app-nodejs-codechallenge - Josmel Yupanqui

anti-fraud/.dockerignore

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+Dockerfile
+.dockerignore
+node_modules
+npm-debug.log
+dist

anti-fraud/.editorconfig

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+root = true
+
+[*.{js,ts,json}]
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+indent_style = space
+indent_size = 2

anti-fraud/.env.example

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+APP_HOST = '0.0.0.0'
+PORT = 3000
+TOPIC_KAFKA_RECIVE_STATUS_TRANSACTION = 'transaction-status'
+KAFKA_GROUP_ID = 'transaction-validate'
+KAFKA_CLIENT_ID = 'my-transaction-app'
+KAFKA_BROKERS = 'kafka:29092' //local localhost:9092'
+TOPIC_KAFKA_SEND_TRANSACTION = 'transaction-created'
+KAFKA_SERVICE = 'KAFKA_SERVICE'
+KAFKA_TRANSACTION_ID = 'KAFKA_TRANSACTION_ID'

anti-fraud/.eslintrc.js

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+module.exports = {
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    project: 'tsconfig.json',
+    sourceType: 'module',
+  },
+  plugins: ['@typescript-eslint/eslint-plugin'],
+  extends: ['plugin:@typescript-eslint/recommended', 'plugin:prettier/recommended'],
+  root: true,
+  env: {
+    node: true,
+    jest: true,
+  },
+  ignorePatterns: ['.eslintrc.js'],
+  rules: {
+    '@typescript-eslint/interface-name-prefix': 'off',
+    '@typescript-eslint/explicit-function-return-type': 'off',
+    '@typescript-eslint/explicit-module-boundary-types': 'off',
+    '@typescript-eslint/no-explicit-any': 'off',
+    '@typescript-eslint/no-inferrable-types': 'off',
+    'prettier/prettier': [
+      'warn',
+      {
+        singleQuote: true,
+        trailingComma: 'all',
+        arrowParens: 'always',
+        tabWidth: 2,
+        printWidth: 100,
+      },
+    ],
+  },
+};

anti-fraud/.gitignore

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+# compiled output
+/dist
+/node_modules
+
+# Logs
+logs
+*.log
+npm-debug.log*
+pnpm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# OS
+.DS_Store
+
+# Tests
+/coverage
+/.nyc_output
+
+# IDEs and editors
+/.idea
+.project
+.classpath
+.c9/
+*.launch
+.settings/
+*.sublime-workspace
+
+# IDE - VSCode
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+.env

anti-fraud/.prettierrc

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+{
+  "singleQuote": true,
+  "trailingComma": "all",
+  "arrowParens": "always",
+  "tabWidth": 2,
+  "printWidth": 100
+}

anti-fraud/Dockerfile

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+FROM node:16-alpine 
+
+# Bundle APP files
+WORKDIR /usr/src/app
+COPY . .
+
+RUN yarn install
+COPY . .
+CMD ["npm", "run","start:dev"]

anti-fraud/README.md

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+## Description Microservice anti-fraud
+
+## Anti-Fraud Microservice
+
+Este microservicio está diseñado para detectar y manejar transacciones fraudulentas en tiempo real. Se basa en el framework [Nest](https://github.com/nestjs/nest) utilizando Kafka para la comunicación entre microservicios y MongoDB para persistir las transacciones.
+
+## Descripción
+
+El Microservicio Anti-Fraude consume transacciones desde un tópico de Kafka y valida el estado de cada transacción basándose en reglas predefinidas. Si la transacción supera ciertos límites, se marca como fraudulenta, y se publica el resultado en otro tópico de Kafka para su procesamiento.
+
+## Installation
+
+```bash
+$ cp .env.example  .env
+```
+
+```bash
+$ npm install
+```
+
+## Running the app
+
+```bash
+# development
+$ npm run start
+
+# watch mode
+$ npm run start:dev
+
+# production mode
+$ npm run start:prod
+```
+
+## Test
+
+```bash
+# unit tests
+$ npm run test
+
+# e2e tests
+$ npm run test:e2e
+
+# test coverage
+$ npm run test:cov
+```
+
+## Endpoints y API
+
+Este microservicio no expone directamente endpoints HTTP, ya que se comunica a través de Kafka con otros microservicios. A continuación se detallan los principales tópicos utilizados:
+
+- **TOPIC_KAFKA_SEND_TRANSACTION**: Tópico para recibir transacciones a validar.
+- **TOPIC_KAFKA_RECIVE_STATUS_TRANSACTION**: Tópico para enviar el resultado del proceso de validación.
+
+## Tecnologías utilizadas
+
+- **NestJS**: Framework para construir aplicaciones Node.js escalables.
+- **Kafka**: Plataforma de transmisión distribuida para manejar los mensajes entre microservicios.
+- **MongoDB**: Base de datos NoSQL para almacenar las transacciones.

