import 'dart:collection';

import 'package:comunic/models/post.dart';

/// Posts List
///
/// Contains method to easily process a list of posts
///
/// @author Pierre HUBERT

class PostsList extends ListBase<Post> {
  List<Post> _list = [];

  int get length => _list.length;

  set length(int l) => _list.length = l;

  @override
  Post operator [](int index) => _list[index];

  @override
  void operator []=(int index, Post value) => _list[index] = value;

  // Get the list of users ID in this set
  Set<int> get usersID {
    Set<int> set = Set();

    forEach((p) {
      set.add(p.userID);

      if (p.userPageID != null && p.userPageID > 0) set.add(p.userPageID);

      if (p.comments != null) set.addAll(p.comments.usersID);
    });

    return set;
  }

  /// Get the list of groups in this list of posts
  Set<int> get groupsID {
    Set<int> set = Set();

    forEach((p) {
      if (p.isGroupPost) set.add(p.groupID);
    });

    return set;
  }

  /// Get the ID of the oldest post of this list. Returns 0 if the list is empty
  int get oldestID {
    if(isEmpty)
      return 0;

    return this.elementAt(length - 1).id;
  }
}