import 'package:flutter/material.dart';
import 'package:sales_chat/models/group.dart';
import 'package:sales_chat/models/message.dart';
import 'package:sales_chat/services/api_service.dart';

class ChatProvider with ChangeNotifier {
  final ApiService _apiService;

  List<Group> _groups = [];
  Map<String, List<Message>> _messagesByConverse = {};
  Group? _currentGroup;
  bool _isLoading = false;
  bool _isLoadingMessages = false;
  String? _error;

  ChatProvider(this._apiService);

  List<Group> get groups => _groups;
  Group? get currentGroup => _currentGroup;
  bool get isLoading => _isLoading;
  bool get isLoadingMessages => _isLoadingMessages;
  String? get error => _error;

  List<Message> get currentMessages {
    if (_currentGroup == null) return [];
    // 使用第一个文本面板的 ID 作为 converseId
    final converseId = _currentGroup!.firstTextPanel?.id ?? _currentGroup!.id;
    return _messagesByConverse[converseId] ?? [];
  }

  /// 获取群组的 converseId（第一个文本面板，或以群组 ID 作为备选）
  String _getConverseIdForGroup(Group group) {
    return group.firstTextPanel?.id ?? group.id;
  }

  Future<void> loadGroups() async {
    _isLoading = true;
    _error = null;
    notifyListeners();

    try {
      _groups = await _apiService.getGroups();
      _isLoading = false;
      notifyListeners();
    } catch (e) {
      _error = 'Failed to load groups';
      _isLoading = false;
      notifyListeners();
    }
  }

  void selectGroup(Group group) {
    _currentGroup = group;
    notifyListeners();

    final converseId = _getConverseIdForGroup(group);
    if (_messagesByConverse[converseId] == null) {
      loadMessages(converseId);
    }
  }

  void deselectGroup() {
    _currentGroup = null;
    notifyListeners();
  }

  Future<void> loadMessages(String converseId, {bool refresh = false}) async {
    if (_isLoadingMessages) return;

    _isLoadingMessages = true;
    notifyListeners();

    try {
      final messages = await _apiService.getMessages(
        converseId,
        limit: 50,
        before: refresh ? null : (_messagesByConverse[converseId]?.first.id),
      );

      if (refresh) {
        _messagesByConverse[converseId] = messages;
      } else {
        _messagesByConverse[converseId] = [
          ...messages,
          ...(_messagesByConverse[converseId] ?? [])
        ];
      }

      _isLoadingMessages = false;
      notifyListeners();
    } catch (e) {
      _error = 'Failed to load messages';
      _isLoadingMessages = false;
      notifyListeners();
    }
  }

  Future<void> sendMessage(String content) async {
    if (_currentGroup == null || content.isEmpty) return;

    final converseId = _getConverseIdForGroup(_currentGroup!);
    final groupId = _currentGroup!.id;

    try {
      final message = await _apiService.sendMessage(
        converseId,
        content,
        groupId: groupId,
      );

      _messagesByConverse[converseId] = [
        ...(_messagesByConverse[converseId] ?? []),
        message,
      ];
      notifyListeners();
    } catch (e) {
      _error = 'Failed to send message';
      notifyListeners();
    }
  }

  /// 撤回消息
  Future<bool> recallMessage(String messageId) async {
    try {
      await _apiService.recallMessage(messageId);

      // 更新本地消息列表
      if (_currentGroup != null) {
        final converseId = _getConverseIdForGroup(_currentGroup!);
        final messages = _messagesByConverse[converseId];
        if (messages != null) {
          final idx = messages.indexWhere((m) => m.id == messageId);
          if (idx != -1) {
            // 标记为已撤回而非删除
            final old = messages[idx];
            messages[idx] = Message(
              id: old.id,
              content: 'Message recalled',
              author: old.author,
              groupId: old.groupId,
              converseId: old.converseId,
              hasRecall: true,
              meta: old.meta,
              createdAt: old.createdAt,
              updatedAt: old.updatedAt,
            );
            notifyListeners();
          }
        }
      }

      return true;
    } catch (e) {
      _error = 'Failed to recall message: $e';
      notifyListeners();
      return false;
    }
  }

  /// 删除消息（管理员）
  Future<bool> deleteMessage(String messageId) async {
    try {
      await _apiService.deleteMessage(messageId);

      // 从本地消息列表中移除
      if (_currentGroup != null) {
        final converseId = _getConverseIdForGroup(_currentGroup!);
        final messages = _messagesByConverse[converseId];
        if (messages != null) {
          messages.removeWhere((m) => m.id == messageId);
          notifyListeners();
        }
      }

      return true;
    } catch (e) {
      _error = 'Failed to delete message: $e';
      notifyListeners();
      return false;
    }
  }

  /// 添加通过 socket.io 接收的消息
  void addMessage(Message message) {
    final converseId = message.converseId;
    _messagesByConverse[converseId] = [
      ...(_messagesByConverse[converseId] ?? []),
      message,
    ];
    notifyListeners();
  }

  void clearError() {
    _error = null;
    notifyListeners();
  }
}