// Edit Invoice Logic
    const parseInvoiceButtonPayload = (btn) => {
        if (!btn || !btn.dataset || !btn.dataset.json) return {};
        try {
            return JSON.parse(btn.dataset.json);
        } catch (error) {
            console.warn('Failed to parse invoice payload from button data.', error);
            return {};
        }
    };

    const normalizeEditPaymentType = (paymentType) => {
        let normalized = String(paymentType || 'cash').toLowerCase().replace(/[\s-]+/g, '_');
        if (normalized === 'pos') normalized = 'cash';
        if (!['cash', 'card', 'bank_transfer', 'credit'].includes(normalized)) {
            normalized = 'cash';
        }
        return normalized;
    };

    const renderEditInvoiceItems = (items) => {
        const tableBody = document.getElementById('editInvoiceItemsTableBody');
        const grandTotalEl = document.getElementById('edit_grandTotal');
        const subtotalEl = document.getElementById('edit_subtotal');
        const totalVatEl = document.getElementById('edit_totalVat');

        if (!tableBody) return;
        tableBody.innerHTML = '';

        if (!Array.isArray(items) || items.length === 0) {
            if (typeof recalculate === 'function') {
                recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl);
            }
            return;
        }

        items.forEach(item => {
            addItemToTable({
                id: item.item_id || item.id,
                name_en: item.name_en || item.item_name_en || 'Item',
                name_ar: item.name_ar || item.item_name_ar || '',
                sku: item.sku || '',
                vat_rate: item.vat_rate || 0,
                purchase_price: item.purchase_price || 0,
                last_sale_price: item.last_sale_price || 0,
                stock_quantity: item.stock_quantity || 0
            }, tableBody, null, null, grandTotalEl, subtotalEl, totalVatEl, {
                quantity: item.quantity,
                unit_price: item.unit_price,
                purchase_price: item.purchase_price || 0,
                last_sale_price: item.last_sale_price || 0
            });
        });
    };

    const populateEditInvoiceModal = (data) => {
        if (!data) return;

        const invoiceIdInput = document.getElementById('edit_invoice_id');
        const partySelect = document.getElementById('edit_customer_id');
        const invoiceDateInput = document.getElementById('edit_invoice_date');
        const dueDateInput = document.getElementById('edit_due_date');
        const paymentTypeSelect = document.getElementById('edit_payment_type');
        const statusSelect = document.getElementById('edit_status');
        const paidAmountInput = document.getElementById('edit_paid_amount');
        const paidAmountContainer = document.getElementById('editPaidAmountContainer');
        const discountAmountInput = document.getElementById('edit_discount_amount');

        const partyId = data.customer_id ?? data.supplier_id ?? '';
        const partyLabel = data.party_name || data.customer_name || data.supplier_name || '';

        invoiceEnsureSelectOption('edit_customer_id', partyId, partyLabel);

        if (invoiceIdInput) invoiceIdInput.value = data.id || '';
        if (partySelect) {
            invoiceSetBlankSelectOptionLabel(partySelect, (partyId === '' && partyLabel) ? partyLabel : '---');
            partySelect.value = partyId;
            invoiceSyncSelect2Value(partySelect);
        }
        if (invoiceDateInput) invoiceDateInput.value = data.invoice_date || '';
        if (dueDateInput) dueDateInput.value = data.due_date || '';
        if (paymentTypeSelect) paymentTypeSelect.value = normalizeEditPaymentType(data.payment_type);
        if (statusSelect) statusSelect.value = data.status || 'unpaid';
        if (paidAmountInput) paidAmountInput.value = parseFloat(data.paid_amount || 0).toFixed(3);
        if (discountAmountInput) discountAmountInput.value = parseFloat(data.discount_amount || 0).toFixed(3);
        if (paidAmountContainer) {
            paidAmountContainer.style.display = data.status === 'partially_paid' ? 'block' : 'none';
        }

        renderEditInvoiceItems(data.items || []);

        const tableBody = document.getElementById('editInvoiceItemsTableBody');
        const grandTotalEl = document.getElementById('edit_grandTotal');
        const subtotalEl = document.getElementById('edit_subtotal');
        const totalVatEl = document.getElementById('edit_totalVat');
        if (tableBody && typeof recalculate === 'function') {
            recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl);
        }
    };

    document.querySelectorAll('.edit-invoice-btn').forEach(btn => {
        btn.addEventListener('click', async function() {
            const fallbackData = parseInvoiceButtonPayload(this);
            const invoiceId = this.dataset.id || fallbackData.id || '';
            const type = this.dataset.type || fallbackData.type || invoiceType || 'sale';
            const tableBody = document.getElementById('editInvoiceItemsTableBody');