anti-fraud/nest-cli.json

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+{
+    "collection": "@nestjs/schematics",
+    "sourceRoot": "src"
+  }

anti-fraud/package.json

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+{
+  "name": "anti-fraud",
+  "version": "0.0.1",
+  "description": "",
+  "author": "",
+  "private": true,
+  "license": "UNLICENSED",
+  "scripts": {
+    "prebuild": "rimraf dist",
+    "build": "nest build",
+    "format": "prettier --write \"src/**/*.ts\" \"test/**/*.ts\"",
+    "start": "nest start",
+    "start:dev": "nest start --watch",
+    "start:debug": "npm run prebuild && nest start --debug --watch",
+    "start:prod": "node dist/main",
+    "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix",
+    "test": "jest",
+    "test:watch": "jest --watch",
+    "test:cov": "jest --coverage",
+    "test:debug": "node --inspect-brk -r tsconfig-paths/register -r ts-node/register node_modules/.bin/jest --runInBand",
+    "test:e2e": "jest --config ./test/jest-e2e.json"
+  },
+  "dependencies": {
+    "@nestjs/common": "^8.0.0",
+    "@nestjs/config": "^2.0.0",
+    "@nestjs/core": "^8.0.0",
+    "@nestjs/cqrs": "^8.0.3",
+    "@nestjs/event-emitter": "^1.1.0",
+    "@nestjs/microservices": "^8.4.4",
+    "@nestjs/platform-express": "^8.0.0",
+    "@nestjs/swagger": "^5.2.0",
+    "@nestjs/typeorm": "^8.0.3",
+    "class-transformer": "^0.5.1",
+    "class-validator": "^0.13.2",
+    "kafkajs": "^1.16.0",
+    "mongodb": "^4.5.0",
+    "pg": "^8.7.3",
+    "reflect-metadata": "^0.1.13",
+    "rimraf": "^3.0.2",
+    "rxjs": "^7.2.0",
+    "swagger-ui-express": "^4.5.0",
+    "typeorm": "^0.2.45"
+  },
+  "devDependencies": {
+    "@nestjs/cli": "^8.0.0",
+    "@nestjs/schematics": "^8.0.0",
+    "@nestjs/testing": "^8.0.0",
+    "@types/express": "^4.17.13",
+    "@types/jest": "27.4.1",
+    "@types/node": "^16.0.0",
+    "@types/supertest": "^2.0.11",
+    "@typescript-eslint/eslint-plugin": "^5.0.0",
+    "@typescript-eslint/parser": "^5.0.0",
+    "eslint": "^8.0.1",
+    "eslint-config-prettier": "^8.3.0",
+    "eslint-plugin-prettier": "^4.0.0",
+    "jest": "^27.2.5",
+    "prettier": "^2.3.2",
+    "source-map-support": "^0.5.20",
+    "supertest": "^6.1.3",
+    "ts-jest": "^27.0.3",
+    "ts-loader": "^9.2.3",
+    "ts-node": "^10.0.0",
+    "tsconfig-paths": "^3.10.1",
+    "typescript": "^4.3.5"
+  },
+  "jest": {
+    "moduleFileExtensions": [
+      "js",
+      "json",
+      "ts"
+    ],
+    "rootDir": "src",
+    "testRegex": ".*\\.spec\\.ts$",
+    "transform": {
+      "^.+\\.(t|j)s$": "ts-jest"
+    },
+    "collectCoverageFrom": [
+      "**/*.(t|j)s"
+    ],
+    "coverageDirectory": "../coverage",
+    "testEnvironment": "node"
+  },
+  "_moduleAliases": {
+    "@constants": "dist/constants"
+  }
+}

