import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

import '../components/user_tile_likes.dart';
import '../constants.dart';
import '../enumerations.dart';
import '../models/swipe.dart';
import '../services/auth/auth_service.dart';
import '../utils/helper_dialogs.dart';
import 'chat_page.dart';
import 'user_profile_page.dart';

class LikedUsersPage extends StatefulWidget {
  const LikedUsersPage({super.key});

  @override
  LikedUsersPageState createState() => LikedUsersPageState();
}

class LikedUsersPageState extends State<LikedUsersPage> {
  final String currentUserId = AuthService().getCurrentUser()!.uid;
  final Map<String, bool> _cachedMatches = {};
  List<MapEntry<Swipe, DocumentSnapshot>> _likedUsersWithSwipes = [];
  bool _isLoading = true;
  String? _fetchError;

  ViewOrder _orderPreference = ViewOrder.swipedFirst;
  MenuSort _sortPreference = MenuSort.nameAsc;

  @override
  void initState() {
    super.initState();
    _fetchLikedUsersWithSwipes();
  }

  Future<void> _fetchLikedUsersWithSwipes() async {
    try {
      QuerySnapshot likedUsersSnapshot = await FirebaseFirestore.instance
          .collection(Constants.dbCollectionUsers)
          .doc(currentUserId)
          .collection(Constants.dbCollectionSwipes)
          .where(Constants.dbFieldSwipesLike, isEqualTo: true)
          .get();

      List<MapEntry<Swipe, DocumentSnapshot>> likedUsersWithSwipes = [];

      for (var doc in likedUsersSnapshot.docs) {
        Swipe swipe = Swipe.fromDocument(doc);
        DocumentSnapshot userDoc = await FirebaseFirestore.instance
            .collection(Constants.dbCollectionUsers)
            .doc(swipe.swipedId)
            .get();

        // Initialize _cachedMatches to keep database accesses to a minimum
        bool hasMatch = await _hasMatch(swipe.swipedId);
        _cachedMatches[swipe.swipedId] = hasMatch;

        likedUsersWithSwipes.add(MapEntry(swipe, userDoc));
      }

      setState(() {
        _likedUsersWithSwipes = likedUsersWithSwipes;
        _isLoading = false;
      });
    } catch (e) {
      setState(() {
        _fetchError = e.toString();
        _isLoading = false;
      });
    }
  }

  Future<bool> _hasMatch(String userId) async {
    DocumentSnapshot matchDoc = await FirebaseFirestore.instance
        .collection(Constants.dbCollectionUsers)
        .doc(currentUserId)
        .collection(Constants.dbCollectionMatches)
        .doc(userId)
        .get();
    return matchDoc.exists;
  }

  Future<void> _unlikeUser(String userId) async {
    try {
      await FirebaseFirestore.instance
          .collection(Constants.dbCollectionUsers)
          .doc(currentUserId)
          .collection(Constants.dbCollectionSwipes)
          .doc(userId)
          .delete();

      // Refresh the UI
      setState(() {
        _likedUsersWithSwipes
            .removeWhere((entry) => entry.key.swipedId == userId);
      });
    } catch (e) {
      if (mounted) {
        showMsg(context, 'Error during unlike', e.toString());
      }
    }
  }

  Future<bool?> _showConfirmationDialog(String userId, String userName) async {
    bool? confirm = await showDialog<bool>(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text('Confirm Removal'),
          content:
              Text('Are you sure you want to remove $userName from your list?'),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(context).pop(false),
              child: const Text('Cancel'),
            ),
            TextButton(
              onPressed: () => Navigator.of(context).pop(true),
              child: const Text('Confirm'),
            ),
          ],
        );
      },
    );

    return confirm;
  }

  List<MapEntry<Swipe, DocumentSnapshot>> _getSortedLikedUsersWithSwipes() {
    List<MapEntry<Swipe, DocumentSnapshot>> likedOnlyUsers = [];
    List<MapEntry<Swipe, DocumentSnapshot>> matchedUsers = [];

    for (var entry in _likedUsersWithSwipes) {
      bool hasMatch = _cachedMatches.containsKey(entry.key.swipedId)
          ? _cachedMatches[entry.key.swipedId]!
          : false;

      if (hasMatch) {
        matchedUsers.add(entry);
      } else {
        likedOnlyUsers.add(entry);
      }
    }

    if (_sortPreference == MenuSort.timestampAsc) {
      likedOnlyUsers.sort((a, b) => a.key.timestamp.compareTo(b.key.timestamp));
      matchedUsers.sort((a, b) => a.key.timestamp.compareTo(b.key.timestamp));
    } else if (_sortPreference == MenuSort.timestampDesc) {
      likedOnlyUsers.sort((a, b) => b.key.timestamp.compareTo(a.key.timestamp));
      matchedUsers.sort((a, b) => b.key.timestamp.compareTo(a.key.timestamp));
    } else if (_sortPreference == MenuSort.nameAsc) {
      likedOnlyUsers.sort((a, b) => _compareNames(a, b));
      matchedUsers.sort((a, b) => _compareNames(a, b));
    } else if (_sortPreference == MenuSort.nameDesc) {
      likedOnlyUsers.sort((a, b) => _compareNames(b, a));
      matchedUsers.sort((a, b) => _compareNames(b, a));
    }

    if (_orderPreference == ViewOrder.matchedFirst) {
      return [...matchedUsers, ...likedOnlyUsers];
    } else if (_orderPreference == ViewOrder.swipedOnly) {
      return [...likedOnlyUsers];
    } else if (_orderPreference == ViewOrder.matchedOnly) {
      return [...matchedUsers];
    } else {
      // default: swipesFirst
      return [...likedOnlyUsers, ...matchedUsers];
    }
  }

