import { Injectable } from '@nestjs/common';
import { generateShortId } from '../../common/utils/id.util';
import { KnowledgeItemType } from './types/knowledge-item.types';

export interface KnowledgeItem {
  id: string;
  userId: string;
  knowledgeBaseId: string;
  parentId: string | null;
  itemType: KnowledgeItemType;
  title: string;
  content: string;
  orderIndex: number;
  createdAt: Date;
  updatedAt: Date;
}

@Injectable()
export class KnowledgeItemsRepository {
  private items: Map<string, KnowledgeItem> = new Map();

  async create(userId: string, knowledgeBaseId: string, dto: any): Promise<KnowledgeItem> {
    const item: KnowledgeItem = {
      id: generateShortId(),
      userId,
      knowledgeBaseId,
      parentId: dto.parentId || null,
      itemType: dto.itemType || 'lesson',
      title: dto.title || '',
      content: dto.content || '',
      orderIndex: dto.orderIndex || 0,
      createdAt: new Date(),
      updatedAt: new Date(),
    };
    this.items.set(item.id, item);
    return item;
  }

  async findById(id: string): Promise<KnowledgeItem | undefined> {
    return this.items.get(id);
  }

  async findByKnowledgeBaseId(knowledgeBaseId: string): Promise<KnowledgeItem[]> {
    return Array.from(this.items.values()).filter((i) => i.knowledgeBaseId === knowledgeBaseId);
  }

  async update(id: string, dto: any): Promise<KnowledgeItem | undefined> {
    const item = this.items.get(id);
    if (!item) return undefined;
    Object.assign(item, { ...dto, updatedAt: new Date() });
    return item;
  }
}