<?php

declare(strict_types=1);

namespace App\Core\Database;

use App\Core\Config;
use PDO;
use PDOException;

class Database
{
    private static ?PDO $instance = null;

    public static function getConnection(): PDO
    {
        if (self::$instance === null) {
            $connection = Config::get('DB_CONNECTION', 'sqlite');

            try {
                if ($connection === 'sqlite') {
                    $databasePath = Config::get('DB_DATABASE', __DIR__ . '/../../../storage/database.sqlite');
                    $dir = dirname($databasePath);
                    if (!is_dir($dir)) {
                        mkdir($dir, 0777, true);
                    }

                    self::$instance = new PDO("sqlite:{$databasePath}", null, null, [
                        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                        PDO::ATTR_EMULATE_PREPARES => false,
                    ]);
                    
                    self::$instance->exec('PRAGMA foreign_keys = ON;');
                } else {
                    $host = Config::get('DB_HOST', '127.0.0.1');
                    $port = Config::get('DB_PORT', '3306');
                    $database = Config::get('DB_DATABASE', 'order_system');
                    $username = Config::get('DB_USERNAME', 'root');
                    $password = Config::get('DB_PASSWORD', '');

                    $dsn = "mysql:host={$host};port={$port};dbname={$database};charset=utf8mb4";
                    self::$instance = new PDO($dsn, $username, $password, [
                        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                        PDO::ATTR_EMULATE_PREPARES => false,
                    ]);
                }
            } catch (PDOException $e) {
                die('Database Connection Error: ' . $e->getMessage());
            }
        }

        return self::$instance;
    }

    /**
     * Initializes database tables and seed data for the Collaborative Canteen Ordering System
     */
    public static function initSchema(): void
    {
        $db = self::getConnection();
        $isSqlite = Config::get('DB_CONNECTION', 'sqlite') === 'sqlite';

        // Auto-migration check: If old schema exists without user_id / creator_id, drop old tables
        if ($isSqlite) {
            $checkTable = $db->query("SELECT name FROM sqlite_master WHERE type='table' AND name='employee_orders'")->fetchColumn();
            if ($checkTable) {
                $columns = $db->query("PRAGMA table_info(employee_orders)")->fetchAll();
                $hasUserId = false;
                foreach ($columns as $col) {
                    if ($col['name'] === 'user_id') {
                        $hasUserId = true;
                        break;
                    }
                }
                if (!$hasUserId) {
                    $db->exec("DROP TABLE IF EXISTS employee_order_items;");
                    $db->exec("DROP TABLE IF EXISTS employee_orders;");
                    $db->exec("DROP TABLE IF EXISTS session_menus;");
                    $db->exec("DROP TABLE IF EXISTS daily_sessions;");
                    $db->exec("DROP TABLE IF EXISTS employees;");
                    $db->exec("DROP TABLE IF EXISTS users;");
                    $db->exec("DROP TABLE IF EXISTS orders;");
                    $db->exec("DROP TABLE IF EXISTS order_items;");
                    $db->exec("DROP TABLE IF EXISTS products;");
                    $db->exec("DROP TABLE IF EXISTS customers;");
                }
            }
        }

        $autoIncrement = $isSqlite ? 'AUTOINCREMENT' : 'AUTO_INCREMENT';
        $dateTimeDefault = $isSqlite ? "DATETIME DEFAULT (datetime('now', 'localtime'))" : 'DATETIME DEFAULT CURRENT_TIMESTAMP';

        // Users Table
        $db->exec("
            CREATE TABLE IF NOT EXISTS users (
                id INTEGER PRIMARY KEY {$autoIncrement},
                name VARCHAR(255) NOT NULL,
                username VARCHAR(100) NOT NULL UNIQUE,
                email VARCHAR(255) NOT NULL UNIQUE,
                password_hash VARCHAR(255) NOT NULL,
                created_at {$dateTimeDefault}
            );
        ");

        // Daily Sessions Table
        $db->exec("
            CREATE TABLE IF NOT EXISTS daily_sessions (
                id INTEGER PRIMARY KEY {$autoIncrement},
                creator_id INTEGER NOT NULL,
                session_date DATE NOT NULL,
                title VARCHAR(255) NOT NULL,
                canteen_name VARCHAR(255) NOT NULL,
                status VARCHAR(50) NOT NULL DEFAULT 'open',
                notes TEXT DEFAULT NULL,
                created_at {$dateTimeDefault},
                updated_at {$dateTimeDefault},
                FOREIGN KEY (creator_id) REFERENCES users(id) ON DELETE CASCADE
            );
        ");

