Ezequiel Challenge Solution

.gitignore

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+node_modules
+build
+.env

Dockerfile

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+FROM node:12.18-alpine as builder
+RUN mkdir -p /home/node/app/node_modules && chown -R node:node /home/node/app
+WORKDIR /home/node/app
+COPY package*.json ./
+RUN npm config set unsafe-perm true
+RUN npm install -g typescript
+RUN npm install -g ts-node
+USER node
+RUN npm install
+COPY --chown=node:node . .
+RUN npm run build
+
+FROM node:12.18-alpine
+RUN mkdir -p /home/node/app/node_modules && chown -R node:node /home/node/app
+WORKDIR /home/node/app
+COPY package*.json ./
+USER node
+RUN npm install --production
+COPY --from=builder /home/node/app/build ./build
+COPY --chown=node:node .env .
+EXPOSE 8000
+CMD [ "node", "build/index.js" ]

README.md

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-
-## Cryptologic web3/backend application challenge.
-
-The main goal of this challenge is to create a backend application writen in nodejs/typescript that consumes, processes and store blockchain data.
-
-To achieve this, the following items are required.
-
-- Create a fork of the current repository, once the challenge is done submit a proper PR.
-- Instantiate a web3 o etherjs object with an public RPC (in this case we will use Avalanche EVM C-Chain)
-- create a MongoDB database connection withing the runtime
-
-Having this transaction as a starting point [0x508217c172c3cfe006ee9ca5bef621ba11a359461bacfc0494f1449a7d00f443](https://snowtrace.io/tx/0x508217c172c3cfe006ee9ca5bef621ba11a359461bacfc0494f1449a7d00f443) it is required to:
-
-- Use web3.js or ethers.js proper methods to fetch transaction data details
-
-- Fetch and save main contract ABI and bytecode and save them into a file and database
-
-- Understand and parse the event log to show in a básic REST response the decoded events and its parameters
-
-- Create a basic REST endpoint that once queried saves the parsed data into a MongoDB document.
-
-- Create a basic REST endpoint to get the previously saved data.
-
-
-Must have:
-
-- Basic error handling
-- Basic README file
-- Basic explaination of the work done
-
-Extra points:
-- unit testing
-- Docker build
-
-#### References:
-
-[Event logs](https://medium.com/mycrypto/understanding-event-logs-on-the-ethereum-blockchain-f4ae7ba50378)
-
-[Web3 doc](https://web3js.readthedocs.io/en/1.0/web3-eth.html)
-
-[EthersJS dock](https://docs.ethers.io/v5/)
-
-[topics & getPastLogs](https://ethereum.stackexchange.com/questions/61585/how-to-setup-topics-for-function-getpastlogs)
+## Ezequiel web3/backend application challenge Solution.
+
+Project Structure
+
+- Dependency Injection for instanciating classes
+  - Here we have a di-container that will register, in singleton scope, Services, Repositories and External Providers. Advantage: Responsible for instantiation in one place.
+- API
+  - We have routes and middlewares for the REST API. Inside of API we will find 2 endpoints:
+  * Get All Transactions (This endpoint has some limitations, returns everything it finds in database. One improvement will be adding pagination and query params. Other improvemnt is to add Json Validation schema for POST methods).
+  - Middlewares: We have an error handler middleware responsible for capturing and formating errors.
+- Services
+  - We have services to be consumed from API and Workers.
+  - Services has services.interface responsible for declaring all services contracts.
+- Smart Contract Component
+  - Here we have a package responsible for interacting with Ethereum Network, create contracts and retrieve transaction information from the network.
+  - We have ABI provider that creates a contract with SmartContractService. ABI provider has 2 providers that get abi information.
+- Workers
+  - Here we register for events. In this case only have the possibility to register event for Joe Doe contract address. Events will be saved to DB in order to be consumed by API
+  - Further enhancement: Have the possibility to register events for a lot of addresses.

index.ts

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+import express, { Express, Request, Response } from "express";
+import dotenv from "dotenv";
+import cors from "cors";
+import helmet from "helmet";
+import bodyParser from "body-parser";
+import morgan from "morgan";
+import fs from "fs";
+import path from "path";
+
+import diContainer from "./src/di-container";
+import { IContractConsumer } from "./src/workers/contractConsumer.interface";
+import { transactionRoutes } from "./src/api/routes/transaction.routes";
+import { initDb } from "./src/db/db";
+import errorHandler from "./src/api/middlewares/error-handler.middleware";
+import AppConfig from "./src/config/app.config";
+import swaggerUi from "swagger-ui-express";
+
+dotenv.config();
+
+var accessLogStream = fs.createWriteStream(
+  path.join(path.resolve("./"), "access.log"),
+  {
+    flags: "a",
+  }
+);
+
+const app: Express = express();
+
+app.use(bodyParser.json());
+app.use(bodyParser.urlencoded({ extended: true }));
+
+app.use(helmet());
+app.use(cors());
+
+//Using logger middleware
+app.use(morgan("combined", { stream: accessLogStream }));
+
+app.use(transactionRoutes);
+app.use(errorHandler);
+
+//Initialize DB
+initDb();
+
+app.get("/health", (req: Request, res: Response) => {
+  res.send("Server is running ok");
+});
+
+const server = app.listen(AppConfig.PORT, () => {
+  console.log(`Server is running at https://localhost:${AppConfig.PORT}`);
+});
+
+//Start Consumer
+diContainer.get<IContractConsumer>("IContractConsumer").start();
+
+app.use(
+  "/docs",
+  swaggerUi.serve,
+  swaggerUi.setup(undefined, {
+    swaggerOptions: {
+      url: "./swagger.json",
+    },
+  })
+);
+
+//Todo: Move this to termination signals.
+process.on("exit", () => {
+  console.log("Server is shutting down");
+  server.close();
+});
+
+process.on("SIGINT", () => {
+  console.log("Server is shutting down");
+  server.close();
+});