feat: initial foundation for collaborative canteen ordering system in vanilla PHP

2026-08-27 17:29:13 +07:00
commit 5effce30cb
52 changed files with 4915 additions and 0 deletions
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class Customer
+{
+    public static function all(): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->query("SELECT * FROM customers ORDER BY name ASC");
+        return $stmt->fetchAll();
+    }
+
+    public static function find(int $id): ?array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("SELECT * FROM customers WHERE id = ?");
+        $stmt->execute([$id]);
+        $row = $stmt->fetch();
+        return $row ?: null;
+    }
+
+    public static function count(): int
+    {
+        $db = Database::getConnection();
+        return (int)$db->query("SELECT COUNT(*) FROM customers")->fetchColumn();
+    }
+
+    public static function create(array $data): int
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            INSERT INTO customers (name, email, phone, address) 
+            VALUES (:name, :email, :phone, :address)
+        ");
+        $stmt->execute([
+            ':name' => $data['name'],
+            ':email' => $data['email'],
+            ':phone' => $data['phone'] ?? '',
+            ':address' => $data['address'] ?? '',
+        ]);
+        return (int)$db->lastInsertId();
+    }
+
+    public static function update(int $id, array $data): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            UPDATE customers 
+            SET name = :name, email = :email, phone = :phone, address = :address
+            WHERE id = :id
+        ");
+        return $stmt->execute([
+            ':id' => $id,
+            ':name' => $data['name'],
+            ':email' => $data['email'],
+            ':phone' => $data['phone'] ?? '',
+            ':address' => $data['address'] ?? '',
+        ]);
+    }
+}
@@ -0,0 +1,114 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class DailySession
+{
+    public static function create(int $creatorId, string $title, string $canteenName, string $sessionDate, ?string $notes): int
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            INSERT INTO daily_sessions (creator_id, session_date, title, canteen_name, status, notes) 
+            VALUES (?, ?, ?, ?, 'open', ?)
+        ");
+        $stmt->execute([
+            $creatorId,
+            $sessionDate,
+            trim($title),
+            trim($canteenName),
+            trim((string)$notes)
+        ]);
+
+        return (int)$db->lastInsertId();
+    }
+
+    public static function find(int $id): ?array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            SELECT s.*, u.name as creator_name, u.username as creator_username
+            FROM daily_sessions s
+            JOIN users u ON s.creator_id = u.id
+            WHERE s.id = ?
+        ");
+        $stmt->execute([$id]);
+        $session = $stmt->fetch();
+
+        if (!$session) {
+            return null;
+        }
+
+        $session['menus'] = SessionMenu::getBySessionId($id);
+        $session['orders'] = EmployeeOrder::getBySessionId($id);
+        $session['recap'] = self::getCanteenRecap($id);
+
+        return $session;
+    }
+
+    public static function all(): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->query("
+            SELECT s.*, u.name as creator_name, u.username as creator_username,
+                   (SELECT COUNT(*) FROM employee_orders WHERE session_id = s.id) as order_count,
+                   (SELECT COUNT(*) FROM session_menus WHERE session_id = s.id) as menu_count,
+                   (SELECT COALESCE(SUM(total_bill), 0) FROM employee_orders WHERE session_id = s.id) as total_session_amount
+            FROM daily_sessions s
+            JOIN users u ON s.creator_id = u.id
+            ORDER BY s.id DESC
+        ");
+        return $stmt->fetchAll();
