectedInvoices.map(inv => `
        <div class="flex items-center justify-between px-4 py-2 border-b border-gray-100 last:border-0 hover:bg-gray-50">
            <div>
                <span class="font-medium text-gray-900">#${inv.invoice_number || 'Draft'}</span>
                <span class="text-gray-500 text-sm ml-2">${inv.customer_name || ''}</span>
            </div>
            <div class="flex items-center gap-3">
                <span class="font-semibold text-gray-900">$${parseFloat(inv.total).toFixed(2)}</span>
                <button onclick="window.paymentModal.removeInvoice(${inv.id})" 
                        class="text-red-400 hover:text-red-600 text-sm">✕</button>
            </div>
        </div>
    `).join('');
}

function updateTotal() {
    const totalEl = document.getElementById('payment-total');
    if (!totalEl) return;
    
    const total = selectedInvoices.reduce((sum, inv) => sum + parseFloat(inv.total), 0);
    totalEl.textContent = `$${total.toFixed(2)}`;
    
    // Submit-Button deaktivieren wenn keine Rechnungen
    const submitBtn = document.getElementById('payment-submit-btn');
    if (submitBtn) {
        submitBtn.disabled = selectedInvoices.length === 0;
        submitBtn.classList.toggle('opacity-50', selectedInvoices.length === 0);
    }
}

// ============================================================
// Submit Payment
// ============================================================

async function submitPayment() {
    if (selectedInvoices.length === 0) {
        alert('Bitte mindestens eine Rechnung auswählen.');
        return;
    }

    const paymentDate = document.getElementById('payment-date').value;
    const reference = document.getElementById('payment-reference').value;
    const methodId = document.getElementById('payment-method').value;
    const depositToId = document.getElementById('payment-deposit-to').value;

    if (!paymentDate) {
        alert('Bitte ein Zahlungsdatum angeben.');
        return;
    }

    if (!methodId || !depositToId) {
        alert('Bitte Payment Method und Deposit To auswählen.');
        return;
    }

    const total = selectedInvoices.reduce((sum, inv) => sum + parseFloat(inv.total), 0);
    const invoiceNums = selectedInvoices.map(i => i.invoice_number || `ID:${i.id}`).join(', ');
    
    if (!confirm(`Payment von $${total.toFixed(2)} für Rechnung(en) ${invoiceNums} an QBO senden?`)) {
        return;
    }

    const submitBtn = document.getElementById('payment-submit-btn');
    const origText = submitBtn.innerHTML;
    submitBtn.innerHTML = '⏳ Wird gesendet...';
    submitBtn.disabled = true;

    try {
        const response = await fetch('/api/qbo/record-payment', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({
                invoice_ids: selectedInvoices.map(inv => inv.id),
                payment_date: paymentDate,
                reference_number: reference,
                payment_method_id: methodId,
                deposit_to_account_id: depositToId
            })
        });

        const result = await response.json();

        if (response.ok) {
            alert(`✅ ${result.message}`);
            closePaymentModal();
            // Invoice-Liste aktualisieren
            if (window.invoiceView) {
                window.invoiceView.loadInvoices();
            } else if (typeof window.loadInvoices === 'function') {
                window.loadInvoices();
            }
        } else {
            alert(`❌ Fehler: ${result.error}`);
        }
    } catch (error) {
        console.error('Payment error:', error);
        alert('Netzwerkfehler beim Payment.');
    } finally {
        submitBtn.innerHTML = origText;
        submitBtn.disabled = false;
    }
}

// ============================================================
// Helper: Add by ID from input field
// ============================================================

async function addInvoiceById() {
    const input = document.getElementById('payment-add-invoice-id');
    const id = parseInt(input.value);
    if (!id) return;
    
    await addInvoiceToPayment(id);
    input.value = '';
}

// ============================================================
// Expose to window
// ============================================================

window.paymentModal = {
    open: openPaymentModal,
    close: closePaymentModal,
    submit: submitPayment,
    addInvoice: addInvoiceToPayment,
    removeInvoice: removeInvoiceFromPayment,
    addById: addInvoiceById
};