<?php
declare(strict_types=1);

final class NamePolicy
{
    public const MAX_IDENTIFIER_LEN = 64;
    public const MAX_HOST_COMMENT_LEN = 180;

    /**
     * @var array<string,string>
     */
    public const PRIVILEGE_LABELS = [
        'ALL' => 'Wszystkie uprawnienia',
        'SELECT' => 'SELECT',
        'INSERT' => 'INSERT',
        'UPDATE' => 'UPDATE',
        'DELETE' => 'DELETE',
        'CREATE' => 'CREATE',
        'ALTER' => 'ALTER',
        'DROP' => 'DROP',
        'INDEX' => 'INDEX',
        'REFERENCES' => 'REFERENCES',
        'CREATE_VIEW' => 'CREATE VIEW',
        'SHOW_VIEW' => 'SHOW VIEW',
        'TRIGGER' => 'TRIGGER',
        'EXECUTE' => 'EXECUTE',
        'EVENT' => 'EVENT',
        'LOCK_TABLES' => 'LOCK TABLES',
    ];

    public static function defaultPrivileges(): array
    {
        return ['ALL'];
    }

    public static function normalizeDatabaseName(string $input, string $prefix): string
    {
        return self::normalizeIdentifier($input, $prefix, 'Nazwa bazy');
    }

    public static function normalizeRoleName(string $input, string $prefix): string
    {
        return self::normalizeIdentifier($input, $prefix, 'Nazwa użytkownika');
    }

    public static function assertBelongsToUser(string $name, string $prefix, string $entityLabel = 'Obiekt'): void
    {
        if (strpos($name, $prefix) !== 0) {
            throw new InvalidArgumentException($entityLabel . ' musi zaczynać się od prefiksu: ' . $prefix);
        }
    }

    public static function normalizeIdentifier(string $input, string $prefix, string $label): string
    {
        $value = strtolower(trim($input));
        if ($value === '') {
            throw new InvalidArgumentException($label . ' jest wymagana.');
        }

        if (!preg_match('/^[a-z0-9_]+$/', $value)) {
            throw new InvalidArgumentException($label . ' może zawierać wyłącznie znaki a-z, 0-9 oraz _.');
        }

        if (strpos($value, $prefix) !== 0) {
            $value = $prefix . $value;
        }

        if (strlen($value) > self::MAX_IDENTIFIER_LEN) {
            throw new InvalidArgumentException($label . ' przekracza limit 64 znaków MySQL.');
        }

        if ($value === $prefix) {
            throw new InvalidArgumentException($label . ' nie może być równa samemu prefiksowi.');
        }

        return $value;
    }

    /**
     * @return string[]
     */
    public static function parseHosts(string $raw): array
    {
        $raw = str_replace(["\r\n", "\r", ';'], ["\n", "\n", "\n"], $raw);
        $raw = str_replace(',', "\n", $raw);
        $parts = explode("\n", $raw);

        $hosts = [];
        foreach ($parts as $part) {
            $part = trim($part);
            if ($part === '') {
                continue;
            }
            $hosts[] = $part;
        }

        return array_values(array_unique($hosts));
    }

    public static function normalizeHost(string $input, bool $allowWildcard): string
    {
        $host = strtolower(trim($input));
        if ($host === '') {
            throw new InvalidArgumentException('Pusty host.');
        }

        if (in_array($host, ['localhost', '127.0.0.1', '::1', '%'], true)) {
            return $host;
        }

        if (self::isStrictIpv4($host)) {
            return $host;
        }

        if ($allowWildcard && preg_match('/^[A-Za-z0-9._%-]+$/', $host)) {
            return $host;
        }

        throw new InvalidArgumentException('Nieobsługiwany format hosta: ' . $input);
    }

    public static function normalizeRemoteIpv4Host(string $input): string
    {
        $host = trim($input);
        if ($host === '') {
            throw new InvalidArgumentException('Adres IPv4 jest wymagany.');
        }

        if (!self::isStrictIpv4($host)) {
            throw new InvalidArgumentException('Dozwolone są tylko pojedyncze adresy IPv4, np. 203.0.113.10.');
        }

        return $host;
    }

    public static function normalizeHostComment(string $input): string
    {
        $comment = trim(preg_replace('/[\r\n\t]+/', ' ', $input) ?? '');
        $comment = preg_replace('/\s+/', ' ', $comment) ?? '';
        $comment = trim($comment);

        if (strlen($comment) > self::MAX_HOST_COMMENT_LEN) {
            throw new InvalidArgumentException('Komentarz hosta przekracza limit ' . self::MAX_HOST_COMMENT_LEN . ' znaków.');
        }

        return $comment;
    }

    /**
     * @param array<int,string> $input
     * @return string[]
     */
    public static function sanitizePrivileges(array $input): array
    {
        $allowed = array_keys(self::PRIVILEGE_LABELS);
        $result = [];

        foreach ($input as $priv) {
            $priv = strtoupper(trim((string)$priv));
            if ($priv === '' || !in_array($priv, $allowed, true)) {
                continue;
            }
            $result[] = $priv;
        }

        $result = array_values(array_unique($result));
        if (in_array('ALL', $result, true)) {
            return ['ALL'];
        }

        return $result;
    }

    private static function isStrictIpv4(string $value): bool
    {
        if (!preg_match('/^(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?:\.(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])){3}$/', $value)) {
            return false;
        }

        return filter_var($value, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) !== false;
    }
}