  int _compareNames(MapEntry<Swipe, DocumentSnapshot> a,
      MapEntry<Swipe, DocumentSnapshot> b) {
    final dataA = (a.value.data() as Map<String, dynamic>);
    final dataB = (b.value.data() as Map<String, dynamic>);

    final nameA =
        dataA.isNotEmpty && dataA.containsKey(Constants.dbFieldUsersName)
            ? a.value[Constants.dbFieldUsersName]
            : '';
    final nameB =
        dataB.isNotEmpty && dataB.containsKey(Constants.dbFieldUsersName)
            ? b.value[Constants.dbFieldUsersName]
            : '';

    return nameA.compareTo(nameB);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('My favored profiles'),
      ),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.all(8.0),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                DropdownButton<ViewOrder>(
                  value: _orderPreference,
                  items: const [
                    DropdownMenuItem(
                      value: ViewOrder.swipedFirst,
                      child: Text('Swipes First'),
                    ),
                    DropdownMenuItem(
                      value: ViewOrder.matchedFirst,
                      child: Text('Matches First'),
                    ),
                    DropdownMenuItem(
                      value: ViewOrder.swipedOnly,
                      child: Text('Swipes Only'),
                    ),
                    DropdownMenuItem(
                      value: ViewOrder.matchedOnly,
                      child: Text('Matches Only'),
                    ),
                  ],
                  onChanged: (value) {
                    // update UI on change only
                    if (_orderPreference != value) {
                      setState(() {
                        _orderPreference = value!;
                      });
                    }
                  },
                ),
                Align(
                  alignment: Alignment.centerRight,
                  child: PopupMenuButton<MenuSort>(
                    icon: const Icon(Icons.sort),
                    onSelected: (MenuSort item) {
                      // update UI on change only
                      if (_sortPreference != item) {
                        setState(() {
                          _sortPreference = item;
                        });
                      }
                    },
                    itemBuilder: (BuildContext context) =>
                        <PopupMenuEntry<MenuSort>>[
                      PopupMenuItem<MenuSort>(
                        value: MenuSort.nameAsc,
                        child: ListTile(
                          leading: _sortPreference == MenuSort.nameAsc
                              ? const Icon(Icons.check)
                              : const Icon(null),
                          title: const Text('Name Ascending'),
                        ),
                      ),
                      PopupMenuItem<MenuSort>(
                        value: MenuSort.nameDesc,
                        child: ListTile(
                          leading: _sortPreference == MenuSort.nameDesc
                              ? const Icon(Icons.check)
                              : const Icon(null),
                          title: const Text('Name Descending'),
                        ),
                      ),
                      PopupMenuItem<MenuSort>(
                        value: MenuSort.timestampAsc,
                        child: ListTile(
                          leading: _sortPreference == MenuSort.timestampAsc
                              ? const Icon(Icons.check)
                              : const Icon(null),
                          title: const Text('Oldest first'),
                        ),
                      ),
                      PopupMenuItem<MenuSort>(
                        value: MenuSort.timestampDesc,
                        child: ListTile(
                          leading: _sortPreference == MenuSort.timestampDesc
                              ? const Icon(Icons.check)
                              : const Icon(null),
                          title: const Text('Newest first'),
                        ),
                      ),
                    ],
                  ),
                ),
              ],
            ),
          ),
          _isLoading
              ? const Center(child: CircularProgressIndicator())
              : _fetchError != null
                  ? Center(child: Text('Error: $_fetchError'))
                  : _likedUsersWithSwipes.isEmpty
                      ? const Center(child: Text('No liked users found.'))
                      : buildLikedUserList(),
        ],
      ),
    );
  }

  Widget buildLikedUserList() {
    var sortedSwipeUsers = _getSortedLikedUsersWithSwipes();

    return Expanded(
      child: ListView.builder(
        itemCount: sortedSwipeUsers.length,
        itemBuilder: (BuildContext context, int index) {
          var entry = sortedSwipeUsers[index];
          var user = entry.value;
          bool hasMatch = _cachedMatches.containsKey(user.id)
              ? _cachedMatches[user.id]!
              : false;

          return UserTileLikes(
            user: user,
            hasMatch: hasMatch,
            onUnlike: () async {
              Map<String, dynamic> userMap =
                  user.data() as Map<String, dynamic>;
              bool hasName = userMap.containsKey(Constants.dbFieldUsersName);

              bool? confirm = await _showConfirmationDialog(
                user.id,
                (hasName ? user[Constants.dbFieldUsersName] : 'Name: n/a'),
              );

              if (confirm == true) {
                bool hasMatch = await _hasMatch(user.id);
                if (!hasMatch) {
                  await _unlikeUser(user.id);
                } else {
                  // abort, update _cachedMatches and UI
                  _cachedMatches[user.id] = hasMatch;
                  setState(() {});
                }
              }
            },
            onShowChat: () {
              Navigator.push(
                context,
                MaterialPageRoute(
                  builder: (context) => ChatPage(
                    receiverEmail: user[Constants.dbFieldUsersEmail],
                    receiverID: user[Constants.dbFieldUsersID],
                    chatTitle: user[Constants.dbFieldUsersName],
                    profileImageUrl: user[Constants.dbFieldUsersProfilePic],
                  ),
                ),
              );
            },
            onViewInfo: () {
              Navigator.push(
                context,
                MaterialPageRoute(
                  builder: (BuildContext context) => UserProfilePage(
                    userId: user.id,
                  ),
                ),
              );
            },
          );
        },
      ),
    );
  }
}