        // Session Menus Table
        $db->exec("
            CREATE TABLE IF NOT EXISTS session_menus (
                id INTEGER PRIMARY KEY {$autoIncrement},
                session_id INTEGER NOT NULL,
                name VARCHAR(255) NOT NULL,
                final_price DECIMAL(10,2) DEFAULT 0.00,
                created_at {$dateTimeDefault},
                FOREIGN KEY (session_id) REFERENCES daily_sessions(id) ON DELETE CASCADE
            );
        ");

        // Employee Orders Table
        $db->exec("
            CREATE TABLE IF NOT EXISTS employee_orders (
                id INTEGER PRIMARY KEY {$autoIncrement},
                session_id INTEGER NOT NULL,
                user_id INTEGER NOT NULL,
                status VARCHAR(50) NOT NULL DEFAULT 'unpaid',
                notes TEXT DEFAULT NULL,
                total_bill DECIMAL(10,2) NOT NULL DEFAULT 0.00,
                created_at {$dateTimeDefault},
                updated_at {$dateTimeDefault},
                FOREIGN KEY (session_id) REFERENCES daily_sessions(id) ON DELETE CASCADE,
                FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
            );
        ");

        // Employee Order Items Table
        $db->exec("
            CREATE TABLE IF NOT EXISTS employee_order_items (
                id INTEGER PRIMARY KEY {$autoIncrement},
                employee_order_id INTEGER NOT NULL,
                session_menu_id INTEGER DEFAULT NULL,
                item_name VARCHAR(255) NOT NULL,
                quantity INTEGER NOT NULL DEFAULT 1,
                unit_price DECIMAL(10,2) NOT NULL DEFAULT 0.00,
                total_price DECIMAL(10,2) NOT NULL DEFAULT 0.00,
                notes VARCHAR(255) DEFAULT NULL,
                created_at {$dateTimeDefault},
                FOREIGN KEY (employee_order_id) REFERENCES employee_orders(id) ON DELETE CASCADE
            );
        ");

        // Check if seed data exists
        $stmt = $db->query("SELECT COUNT(*) FROM users");
        $count = (int)$stmt->fetchColumn();

        if ($count === 0) {
            self::seedInitialData($db);
        }
    }

    private static function seedInitialData(PDO $db): void
    {
        $hash = password_hash('password', PASSWORD_DEFAULT);

        // Seed Users
        $users = [
            ['Dea (Coordinator)', 'dea', 'dea@company.com', $hash],
            ['Alex Turner', 'alex', 'alex@company.com', $hash],
            ['Sarah Jenkins', 'sarah', 'sarah@company.com', $hash],
            ['Budi Santoso', 'budi', 'budi@company.com', $hash],
            ['Michael Chen', 'michael', 'michael@company.com', $hash],
        ];

        $stmtUser = $db->prepare("INSERT INTO users (name, username, email, password_hash) VALUES (?, ?, ?, ?)");
        foreach ($users as $u) {
            $stmtUser->execute($u);
        }

        // Seed Today's Session created by Dea (id = 1)
        $today = date('Y-m-d');
        $title = "Dea's Lunch Hub - Kantin Bu Siti";
        $stmtSession = $db->prepare("INSERT INTO daily_sessions (creator_id, session_date, title, canteen_name, status, notes) VALUES (1, ?, ?, 'Kantin Bu Siti', 'open', 'Please submit your lunch orders before 11:30 AM!')");
        $stmtSession->execute([$today, $title]);
        $sessionId = (int)$db->lastInsertId();

        // Seed Menu Items
        $menuItems = [
            'Ayam Bakar Madu + Nasi',
            'Ayam Geprek Sambal Bawang + Nasi',
            'Nasi Goreng Spesial',
            'Mie Goreng Seafood',
            'Soto Ayam Lamongan + Nasi',
            'Gado-Gado Lontong',
            'Tahu & Tempe Goreng (Extra)',
            'Es Teh Manis',
            'Es Jeruk Segar',
        ];

        $stmtMenu = $db->prepare("INSERT INTO session_menus (session_id, name, final_price) VALUES (?, ?, 0.00)");
        foreach ($menuItems as $item) {
            $stmtMenu->execute([$sessionId, $item]);
        }

        // Seed an order for Alex (user_id = 2)
        $stmtOrder = $db->prepare("INSERT INTO employee_orders (session_id, user_id, status, notes, total_bill) VALUES (?, 2, 'unpaid', 'Pedas sedang ya', 0.00)");
        $stmtOrder->execute([$sessionId]);
        $alexOrderId = (int)$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 (?, ?, ?, ?, 0.00, 0.00, ?)");
        $stmtItem->execute([$alexOrderId, 1, 'Ayam Bakar Madu + Nasi', 1, 'Pedas sedang']);
        $stmtItem->execute([$alexOrderId, 8, 'Es Teh Manis', 1, 'Kurang manis / less sugar']);
    }
}