<?php

declare(strict_types=1);

namespace App\Core;

use PDO;
use PDOException;
use RuntimeException;

/**
 * SQLite-basierte Datenbank für Test-/Entwicklungsumgebungen.
 * Ersetzt die MySQL-Database-Klasse und emuliert MySQL-spezifische Features.
 */
final class DatabaseSqlite implements DatabaseInterface
{
    private ?PDO $pdo = null;
    private readonly string $dbPath;

    public function __construct(private readonly array $config = [])
    {
        $this->dbPath = $this->config['path']
            ?? dirname(__DIR__, 2) . '/storage/database.sqlite';
    }

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

        $dbDir = dirname($this->dbPath);

        if (!is_dir($dbDir) && !mkdir($dbDir, 0775, true) && !is_dir($dbDir)) {
            throw new RuntimeException('Das Datenbank-Verzeichnis konnte nicht erstellt werden: ' . $dbDir);
        }

        try {
            $this->pdo = new PDO(
                'sqlite:' . $this->dbPath,
                null,
                null,
                [
                    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                    PDO::ATTR_EMULATE_PREPARES => false,
                ]
            );

            $this->pdo->exec('PRAGMA journal_mode=WAL');
            $this->pdo->exec('PRAGMA foreign_keys=ON');
            $this->pdo->exec('PRAGMA busy_timeout=5000');
        } catch (PDOException $exception) {
            throw new PDOException(
                'SQLite connection failed: ' . $exception->getMessage(),
                (int) $exception->getCode(),
                $exception
            );
        }

        return $this->pdo;
    }

    public function isConfigured(): bool
    {
        return $this->dbPath !== '';
    }

    /**
     * Führt schema.sqlite.sql aus, um die Datenbank zu initialisieren.
     */
    public function initializeSchema(): void
    {
        $schemaFile = dirname(__DIR__, 2) . '/database/schema.sqlite.sql';

        if (!is_file($schemaFile)) {
            throw new RuntimeException('SQLite-Schema nicht gefunden: ' . $schemaFile);
        }

        $schema = file_get_contents($schemaFile);

        if (!is_string($schema) || $schema === '') {
            throw new RuntimeException('SQLite-Schema konnte nicht geladen werden.');
        }

        $this->pdo()->exec($schema);
    }

    /**
     * SQLite-kompatibler UPSERT: INSERT OR REPLACE + SELECT als Alternative zu ON DUPLICATE KEY.
     */
    public function upsertRateLimit(string $actionKey, string $bucketKey, string $now): void
    {
        $pdo = $this->pdo();

        $existing = $pdo->prepare(
            'SELECT id FROM rate_limits WHERE action_key = :action_key AND bucket_key = :bucket_key LIMIT 1'
        );
        $existing->execute([
            'action_key' => $actionKey,
            'bucket_key' => $bucketKey,
        ]);

        if (!$existing->fetchColumn()) {
            $insert = $pdo->prepare(
                'INSERT INTO rate_limits (action_key, bucket_key, attempts, window_start, last_attempt_at, created_at)
                 VALUES (:action_key, :bucket_key, 0, :window_start, :last_attempt_at, :created_at)'
            );
            $insert->execute([
                'action_key' => $actionKey,
                'bucket_key' => $bucketKey,
                'window_start' => $now,
                'last_attempt_at' => $now,
                'created_at' => $now,
            ]);
        }
    }

    public function getDbPath(): string
    {
        return $this->dbPath;
    }
}