import 'dart:async';
import '../models/user_model.dart';
import '../../bootstrap/supabase_client.dart';
import '../../core/utils/unit_conversion_utils.dart';
import 'package:supabase_flutter/supabase_flutter.dart' as supabase;
import 'package:google_sign_in/google_sign_in.dart';

class AuthRepository {
  final supabase.SupabaseClient? _client;
  StreamSubscription<supabase.AuthState>? _authStateSubscription;

  AuthRepository([supabase.SupabaseClient? client]) : _client = client;

  Stream<User?> get authStateChanges {
    final client = supabaseClient;
    if (client == null) {
      // Return a stream that never emits if Supabase is not initialized
      return Stream.empty();
    }
    return client.auth.onAuthStateChange.map((data) {
      final session = data.session;
      if (session?.user != null) {
        return _mapSupabaseUserToAppUser(session!.user);
      }
      return null;
    });
  }

  User? get currentUser {
    final client = supabaseClient;
    if (client == null) return null;
    final user = client.auth.currentUser;
    return user != null ? _mapSupabaseUserToAppUser(user) : null;
  }

  bool get isAuthenticated {
    final client = supabaseClient;
    if (client == null) return false;
    return client.auth.currentUser != null;
  }

  String? get currentUserId {
    final client = supabaseClient;
    if (client == null) return null;
    return client.auth.currentUser?.id;
  }

  Future<bool> isSessionValid() async {
    assert(_client != null, 'Client must not be null');
    final session = _client!.auth.currentSession;
    if (session == null) return false;

    final now = DateTime.now();
    final expiresAt = session.expiresAt;
    if (expiresAt == null) return true;

    return now.isBefore(DateTime.fromMillisecondsSinceEpoch(expiresAt * 1000));
  }

  Future<void> refreshSession() async {
    assert(_client != null, 'Client must not be null');
    try {
      await _client!.auth.refreshSession();
    } catch (e) {
      throw Exception('Failed to refresh session: $e');
    }
  }

  Future<supabase.Session?> getCurrentSession() async {
    assert(_client != null, 'Client must not be null');
    return _client!.auth.currentSession;
  }

  void listenToAuthStateChanges(Function(User?) callback) {
    assert(_client != null, 'Client must not be null');
    _authStateSubscription = _client!.auth.onAuthStateChange.listen((data) {
      final session = data.session;
      if (session?.user != null) {
        callback(_mapSupabaseUserToAppUser(session!.user));
      } else {
        callback(null);
      }
    });
  }

  void dispose() {
    _authStateSubscription?.cancel();
  }

  Future<void> signInWithEmail(String email, String password) async {
    assert(_client != null, 'Client must not be null');
    await _client!.auth.signInWithPassword(email: email, password: password);
  }

  Future<void> signUpWithEmail(String email, String password, String username, {double? heightCm, double? weightKg, int? age, Gender? gender, HeightUnit? heightUnit, WeightUnit? weightUnit}) async {
    assert(_client != null, 'Client must not be null');
    final response = await _client!.auth.signUp(
      email: email,
      password: password,
      data: {'username': username},
    );

    if (response.user != null) {
      await _createUserProfile(response.user!.id, username, email, heightCm: heightCm, weightKg: weightKg, age: age, gender: gender, heightUnit: heightUnit, weightUnit: weightUnit);
    }
  }

  Future<void> signInWithGoogle() async {
    assert(_client != null, 'Client must not be null');
    try {
      final GoogleSignIn googleSignIn = GoogleSignIn(
        scopes: ['email', 'profile'],
      );

      // Check if user is already signed in
      final googleUser = await googleSignIn.signInSilently();
      if (googleUser != null) {
        await _handleGoogleUser(googleUser);
        return;
      }

      // Sign in interactively
      final interactiveUser = await googleSignIn.signIn();
      if (interactiveUser == null) {
        throw Exception('Google sign-in was cancelled');
      }

      await _handleGoogleUser(interactiveUser);
    } catch (e) {
      throw Exception('Google sign-in failed: ${e.toString()}');
    }
  }

  Future<void> _handleGoogleUser(dynamic googleUser) async {
    assert(_client != null, 'Client must not be null');
    try {
      final googleAuth = await googleUser.authentication;
      final idToken = googleAuth.idToken;
      final accessToken = googleAuth.accessToken;

      if (idToken == null && accessToken == null) {
        throw Exception('No ID token or access token from Google sign-in');
      }

      final response = await _client!.auth.signInWithIdToken(
        provider: supabase.OAuthProvider.google,
        idToken: idToken,
        accessToken: accessToken,
      );

      if (response.user != null) {
        await _ensureUserProfileExists(response.user!.id, response.user!);
      }
    } catch (e) {
      throw Exception('Failed to authenticate with Google: ${e.toString()}');
    }
  }

  Future<void> signInWithGithub() async {
    assert(_client != null, 'Client must not be null');
    await _client!.auth.signInWithOAuth(
      supabase.OAuthProvider.github,
    );
  }

  Future<void> signOut() async {
    assert(_client != null, 'Client must not be null');
    await _client!.auth.signOut();
  }

  Future<void> resetPassword(String email) async {
    assert(_client != null, 'Client must not be null');
    await _client!.auth.resetPasswordForEmail(email);
  }

