<?php
/**
 * NIS2 Agile - Configurazione Database
 *
 * Database dedicato: nis2_agile_db
 * Utente dedicato: nis2_user
 * COMPLETAMENTE ISOLATO dagli altri applicativi
 */

require_once __DIR__ . '/env.php';

define('DB_HOST', Env::get('DB_HOST', 'localhost'));
define('DB_PORT', Env::get('DB_PORT', '3306'));
define('DB_NAME', Env::get('DB_NAME', 'nis2_agile_db'));
define('DB_USER', Env::get('DB_USER', 'nis2_user'));
define('DB_PASS', Env::getRequired('DB_PASS'));
define('DB_CHARSET', 'utf8mb4');

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

    /**
     * Ottiene l'istanza PDO (singleton)
     */
    public static function getInstance(): PDO
    {
        if (self::$instance === null) {
            $dsn = sprintf(
                'mysql:host=%s;port=%s;dbname=%s;charset=%s',
                DB_HOST,
                DB_PORT,
                DB_NAME,
                DB_CHARSET
            );

            $options = [
                PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES   => false,
                PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci",
            ];

            try {
                self::$instance = new PDO($dsn, DB_USER, DB_PASS, $options);
            } catch (PDOException $e) {
                if (defined('APP_DEBUG') && APP_DEBUG) {
                    throw new Exception('Database connection failed: ' . $e->getMessage());
                } else {
                    throw new Exception('Database connection failed');
                }
            }
        }

        return self::$instance;
    }

    /**
     * Esegue una query con parametri
     */
    public static function query(string $sql, array $params = []): PDOStatement
    {
        $stmt = self::getInstance()->prepare($sql);
        $stmt->execute($params);
        return $stmt;
    }

    /**
     * Ottiene una singola riga
     */
    public static function fetchOne(string $sql, array $params = []): ?array
    {
        $result = self::query($sql, $params)->fetch();
        return $result ?: null;
    }

    /**
     * Ottiene tutte le righe
     */
    public static function fetchAll(string $sql, array $params = []): array
    {
        return self::query($sql, $params)->fetchAll();
    }

    /**
     * Inserisce e restituisce l'ID
     */
    public static function insert(string $table, array $data): int
    {
        $columns = implode(', ', array_keys($data));
        $placeholders = implode(', ', array_fill(0, count($data), '?'));

        $sql = "INSERT INTO {$table} ({$columns}) VALUES ({$placeholders})";
        self::query($sql, array_values($data));

        return (int) self::getInstance()->lastInsertId();
    }

    /**
     * Aggiorna righe
     */
    public static function update(string $table, array $data, string $where, array $whereParams = []): int
    {
        $setParts = [];
        foreach (array_keys($data) as $column) {
            $setParts[] = "{$column} = ?";
        }
        $setClause = implode(', ', $setParts);

        $sql = "UPDATE {$table} SET {$setClause} WHERE {$where}";
        $params = array_merge(array_values($data), $whereParams);

        return self::query($sql, $params)->rowCount();
    }

    /**
     * Elimina righe
     */
    public static function delete(string $table, string $where, array $params = []): int
    {
        $sql = "DELETE FROM {$table} WHERE {$where}";
        return self::query($sql, $params)->rowCount();
    }

    /**
     * Conta righe
     */
    public static function count(string $table, string $where = '1=1', array $params = []): int
    {
        $sql = "SELECT COUNT(*) as cnt FROM {$table} WHERE {$where}";
        $result = self::fetchOne($sql, $params);
        return (int) ($result['cnt'] ?? 0);
    }

    /**
     * Inizia una transazione
     */
    public static function beginTransaction(): bool
    {
        return self::getInstance()->beginTransaction();
    }

    /**
     * Commit transazione
     */
    public static function commit(): bool
    {
        return self::getInstance()->commit();
    }

    /**
     * Rollback transazione
     */
    public static function rollback(): bool
    {
        return self::getInstance()->rollBack();
    }

    /**
     * Restituisce l'ultimo ID inserito
     */
    public static function lastInsertId(): int
    {
        return (int) self::getInstance()->lastInsertId();
    }

    private function __clone() {}
}