+    }
+
+    public static function getActiveSessions(): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->query("
+            SELECT s.*, u.name as creator_name, u.username as creator_username,
+                   (SELECT COUNT(*) FROM employee_orders WHERE session_id = s.id) as order_count,
+                   (SELECT COUNT(*) FROM session_menus WHERE session_id = s.id) as menu_count,
+                   (SELECT COALESCE(SUM(total_bill), 0) FROM employee_orders WHERE session_id = s.id) as total_session_amount
+            FROM daily_sessions s
+            JOIN users u ON s.creator_id = u.id
+            WHERE s.status IN ('open', 'closed', 'arrived')
+            ORDER BY s.id DESC
+        ");
+        return $stmt->fetchAll();
+    }
+
+    public static function updateStatus(int $id, string $status): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("UPDATE daily_sessions SET status = ?, updated_at = datetime('now', 'localtime') WHERE id = ?");
+        return $stmt->execute([$status, $id]);
+    }
+
+    public static function updateCanteenInfo(int $id, string $canteenName, ?string $notes): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("UPDATE daily_sessions SET canteen_name = ?, notes = ?, updated_at = datetime('now', 'localtime') WHERE id = ?");
+        return $stmt->execute([$canteenName, $notes, $id]);
+    }
+
+    public static function getCanteenRecap(int $sessionId): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            SELECT eoi.item_name, 
+                   SUM(eoi.quantity) as total_quantity,
+                   GROUP_CONCAT(DISTINCT eoi.notes) as combined_notes
+            FROM employee_order_items eoi
+            JOIN employee_orders eo ON eoi.employee_order_id = eo.id
+            WHERE eo.session_id = ?
+            GROUP BY eoi.item_name
+            ORDER BY total_quantity DESC
+        ");
+        $stmt->execute([$sessionId]);
+        return $stmt->fetchAll();
+    }
+}
@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class Employee
+{
+    public static function all(): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->query("
+            SELECT e.*, 
+                   (SELECT COUNT(*) FROM employee_orders WHERE employee_id = e.id) as total_orders,
+                   (SELECT COALESCE(SUM(total_bill), 0) FROM employee_orders WHERE employee_id = e.id AND status = 'unpaid') as unpaid_balance
+            FROM employees e 
+            ORDER BY e.name ASC
+        ");
+        return $stmt->fetchAll();
+    }
+
+    public static function find(int $id): ?array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("SELECT * FROM employees WHERE id = ?");
+        $stmt->execute([$id]);
+        $res = $stmt->fetch();
+        return $res ?: null;
+    }
+
+    public static function findOrCreateByName(string $name, ?string $mattermostUsername = null): int
+    {
+        $db = Database::getConnection();
+        $name = trim($name);
+
+        $stmt = $db->prepare("SELECT id FROM employees WHERE LOWER(name) = LOWER(?)");
+        $stmt->execute([$name]);
+        $id = $stmt->fetchColumn();
+
+        if ($id) {
+            return (int)$id;
+        }
+
+        $stmt = $db->prepare("INSERT INTO employees (name, mattermost_username) VALUES (?, ?)");
+        $stmt->execute([$name, $mattermostUsername ?: strtolower(preg_replace('/[^a-zA-Z0-9]/', '', $name))]);
+        return (int)$db->lastInsertId();
+    }
+}
@@ -0,0 +1,130 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class EmployeeOrder
+{
+    public static function getBySessionId(int $sessionId): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            SELECT eo.*, u.name as user_name, u.username as mattermost_username, u.email as user_email
+            FROM employee_orders eo
+            JOIN users u ON eo.user_id = u.id
+            WHERE eo.session_id = ?
