VeloeKemonoPartyFlutter/lib/models/post.dart

import 'attachment.dart';

class Post {
  final String added;
  final List<Attachment> attachments;
  final Attachment? files;
  final String content;
  final String edited;
  final String id;
  final String published;
  final String service;
  final String title;
  final String user;
  final String baseUrl;

  Post({
    required this.added,
    required this.attachments,
    required this.files,
    required this.content,
    required this.edited,
    required this.id,
    required this.published,
    required this.service,
    required this.title,
    required this.user,
    required this.baseUrl,
  });

  List<Attachment> get mediaAttachments {
    final allAttachments = files == null ? 
      [...attachments.where((a) => a.isImage || a.isVideo)] : 
      [...attachments.where((a) => a.isImage || a.isVideo),files!];

    final ids = allAttachments.map((e) => e.path).toSet();
    allAttachments.retainWhere((x) => ids.remove(x.path));
    return allAttachments;
  }

  factory Post.fromJson(Map<String, dynamic> json, String baseUrl) => Post(
        added: _parseString(json['added']),
        attachments: _parseAttachments(json['attachments'], baseUrl),
        files: (json["file"] as Map)?.isNotEmpty == true ?  Attachment.fromJson(json["file"], baseUrl) : null,
        content: _parseString(json['substring']),
        edited: _parseString(json['edited']),
        id: _parseString(json['id']),
        published: _parseString(json['published']),
        service: _parseString(json['service']),
        title: _parseString(json['title']),
        user: _parseString(json['user']),
        baseUrl: baseUrl,
      );

  static String _parseString(dynamic value) => 
      (value is String) ? value : '';

  static List<Attachment> _parseAttachments(
    dynamic jsonData, 
    String baseUrl
  ) {
    if (jsonData is! List) return [];
    
    return jsonData
        .whereType<Map<String, dynamic>>()
        .map((x) => Attachment.fromJson(x, baseUrl))
        .whereType<Attachment>()
        .toList();
  }
}