<?php

namespace App\Services;

use PDO;
use RuntimeException;

final class SetupService
{
    public function __construct(private readonly string $rootPath)
    {
    }

    public function isInstalled(): bool
    {
        return is_file($this->rootPath . '/storage/installed.lock');
    }

    public function install(array $input): void
    {
        $required = [
            'app_url',
            'db_host',
            'db_port',
            'db_name',
            'db_user',
            'admin_name',
            'admin_email',
            'admin_password',
        ];

        foreach ($required as $field) {
            if (trim((string) ($input[$field] ?? '')) === '') {
                throw new RuntimeException('Bitte alle Pflichtfelder ausfuellen.');
            }
        }

        if (!filter_var($input['admin_email'], FILTER_VALIDATE_EMAIL)) {
            throw new RuntimeException('Die Admin-E-Mail ist ungueltig.');
        }

        if (mb_strlen($input['admin_password']) < 12) {
            throw new RuntimeException('Das Admin-Passwort muss mindestens 12 Zeichen lang sein.');
        }

        $this->resolveMailFrom($input, $this->normalizeAppUrl((string) $input['app_url']));

        // Prüfe verfügbare PDO-Treiber und verwende entsprechende Datenbank
        $availableDrivers = PDO::getAvailableDrivers();
        $useMySQL = in_array('mysql', $availableDrivers) && trim((string) $input['db_host']) !== 'sqlite';
        
        if ($useMySQL) {
            $pdo = $this->setupMySQLDatabase($input);
        } else {
            $pdo = $this->setupSQLiteDatabase();
        }

        $statement = $pdo->prepare('SELECT id FROM users WHERE email = :email LIMIT 1');
        $statement->execute(['email' => mb_strtolower((string) $input['admin_email'])]);
        $existing = $statement->fetchColumn();

        if (!$existing) {
            $insert = $pdo->prepare(
                'INSERT INTO users (full_name, email, password_hash, platform_role)
                 VALUES (:full_name, :email, :password_hash, "platform_admin")'
            );
            $insert->execute([
                'full_name' => trim((string) $input['admin_name']),
                'email' => mb_strtolower((string) $input['admin_email']),
                'password_hash' => secure_password_hash((string) $input['admin_password']),
            ]);
        }

        $envContent = $this->buildEnvFile($input, $useMySQL);

        if (file_put_contents($this->rootPath . '/.env', $envContent) === false) {
            throw new RuntimeException('Die .env-Datei konnte nicht geschrieben werden.');
        }

        $lockContent = json_encode([
            'installed_at' => gmdate(DATE_ATOM),
            'app_url' => trim((string) $input['app_url']),
            'database_type' => $useMySQL ? 'mysql' : 'sqlite',
        ], JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);

        file_put_contents($this->rootPath . '/storage/installed.lock', (string) $lockContent);
    }

    private function setupMySQLDatabase(array $input): PDO
    {
        $config = [
            'host' => trim((string) $input['db_host']),
            'port' => (int) $input['db_port'],
            'name' => trim((string) $input['db_name']),
            'user' => trim((string) $input['db_user']),
            'pass' => (string) ($input['db_pass'] ?? ''),
            'charset' => 'utf8mb4',
        ];

        $dsn = sprintf(
            'mysql:host=%s;port=%d;dbname=%s;charset=%s',
            $config['host'],
            $config['port'],
            $config['name'],
            $config['charset']
        );

        try {
            $pdo = new PDO($dsn, $config['user'], $config['pass'], [
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES => false,
            ]);

            $schema = file_get_contents($this->rootPath . '/database/schema.sql');

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

            $pdo->exec($schema);
            return $pdo;
        } catch (\PDOException $e) {
            throw new RuntimeException('MySQL-Datenbankverbindung fehlgeschlagen: ' . $e->getMessage() . '. Bitte prüfen Sie Ihre Datenbankeinstellungen oder verwenden Sie SQLite als Alternative.');
        }
    }

    private function setupSQLiteDatabase(): PDO
    {
        $dbPath = $this->rootPath . '/storage/database.sqlite';
        $dbDir = dirname($dbPath);

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

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

            $pdo->exec('PRAGMA journal_mode=WAL');
            $pdo->exec('PRAGMA foreign_keys=ON');
            $pdo->exec('PRAGMA busy_timeout=5000');

