import 'package:comunic/enums/load_error_level.dart';
import 'package:comunic/helpers/conversations_helper.dart';
import 'package:comunic/helpers/users_helper.dart';
import 'package:comunic/lists/conversations_list.dart';
import 'package:comunic/ui/tiles/conversation_tile.dart';
import 'package:comunic/utils/intl_utils.dart';
import 'package:comunic/utils/ui_utils.dart';
import 'package:flutter/material.dart';

/// Conversations screen
///
/// @author Pierre HUBERT

class ConversationsScreen extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => _ConversationScreenState();
}

class _ConversationScreenState extends State<ConversationsScreen> {
  final ConversationsHelper _conversationsHelper = ConversationsHelper();
  final UsersHelper _usersHelper = UsersHelper();
  ConversationsList _list;
  LoadErrorLevel _error = LoadErrorLevel.NONE;
  bool _loading = true;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _loadConversations();
  }

  void setError(LoadErrorLevel err) => setState(() => _error = err);

  void setLoading(bool loading) => setState(() => _loading = loading);

  void _gotLoadingError() {
    setLoading(false);
    setError(_list == null ? LoadErrorLevel.MAJOR : LoadErrorLevel.MINOR);
  }

  /// Load the list of conversations
  Future<void> _loadConversations() async {
    setError(LoadErrorLevel.NONE);
    setLoading(true);

    //Process the list of conversations
    final list = await _conversationsHelper.downloadList();
    if (list == null) return _gotLoadingError();

    //Get information about the members of the conversations
    list.users = await _usersHelper.downloadInfo(list.allUsersID);
    if(list.users == null) return _gotLoadingError();

    //Save list
    setState(() {
      _list = list;
    });

    setLoading(false);
  }

  /// Build an error card
  Widget _buildErrorCard() {
    return buildErrorCard(
      tr("Could not retrieve the list of conversations!"),
      actions: <Widget>[
        FlatButton(
          onPressed: _loadConversations,
          child: Text(
            tr("Retry").toUpperCase(),
            style: TextStyle(
              color: Colors.white,
            ),
          ),
        )
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    if (_error == LoadErrorLevel.MAJOR) return _buildErrorCard();
    if (_list == null) return buildCenteredProgressBar();

    // Show the list of conversations
    return ListView.builder(
      itemBuilder: (context, index) {
        return ConversationTile(
          conversation: _list.elementAt(index),
          usersList: _list.users,
        );
      },
      itemCount: _list.length,
    );
  }
}