import { KnowledgeEntry } from '@prisma/client';
import { NotFoundError, ConflictError } from '@/common/errors';
import {
  knowledgeRepository,
  KnowledgeRepository,
  CreateKnowledgeEntryData,
  RetrieveFilters,
} from '../repository';

export class KnowledgeService {
  constructor(private readonly repo: KnowledgeRepository = knowledgeRepository) {}

  /** FR-002: new entries always default to status: draft, version: 1 — set by the repository. */
  async create(data: CreateKnowledgeEntryData): Promise<KnowledgeEntry> {
    return this.repo.create(data);
  }

  async publish(code: string, effectiveDate?: Date): Promise<KnowledgeEntry> {
    const updated = await this.repo.publish(code, effectiveDate);
    if (!updated) throw new NotFoundError('Knowledge entry not found.');
    return updated;
  }

  async unpublish(code: string): Promise<KnowledgeEntry> {
    const updated = await this.repo.unpublish(code);
    if (!updated) throw new NotFoundError('Knowledge entry not found.');
    return updated;
  }

  async setValidationStatus(code: string, validationStatus: string): Promise<KnowledgeEntry> {
    const updated = await this.repo.setValidationStatus(code, validationStatus);
    if (!updated) throw new NotFoundError('Knowledge entry not found.');
    return updated;
  }

  /** FR-004: an edit always creates a new version; a stale `expectedVersion` is rejected. */
  async edit(
    code: string,
    expectedVersion: number,
    content: Omit<CreateKnowledgeEntryData, 'code' | 'productId'>,
  ): Promise<KnowledgeEntry> {
    const updated = await this.repo.createNewVersion(code, expectedVersion, content);
    if (!updated) {
      throw new ConflictError(
        'Knowledge entry was modified by another request — refresh and retry.',
      );
    }
    return updated;
  }

  async listVersions(code: string): Promise<KnowledgeEntry[]> {
    const versions = await this.repo.findAllVersionsByCode(code);
    if (versions.length === 0) throw new NotFoundError('Knowledge entry not found.');
    return versions;
  }

  async retrieve(filters: RetrieveFilters): Promise<KnowledgeEntry[]> {
    return this.repo.retrieve(filters);
  }

  /** 012-admin-list-views follow-up: every entry for a product, any status — the governance
   * screen's own data source (unlike `retrieve`, which is published-only). */
  async listForGovernance(productId: string): Promise<KnowledgeEntry[]> {
    return this.repo.findAllForProduct(productId);
  }
}

export const knowledgeService = new KnowledgeService();