            if (Object.keys(fallbackData).length > 0) {
                populateEditInvoiceModal(fallbackData);
            } else if (tableBody) {
                tableBody.innerHTML = '<tr><td colspan="6" class="text-center"><div class="spinner-border spinner-border-sm text-primary"></div> <span data-en="Loading invoice..." data-ar="جاري تحميل الفاتورة...">Loading invoice...</span></td></tr>';
            }

            if (!invoiceId) return;

            try {
                const resp = await fetch(`index.php?action=get_invoice_details&invoice_id=${encodeURIComponent(invoiceId)}&type=${encodeURIComponent(type)}`);
                const data = await resp.json();

                if (data && data.id) {
                    populateEditInvoiceModal(data);
                } else if (data && data.error) {
                    throw new Error(data.error);
                }
            } catch (error) {
                console.error('Failed to load invoice details for edit modal.', error);
                if (window.Swal) {
                    Swal.fire('Error', 'Failed to load invoice details', 'error');
                }
            }
        });
    });

    // View and Print Invoice Logic
    const invoiceActionErrorTitle = <?= json_encode(($lang ?? 'en') === 'ar' ? 'خطأ' : 'Error', JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) ?>;
    const invoiceActionLoadError = <?= json_encode(($lang ?? 'en') === 'ar' ? 'تعذر تحميل بيانات الفاتورة' : 'Failed to load invoice details', JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) ?>;
    const invoicePrintChooserTitle = <?= json_encode(($lang ?? 'en') === 'ar' ? 'اختر طريقة الطباعة' : 'Choose print format', JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) ?>;
    const invoicePrintChooserText = <?= json_encode(($lang ?? 'en') === 'ar' ? 'هل تريد طباعة الفاتورة كإيصال أو كفاتورة عادية؟' : 'Do you want to print this sale as a receipt or a normal invoice?', JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) ?>;
    const invoicePrintNormalLabel = <?= json_encode(($lang ?? 'en') === 'ar' ? 'فاتورة عادية' : 'Normal Invoice', JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) ?>;
    const invoicePrintReceiptLabel = <?= json_encode(($lang ?? 'en') === 'ar' ? 'إيصال' : 'Receipt', JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) ?>;
    const invoicePrintCancelLabel = <?= json_encode(($lang ?? 'en') === 'ar' ? 'إلغاء' : 'Cancel', JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) ?>;
    const invoicePrintFallbackPrompt = <?= json_encode(($lang ?? 'en') === 'ar' ? 'اضغط موافق لطباعة الفاتورة العادية، أو إلغاء لطباعة الإيصال.' : 'Press OK for a normal invoice, or Cancel for a receipt.', JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) ?>;

    const buildInvoiceDocumentNo = (data) => {
        const prefix = (data && data.type === 'purchase') ? 'PUR-' : 'INV-';
        const numericId = parseInt(data && data.id ? data.id : 0, 10);
        return prefix + String(Number.isFinite(numericId) && numericId > 0 ? numericId : 0).padStart(5, '0');
    };

    const normalizeInvoiceActionData = (payload, fallback = {}) => {
        const merged = {
            ...(fallback || {}),
            ...(payload || {})
        };

        merged.type = String(merged.type || invoiceType || 'sale').toLowerCase() === 'purchase' ? 'purchase' : 'sale';
        merged.party_name = merged.party_name || merged.customer_name || merged.supplier_name || (merged.type === 'sale' && merged.is_pos ? 'Walk-in Customer' : '---');
        merged.customer_name = merged.customer_name || merged.supplier_name || merged.party_name || '---';
        merged.customer_phone = merged.customer_phone || merged.party_phone || '';
        merged.customer_tax_id = merged.customer_tax_id || merged.party_tax_id || '';
        merged.outlet_name = merged.outlet_name || '';
        merged.items = Array.isArray(merged.items) ? merged.items : (Array.isArray(fallback.items) ? fallback.items : []);
        merged.document_no = merged.document_no || merged.transaction_no || (merged.id ? buildInvoiceDocumentNo(merged) : '');
        merged.total_in_words = merged.total_in_words || fallback.total_in_words || '';

        return merged;
    };

    const showInvoiceActionError = (message = invoiceActionLoadError) => {
        if (window.Swal) {
            Swal.fire(invoiceActionErrorTitle, message, 'error');
            return;
        }
        window.alert(message);
    };

