import 'dart:convert';
import 'dart:developer' as developer;

import 'package:dio/dio.dart';
import 'package:flutter/foundation.dart' show kIsWeb;
import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'package:shared_preferences/shared_preferences.dart';

import '../config/app_config.dart';
import 'auth_datasource.dart';
import 'auth_state.dart';
import 'oidc_service.dart';
import 'permissions.dart';
import 'user_preferences.dart';

part 'auth_provider.g.dart';

/// Provides authentication state and operations.
///
/// Supports two authentication flows:
/// - **Web**: NPM forward auth with Authentik (cookies handled by proxy)
/// - **Mobile**: OIDC Authorization Code flow with flutter_appauth
///
/// On web, the app calls GET /auth/me to check if user is authenticated
/// via NPM forward auth headers. On mobile, uses OIDC flow then POST /auth/sync.
@riverpod
class AuthNotifier extends _$AuthNotifier {
  // Storage keys
  static const _accessTokenKey = 'auth_access_token';
  static const _refreshTokenKey = 'auth_refresh_token';
  static const _expiresAtKey = 'auth_expires_at';
  static const _userIdKey = 'auth_user_id';
  static const _authentikIdKey = 'auth_authentik_id';
  static const _userNameKey = 'auth_user_name';
  static const _userEmailKey = 'auth_user_email';
  static const _avatarUrlKey = 'auth_avatar_url';
  static const _rolesKey = 'auth_roles';
  static const _preferencesKey = 'auth_preferences';

  @override
  Future<AuthState> build() async {
    // On web with auth required, try to get user from NPM forward auth
    if (kIsWeb && AppConfig.requiresAuth) {
      final webAuth = await _tryWebAuth();
      if (webAuth != null) {
        return webAuth;
      }
      // If web auth failed, user needs to refresh to trigger NPM login
      developer.log('Web auth not available - user may need to login via proxy', name: 'auth');
      return const AuthState();
    }

    // On mobile or LAN, load from stored auth
    return _loadStoredAuth();
  }

  /// Try to authenticate via NPM forward auth (web only).
  ///
  /// Returns AuthState if authenticated, null if not.
  Future<AuthState?> _tryWebAuth() async {
    try {
      developer.log('Attempting web auth via /auth/me', name: 'auth');
      final authDatasource = ref.read(authDatasourceProvider);
      final syncResponse = await authDatasource.getCurrentUser();

      developer.log(
        'Web auth successful: ${syncResponse.name} with ${syncResponse.roles.length} roles',
        name: 'auth',
      );

      // Store auth data for offline/cached access
      await _storeAuth(
        accessToken: 'web-session', // Placeholder - web uses cookies
        userId: syncResponse.userId,
        authentikId: syncResponse.authentikId,
        userName: syncResponse.name,
        userEmail: syncResponse.email,
        avatarUrl: syncResponse.avatarUrl,
        roles: syncResponse.roles,
        preferences: syncResponse.preferences,
      );

      return AuthState(
        isAuthenticated: true,
        accessToken: 'web-session',
        userId: syncResponse.userId,
        authentikId: syncResponse.authentikId,
        userName: syncResponse.name,
        userEmail: syncResponse.email,
        avatarUrl: syncResponse.avatarUrl,
        roles: syncResponse.roles,
        preferences: syncResponse.preferences,
      );
    } on DioException catch (e) {
      if (e.response?.statusCode == 401) {
        developer.log('Web auth: not authenticated via proxy', name: 'auth');
        return null;
      }
      developer.log('Web auth error: $e', name: 'auth');
      return null;
    } catch (e) {
      developer.log('Web auth unexpected error: $e', name: 'auth');
      return null;
    }
  }

  Future<AuthState> _loadStoredAuth() async {
    try {
      final prefs = await SharedPreferences.getInstance();

      final accessToken = prefs.getString(_accessTokenKey);
      if (accessToken == null) {
        return const AuthState();
      }

      final expiresAtMs = prefs.getInt(_expiresAtKey);
      final expiresAt = expiresAtMs != null
          ? DateTime.fromMillisecondsSinceEpoch(expiresAtMs)
          : null;

      // Load roles from JSON
      final rolesJson = prefs.getString(_rolesKey);
      final roles = rolesJson != null ? _parseRoles(rolesJson) : <Role>[];