+            ORDER BY eo.id ASC
+        ");
+        $stmt->execute([$sessionId]);
+        $orders = $stmt->fetchAll();
+
+        foreach ($orders as &$order) {
+            $order['items'] = self::getItemsByOrderId((int)$order['id']);
+        }
+
+        return $orders;
+    }
+
+    public static function getItemsByOrderId(int $orderId): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("SELECT * FROM employee_order_items WHERE employee_order_id = ? ORDER BY id ASC");
+        $stmt->execute([$orderId]);
+        return $stmt->fetchAll();
+    }
+
+    public static function findUserOrderBySession(int $sessionId, int $userId): ?array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("SELECT * FROM employee_orders WHERE session_id = ? AND user_id = ?");
+        $stmt->execute([$sessionId, $userId]);
+        $order = $stmt->fetch();
+
+        if (!$order) {
+            return null;
+        }
+
+        $order['items'] = self::getItemsByOrderId((int)$order['id']);
+        return $order;
+    }
+
+    public static function createOrder(int $sessionId, int $userId, ?string $notes, array $items): int
+    {
+        $db = Database::getConnection();
+        $db->beginTransaction();
+
+        try {
+            $stmtOrder = $db->prepare("
+                INSERT INTO employee_orders (session_id, user_id, status, notes, total_bill) 
+                VALUES (?, ?, 'unpaid', ?, 0.00)
+            ");
+            $stmtOrder->execute([$sessionId, $userId, $notes]);
+            $orderId = (int)$db->lastInsertId();
+
+            $stmtItem = $db->prepare("
+                INSERT INTO employee_order_items (employee_order_id, session_menu_id, item_name, quantity, unit_price, total_price, notes) 
+                VALUES (?, ?, ?, ?, ?, ?, ?)
+            ");
+
+            $totalBill = 0.0;
+
+            foreach ($items as $item) {
+                $menuId = !empty($item['session_menu_id']) ? (int)$item['session_menu_id'] : null;
+                $name = trim((string)($item['item_name'] ?? ''));
+                $qty = max(1, (int)($item['quantity'] ?? 1));
+                $unitPrice = (float)($item['unit_price'] ?? 0.0);
+                $lineTotal = $qty * $unitPrice;
+                $itemNotes = trim((string)($item['notes'] ?? ''));
+
+                if (empty($name)) {
+                    continue;
+                }
+
+                $stmtItem->execute([
+                    $orderId,
+                    $menuId,
+                    $name,
+                    $qty,
+                    $unitPrice,
+                    $lineTotal,
+                    $itemNotes
+                ]);
+
+                $totalBill += $lineTotal;
+            }
+
+            // Update total bill
+            $stmtUpdateTotal = $db->prepare("UPDATE employee_orders SET total_bill = ? WHERE id = ?");
+            $stmtUpdateTotal->execute([$totalBill, $orderId]);
+
+            $db->commit();
+            return $orderId;
+        } catch (\Throwable $e) {
+            $db->rollBack();
+            throw $e;
+        }
+    }
+
+    public static function togglePaid(int $orderId): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            UPDATE employee_orders 
+            SET status = CASE WHEN status = 'paid' THEN 'unpaid' ELSE 'paid' END,
+                updated_at = datetime('now', 'localtime')
+            WHERE id = ?
+        ");
+        return $stmt->execute([$orderId]);
+    }
+
+    public static function delete(int $orderId): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("DELETE FROM employee_orders WHERE id = ?");
+        return $stmt->execute([$orderId]);
+    }
+}
@@ -0,0 +1,171 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class Order
+{
+    public static function all(?string $status = null, ?string $search = null): array
+    {
+        $db = Database::getConnection();
+        $query = "
+            SELECT o.*, c.name as customer_name, c.email as customer_email,
+                   (SELECT COUNT(*) FROM order_items WHERE order_id = o.id) as item_count
+            FROM orders o
+            JOIN customers c ON o.customer_id = c.id
+        ";
+        
+        $conditions = [];
+        $params = [];
+
+        if ($status && $status !== 'all') {
+            $conditions[] = "o.status = :status";
+            $params[':status'] = $status;
+        }
+
+        if ($search) {
+            $conditions[] = "(o.order_number LIKE :search OR c.name LIKE :search OR c.email LIKE :search)";
+            $params[':search'] = "%{$search}%";
+        }
+
+        if (!empty($conditions)) {
+            $query .= " WHERE " . implode(" AND ", $conditions);
+        }
+
+        $query .= " ORDER BY o.id DESC";
+
+        $stmt = $db->prepare($query);
+        $stmt->execute($params);
+        return $stmt->fetchAll();
+    }
+
+    public static function find(int $id): ?array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            SELECT o.*, c.name as customer_name, c.email as customer_email, 
+                   c.phone as customer_phone, c.address as customer_address
+            FROM orders o
+            JOIN customers c ON o.customer_id = c.id
+            WHERE o.id = ?