    const loadInvoiceActionData = async (btn) => {
        const fallbackData = normalizeInvoiceActionData(parseInvoiceButtonPayload(btn));
        const invoiceId = btn?.dataset?.id || fallbackData.id || '';
        const type = btn?.dataset?.type || fallbackData.type || invoiceType || 'sale';
        const baseData = normalizeInvoiceActionData({ ...fallbackData, id: invoiceId || fallbackData.id, type }, fallbackData);

        if (!invoiceId) {
            return baseData;
        }

        try {
            const response = await fetch(`index.php?action=get_invoice_details&invoice_id=${encodeURIComponent(invoiceId)}&type=${encodeURIComponent(type)}`);
            const data = await response.json();

            if (data && data.id) {
                return normalizeInvoiceActionData(data, baseData);
            }

            if (data && data.error) {
                throw new Error(data.error);
            }
        } catch (error) {
            console.error('Failed to load invoice details for view/print.', error);
        }

        return baseData;
    };

    const printInvoiceAsReceipt = (data) => {
        if (typeof window.printPosReceiptFromInvoice !== 'function') {
            if (typeof window.viewAndPrintA4Invoice === 'function') {
                window.viewAndPrintA4Invoice(data, true);
            }
            return;
        }

        window.printPosReceiptFromInvoice(data);

        setTimeout(() => {
            const receiptContent = document.getElementById('posReceiptContent');
            if (!receiptContent) {
                return;
            }

            if (typeof window.printReceiptHtml === 'function') {
                window.printReceiptHtml(receiptContent.innerHTML, {
                    title: data.document_no || data.transaction_no || 'Sale Receipt'
                });
            } else {
                const printArea = document.getElementById('posPrintArea');
                if (printArea) {
                    if (typeof window.prepareReceiptPrintArea === 'function') {
                        window.prepareReceiptPrintArea(receiptContent.innerHTML, printArea);
                    } else {
                        printArea.innerHTML = receiptContent.innerHTML;
                        const receipt = printArea.querySelector('.thermal-receipt');
                        if (receipt) {
                            receipt.classList.add('thermal-receipt-print');
                        }
                    }

                    document.body.classList.add('printing-receipt');
                    window.print();
                    document.body.classList.remove('printing-receipt');
                    printArea.innerHTML = '';
                }
            }

            const receiptModalEl = document.getElementById('posReceiptModal');
            const receiptModal = receiptModalEl ? bootstrap.Modal.getInstance(receiptModalEl) : null;
            if (receiptModal) {
                receiptModal.hide();
            }
        }, 250);
    };

    const promptInvoicePrintMode = async (data) => {
        const isSaleInvoice = String(data?.type || invoiceType || 'sale').toLowerCase() === 'sale';

        if (!isSaleInvoice || typeof window.printPosReceiptFromInvoice !== 'function') {
            if (typeof window.viewAndPrintA4Invoice === 'function') {
                window.viewAndPrintA4Invoice(data, true);
            }
            return;
        }

        if (window.Swal) {
            const result = await Swal.fire({
                title: invoicePrintChooserTitle,
                text: invoicePrintChooserText,
                icon: 'question',
                showCancelButton: true,
                showDenyButton: true,
                confirmButtonText: invoicePrintNormalLabel,
                denyButtonText: invoicePrintReceiptLabel,
                cancelButtonText: invoicePrintCancelLabel,
                reverseButtons: true
            });

            if (result.isConfirmed) {
                if (typeof window.viewAndPrintA4Invoice === 'function') {
                    setTimeout(() => window.viewAndPrintA4Invoice(data, true), 120);
                }
            } else if (result.isDenied) {
                setTimeout(() => printInvoiceAsReceipt(data), 120);
            }
            return;
        }

        if (window.confirm(invoicePrintFallbackPrompt)) {
            if (typeof window.viewAndPrintA4Invoice === 'function') {
                window.viewAndPrintA4Invoice(data, true);
            }
        } else {
            printInvoiceAsReceipt(data);
        }
    };

    document.querySelectorAll('.view-invoice-btn').forEach(btn => {
        btn.addEventListener('click', async function(event) {
            event.preventDefault();
            const data = await loadInvoiceActionData(this);

            if (!data || !data.id) {
                showInvoiceActionError();
                return;
            }

            if (typeof window.viewAndPrintA4Invoice === 'function') {
                window.viewAndPrintA4Invoice(data, false);
            }
        });
    });

    document.querySelectorAll('.print-a4-btn').forEach(btn => {
        btn.addEventListener('click', async function(event) {
            event.preventDefault();
            const data = await loadInvoiceActionData(this);

            if (!data || !data.id) {
                showInvoiceActionError();
                return;
            }

            await promptInvoicePrintMode(data);
        });
    });