// Invoice Form Logic
    const getInvoiceDiscountInput = (tableBody) => {
        const form = tableBody && typeof tableBody.closest === 'function' ? tableBody.closest('form') : null;
        return form ? form.querySelector('[data-invoice-discount-input]') : null;
    };

    const getInvoiceDiscountValue = (tableBody) => {
        const input = getInvoiceDiscountInput(tableBody);
        if (!input) return 0;
        let value = parseFloat(input.value);
        if (!Number.isFinite(value) || value < 0) value = 0;
        return value;
    };

    const getInvoiceManualDiscountPercent = () => {
        let value = (typeof companySettings !== 'undefined' && companySettings && companySettings.manual_discount_profit_limit_percent !== undefined)
            ? parseFloat(companySettings.manual_discount_profit_limit_percent)
            : 5;
        if (!Number.isFinite(value) || value < 0) value = 5;
        return Math.min(100, Math.max(0, value));
    };

    const getInvoiceManualDiscountMetrics = (tableBody) => {
        const percent = getInvoiceManualDiscountPercent();
        if (!tableBody || invoiceType !== 'sale') {
            return { percent, profitAmount: 0, maxDiscount: 0 };
        }

        let profitAmount = 0;
        tableBody.querySelectorAll('.item-row').forEach(row => {
            const qty = normalizeQuantity(row.querySelector('.item-qty')?.value || 0);
            const unitPrice = parseFloat(row.querySelector('.item-price')?.value) || 0;
            const purchasePrice = parseFloat(row.querySelector('.item-purchase-price')?.value) || 0;
            profitAmount += (unitPrice - purchasePrice) * qty;
        });

        profitAmount = Math.max(0, profitAmount);
        return {
            percent,
            profitAmount,
            maxDiscount: Math.max(0, profitAmount * (percent / 100))
        };
    };

    const updateInvoiceDiscountHelp = (tableBody, limitAmount = 0, metrics = null) => {
        const input = getInvoiceDiscountInput(tableBody);
        if (!input) return;
        const form = tableBody && typeof tableBody.closest === 'function' ? tableBody.closest('form') : null;
        const help = form ? form.querySelector('[data-invoice-discount-help]') : null;
        if (!help) return;
        const activeMetrics = metrics || getInvoiceManualDiscountMetrics(tableBody);
        const safeLimit = Math.max(0, Number(limitAmount) || 0);
        const percentLabel = activeMetrics.percent.toFixed(3).replace(/\.0+$/, '').replace(/(\.\d*[1-9])0+$/, '$1');
        const isArabic = (document.documentElement.lang || 'en') === 'ar';
        help.textContent = isArabic
            ? `الحد الأقصى الآن: <?= __('currency') ?> ${safeLimit.toFixed(3)} (${percentLabel}% من ربح الفاتورة <?= __('currency') ?> ${activeMetrics.profitAmount.toFixed(3)})`
            : `Max allowed now: <?= __('currency') ?> ${safeLimit.toFixed(3)} (${percentLabel}% of invoice profit <?= __('currency') ?> ${activeMetrics.profitAmount.toFixed(3)})`;
    };

    const initInvoiceForm = (searchInputId, suggestionsId, tableBodyId, grandTotalId, subtotalId, totalVatId) => {
        const searchInput = document.getElementById(searchInputId);
        const suggestions = document.getElementById(suggestionsId);
        const tableBody = document.getElementById(tableBodyId);
        const grandTotalEl = document.getElementById(grandTotalId);
        const subtotalEl = document.getElementById(subtotalId);
        const totalVatEl = document.getElementById(totalVatId);

        if (!searchInput || !tableBody) return;

        const discountInput = getInvoiceDiscountInput(tableBody);
        if (discountInput && discountInput.dataset.discountBound !== '1') {
            discountInput.dataset.discountBound = '1';
            discountInput.addEventListener('input', function() {
                const nextValue = parseFloat(this.value);
                if (Number.isFinite(nextValue) && nextValue < 0) {
                    this.value = '0';
                }
                recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl);
            });
        }

        let timeout = null;
        searchInput.addEventListener('input', function() {
            clearTimeout(timeout);
            const q = this.value.trim();
            if (q.length < 2) {
                suggestions.style.display = 'none';
                return;
            }

            timeout = setTimeout(() => {
                fetch(`index.php?action=search_items&q=${encodeURIComponent(q)}`)
                    .then(res => res.ok ? res.json() : [])
                    .then(data => {
                        suggestions.innerHTML = '';
                        if (data.length > 0) {
                            data.forEach(item => {
                                const btn = document.createElement('button');
                                btn.type = 'button';
                                btn.className = 'list-group-item list-group-item-action';
                                btn.innerHTML = `
                                    <div class="d-flex justify-content-between">
                                        <span><strong>${item.sku}</strong> - ${item.name_en} / ${item.name_ar}</span>
                                        <span class="text-muted small">Stock: ${formatQuantity(item.stock_quantity)}</span>
                                    </div>
                                `;
                                btn.onclick = () => addItemToTable(item, tableBody, searchInput, suggestions, grandTotalEl, subtotalEl, totalVatEl);
                                suggestions.appendChild(btn);
                            });
                            suggestions.style.display = 'block';
                        } else {
                            suggestions.style.display = 'none';
                        }
                    });
            }, 300);
        });

