import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';

/// Defines a room in the application.
///
/// Each feature/room registers itself with metadata for navigation,
/// routing, and permission-based access control.
class RoomDefinition {
  const RoomDefinition({
    required this.id,
    required this.label,
    required this.icon,
    required this.selectedIcon,
    required this.defaultRoute,
    required this.routes,
    this.requiredPermissions = const [],
  });

  /// Unique identifier used in preferences (e.g., 'front-hall', 'control-room').
  final String id;

  /// Display label for UI.
  final String label;

  /// Icon when not selected.
  final IconData icon;

  /// Icon when selected.
  final IconData selectedIcon;

  /// Default route path when room is selected.
  final String defaultRoute;

  /// All routes this room provides to go_router.
  final List<RouteBase> Function() routes;

  /// Permissions required to access this room (empty = accessible to all).
  /// User must have ALL listed permissions.
  final List<String> requiredPermissions;
}

/// Central registry of all rooms in the application.
///
/// Each room's router.dart file registers itself here.
/// UI components query this registry to build navigation.
class RoomRegistry {
  RoomRegistry._();

  static final RoomRegistry instance = RoomRegistry._();

  final List<RoomDefinition> _rooms = [];

  /// Register a room. Called by each room's router.dart.
  void register(RoomDefinition room) {
    // Avoid duplicate registration
    if (!_rooms.any((r) => r.id == room.id)) {
      _rooms.add(room);
    }
  }

  /// Get all registered rooms.
  List<RoomDefinition> get all => List.unmodifiable(_rooms);

  /// Get rooms filtered by user permissions.
  ///
  /// [userPermissions] is the set of permissions the user has.
  /// Returns rooms where the user has ALL required permissions.
  List<RoomDefinition> accessibleTo(Set<String> userPermissions) {
    return _rooms.where((room) {
      if (room.requiredPermissions.isEmpty) return true;
      return room.requiredPermissions.every(userPermissions.contains);
    }).toList();
  }

  /// Get a room by its ID.
  RoomDefinition? byId(String id) {
    try {
      return _rooms.firstWhere((r) => r.id == id);
    } catch (_) {
      return null;
    }
  }

  /// Get the index of a room by its ID.
  int indexOfId(String id) {
    return _rooms.indexWhere((r) => r.id == id);
  }

  /// Get the index of a room by route path.
  int indexOfRoute(String path) {
    // Find room whose defaultRoute matches or whose routes start with path
    for (var i = 0; i < _rooms.length; i++) {
      final room = _rooms[i];
      if (path == room.defaultRoute || path.startsWith('/${room.id}')) {
        return i;
      }
    }
    return 0; // Default to first room
  }

  /// Get all routes from all registered rooms.
  List<RouteBase> allRoutes() {
    return _rooms.expand((room) => room.routes()).toList();
  }

  /// Clear registry (useful for testing).
  void clear() {
    _rooms.clear();
  }
}

/// Global registry instance.
final roomRegistry = RoomRegistry.instance;