adding usecase

src/modules/ad/domain/usecases/create-ad.usecase.ts

@@ -0,0 +1,45 @@
+import { Mapper } from '@automapper/core';
+import { InjectMapper } from '@automapper/nestjs';
+import { CommandHandler } from '@nestjs/cqrs';
+import { Messager } from '../../adapters/secondaries/messager';
+import { AdsRepository } from '../../adapters/secondaries/ads.repository';
+import { CreateAdCommand } from '../../commands/create-ad.command';
+import { CreateAdRequest } from '../dtos/create-ad.request';
+import { Ad } from '../entities/ad';
+
+@CommandHandler(CreateAdCommand)
+export class CreateAdUseCase {
+  constructor(
+    private readonly _repository: AdsRepository,
+    private readonly _messager: Messager,
+    @InjectMapper() private readonly _mapper: Mapper,
+  ) {}
+
+  async execute(command: CreateAdCommand): Promise<Ad> {
+    const entity = this._mapper.map(
+      command.createAdRequest,
+      CreateAdRequest,
+      Ad,
+    );
+
+    try {
+      const ad = await this._repository.create(entity);
+      this._messager.publish('ad.create', JSON.stringify(ad));
+      this._messager.publish('logging.ad.create.info', JSON.stringify(ad));
+      return ad;
+    } catch (error) {
+      let key = 'logging.ad.create.crit';
+      if (error.message.includes('Already exists')) {
+        key = 'logging.ad.create.warning';
+      }
+      this._messager.publish(
+        key,
+        JSON.stringify({
+          command,
+          error,
+        }),
+      );
+      throw error;
+    }
+  }
+}