      // Load preferences from JSON
      final prefsJson = prefs.getString(_preferencesKey);
      final preferences = prefsJson != null
          ? UserPreferences.fromJson(jsonDecode(prefsJson) as Map<String, dynamic>)
          : null;

      final authState = AuthState(
        isAuthenticated: true,
        accessToken: accessToken,
        refreshToken: prefs.getString(_refreshTokenKey),
        expiresAt: expiresAt,
        userId: prefs.getString(_userIdKey),
        authentikId: prefs.getString(_authentikIdKey),
        userName: prefs.getString(_userNameKey),
        userEmail: prefs.getString(_userEmailKey),
        avatarUrl: prefs.getString(_avatarUrlKey),
        roles: roles,
        preferences: preferences,
      );

      // Check if token is expired - try to refresh
      if (authState.isTokenExpired && authState.refreshToken != null) {
        developer.log('Token expired, attempting refresh', name: 'auth');
        return _tryRefreshToken(authState);
      }

      if (authState.isTokenExpired) {
        developer.log('Stored token expired, clearing auth', name: 'auth');
        await _clearStoredAuth();
        return const AuthState();
      }

      developer.log('Restored auth for ${authState.userName}', name: 'auth');
      return authState;
    } catch (e) {
      developer.log('Failed to load stored auth: $e', name: 'auth');
      return const AuthState();
    }
  }

  /// Parse roles from stored JSON.
  List<Role> _parseRoles(String json) {
    try {
      final list = jsonDecode(json) as List<dynamic>;
      return list.map((item) {
        final map = item as Map<String, dynamic>;
        final domain = Domain.fromString(map['domain'] as String);
        final action = Action.fromString(map['action'] as String);

        if (domain == null || action == null) {
          return null;
        }

        return Role(
          id: map['id'] as String,
          name: map['name'] as String,
          domain: domain,
          category: map['category'] as String? ?? 'general',
          action: action,
        );
      }).whereType<Role>().toList();
    } catch (e) {
      developer.log('Failed to parse roles: $e', name: 'auth');
      return [];
    }
  }

  /// Try to refresh the access token.
  Future<AuthState> _tryRefreshToken(AuthState currentState) async {
    if (currentState.refreshToken == null) {
      await _clearStoredAuth();
      return const AuthState();
    }

    try {
      final oidcService = ref.read(oidcServiceProvider);
      final tokens = await oidcService.refreshToken(currentState.refreshToken!);

      // Update stored tokens
      final prefs = await SharedPreferences.getInstance();
      await prefs.setString(_accessTokenKey, tokens.accessToken);
      if (tokens.refreshToken != null) {
        await prefs.setString(_refreshTokenKey, tokens.refreshToken!);
      }
      await prefs.setInt(_expiresAtKey, tokens.expiresAt.millisecondsSinceEpoch);

      developer.log('Token refreshed successfully', name: 'auth');

      return currentState.copyWith(
        accessToken: tokens.accessToken,
        refreshToken: tokens.refreshToken ?? currentState.refreshToken,
        expiresAt: tokens.expiresAt,
      );
    } catch (e) {
      developer.log('Token refresh failed: $e', name: 'auth');
      await _clearStoredAuth();
      return const AuthState();
    }
  }

  /// Sign in with the appropriate method for the platform.
  ///
  /// - **Web**: Triggers page reload to go through NPM forward auth
  /// - **Mobile**: Opens Authentik login via OIDC, then syncs with core-api
  Future<void> signIn() async {
    if (!AppConfig.requiresAuth) {
      developer.log('Auth not required in LAN mode', name: 'auth');
      // In LAN mode, set a minimal authenticated state
      state = const AsyncData(AuthState(isAuthenticated: true));
      return;
    }

    // On web, auth is handled by NPM forward auth
    // User needs to access via the authenticated proxy URL
    if (kIsWeb) {
      developer.log('Web sign-in: user should access via authenticated proxy', name: 'auth');
      // Try to refresh auth state from /auth/me
      state = const AsyncLoading();
      final webAuth = await _tryWebAuth();
      if (webAuth != null) {
        state = AsyncData(webAuth);
      } else {
        state = AsyncError(
          Exception('Not authenticated - please access via the authenticated URL'),
          StackTrace.current,
        );
      }
      return;
    }

    // Mobile: Use OIDC flow
    state = const AsyncLoading();

    try {
      // Step 1: OIDC authentication with Authentik
      developer.log('Starting OIDC authentication', name: 'auth');
      final oidcService = ref.read(oidcServiceProvider);
      final tokens = await oidcService.signIn();

      // Step 2: Sync with core-api to get user profile and roles
      developer.log('Syncing with core-api', name: 'auth');
      final authDatasource = ref.read(authDatasourceProvider);
      final syncResponse = await authDatasource.syncUser(tokens.accessToken);

