<?php

declare(strict_types=1);

namespace ServerManager\Core;

use PDO;
use PDOException;

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

    private function __construct(array $config)
    {
        $dsn = sprintf(
            'mysql:host=%s;port=%d;dbname=%s;charset=%s',
            $config['host'],
            $config['port'],
            $config['database'],
            $config['charset'] ?? 'utf8mb4'
        );

        $initCommand = PHP_VERSION_ID >= 80500
            ? \Pdo\Mysql::ATTR_INIT_COMMAND
            : \PDO::MYSQL_ATTR_INIT_COMMAND;

        try {
            $this->pdo = new PDO($dsn, $config['username'], $config['password'], [
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES => false,
                $initCommand => 'SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci',
            ]);

            $tz = $config['timezone'] ?? 'UTC';
            $offset = (new \DateTimeZone($tz))->getOffset(new \DateTimeImmutable('now', new \DateTimeZone('UTC')));
            $sign = $offset >= 0 ? '+' : '-';
            $offset = abs($offset);
            $hours = str_pad((string) intdiv($offset, 3600), 2, '0', STR_PAD_LEFT);
            $minutes = str_pad((string) (($offset % 3600) / 60), 2, '0', STR_PAD_LEFT);
            $tzOffset = sprintf('%s%s:%s', $sign, $hours, $minutes);

            $this->pdo->exec("SET time_zone = '{$tzOffset}'");
        } catch (PDOException $e) {
            throw new \RuntimeException('Database connection failed: ' . $e->getMessage());
        }
    }

    public static function getInstance(array $config = []): self
    {
        if (self::$instance === null) {
            if (empty($config)) {
                throw new \RuntimeException('Database configuration is required for first initialization');
            }
            self::$instance = new self($config);
        }

        return self::$instance;
    }

    public static function resetInstance(): void
    {
        self::$instance = null;
    }

    public function getPdo(): PDO
    {
        return $this->pdo;
    }

    public function query(string $sql, array $params = []): \PDOStatement
    {
        $stmt = $this->pdo->prepare($sql);
        $stmt->execute($params);
        return $stmt;
    }

    public function fetch(string $sql, array $params = []): ?array
    {
        $result = $this->query($sql, $params)->fetch();
        return $result ?: null;
    }

    public function fetchAll(string $sql, array $params = []): array
    {
        return $this->query($sql, $params)->fetchAll();
    }

    public function fetchCol(string $sql, array $params = []): array
    {
        return $this->query($sql, $params)->fetchAll(\PDO::FETCH_COLUMN);
    }

    public 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})";
        $this->query($sql, array_values($data));

        return (int) $this->pdo->lastInsertId();
    }

    public function update(string $table, array $data, string $where, array $whereParams = []): int
    {
        $sets = implode(', ', array_map(fn($col) => "{$col} = ?", array_keys($data)));
        $sql = "UPDATE {$table} SET {$sets} WHERE {$where}";

        $stmt = $this->query($sql, array_merge(array_values($data), $whereParams));
        return $stmt->rowCount();
    }

    public function delete(string $table, string $where, array $params = []): int
    {
        $sql = "DELETE FROM {$table} WHERE {$where}";
        $stmt = $this->query($sql, $params);
        return $stmt->rowCount();
    }

    public function beginTransaction(): bool
    {
        return $this->pdo->beginTransaction();
    }

    public function commit(): bool
    {
        return $this->pdo->commit();
    }

    public function rollback(): bool
    {
        return $this->pdo->rollBack();
    }
}