import { Resolver, Query, Mutation, Args, ID, Int, ResolveField, Parent } from '@nestjs/graphql';
import { GraphQLUpload } from 'graphql-upload-ts';
import type { FileUpload } from 'graphql-upload-ts';
import { CasesService } from './cases.service';
import { CaseLaw } from './entities/case-law.entity';
import { StorageService } from '../common/storage/storage.service';
import { CaseFileValidationPipe } from '../common/pipes/file-validation.pipe';
import { CaseStatus } from '../generated/prisma/client.js';

@Resolver(() => CaseLaw)
export class CasesResolver {
  constructor(
    private readonly casesService: CasesService,
    private readonly storage: StorageService,
  ) {}

  @Query(() => CaseLaw, { name: 'caseLaw', nullable: true })
  async findOne(
    @Args('id', { type: () => String, nullable: true }) id?: string,
    @Args('caseNumber', { type: () => String, nullable: true }) caseNumber?: string,
  ) {
    return this.casesService.findOne(id, caseNumber);
  }

  @ResolveField(() => String, { name: 'downloadUrl', nullable: true })
  async getDownloadUrl(@Parent() caseLaw: CaseLaw): Promise<string | null> {
    const key = caseLaw.storageKey;
    if (!key) return null;
    
    return this.storage.getPresignedUrl(key);
  }

  @Mutation(() => CaseLaw)
  async uploadCase(
    @Args({ name: 'file', type: () => GraphQLUpload }, CaseFileValidationPipe)
    { createReadStream, filename, mimetype }: FileUpload,
  ) {
    const chunks: any[] = [];
    for await (const chunk of createReadStream()) {
      chunks.push(chunk);
    }

    const buffer = Buffer.concat(chunks);
    // Buffering into memory like this might not be perfectly "scalable" for 1GB files, 
    // but for this project and 10MB limit it's simpler to handle than passing a stream.
    return this.casesService.processAndSave(buffer, mimetype, filename);
  }


  // An additional simple fetch all endpoint to demonstrate pagination
  @Query(() => [CaseLaw], { name: 'caseLaws' })
  async findAll(
    @Args('status', { type: () => CaseStatus, nullable: true }) status?: CaseStatus,
    @Args('take', { type: () => Int, nullable: true, defaultValue: 20 }) take?: number,
    @Args('skip', { type: () => Int, nullable: true, defaultValue: 0 }) skip?: number,
  ) {
    return this.casesService.findAll(status, take, skip);
  }
}