import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import '../models/user_model.dart';

class AuthService {
  final FirebaseAuth _auth = FirebaseAuth.instance;
  final FirebaseFirestore _firestore = FirebaseFirestore.instance;

  // Hent nåværende bruker
  User? get currentUser => _auth.currentUser;

  // Stream av autentiseringstilstand
  Stream<User?> get authStateChanges => _auth.authStateChanges();

  // Registrer ny bruker med e-post og passord
  Future<UserCredential> signUpWithEmail({
    required String email,
    required String password,
    required String displayName,
    required String organizationId,
    String? departmentId,
  }) async {
    try {
      // Opprett bruker i Firebase Auth
      final userCredential = await _auth.createUserWithEmailAndPassword(
        email: email,
        password: password,
      );

      // Oppdater displayName
      await userCredential.user?.updateDisplayName(displayName);

      // Opprett brukerdata i Firestore
      await _createUserDocument(
        uid: userCredential.user!.uid,
        email: email,
        displayName: displayName,
        organizationId: organizationId,
        departmentId: departmentId,
      );

      return userCredential;
    } on FirebaseAuthException catch (e) {
      throw _handleAuthException(e);
    }
  }

  // Logg inn med e-post og passord
  Future<UserCredential> signInWithEmail({
    required String email,
    required String password,
  }) async {
    try {
      return await _auth.signInWithEmailAndPassword(
        email: email,
        password: password,
      );
    } on FirebaseAuthException catch (e) {
      throw _handleAuthException(e);
    }
  }

  // Tilbakestill passord
  Future<void> resetPassword(String email) async {
    try {
      await _auth.sendPasswordResetEmail(email: email);
    } on FirebaseAuthException catch (e) {
      throw _handleAuthException(e);
    }
  }

  // Logg ut
  Future<void> signOut() async {
    await _auth.signOut();
  }

  // Hent brukerdata fra Firestore
  Future<UserModel?> getUserData(String uid) async {
    try {
      final doc = await _firestore.collection('users').doc(uid).get();
      if (doc.exists) {
        return UserModel.fromFirestore(doc);
      }
      return null;
    } catch (e) {
      throw Exception('Kunne ikke hente brukerdata: $e');
    }
  }

  // Stream av brukerdata
  Stream<UserModel?> userDataStream(String uid) {
    return _firestore
        .collection('users')
        .doc(uid)
        .snapshots()
        .map((doc) => doc.exists ? UserModel.fromFirestore(doc) : null);
  }

  // Opprett brukerdokument i Firestore
  Future<void> _createUserDocument({
    required String uid,
    required String email,
    required String displayName,
    required String organizationId,
    String? departmentId,
  }) async {
    // Hent standard tariffprofil for organisasjonen
    final defaultProfile = await _getDefaultTariffProfile(organizationId);

    final userData = UserModel(
      uid: uid,
      email: email,
      displayName: displayName,
      role: UserRole.employee,
      tariffProfileId: defaultProfile,
      organizationId: organizationId,
      departmentId: departmentId,
      createdAt: DateTime.now(),
      updatedAt: DateTime.now(),
      preferences: UserPreferences(),
    );

    await _firestore.collection('users').doc(uid).set(userData.toFirestore());
  }

  // Hent standard tariffprofil for organisasjon
  Future<String> _getDefaultTariffProfile(String organizationId) async {
    final query = await _firestore
        .collection('tariff_profiles')
        .where('organizationId', isEqualTo: organizationId)
        .where('isDefault', isEqualTo: true)
        .limit(1)
        .get();

    if (query.docs.isNotEmpty) {
      return query.docs.first.id;
    }

    // Hvis ingen standard profil finnes, returner en placeholder
    return 'default_aml';
  }

  // Håndter Firebase Auth exceptions
  String _handleAuthException(FirebaseAuthException e) {
    switch (e.code) {
      case 'weak-password':
        return 'Passordet er for svakt';
      case 'email-already-in-use':
        return 'E-postadressen er allerede i bruk';
      case 'invalid-email':
        return 'Ugyldig e-postadresse';
      case 'user-not-found':
        return 'Ingen bruker funnet med denne e-postadressen';
      case 'wrong-password':
        return 'Feil passord';
      case 'user-disabled':
        return 'Denne brukerkontoen er deaktivert';
      case 'too-many-requests':
        return 'For mange forsøk. Prøv igjen senere';
      case 'operation-not-allowed':
        return 'Denne operasjonen er ikke tillatt';
      default:
        return 'En feil oppstod: ${e.message}';
    }
  }
}