  Future<void> updateProfile({
    String? username,
    String? bio,
    String? avatarUrl,
    bool? isPublicProfile,
    double? heightCm,
    double? weightKg,
    int? age,
    Gender? gender,
    HeightUnit? heightUnit,
    WeightUnit? weightUnit,
  }) async {
    assert(_client != null, 'Client must not be null');
    final userId = _client!.auth.currentUser?.id;
    if (userId == null) throw Exception('User not authenticated');

    final updates = <String, dynamic>{};
    if (username != null) updates['username'] = username;
    if (bio != null) updates['bio'] = bio;
    if (avatarUrl != null) updates['avatar_url'] = avatarUrl;
    if (isPublicProfile != null) updates['is_public_profile'] = isPublicProfile;
    if (heightCm != null) updates['height_cm'] = heightCm;
    if (weightKg != null) updates['weight_kg'] = weightKg;
    if (age != null) updates['age'] = age;
    if (gender != null) updates['gender'] = gender.toDatabaseString();
    if (heightUnit != null) updates['height_unit'] = heightUnit.code;
    if (weightUnit != null) updates['weight_unit'] = weightUnit.code;
    updates['updated_at'] = DateTime.now().toIso8601String();

    await _client!
        .from('users')
        .update(updates)
        .eq('id', userId);
  }

  Future<User> _createUserProfile(String userId, String username, String email, {double? heightCm, double? weightKg, int? age, Gender? gender, HeightUnit? heightUnit, WeightUnit? weightUnit}) async {
    assert(_client != null, 'Client must not be null');
    final now = DateTime.now().toIso8601String();

    try {
      // First try with the regular client (might fail due to RLS)
      final response = await _client!.from('users').insert({
        'id': userId,
        'username': username,
        'email': email,
        'height_cm': heightCm,
        'weight_kg': weightKg,
        'age': age,
        'gender': gender?.toDatabaseString(),
        'height_unit': heightUnit?.code ?? HeightUnit.metric.code,
        'weight_unit': weightUnit?.code ?? WeightUnit.metric.code,
        'created_at': now,
        'updated_at': now,
      }).select();

      if (response.isNotEmpty) {
        return _mapSupabaseDataToUser(response.first);
      }
    } catch (e) {
      // If regular client fails due to RLS, try with service role client
      try {
        final serviceClient = getServiceRoleClient();
        final response = await serviceClient.from('users').insert({
          'id': userId,
          'username': username,
          'email': email,
          'height_cm': heightCm,
          'weight_kg': weightKg,
          'age': age,
          'gender': gender?.toDatabaseString(),
          'height_unit': heightUnit?.code ?? HeightUnit.metric.code,
          'weight_unit': weightUnit?.code ?? WeightUnit.metric.code,
          'created_at': now,
          'updated_at': now,
        }).select();

        if (response.isNotEmpty) {
          return _mapSupabaseDataToUser(response.first);
        }
      } catch (e2) {
        // If both fail, create a basic user profile from auth metadata
        // This allows the app to function even without database profile creation
        return User(
          id: userId,
          username: username,
          email: email,
          storedAge: age,
          heightCm: heightCm,
          weightKg: weightKg,
          gender: gender,
          heightUnit: heightUnit ?? HeightUnit.metric,
          weightUnit: weightUnit ?? WeightUnit.metric,
          createdAt: DateTime.parse(now),
          updatedAt: DateTime.parse(now),
        );
      }
    }

    // Fallback if no response but no error
    return User(
      id: userId,
      username: username,
      email: email,
      storedAge: age,
      heightCm: heightCm,
      weightKg: weightKg,
      gender: gender,
      heightUnit: heightUnit ?? HeightUnit.metric,
      weightUnit: weightUnit ?? WeightUnit.metric,
      createdAt: DateTime.parse(now),
      updatedAt: DateTime.parse(now),
    );
  }

  Future<void> _ensureUserProfileExists(String userId, dynamic supabaseUser) async {
    assert(_client != null, 'Client must not be null');
    try {
      final existingProfile = await _client!
          .from('users')
          .select('id')
          .eq('id', userId)
          .maybeSingle();

      if (existingProfile == null) {
        final username = supabaseUser.userMetadata?['username'] ??
            'user_${userId.substring(0, 8)}';
        final email = supabaseUser.email ?? '';
        await _createUserProfile(userId, username, email);
      }
    } catch (e) {
      // If RLS policy prevents reading, we'll assume the profile doesn't exist
      // and let the _createUserProfile method handle the creation gracefully
      final username = supabaseUser.userMetadata?['username'] ??
          'user_${userId.substring(0, 8)}';
      final email = supabaseUser.email ?? '';
      await _createUserProfile(userId, username, email);
    }
  }

  User _mapSupabaseUserToAppUser(dynamic supabaseUser) {
    return User(
      id: supabaseUser.id,
      username: supabaseUser.userMetadata?['username'] ?? '',
      email: supabaseUser.email ?? '',
      createdAt: DateTime.tryParse(supabaseUser.createdAt ?? '') ?? DateTime.now(),
      updatedAt: DateTime.tryParse(supabaseUser.updatedAt ?? '') ?? DateTime.now(),
    );
  }

  User _mapSupabaseDataToUser(Map<String, dynamic> data) {
    return User(
      id: data['id'],
      username: data['username'],
      email: data['email'],
      avatarUrl: data['avatar_url'],
      bio: data['bio'],
      isPublicProfile: data['is_public_profile'] ?? false,
      countdownStartDate: data['countdown_start_date'] != null 
          ? DateTime.parse(data['countdown_start_date'])
          : null,
      countdownEndDate: data['countdown_end_date'] != null
          ? DateTime.parse(data['countdown_end_date'])
          : null,
      gender: data['gender'] != null ? Gender.fromString(data['gender']) : null,
      storedAge: data['age'] as int?,
      heightCm: (data['height_cm'] as num?)?.toDouble(),
      weightKg: (data['weight_kg'] as num?)?.toDouble(),
      createdAt: DateTime.parse(data['created_at']),
      updatedAt: DateTime.parse(data['updated_at']),
    );
  }
}