+        ");
+        $stmt->execute([$id]);
+        $order = $stmt->fetch();
+
+        if (!$order) {
+            return null;
+        }
+
+        $order['items'] = OrderItem::getByOrderId($id);
+        return $order;
+    }
+
+    public static function count(?string $status = null): int
+    {
+        $db = Database::getConnection();
+        if ($status) {
+            $stmt = $db->prepare("SELECT COUNT(*) FROM orders WHERE status = ?");
+            $stmt->execute([$status]);
+            return (int)$stmt->fetchColumn();
+        }
+        return (int)$db->query("SELECT COUNT(*) FROM orders")->fetchColumn();
+    }
+
+    public static function totalRevenue(): float
+    {
+        $db = Database::getConnection();
+        return (float)$db->query("SELECT COALESCE(SUM(total), 0) FROM orders WHERE status != 'Cancelled'")->fetchColumn();
+    }
+
+    public static function recent(int $limit = 5): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            SELECT o.*, c.name as customer_name,
+                   (SELECT COUNT(*) FROM order_items WHERE order_id = o.id) as item_count
+            FROM orders o
+            JOIN customers c ON o.customer_id = c.id
+            ORDER BY o.id DESC
+            LIMIT :limit
+        ");
+        $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
+        $stmt->execute();
+        return $stmt->fetchAll();
+    }
+
+    public static function createOrderWithItems(array $orderData, array $items): int
+    {
+        $db = Database::getConnection();
+        $db->beginTransaction();
+
+        try {
+            $orderNumber = 'ORD-' . date('Ymd') . '-' . strtoupper(substr(uniqid(), -4));
+
+            $stmt = $db->prepare("
+                INSERT INTO orders (order_number, customer_id, status, subtotal, tax, discount, total, notes) 
+                VALUES (:order_number, :customer_id, :status, :subtotal, :tax, :discount, :total, :notes)
+            ");
+            
+            $stmt->execute([
+                ':order_number' => $orderNumber,
+                ':customer_id' => $orderData['customer_id'],
+                ':status' => $orderData['status'] ?? 'Pending',
+                ':subtotal' => $orderData['subtotal'],
+                ':tax' => $orderData['tax'] ?? 0.00,
+                ':discount' => $orderData['discount'] ?? 0.00,
+                ':total' => $orderData['total'],
+                ':notes' => $orderData['notes'] ?? '',
+            ]);
+
+            $orderId = (int)$db->lastInsertId();
+
+            foreach ($items as $item) {
+                if (empty($item['product_id']) || empty($item['quantity'])) {
+                    continue;
+                }
+
+                $productId = (int)$item['product_id'];
+                $quantity = (int)$item['quantity'];
+                $unitPrice = (float)$item['unit_price'];
+                $totalPrice = $quantity * $unitPrice;
+                $productName = $item['product_name'] ?? 'Item';
+
+                OrderItem::create([
+                    'order_id' => $orderId,
+                    'product_id' => $productId,
+                    'product_name' => $productName,
+                    'quantity' => $quantity,
+                    'unit_price' => $unitPrice,
+                    'total_price' => $totalPrice,
+                ]);
+
+                // Deduct stock inventory
+                Product::deductStock($productId, $quantity);
+            }
+
+            $db->commit();
+            return $orderId;
+        } catch (\Throwable $e) {
+            $db->rollBack();
+            throw $e;
+        }
+    }
+
+    public static function updateStatus(int $id, string $status): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("UPDATE orders SET status = ?, updated_at = datetime('now', 'localtime') WHERE id = ?");
+        return $stmt->execute([$status, $id]);
+    }
+
+    public static function delete(int $id): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("DELETE FROM orders WHERE id = ?");
+        return $stmt->execute([$id]);
+    }
+}
@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class OrderItem
+{
+    public static function getByOrderId(int $orderId): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            SELECT oi.*, p.sku, p.category 
+            FROM order_items oi
+            LEFT JOIN products p ON oi.product_id = p.id
+            WHERE oi.order_id = ?
