import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:collection/collection.dart';
import 'package:firebase_auth/firebase_auth.dart';
import '../constants.dart';
import '../enumerations.dart';
import '../models/language.dart';
import '../models/location.dart';
import '../models/user_profile.dart';

class UserService {
  UserService._(); // Private constructor to prevent instantiation

  static Future<void> saveUserRegistrationData(UserCredential userCredential,
      String email, String firstname, String lastname) async {
    // create full name
    String fullName = (firstname.isNotEmpty && lastname.isNotEmpty)
        ? '$firstname $lastname'
        : (firstname.isNotEmpty
            ? firstname
            : (lastname.isNotEmpty ? lastname : ''));

    // save user info to users document
    await FirebaseFirestore.instance
        .collection(Constants.dbCollectionUsers)
        .doc(userCredential.user!.uid)
        .set(
      {
        Constants.dbFieldUsersID: userCredential.user!.uid,
        Constants.dbFieldUsersEmail: email,
        Constants.dbFieldUsersFirstName: firstname,
        Constants.dbFieldUsersLastName: lastname,
        Constants.dbFieldUsersName: fullName,
      },
    );
  }

  static Future<List<SkillOption>> getSkillsFromFirebase(
      bool skillsSought, String userId) async {
    // Fetch skills from Firestore
    DocumentSnapshot userDoc = await FirebaseFirestore.instance
        .collection(Constants.dbCollectionUsers)
        .doc(userId)
        .get();

    if (userDoc.exists && userDoc.data() != null) {
      Map<String, dynamic> userData = userDoc.data()! as Map<String, dynamic>;

      List<dynamic>? skills;
      if (skillsSought) {
        skills = userData[Constants.dbFieldUsersSkillsSought];
      } else {
        skills = userData[Constants.dbFieldUsersSkills];
      }

      return convertSkillStringToEnum(skills);
    }

    return [];
  }

  static List<SkillOption> convertSkillStringToEnum(List<dynamic>? skills) {
    List<SkillOption> userSkills = [];
    if (skills != null && skills.isNotEmpty) {
      // Convert skills from strings to enum values
      for (var skill in skills) {
        try {
          SkillOption skillOption = SkillOption.values.firstWhere(
            (x) => x.toString() == 'SkillOption.$skill',
          );
          userSkills.add(skillOption);
        } catch (e) {
          // Ignore invalid values
          continue;
        }
      }
    }
    return userSkills;
  }

  static List<SectorOption> convertSectorStringToEnum(List<dynamic>? sectors) {
    if (sectors != null && sectors.isNotEmpty) {
      List<SectorOption> userSectors = sectors
          .map((sector) =>
              SectorOption.values.firstWhere((x) => x.toString() == sector))
          .toList();
      return userSectors;
    }
    return [];
  }

  static List<VisionOption> convertVisionStringToEnum(List<dynamic>? visions) {
    if (visions != null && visions.isNotEmpty) {
      List<VisionOption> userVisions = visions
          .map((vision) =>
              VisionOption.values.firstWhere((x) => x.toString() == vision))
          .toList();
      return userVisions;
    }
    return [];
  }

  static List<WorkValueOption> convertWorkValuesStringToEnum(
      List<dynamic>? values) {
    if (values != null && values.isNotEmpty) {
      List<WorkValueOption> userWorkValues = values
          .map((workValue) => WorkValueOption.values
              .firstWhere((x) => x.toString() == workValue))
          .toList();
      return userWorkValues;
    }
    return [];
  }

  static Future<bool> saveSkillsToFirebase(List<SkillOption> selectedOptions,
      bool skillsSought, String userId) async {
    try {
      // Convert enum values to strings, removing leading EnumType with split
      List<String> skills = selectedOptions
          .map((option) => option.toString().split('.').last)
          .toList();

      // Update the corresponding 'skills' field in the user's document
      String keyToUpdate = skillsSought
          ? Constants.dbFieldUsersSkillsSought
          : Constants.dbFieldUsersSkills;