            $schema = file_get_contents($this->rootPath . '/database/schema.sqlite.sql');

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

            $pdo->exec($schema);
            return $pdo;
        } catch (\PDOException $e) {
            throw new RuntimeException('SQLite-Datenbankverbindung fehlgeschlagen: ' . $e->getMessage());
        }
    }

    private function buildEnvFile(array $input, bool $useMySQL = true): string
    {
        $appUrl = $this->normalizeAppUrl((string) $input['app_url']);
        $mailFrom = $this->resolveMailFrom($input, $appUrl);
        $appKey = bin2hex(random_bytes(32));
        $rfidSecret = bin2hex(random_bytes(24));

        $lines = [
            'APP_NAME="Kaffeekasse SaaS"',
            'APP_ENV=production',
            'APP_DEBUG=0',
            'APP_URL=' . $appUrl,
            'APP_TIMEZONE=Europe/Berlin',
            'APP_KEY=' . $appKey,
            'ALLOW_PUBLIC_REGISTRATION=1',
            'RFID_INGEST_ENABLED=0',
            '',
        ];

        // Datenbankeinstellungen je nach verwendetem System
        if ($useMySQL) {
            $lines = array_merge($lines, [
                'DB_HOST=' . trim((string) $input['db_host']),
                'DB_PORT=' . (int) $input['db_port'],
                'DB_NAME=' . trim((string) $input['db_name']),
                'DB_USER=' . trim((string) $input['db_user']),
                'DB_PASS=' . (string) ($input['db_pass'] ?? ''),
            ]);
        } else {
            // SQLite-Konfiguration
            $lines = array_merge($lines, [
                'DB_HOST=sqlite',
                'DB_PORT=0',
                'DB_NAME=' . $this->rootPath . '/storage/database.sqlite',
                'DB_USER=',
                'DB_PASS=',
            ]);
        }

        $lines = array_merge($lines, [
            '',
            'MAIL_FROM=' . $mailFrom,
            'MAIL_REPLY_TO=' . $mailFrom,
            'MAIL_SUBJECT_PREFIX="[Kaffeekasse] "',
            'MAIL_LOG_FALLBACK=1',
            'MAIL_LOG_FILE=storage/logs/mail.log',
            '',
            'PASSWORD_RESET_URL=' . $appUrl . '/reset-password?token={{token}}',
            'PASSWORD_RESET_TTL_MINUTES=60',
            'PASSWORD_RESET_MAX_ACTIVE_TOKENS=3',
            'PASSWORD_RESET_SUBJECT="Passwort zuruecksetzen"',
            '',
            'RATE_LIMIT_LOGIN_MAX_ATTEMPTS=5',
            'RATE_LIMIT_LOGIN_WINDOW_SECONDS=900',
            'RATE_LIMIT_LOGIN_BLOCK_SECONDS=900',
            'RATE_LIMIT_REGISTRATION_MAX_ATTEMPTS=3',
            'RATE_LIMIT_REGISTRATION_WINDOW_SECONDS=3600',
            'RATE_LIMIT_REGISTRATION_BLOCK_SECONDS=3600',
            '',
            'RFID_SHARED_SECRET=' . $rfidSecret,
        ]);

        return implode(PHP_EOL, $lines) . PHP_EOL;
    }

    private function normalizeAppUrl(string $appUrl): string
    {
        return rtrim(trim($appUrl), '/');
    }

    private function resolveMailFrom(array $input, string $appUrl): string
    {
        $mailFrom = mb_strtolower(trim((string) ($input['mail_from'] ?? '')));

        if ($mailFrom === '' || $mailFrom === 'noreply@example.com') {
            return $this->defaultMailFrom($appUrl);
        }

        if (!filter_var($mailFrom, FILTER_VALIDATE_EMAIL)) {
            throw new RuntimeException('Die Mail-Absenderadresse ist ungueltig.');
        }

        return $mailFrom;
    }

    private function defaultMailFrom(string $appUrl): string
    {
        $host = parse_url($appUrl, PHP_URL_HOST);

        if (!is_string($host)) {
            return 'noreply@example.com';
        }

        $host = preg_replace('/^www\./i', '', mb_strtolower(trim($host))) ?? '';

        if ($host === '' || !str_contains($host, '.')) {
            return 'noreply@example.com';
        }

        return 'noreply@' . $host;
    }
}