+            ORDER BY oi.id ASC
+        ");
+        $stmt->execute([$orderId]);
+        return $stmt->fetchAll();
+    }
+
+    public static function create(array $data): int
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            INSERT INTO order_items (order_id, product_id, product_name, quantity, unit_price, total_price) 
+            VALUES (:order_id, :product_id, :product_name, :quantity, :unit_price, :total_price)
+        ");
+        $stmt->execute([
+            ':order_id' => $data['order_id'],
+            ':product_id' => $data['product_id'],
+            ':product_name' => $data['product_name'],
+            ':quantity' => $data['quantity'],
+            ':unit_price' => $data['unit_price'],
+            ':total_price' => $data['total_price'],
+        ]);
+        return (int)$db->lastInsertId();
+    }
+}
@@ -0,0 +1,86 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class Product
+{
+    public static function all(): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->query("SELECT * FROM products ORDER BY name ASC");
+        return $stmt->fetchAll();
+    }
+
+    public static function find(int $id): ?array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("SELECT * FROM products WHERE id = ?");
+        $stmt->execute([$id]);
+        $row = $stmt->fetch();
+        return $row ?: null;
+    }
+
+    public static function count(): int
+    {
+        $db = Database::getConnection();
+        return (int)$db->query("SELECT COUNT(*) FROM products")->fetchColumn();
+    }
+
+    public static function lowStockCount(int $threshold = 25): int
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("SELECT COUNT(*) FROM products WHERE stock <= ?");
+        $stmt->execute([$threshold]);
+        return (int)$stmt->fetchColumn();
+    }
+
+    public static function create(array $data): int
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            INSERT INTO products (sku, name, description, price, stock, category) 
+            VALUES (:sku, :name, :description, :price, :stock, :category)
+        ");
+        $stmt->execute([
+            ':sku' => $data['sku'],
+            ':name' => $data['name'],
+            ':description' => $data['description'] ?? '',
+            ':price' => $data['price'],
+            ':stock' => (int)($data['stock'] ?? 0),
+            ':category' => $data['category'] ?? 'General',
+        ]);
+        return (int)$db->lastInsertId();
+    }
+
+    public static function update(int $id, array $data): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("
+            UPDATE products 
+            SET sku = :sku, name = :name, description = :description, 
+                price = :price, stock = :stock, category = :category
+            WHERE id = :id
+        ");
+        return $stmt->execute([
+            ':id' => $id,
+            ':sku' => $data['sku'],
+            ':name' => $data['name'],
+            ':description' => $data['description'] ?? '',
+            ':price' => $data['price'],
+            ':stock' => (int)($data['stock'] ?? 0),
+            ':category' => $data['category'] ?? 'General',
+        ]);
+    }
+
+    public static function deductStock(int $id, int $quantity): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("UPDATE products SET stock = MAX(0, stock - ?) WHERE id = ?");
+        return $stmt->execute([$quantity, $id]);
+    }
+}
@@ -0,0 +1,80 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class SessionMenu
+{
+    public static function getBySessionId(int $sessionId): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("SELECT * FROM session_menus WHERE session_id = ? ORDER BY id ASC");
+        $stmt->execute([$sessionId]);
+        return $stmt->fetchAll();
+    }
+
+    public static function add(int $sessionId, string $name, float $price = 0.00): int
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("INSERT INTO session_menus (session_id, name, final_price) VALUES (?, ?, ?)");
+        $stmt->execute([$sessionId, trim($name), $price]);
+        return (int)$db->lastInsertId();
+    }
+
+    public static function delete(int $id): bool
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("DELETE FROM session_menus WHERE id = ?");
+        return $stmt->execute([$id]);
+    }
+
+    /**
+     * Update final prices from canteen bill and recalculate all employee order line items
+     */
+    public static function updatePricesAndRecalculate(int $sessionId, array $menuPrices): void
+    {
+        $db = Database::getConnection();
+        $db->beginTransaction();
+
+        try {
+            $stmtUpdateMenu = $db->prepare("UPDATE session_menus SET final_price = ? WHERE id = ? AND session_id = ?");
+            $stmtUpdateItems = $db->prepare("
+                UPDATE employee_order_items 
+                SET unit_price = ?, total_price = quantity * ? 
