<?php
// Shared Sales/Purchases create/update handlers extracted from index.php
// to reduce regression risk while preserving the existing behavior.
    // Invoices
    if (isset($_POST['add_invoice'])) {
        $db = db();
        try {
            $db->beginTransaction();
            $type = $_POST['type'] ?? 'sale';
            $table = ($type === 'purchase') ? 'purchases' : 'invoices';
            $item_table = ($type === 'purchase') ? 'purchase_items' : 'invoice_items';
            $cust_supplier_col = ($type === 'purchase') ? 'supplier_id' : 'customer_id';
            $fk_col = ($type === 'purchase') ? 'purchase_id' : 'invoice_id';
            
            $rawCustomerId = $_POST['customer_id'] ?? '';
            $cust_id = ($type === 'sale' && ($rawCustomerId === '' || $rawCustomerId === null)) ? null : (int)$rawCustomerId;
            $inv_date = $_POST['invoice_date'] ?: date('Y-m-d');
            $due_date = $_POST['due_date'] ?: null;
            $status = $_POST['status'] ?? 'pending';
            $pay_type = $_POST['payment_type'] ?? 'cash';
            
            $items = $_POST['item_ids'] ?? [];
            if (empty($items)) {
                throw new Exception("Please add at least one item.");
            }
            $qtys = $_POST['quantities'] ?? [];
            $prices = $_POST['prices'] ?? [];
            
            $total_subtotal = 0;
            $total_vat = 0;
            
            foreach ($items as $i => $item_id) {
                if (!$item_id) continue;
                $qty = normalize_quantity($qtys[$i] ?? 0);
                $price = (float)$prices[$i];
                $subtotal = $qty * $price;
                
                $stmtVat = $db->prepare("SELECT vat_rate FROM stock_items WHERE id = ?");
                $stmtVat->execute([$item_id]);
                $vatRate = (float)$stmtVat->fetchColumn();
                
                $vatAmount = $subtotal * ($vatRate / 100);
                $total_subtotal += $subtotal;
                $total_vat += $vatAmount;
            }
            
            $total_with_vat = $total_subtotal + $total_vat;
            $paid = (float)($_POST['paid_amount'] ?? 0);
            if ($status === 'paid') $paid = $total_with_vat;
            
            $stmt = $db->prepare("INSERT INTO $table ($cust_supplier_col, invoice_date, due_date, status, payment_type, total_amount, vat_amount, total_with_vat, paid_amount) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)");
            $stmt->execute([$cust_id, $inv_date, $due_date, $status, $pay_type, $total_subtotal, $total_vat, $total_with_vat, $paid]);
            $inv_id = $db->lastInsertId();
            if (db_column_exists($table, 'outlet_id')) {
                $db->prepare("UPDATE $table SET outlet_id = ? WHERE id = ?")->execute([current_outlet_id(), $inv_id]);
            }
            
            $items_for_journal = [];
            foreach ($items as $i => $item_id) {
                if (!$item_id) continue;
                $qty = normalize_quantity($qtys[$i] ?? 0);
                $price = (float)$prices[$i];
                $subtotal = $qty * $price;
                
                $stmtVat = $db->prepare("SELECT vat_rate FROM stock_items WHERE id = ?");
                $stmtVat->execute([$item_id]);
                $vatRate = (float)$stmtVat->fetchColumn();
                $vatAmount = $subtotal * ($vatRate / 100);

                $db->prepare("INSERT INTO $item_table ($fk_col, item_id, quantity, unit_price, vat_amount, total_price) VALUES (?, ?, ?, ?, ?, ?)")->execute([$inv_id, $item_id, $qty, $price, $vatAmount, $subtotal]);
                
                // Update stock
                $change = ($type === 'sale') ? -$qty : $qty;
                update_stock($item_id, $change);
                $items_for_journal[] = ['id' => $item_id, 'qty' => $qty];
            }
            
            // Accounting
            if ($type === 'sale') {
                recordSaleJournal($inv_id, $total_with_vat, $inv_date, $items_for_journal, $total_vat);
            } else {
                // For purchases, you might have recordPurchaseJournal, but let's check if it exists
                if (function_exists('recordPurchaseJournal')) {
                    recordPurchaseJournal($inv_id, $total_with_vat, $inv_date, $items_for_journal, $total_vat);
                }
            }

            $db->commit();

            $wablasNotice = '';
            if ($type === 'sale' && function_exists('wablasQueueInvoiceNotification')) {
                $wablasQueue = wablasQueueInvoiceNotification((int)$inv_id);
                $wablasNotice = (string)($wablasQueue['notice'] ?? '');
            }