        // Close suggestions when clicking outside
        document.addEventListener('click', function(e) {
            if (!searchInput.contains(e.target) && !suggestions.contains(e.target)) {
                suggestions.style.display = 'none';
            }
        });
    };


    const invoiceSyncSelect2Value = (select) => {
        if (!select) return;
        if (select.classList.contains('select2') && window.jQuery && window.jQuery.fn && window.jQuery.fn.select2) {
            window.jQuery(select).trigger('change');
        }
    };

    const invoiceEnsureSelectOption = (selectId, value, label = '') => {
        const select = document.getElementById(selectId);
        if (!select || value === null || value === undefined || String(value) === '') return;

        const alreadyExists = Array.from(select.options || []).some(option => option.value == String(value));
        if (!alreadyExists) {
            const option = document.createElement('option');
            option.value = String(value);
            option.textContent = label || String(value);
            select.appendChild(option);
        }
    };

    const invoiceSetBlankSelectOptionLabel = (select, label = '---') => {
        if (!select) return;
        const emptyOption = Array.from(select.options || []).find(option => option.value === '');
        if (emptyOption) {
            emptyOption.textContent = label;
        }
    };

    const invoiceShowConfirmDialog = async ({
        title = 'Are you sure?',
        text = '',
        confirmButtonText = 'Yes, continue',
        cancelButtonText = 'Cancel',
        icon = 'warning'
    } = {}) => {
        if (window.Swal) {
            const result = await Swal.fire({
                title,
                text,
                icon,
                showCancelButton: true,
                confirmButtonText,
                cancelButtonText,
                reverseButtons: true,
                focusCancel: true,
                confirmButtonColor: '#dc3545',
                cancelButtonColor: '#6c757d'
            });
            return !!result.isConfirmed;
        }

        return window.confirm(text ? `${title}

${text}` : title);
    };

    const bindInvoiceSweetConfirmForms = () => {
        document.querySelectorAll('.js-swal-confirm-form').forEach(form => {
            if (form.dataset.confirmBound === '1') return;
            form.dataset.confirmBound = '1';

            form.addEventListener('submit', async function(event) {
                if (form.dataset.skipConfirm === '1') {
                    delete form.dataset.skipConfirm;
                    return;
                }

                event.preventDefault();

                const confirmed = await invoiceShowConfirmDialog({
                    title: form.dataset.confirmTitle || 'Are you sure?',
                    text: form.dataset.confirmText || '',
                    confirmButtonText: form.dataset.confirmButton || 'Yes, continue',
                    cancelButtonText: form.dataset.cancelButton || 'Cancel',
                    icon: form.dataset.confirmIcon || 'warning'
                });

                if (!confirmed) return;

                const submitter = event.submitter || null;
                if (submitter && typeof form.requestSubmit === 'function') {
                    form.dataset.skipConfirm = '1';
                    form.requestSubmit(submitter);
                    return;
                }

                HTMLFormElement.prototype.submit.call(form);
            });
        });
    };

    bindInvoiceSweetConfirmForms();

    function addItemToTable(item, tableBody, searchInput, suggestions, grandTotalEl, subtotalEl, totalVatEl, customData = null) {
        if (suggestions) suggestions.style.display = 'none';
        if (searchInput) searchInput.value = '';

        const allowZeroStock = (typeof companySettings !== 'undefined' && String(companySettings.allow_zero_stock_sell) === '1');
        const currentStock = normalizeQuantity(item.stock_quantity);

        if (invoiceType === 'sale' && !allowZeroStock && !customData) {
            const existingInTable = Array.from(tableBody.querySelectorAll('.item-row')).find(row => row.querySelector('.item-id-input').value == item.id);
            let currentQtyInTable = 0;
            if (existingInTable) {
                currentQtyInTable = normalizeQuantity(existingInTable.querySelector('.item-qty').value);
            }
            
            if (currentQtyInTable + 1 > currentStock) {
                alert('Insufficient stock! Available: ' + formatQuantity(currentStock));
                return;
            }
        }
        
        const existingRow = Array.from(tableBody.querySelectorAll('.item-id-input')).find(input => input.value == item.id);
        if (existingRow && !customData) {
            const row = existingRow.closest('tr');
            const qtyInput = row.querySelector('.item-qty');
            qtyInput.value = formatQuantity((parseFloat(qtyInput.value) || 0) + 1);
            recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl);
            return;
        }

