import { Injectable } from '@nestjs/common';
import { PrismaService } from '../../infrastructure/database/prisma.service';
import { Prisma } from '@prisma/client';

export const ARTIFACT_TYPES = [
  'analysis_result',
  'focus_item',
  'review_card',
  'quiz',
  'learning_analysis',
  'recommendation',
  'knowledge_import',
] as const;

export type ArtifactType = (typeof ARTIFACT_TYPES)[number];

export interface CreateArtifactInput {
  jobId: string;
  artifactType: ArtifactType;
  artifactId: string;
  ordinal?: number;
  metadata?: Record<string, unknown>;
}

/**
 * M-AI-02-06: Job 产物关联 Repository
 *
 * 多态引用：artifactType + artifactId 关联业务表，不设 FK 到各类型表。
 * 唯一约束 (jobId, artifactType, artifactId) 保证幂等。
 */
@Injectable()
export class AiJobArtifactRepository {
  constructor(private readonly prisma: PrismaService) {}

  /**
   * 幂等创建：若已存在同 (jobId, artifactType, artifactId) 的记录则跳过。
   * 使用 Prisma create + skip-duplicate 语义（Prisma 不支持 INSERT IGNORE MySQL 语法，
   * 但 Prisma 的唯一约束错误可通过 try/catch 转为幂等）。
   */
  async create(input: CreateArtifactInput) {
    try {
      return await this.prisma.aiJobArtifact.create({
        data: {
          jobId: input.jobId,
          artifactType: input.artifactType,
          artifactId: input.artifactId,
          ordinal: input.ordinal ?? 0,
          metadata: input.metadata ?? undefined,
        },
      });
    } catch (error) {
      if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === 'P2002') {
        // 唯一约束冲突 = 已存在，幂等返回已有记录
        const existing = await this.prisma.aiJobArtifact.findUnique({
          where: {
            jobId_artifactType_artifactId: {
              jobId: input.jobId,
              artifactType: input.artifactType,
              artifactId: input.artifactId,
            },
          },
        });
        if (existing) return existing;

        // 极边缘情况：P2002 和 findUnique 之间父 Job 被 CASCADE 删除。
        // 此时记录已不存在，重试 create 一次。
        return this.prisma.aiJobArtifact.create({
          data: {
            jobId: input.jobId,
            artifactType: input.artifactType,
            artifactId: input.artifactId,
            ordinal: input.ordinal ?? 0,
            metadata: input.metadata ?? undefined,
          },
        });
      }
      throw error;
    }
  }

  /** 批量幂等创建（逐个 try/catch，小批量场景适用） */
  async createMany(inputs: CreateArtifactInput[]) {
    const results: Awaited<ReturnType<typeof this.create>>[] = [];
    for (const input of inputs) {
      results.push(await this.create(input));
    }
    return results;
  }

  /** 按 Job 查询所有产物，按 ordinal 排序 */
  async findByJobId(jobId: string) {
    return this.prisma.aiJobArtifact.findMany({
      where: { jobId },
      orderBy: { ordinal: 'asc' },
    });
  }

  /**
   * 反向查询：按产物查找关联的 Job。
   * 通过 (artifactType, artifactId) 复合索引高效查询。
   */
  async findJobsByArtifact(artifactType: ArtifactType, artifactId: string) {
    const artifacts = await this.prisma.aiJobArtifact.findMany({
      where: { artifactType, artifactId },
      select: { jobId: true, ordinal: true, createdAt: true },
      orderBy: { createdAt: 'asc' },
    });
    return artifacts;
  }
}