            $_SESSION['trigger_invoice_modal'] = true;
            $_SESSION['show_invoice_id'] = (int)$inv_id;
            $_SESSION['show_invoice_page'] = ($type === 'purchase') ? 'purchases' : 'sales';
            $msg = ($type === 'purchase' ? "Purchase" : "Invoice") . " #$inv_id created!" . $wablasNotice;
            redirectWithMessage($msg, page_url($type === 'purchase' ? 'purchases' : 'sales'));
        } catch (Exception $e) { $db->rollBack(); $message = "Error: " . $e->getMessage(); }
    }

    if (isset($_POST['edit_invoice'])) {
        $db = db();
        try {
            $db->beginTransaction();
            $id = (int)$_POST['invoice_id'];
            $type = ($page === 'purchases') ? 'purchase' : 'sale';
            $table = ($type === 'purchase') ? 'purchases' : 'invoices';
            $item_table = ($type === 'purchase') ? 'purchase_items' : 'invoice_items';
            $cust_supplier_col = ($type === 'purchase') ? 'supplier_id' : 'customer_id';
            $fk_col = ($type === 'purchase') ? 'purchase_id' : 'invoice_id';

            $rawCustomerId = $_POST['customer_id'] ?? '';
            $cust_id = ($type === 'sale' && ($rawCustomerId === '' || $rawCustomerId === null)) ? null : (int)$rawCustomerId;
            $date = $_POST['invoice_date'] ?: date('Y-m-d');
            $due_date = $_POST['due_date'] ?: null;
            $status = $_POST['status'] ?? 'pending';
            $pay_type = $_POST['payment_type'] ?? 'cash';
            
            $items = $_POST['item_ids'] ?? [];
            $qtys = $_POST['quantities'] ?? [];
            $prices = $_POST['prices'] ?? [];
            
            $total_subtotal = 0;
            $total_vat = 0;
            
            foreach ($items as $i => $item_id) {
                if (!$item_id) continue;
                $qty = normalize_quantity($qtys[$i] ?? 0);
                $price = (float)$prices[$i];
                $subtotal = $qty * $price;
                
                $stmtVat = $db->prepare("SELECT vat_rate FROM stock_items WHERE id = ?");
                $stmtVat->execute([$item_id]);
                $vatRate = (float)$stmtVat->fetchColumn();
                
                $vatAmount = $subtotal * ($vatRate / 100);
                $total_subtotal += $subtotal;
                $total_vat += $vatAmount;
            }
            
            $total_with_vat = $total_subtotal + $total_vat;
            $paid = (float)($_POST['paid_amount'] ?? 0);
            if ($status === 'paid') $paid = $total_with_vat;
            
            $db->prepare("UPDATE $table SET $cust_supplier_col = ?, invoice_date = ?, due_date = ?, status = ?, payment_type = ?, total_amount = ?, vat_amount = ?, total_with_vat = ?, paid_amount = ? WHERE id = ?")
               ->execute([$cust_id, $date, $due_date, $status, $pay_type, $total_subtotal, $total_vat, $total_with_vat, $paid, $id]);
            if (db_column_exists($table, 'outlet_id')) {
                $db->prepare("UPDATE $table SET outlet_id = COALESCE(outlet_id, ?) WHERE id = ?")->execute([current_outlet_id(), $id]);
            }
            
            // Revert stock for old items
            $stmtOld = $db->prepare("SELECT item_id, quantity FROM $item_table WHERE $fk_col = ?");
            $stmtOld->execute([$id]);
            $oldItems = $stmtOld->fetchAll();
            foreach ($oldItems as $old) {
                $change = ($type === 'sale') ? normalize_quantity($old['quantity'] ?? 0) : -normalize_quantity($old['quantity'] ?? 0);
                update_stock($old['item_id'], $change);
            }
            
            // Delete old items
            $db->prepare("DELETE FROM $item_table WHERE $fk_col = ?")->execute([$id]);
            
            // Insert new items and update stock
            foreach ($items as $i => $item_id) {
                if (!$item_id) continue;
                $qty = normalize_quantity($qtys[$i] ?? 0);
                $price = (float)$prices[$i];
                $subtotal = $qty * $price;
                
                $stmtVat = $db->prepare("SELECT vat_rate FROM stock_items WHERE id = ?");
                $stmtVat->execute([$item_id]);
                $vatRate = (float)$stmtVat->fetchColumn();
                $vatAmount = $subtotal * ($vatRate / 100);

                $db->prepare("INSERT INTO $item_table ($fk_col, item_id, quantity, unit_price, vat_amount, total_price) VALUES (?, ?, ?, ?, ?, ?)")->execute([$id, $item_id, $qty, $price, $vatAmount, $subtotal]);
                
                $change = ($type === 'sale') ? -$qty : $qty;
                update_stock($item_id, $change);
            }
            
            $db->commit();
            $msg = ($type === 'purchase' ? "Purchase" : "Invoice") . " updated successfully!";
            redirectWithMessage($msg, page_url($type === 'purchase' ? 'purchases' : 'sales'));
        } catch (Exception $e) { $db->rollBack(); $message = "Error: " . $e->getMessage(); }
    }