      // Step 3: Store credentials and user data
      await _storeAuth(
        accessToken: tokens.accessToken,
        refreshToken: tokens.refreshToken,
        expiresAt: tokens.expiresAt,
        userId: syncResponse.userId,
        authentikId: syncResponse.authentikId,
        userName: syncResponse.name,
        userEmail: syncResponse.email,
        avatarUrl: syncResponse.avatarUrl,
        roles: syncResponse.roles,
        preferences: syncResponse.preferences,
      );

      state = AsyncData(AuthState(
        isAuthenticated: true,
        accessToken: tokens.accessToken,
        refreshToken: tokens.refreshToken,
        expiresAt: tokens.expiresAt,
        userId: syncResponse.userId,
        authentikId: syncResponse.authentikId,
        userName: syncResponse.name,
        userEmail: syncResponse.email,
        avatarUrl: syncResponse.avatarUrl,
        roles: syncResponse.roles,
        preferences: syncResponse.preferences,
      ));

      developer.log(
        'Authenticated as ${syncResponse.name} with ${syncResponse.roles.length} roles',
        name: 'auth',
      );
    } on OidcException catch (e) {
      developer.log('OIDC authentication failed: $e', name: 'auth');
      state = AsyncError(e, StackTrace.current);
    } catch (e, stack) {
      developer.log('Authentication failed: $e', name: 'auth');
      state = AsyncError(e, stack);
    }
  }

  /// Sign out and clear stored credentials.
  Future<void> signOut() async {
    await _clearStoredAuth();
    state = const AsyncData(AuthState());
    developer.log('Signed out', name: 'auth');
  }

  /// Update user preferences.
  Future<void> updatePreferences({
    String? theme,
    String? defaultRoom,
    Map<String, dynamic>? preferencesJson,
  }) async {
    final currentState = state.value;
    if (currentState == null || !currentState.isAuthenticated) return;

    try {
      final authDatasource = ref.read(authDatasourceProvider);
      final newPrefs = await authDatasource.updatePreferences(
        theme: theme,
        defaultRoom: defaultRoom,
        preferencesJson: preferencesJson,
      );

      // Update stored preferences
      final prefs = await SharedPreferences.getInstance();
      await prefs.setString(_preferencesKey, jsonEncode(newPrefs.toJson()));

      state = AsyncData(currentState.copyWith(preferences: newPrefs));
      developer.log('Preferences updated', name: 'auth');
    } catch (e) {
      developer.log('Failed to update preferences: $e', name: 'auth');
      rethrow;
    }
  }

  /// Store authentication data to SharedPreferences.
  Future<void> _storeAuth({
    required String accessToken,
    String? refreshToken,
    DateTime? expiresAt,
    String? userId,
    String? authentikId,
    String? userName,
    String? userEmail,
    String? avatarUrl,
    List<Role>? roles,
    UserPreferences? preferences,
  }) async {
    final prefs = await SharedPreferences.getInstance();

    await prefs.setString(_accessTokenKey, accessToken);
    if (refreshToken != null) {
      await prefs.setString(_refreshTokenKey, refreshToken);
    }
    if (expiresAt != null) {
      await prefs.setInt(_expiresAtKey, expiresAt.millisecondsSinceEpoch);
    }
    if (userId != null) await prefs.setString(_userIdKey, userId);
    if (authentikId != null) await prefs.setString(_authentikIdKey, authentikId);
    if (userName != null) await prefs.setString(_userNameKey, userName);
    if (userEmail != null) await prefs.setString(_userEmailKey, userEmail);
    if (avatarUrl != null) await prefs.setString(_avatarUrlKey, avatarUrl);

    // Store roles as JSON
    if (roles != null) {
      final rolesJson = jsonEncode(roles.map((r) => {
        'id': r.id,
        'name': r.name,
        'domain': r.domain.value,
        'category': r.category,
        'action': r.action.name,
      }).toList());
      await prefs.setString(_rolesKey, rolesJson);
    }

    // Store preferences as JSON
    if (preferences != null) {
      await prefs.setString(_preferencesKey, jsonEncode(preferences.toJson()));
    }
  }

  Future<void> _clearStoredAuth() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(_accessTokenKey);
    await prefs.remove(_refreshTokenKey);
    await prefs.remove(_expiresAtKey);
    await prefs.remove(_userIdKey);
    await prefs.remove(_authentikIdKey);
    await prefs.remove(_userNameKey);
    await prefs.remove(_userEmailKey);
    await prefs.remove(_avatarUrlKey);
    await prefs.remove(_rolesKey);
    await prefs.remove(_preferencesKey);
  }
}