      FirebaseFirestore.instance
          .collection(Constants.dbCollectionUsers)
          .doc(userId)
          .update({keyToUpdate: skills});

      return true;
    } catch (e) {
      return false;
    }
  }

  /// Get UserProfile from Document
  static Future<UserProfile> getUserProfileFromDocument(
      DocumentSnapshot userDoc) async {
    Map<String, dynamic> data = userDoc.data() as Map<String, dynamic>;

    List<SkillOption> skillsOffered = UserService.convertSkillStringToEnum(
        data[Constants.dbFieldUsersSkills]);
    List<SkillOption> skillsSought = UserService.convertSkillStringToEnum(
        data[Constants.dbFieldUsersSkillsSought]);
    List<SectorOption> sectors = UserService.convertSectorStringToEnum(
        data[Constants.dbFieldUsersSectors]);
    List<VisionOption> visions = UserService.convertVisionStringToEnum(
        data[Constants.dbFieldUsersVisions]);
    List<WorkValueOption> works = UserService.convertWorkValuesStringToEnum(
        data[Constants.dbFieldUsersWorkValues]);
    RiskTolerance risk =
        RiskTolerance.fromString(data[Constants.dbFieldUsersRiskTolerance]);
    AvailabilityOption availability =
        AvailabilityOption.fromString(data[Constants.dbFieldUsersAvailability]);
    CultureOption culture =
        CultureOption.fromString(data[Constants.dbFieldUsersCorpCulture]);
    CommunicationPreference communication = CommunicationPreference.fromString(
        data[Constants.dbFieldUsersCommunication]);

    // Retrieve sub collections
    QuerySnapshot languagesSnapshot = await userDoc.reference
        .collection(Constants.dbCollectionLanguages)
        .get();
    List<Language> languages = languagesSnapshot.docs
        .map((doc) => Language.fromDocument(doc))
        .toList();

    QuerySnapshot locationsSnapshot = await userDoc.reference
        .collection(Constants.dbCollectionLocations)
        .get();

    final mainDoc = locationsSnapshot.docs
        .firstWhereOrNull((doc) => doc.id == Constants.dbDocMainLocation);
    final secondaryDoc = locationsSnapshot.docs
        .firstWhereOrNull((doc) => doc.id == Constants.dbDocSecondLocation);
    final locations = {
      Constants.dbDocMainLocation:
          mainDoc != null ? MyLocation.fromDocument(mainDoc) : null,
    };
    if (secondaryDoc != null) {
      locations.addAll({
        Constants.dbDocSecondLocation: MyLocation.fromDocument(secondaryDoc)
      });
    }
    // Map<String, MyLocation?> locations = {
    //   for (var doc in locationsSnapshot.docs)
    //     doc.id: MyLocation.fromDocument(doc)
    // };

    return UserProfile(
      id: userDoc.id,
      uid: data[Constants.dbFieldUsersID] ?? '',
      email: data[Constants.dbFieldUsersEmail] ?? '',
      name: data[Constants.dbFieldUsersName] ?? '',
      firstName: data[Constants.dbFieldUsersFirstName] ?? '',
      lastName: data[Constants.dbFieldUsersLastName] ?? '',
      skills: skillsOffered,
      skillsSought: skillsSought,
      sectors: sectors,
      visions: visions,
      risk: risk,
      availability: availability,
      culture: culture,
      communication: communication,
      workValues: works,
      profilePictureUrl: data[Constants.dbFieldUsersProfilePic],
      bio: data[Constants.dbFieldUsersBio],
      gender: Gender.values[data[Constants.dbFieldUsersGender] ?? 0],
      born: data[Constants.dbFieldUsersYearBorn],
      languages: languages,
      locations: locations,
    );
  }

  /// Get UserProfile for given [userId]
  static Future<UserProfile> getUserProfileById(String userId) async {
    FirebaseFirestore firestore = FirebaseFirestore.instance;

