import { ResolveField, Resolver } from '@nestjs/graphql';
import { InjectRepository } from '@nestjs/typeorm';
import { In, Repository } from 'typeorm';
import { DescriptionChecklistObjectType } from './description-types/description-checklist/description-checklist.dto';
import { DescriptionChecklist } from './description-types/description-checklist/description-checklist.entity';
import { DescriptionTextObjectType } from './description-types/description-text/description-text.dto';
import { DescriptionText } from './description-types/description-text/description-text.entity';
import {
  DescriptionableUnion,
  DescriptionObjectType,
  DescriptionType,
} from './description.dto';
import {
  GraphqlLoader,
  Loader,
  PolymorphicLoaderData,
  SelectedUnionTypes,
  SelectedUnionTypesResult,
} from '../../../loader-lib';

@Resolver(() => DescriptionObjectType)
export class DescriptionResolver {
  constructor(
    @InjectRepository(DescriptionText)
    public readonly descriptionTextRepository: Repository<DescriptionText>,
    @InjectRepository(DescriptionChecklist)
    public readonly descriptionChecklistRepository: Repository<DescriptionChecklist>,
  ) {}

  @ResolveField(() => [DescriptionableUnion], { nullable: true })
  @GraphqlLoader({
    polymorphic: (parent: DescriptionObjectType) => ({
      id: parent.description_id,
      descriminator: parent.description_type,
    }),
  })
  async descriptionable(
    @Loader()
    loader: PolymorphicLoaderData<
      [DescriptionText | DescriptionChecklist],
      number,
      DescriptionType
    >,
    @SelectedUnionTypes() types: SelectedUnionTypesResult,
  ) {
    const results = [];

    for (const item of loader.polimorphicTypes) {
      switch (item.descriminator) {
        case DescriptionType.Text:
          const textDescriptions = await this.descriptionTextRepository
            .createQueryBuilder()
            .select(types.getFields(DescriptionTextObjectType))
            .where({
              id: In(item.ids),
            })
            .getRawMany();

          results.push({
            descriminator: DescriptionType.Text,
            entities: textDescriptions,
          });

          break;
        case DescriptionType.Checklist:
          const checklistDescriptions =
            await this.descriptionChecklistRepository
              .createQueryBuilder()
              .select(types.getFields(DescriptionChecklistObjectType))
              .where({
                id: In(item.ids),
              })
              .getRawMany();

          results.push({
            descriminator: DescriptionType.Checklist,
            entities: checklistDescriptions,
          });

          break;
        default:
          break;
      }
    }
    return loader.helpers.mapOneToManyPolymorphicRelation(results, loader.ids);
  }
}