import 'dart:convert' show jsonDecode, jsonEncode;
import 'dart:developer' as developer;

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

import '../config/app_config.dart';
import 'auth_datasource.dart';
import 'auth_state.dart';
import 'oidc_service_web.dart';
import 'permissions.dart';
import 'user_preferences.dart';
import 'web_utils.dart' as web_utils;

/// Standalone auth controller that handles OIDC flow before app starts.
///
/// This runs outside of Riverpod to avoid lifecycle issues. Call [initialize]
/// in main() before runApp(). The controller will:
/// 1. Handle callback if on /callback route (exchange code, sync, store tokens)
/// 2. Check for valid stored tokens
/// 3. Redirect to silent OIDC if no tokens (app won't continue)
///
/// Once auth is complete, [AuthProvider] can simply read the stored tokens.
class AuthController {
  // Storage keys (same as AuthProvider)
  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';

  /// Initialize auth before app starts.
  ///
  /// Returns true if auth is ready (tokens available).
  /// Returns false if redirecting (app should not continue).
  /// Throws on error.
  static Future<bool> initialize() async {
    // Skip auth entirely for LAN mode
    if (!AppConfig.requiresAuth) {
      developer.log('Auth not required (LAN mode)', name: 'auth_controller');
      return true;
    }

    // Only handle web auth here - mobile uses different flow
    if (!kIsWeb) {
      developer.log('Non-web platform, skipping controller init', name: 'auth_controller');
      return true;
    }

    final currentUrl = web_utils.getCurrentUrl();
    developer.log('Auth controller init, URL: $currentUrl', name: 'auth_controller');

    // Check if we're on the callback route
    if (currentUrl.contains('/callback')) {
      return _handleCallback(currentUrl);
    }

    // Check for valid stored tokens
    final prefs = await SharedPreferences.getInstance();
    final accessToken = prefs.getString(_accessTokenKey);
    if (accessToken != null) {
      final expiresAtMs = prefs.getInt(_expiresAtKey);
      final expiresAt = expiresAtMs != null
          ? DateTime.fromMillisecondsSinceEpoch(expiresAtMs)
          : null;

      if (expiresAt == null || expiresAt.isAfter(DateTime.now())) {
        developer.log('Valid tokens found', name: 'auth_controller');
        return true; // Auth ready
      }
      developer.log('Tokens expired', name: 'auth_controller');
    }

    // No valid tokens - initiate silent OIDC
    developer.log('No valid tokens, starting silent OIDC', name: 'auth_controller');
    await _initiateSilentOidc();
    return false; // Redirecting, app should not continue
  }

  /// Handle the OIDC callback.
  static Future<bool> _handleCallback(String url) async {
    final uri = Uri.parse(url);
    final code = uri.queryParameters['code'];
    final state = uri.queryParameters['state'];
    final error = uri.queryParameters['error'];

    developer.log('Handling callback: code=${code != null}, error=$error', name: 'auth_controller');

    // Handle errors
    if (error != null) {
      if (error == 'login_required') {
        // Silent auth failed - no session, start regular OIDC
        developer.log('Silent auth failed (login_required), starting regular OIDC', name: 'auth_controller');
        await _initiateRegularOidc();
        return false;
      }
      throw Exception('Auth error: $error - ${uri.queryParameters['error_description']}');
    }

    if (code == null || state == null) {
      throw Exception('Invalid callback - missing code or state');
    }

    // Exchange code for tokens
    developer.log('Exchanging code for tokens', name: 'auth_controller');
    final oidcService = OidcServiceWeb();
    final tokens = await oidcService.exchangeCode(code, state);

    // Sync with core-api
    developer.log('Syncing with core-api', name: 'auth_controller');
    final dio = Dio(BaseOptions(
      baseUrl: AppConfig.coreApiUrl,
      headers: {
        'Content-Type': 'application/json',
        'Accept': 'application/json',
      },
    ));
    final authDatasource = AuthDatasource(dio);
    final syncResponse = await authDatasource.syncUser(tokens.accessToken);

    developer.log('Synced user: ${syncResponse.name}', name: 'auth_controller');

    // Store credentials
    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,
    );

    // Redirect to home (removes callback params from URL)
    developer.log('Auth complete, redirecting to home', name: 'auth_controller');
    web_utils.redirectTo('/');
    return false; // Redirecting
  }

  /// Initiate silent OIDC (prompt=none).
  static Future<void> _initiateSilentOidc() async {
    final oidcService = OidcServiceWeb();
    final authUrl = await oidcService.getAuthorizationUrl(silent: true);
    developer.log('Redirecting to silent OIDC', name: 'auth_controller');
    web_utils.redirectTo(authUrl);
  }

  /// Initiate regular OIDC (shows login UI).
  static Future<void> _initiateRegularOidc() async {
    final oidcService = OidcServiceWeb();
    final authUrl = await oidcService.getAuthorizationUrl(silent: false);
    developer.log('Redirecting to regular OIDC', name: 'auth_controller');
    web_utils.redirectTo(authUrl);
  }

  /// Store auth data.
  static 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);

    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);
    }

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

  /// Load stored auth state (for AuthProvider to use).
  static 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;

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

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

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

  static 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) {
      return [];
    }
  }

  /// Clear stored auth (for logout).
  static Future<void> clearAuth() 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);
  }
}