    DocumentSnapshot userDoc = await firestore
        .collection(Constants.dbCollectionUsers)
        .doc(userId)
        .get();

    UserProfile result = await getUserProfileFromDocument(userDoc);

    return result;
  }

  /// Get users stream
  static Stream<List<Map<String, dynamic>>> getUsersStream() {
    return FirebaseFirestore.instance
        .collection(Constants.dbCollectionUsers)
        .snapshots()
        .map((snapshot) {
      return snapshot.docs.map((doc) {
        // iterate and return each user
        final user = doc.data();
        return user;
      }).toList();
    });
  }

  /// Get list of matched user ids for a given [userId]
  static Future<List<String>> getMatchedUserIds(String userId) async {
    List<String> matchedUserIds = [];

    final snapshot = await FirebaseFirestore.instance
        .collection(Constants.dbCollectionUsers)
        .doc(userId)
        .collection(Constants.dbCollectionMatches)
        .get();

    for (var doc in snapshot.docs) {
      final data = doc.data();
      String? otherUserId = data['otherUserId'];
      if (otherUserId != null && otherUserId.isNotEmpty) {
        matchedUserIds.add(otherUserId);
      }
    }

    return matchedUserIds;
  }

  /// Get matched users data for a given [userId] as stream
  static Stream<List<Map<String, dynamic>>> getMatchedUsersStream(
      String userId) {
    return FirebaseFirestore.instance
        .collection(Constants.dbCollectionUsers)
        .doc(userId)
        .collection(Constants.dbCollectionMatches)
        .snapshots()
        .asyncMap((snapshot) async {
      final matchedUserIds = snapshot.docs
          .map((doc) => doc.data()['otherUserId'] as String?)
          .where((otherUserId) => otherUserId != null && otherUserId.isNotEmpty)
          .toList();

      if (matchedUserIds.isEmpty) {
        return [];
      }

      final matchedUsersSnapshot = await FirebaseFirestore.instance
          .collection(Constants.dbCollectionUsers)
          .where(FieldPath.documentId, whereIn: matchedUserIds)
          .get();

      return matchedUsersSnapshot.docs.map((doc) => doc.data()).toList();
    });
  }

  /// Checks if a match between currentUser and [userId] exists.
  /// Returns false in case of an error.
  static Future<bool> hasMatch(String currentUserId, String userId) async {
    try {
      DocumentSnapshot matchDoc = await FirebaseFirestore.instance
          .collection(Constants.dbCollectionUsers)
          .doc(currentUserId)
          .collection(Constants.dbCollectionMatches)
          .doc(userId)
          .get();
      return matchDoc.exists;
    } catch (e) {
      return false;
    }
  }

  static Future<bool> saveSectorsToFirebase(
      List<SectorOption> sectors, String userId) async {
    try {
      List<String> sectorStrings = sectors.map((x) => x.toString()).toList();
      await FirebaseFirestore.instance
          .collection(Constants.dbCollectionUsers)
          .doc(userId)
          .update({
        Constants.dbFieldUsersSectors: sectorStrings,
      });
      return true;
    } catch (e) {
      return false;
    }
  }

  static Future<List<SectorOption>> getSectorsFromFirebase(
      String userId) async {
    try {
      DocumentSnapshot userDoc = await FirebaseFirestore.instance
          .collection(Constants.dbCollectionUsers)
          .doc(userId)
          .get();
      if (userDoc.exists && userDoc.data() != null) {
        var data = userDoc.data() as Map<String, dynamic>;
        List<dynamic> sectors = data[Constants.dbFieldUsersSectors] ?? [];
        return sectors
            .map((x) => SectorOption.values
                .firstWhere((option) => option.toString() == x))
            .toList();
      } else {
        return [];
      }
    } catch (e) {
      throw Exception('Error fetching sectors from Firebase: $e');
    }
  }
}