import '../social/handle_validator.dart';

/// Result of a Club slug validation check.
class ClubSlugValidationResult {
  final bool isValid;
  final String? error;
  final String? normalizedSlug;

  const ClubSlugValidationResult._({
    required this.isValid,
    this.error,
    this.normalizedSlug,
  });

  factory ClubSlugValidationResult.valid(String normalized) =>
      ClubSlugValidationResult._(isValid: true, normalizedSlug: normalized);

  factory ClubSlugValidationResult.invalid(String error) =>
      ClubSlugValidationResult._(isValid: false, error: error);
}

/// Normalization and validation logic for MotorSignal Club slugs.
class ClubSlugValidator {
  static const int minLength = 3;
  static const int maxLength = 30;

  static final RegExp _formatRegex = RegExp(r'^[a-z0-9][a-z0-9-]{1,28}[a-z0-9]$');

  /// Reserved words specific to clubs, chapters, and platform organizations.
  static const Set<String> clubReservedWords = {
    'club',
    'clubs',
    'motorcycle',
    'motorcycles',
    'mc',
    'chapter',
    'chapters',
    'national',
    'international',
    'official',
    'rally',
    'groupride',
    'grouprides',
    'event',
    'events',
    'all',
    'global',
    'feed',
    'roster',
    'members',
    'settings',
    'admin',
  };

  /// Normalizes a raw slug: trims whitespace and lowercases.
  static String normalize(String rawSlug) => rawSlug.trim().toLowerCase();

  /// Validates a candidate slug format and checks against reserved words.
  static ClubSlugValidationResult validate(String rawSlug) {
    final normalized = normalize(rawSlug);

    if (normalized.isEmpty) {
      return ClubSlugValidationResult.invalid('Club slug cannot be empty');
    }

    if (normalized.length < minLength) {
      return ClubSlugValidationResult.invalid(
        'Club slug must be at least $minLength characters',
      );
    }

    if (normalized.length > maxLength) {
      return ClubSlugValidationResult.invalid(
        'Club slug cannot exceed $maxLength characters',
      );
    }

    if (normalized.contains('--')) {
      return ClubSlugValidationResult.invalid(
        'Club slug cannot contain consecutive hyphens',
      );
    }

    if (!_formatRegex.hasMatch(normalized)) {
      return ClubSlugValidationResult.invalid(
        'Club slug must start and end with a letter or number, and contain only lowercase letters, numbers, and hyphens',
      );
    }

    // Check against standard platform handles (admin, support, motorsignal, etc.)
    if (HandleValidator.reservedHandles.contains(normalized)) {
      return ClubSlugValidationResult.invalid('This club slug is reserved');
    }

    // Check against club-specific reserved words
    if (clubReservedWords.contains(normalized)) {
      return ClubSlugValidationResult.invalid('This club slug is reserved');
    }

    return ClubSlugValidationResult.valid(normalized);
  }
}