        const row = document.createElement('tr');
        row.className = 'item-row';
        const price = customData ? customData.unit_price : (invoiceType === 'sale' ? item.sale_price : item.purchase_price);
        const qty = normalizeQuantity(customData ? customData.quantity : 1);
        const vatRate = item.vat_rate || 0;
        const purchasePrice = customData && customData.purchase_price !== undefined && customData.purchase_price !== null
            ? customData.purchase_price
            : (item.purchase_price || 0);
        
        row.innerHTML = `
            <td>
                <input type="hidden" name="item_ids[]" class="item-id-input" value="${item.id}">
                <input type="hidden" class="item-row-stock" value="${formatQuantity(item.stock_quantity)}">
                <input type="hidden" class="item-vat-rate" value="${vatRate}">
                <input type="hidden" class="item-purchase-price" value="${parseFloat(purchasePrice || 0).toFixed(3)}">
                <div><strong>${item.name_en}</strong></div>
                <div class="small text-muted">${item.name_ar} (${item.sku})</div>
            </td>
            <td><input type="number" step="0.01" name="quantities[]" class="form-control item-qty" value="${formatQuantity(qty)}" required></td>
            <td><input type="number" step="0.001" name="prices[]" class="form-control item-price" value="${price}" required></td>
            <td><input type="text" class="form-control bg-light" value="${parseFloat(vatRate || 0).toFixed(2)}%" readonly></td>
            <td><input type="number" step="0.001" class="form-control item-total" value="${(qty * price).toFixed(3)}" readonly></td>
            <td><button type="button" class="btn btn-outline-danger btn-sm remove-row"><i class="bi bi-trash"></i></button></td>
        `;
        
        tableBody.appendChild(row);
        if (typeof syncQuantityInputs === 'function') syncQuantityInputs(row);
        attachRowListeners(row, tableBody, grandTotalEl, subtotalEl, totalVatEl);
        recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl);
    }

    function recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl) {
        let subtotal = 0;
        let totalVat = 0;
        tableBody.querySelectorAll('.item-row').forEach(row => {
            const qtyInput = row.querySelector('.item-qty');
            const qty = normalizeQuantity(qtyInput ? qtyInput.value : 0);
            const price = parseFloat(row.querySelector('.item-price').value) || 0;
            const vatRate = parseFloat(row.querySelector('.item-vat-rate').value) || 0;
            
            const total = qty * price;
            const vatAmount = total * (vatRate / 100);
            
            row.querySelector('.item-total').value = total.toFixed(3);
            subtotal += total;
            totalVat += vatAmount;
        });

        const rawGrandTotal = subtotal + totalVat;
        const discountInput = getInvoiceDiscountInput(tableBody);
        const discountMetrics = getInvoiceManualDiscountMetrics(tableBody);
        const maxDiscountAmount = discountInput ? Math.min(rawGrandTotal, discountMetrics.maxDiscount) : rawGrandTotal;
        let discountAmount = getInvoiceDiscountValue(tableBody);
        if (discountAmount > maxDiscountAmount) {
            discountAmount = maxDiscountAmount;
            if (discountInput) discountInput.value = discountAmount.toFixed(3);
        }
        updateInvoiceDiscountHelp(tableBody, maxDiscountAmount, discountMetrics);
        const grandTotal = Math.max(0, rawGrandTotal - discountAmount);
        
        if (subtotalEl) subtotalEl.textContent = 'OMR ' + subtotal.toFixed(3);
        if (totalVatEl) totalVatEl.textContent = 'OMR ' + totalVat.toFixed(2);
        if (grandTotalEl) grandTotalEl.textContent = 'OMR ' + grandTotal.toFixed(3);
    }

    function attachRowListeners(row, tableBody, grandTotalEl, subtotalEl, totalVatEl) {
        row.querySelector('.item-qty').addEventListener('input', function() {
            const allowZeroStock = (typeof companySettings !== 'undefined' && String(companySettings.allow_zero_stock_sell) === '1');
            if (invoiceType === 'sale' && !allowZeroStock) {
                const stock = normalizeQuantity(row.querySelector('.item-row-stock').value);
                const qty = normalizeQuantity(this.value);
                if (qty > stock) {
                    alert('Insufficient stock! Available: ' + formatQuantity(stock));
                    this.value = formatQuantity(stock);
                }
            }
            recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl);
        });
        row.querySelector('.item-price').addEventListener('input', () => recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl));
        row.querySelector('.remove-row').addEventListener('click', function() {
            row.remove();
            recalculate(tableBody, grandTotalEl, subtotalEl, totalVatEl);
        });
    }

    const invoiceType = '<?= in_array($page, ["sales", "quotations"]) ? "sale" : (in_array($page, ["purchases", "lpos"]) ? "purchase" : "") ?>';
    initInvoiceForm('productSearchInput', 'searchSuggestions', 'invoiceItemsTableBody', 'grandTotal', 'subtotal', 'totalVat');
    initInvoiceForm('editProductSearchInput', 'editSearchSuggestions', 'editInvoiceItemsTableBody', 'edit_grandTotal', 'edit_subtotal', 'edit_totalVat');