class TaskComment {
  final int id;
  final int taskId;
  final int userId;
  final String username;
  final String body;
  final DateTime createdAt;

  const TaskComment({
    required this.id, required this.taskId, required this.userId,
    required this.username, required this.body, required this.createdAt,
  });

  factory TaskComment.fromJson(Map<String, dynamic> j) => TaskComment(
    id: j['id'],
    taskId: j['task_id'],
    userId: j['user_id'],
    username: j['username'] ?? '',
    body: j['body'] ?? '',
    createdAt: DateTime.parse(j['created_at']),
  );
}

class Task {
  final int id;
  final String title;
  final String status;
  final DateTime? dueDate;
  final int? assignedTo;
  final String? assignedUsername;
  final int? parentId;
  final int createdBy;
  final String createdByUsername;
  final DateTime? completedAt;
  final DateTime createdAt;
  final int subtaskCount;
  final int commentCount;
  final List<Task> subtasks;
  final List<TaskComment> comments;

  const Task({
    required this.id, required this.title, required this.status,
    this.dueDate, this.assignedTo, this.assignedUsername, this.parentId,
    required this.createdBy, required this.createdByUsername,
    this.completedAt, required this.createdAt,
    this.subtaskCount = 0, this.commentCount = 0,
    this.subtasks = const [], this.comments = const [],
  });

  factory Task.fromJson(Map<String, dynamic> j) => Task(
    id: j['id'],
    title: j['title'] ?? '',
    status: j['status'] ?? 'todo',
    dueDate: j['due_date'] != null ? DateTime.tryParse(j['due_date']) : null,
    assignedTo: j['assigned_to'],
    assignedUsername: j['assigned_username'],
    parentId: j['parent_id'],
    createdBy: j['created_by'] ?? 0,
    createdByUsername: j['created_by_username'] ?? '',
    completedAt: j['completed_at'] != null ? DateTime.tryParse(j['completed_at']) : null,
    createdAt: DateTime.parse(j['created_at']),
    subtaskCount: j['subtask_count'] ?? 0,
    commentCount: j['comment_count'] ?? 0,
    subtasks: (j['subtasks'] as List<dynamic>? ?? [])
        .map((e) => Task.fromJson(e as Map<String, dynamic>))
        .toList(),
    comments: (j['comments'] as List<dynamic>? ?? [])
        .map((e) => TaskComment.fromJson(e as Map<String, dynamic>))
        .toList(),
  );

  bool get isDone => status == 'done';
  bool get isOverdue => dueDate != null && dueDate!.isBefore(DateTime.now()) && !isDone;
}

class PagedTasks {
  final List<Task> items;
  final int total;
  final int page;
  final int limit;
  const PagedTasks({required this.items, required this.total, required this.page, required this.limit});
  factory PagedTasks.fromJson(Map<String, dynamic> j) => PagedTasks(
    items: (j['items'] as List).map((e) => Task.fromJson(e)).toList(),
    total: j['total'], page: j['page'], limit: j['limit'],
  );
}