anti-fraud/src/anti-fraud.module.ts

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+import { Module, Provider } from '@nestjs/common';
+import { CqrsModule } from '@nestjs/cqrs';
+import { TransactionOpenedHandler } from './application/event/transaction-opened.handler';
+import { InjectionUseCase } from './application/injection.use-case';
+import { ValidateTransactionHandler } from './application/validate-transaction-use-case/validate-transaction.handler';
+import { TransactionFactory } from './domain/transaction.factory';
+import { TransactionConsumer } from './infrastructure/consumers/transaction.consumer';
+import { IntegrationEventPublisherImplement } from './infrastructure/producers/transaction-event.producer';
+import { LoggerService } from './infrastructure/logging/logger.service';
+import { ClientsModule } from '@nestjs/microservices';
+import { kafkaConfig } from './infrastructure/config/kafka.config';
+
+const infrastructure: Provider[] = [
+  {
+    provide: InjectionUseCase.INTEGRATION_EVENT_PUBLISHER,
+    useClass: IntegrationEventPublisherImplement,
+  },
+  LoggerService,
+];
+const application = [TransactionOpenedHandler, ValidateTransactionHandler];
+const domain = [TransactionFactory];
+@Module({
+  imports: [CqrsModule, ClientsModule.register([kafkaConfig])],
+  controllers: [TransactionConsumer],
+  providers: [...infrastructure, ...application, ...domain],
+  exports: [ClientsModule],
+})
+export class AntiFraudModule {}

anti-fraud/src/api/dto/read-transaction.param.dto.ts

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+interface bodyData {
+  id: string;
+  accountExternalIdDebit: string;
+  accountExternalIdCredit: string;
+  tranferTypeId: number;
+  value: number;
+  transactionStatus: number;
+}
+
+export class AntiFraudDto {
+  readonly topic: string;
+  readonly partition: number;
+  readonly value: {
+    subject: string;
+    data: bodyData;
+  };
+}

anti-fraud/src/application/event/integration.ts

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+import { TransactionEssentialProperties } from '../../domain/transaction.aggregate';
+
+export class IntegrationEvent {
+  readonly subject: string;
+  readonly data: TransactionEssentialProperties;
+}
+
+export interface IntegrationEventPublisher {
+  publish: (event: IntegrationEvent) => Promise<void>;
+}
+
+export enum IntegrationEventSubject {
+  OPENED = 'transaction-validate.opened',
+}

anti-fraud/src/application/event/transaction-opened.handler.spec.ts

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+import { Test, TestingModule } from '@nestjs/testing';
+import { TransactionOpenedHandler } from './transaction-opened.handler';
+import { TransactionOpenedEvent } from '../../domain/transaction-opened.event';
+import { IntegrationEventPublisher, IntegrationEventSubject } from './integration';
+import { InjectionUseCase } from '../injection.use-case';
+
+describe('TransactionOpenedHandler', () => {
+  let handler: TransactionOpenedHandler;
+  let publisher: IntegrationEventPublisher;
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        TransactionOpenedHandler,
+        {
+          provide: InjectionUseCase.INTEGRATION_EVENT_PUBLISHER,
+          useValue: {
+            publish: jest.fn(),
+          },
+        },
+      ],
+    }).compile();
+
+    handler = module.get<TransactionOpenedHandler>(TransactionOpenedHandler);
+    publisher = module.get<IntegrationEventPublisher>(InjectionUseCase.INTEGRATION_EVENT_PUBLISHER);
+  });
+
+  it('should handle TransactionOpenedEvent and publish the event', async () => {
+    const mockEvent: TransactionOpenedEvent = {
+      id: 'some-id',
+      transactionStatus: 1,
+      value: 1000,
+    };
+
+    await handler.handle(mockEvent);
+
+    expect(publisher.publish).toHaveBeenCalledWith({
+      subject: IntegrationEventSubject.OPENED,
+      data: mockEvent,
+    });
+  });
+});

anti-fraud/src/application/event/transaction-opened.handler.ts

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+import { Inject } from '@nestjs/common';
+import { EventsHandler, IEventHandler } from '@nestjs/cqrs';
+import { TransactionOpenedEvent } from '../../domain/transaction-opened.event';
+import { InjectionUseCase } from '../injection.use-case';
+
+import { IntegrationEventPublisher, IntegrationEventSubject } from './integration';
+
+@EventsHandler(TransactionOpenedEvent)
+export class TransactionOpenedHandler implements IEventHandler<TransactionOpenedEvent> {
+  constructor(
+    @Inject(InjectionUseCase.INTEGRATION_EVENT_PUBLISHER)
+    private readonly publisher: IntegrationEventPublisher,
+  ) {}
+
+  async handle(event: TransactionOpenedEvent): Promise<void> {
+    await this.publisher.publish({
+      subject: IntegrationEventSubject.OPENED,
+      data: event,
+    });
+  }
+}