+                WHERE session_menu_id = ?
+            ");
+
+            foreach ($menuPrices as $menuId => $price) {
+                $menuId = (int)$menuId;
+                $price = (float)$price;
+
+                $stmtUpdateMenu->execute([$price, $menuId, $sessionId]);
+                $stmtUpdateItems->execute([$price, $price, $menuId]);
+            }
+
+            // Recalculate total_bill on employee_orders
+            $stmtOrders = $db->prepare("SELECT id FROM employee_orders WHERE session_id = ?");
+            $stmtOrders->execute([$sessionId]);
+            $orders = $stmtOrders->fetchAll();
+
+            $stmtUpdateOrderTotal = $db->prepare("
+                UPDATE employee_orders 
+                SET total_bill = (SELECT COALESCE(SUM(total_price), 0) FROM employee_order_items WHERE employee_order_id = ?) 
+                WHERE id = ?
+            ");
+
+            foreach ($orders as $order) {
+                $stmtUpdateOrderTotal->execute([$order['id'], $order['id']]);
+            }
+
+            $db->commit();
+        } catch (\Throwable $e) {
+            $db->rollBack();
+            throw $e;
+        }
+    }
+}
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use App\Core\Database\Database;
+use PDO;
+
+class User
+{
+    public static function all(): array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->query("
+            SELECT u.id, u.name, u.username, u.email, u.created_at,
+                   (SELECT COUNT(*) FROM employee_orders WHERE user_id = u.id) as total_orders,
+                   (SELECT COALESCE(SUM(total_bill), 0) FROM employee_orders WHERE user_id = u.id AND status = 'unpaid') as unpaid_balance
+            FROM users u
+            ORDER BY u.name ASC
+        ");
+        return $stmt->fetchAll();
+    }
+
+    public static function find(int $id): ?array
+    {
+        $db = Database::getConnection();
+        $stmt = $db->prepare("SELECT id, name, username, email, created_at FROM users WHERE id = ?");
+        $stmt->execute([$id]);
+        $res = $stmt->fetch();
+        return $res ?: null;
+    }
+
+    public static function findByIdentifier(string $identifier): ?array
+    {
+        $db = Database::getConnection();
+        $identifier = trim($identifier);
+        $stmt = $db->prepare("SELECT * FROM users WHERE LOWER(username) = LOWER(?) OR LOWER(email) = LOWER(?)");
+        $stmt->execute([$identifier, $identifier]);
+        $res = $stmt->fetch();
+        return $res ?: null;
+    }
+
+    public static function create(string $name, string $username, string $email, string $password): int
+    {
+        $db = Database::getConnection();
+        $hash = password_hash($password, PASSWORD_DEFAULT);
+
+        $stmt = $db->prepare("INSERT INTO users (name, username, email, password_hash) VALUES (?, ?, ?, ?)");
+        $stmt->execute([
+            trim($name),
+            strtolower(trim($username)),
+            strtolower(trim($email)),
+            $hash
+        ]);
+
+        return (int)$db->lastInsertId();
+    }
+}