BLACK-1 | Bielski

jest.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+    preset: 'ts-jest',
+    testEnvironment: 'node',
+    testMatch: ['**/*.spec.ts'],
+};

package.json

@@ -26,8 +26,11 @@
   },
   "devDependencies": {
     "@types/express": "^4.17.21",
+    "@types/jest": "^29.5.12",
     "@types/node": "^20.10.3",
+    "jest": "^29.7.0",
     "nodemon": "^3.0.2",
+    "ts-jest": "^29.1.2",
     "ts-node": "^10.9.2",
     "typescript": "^5.3.2"
   }

src/currency/getExchangeRate.spec.ts

@@ -0,0 +1,20 @@
+import { currencyStore } from './repository';
+import { getExchangeRate } from "./getExchangeRate";
+
+jest.mock('./repository', () => ({
+    currencyStore: {
+        getCurrencyPrice: jest.fn(),
+    },
+}));
+
+describe('getExchangeRate', () => {
+    it('should return the exchange rate', () => {
+        (currencyStore.getCurrencyPrice as jest.Mock).mockImplementation((currency: string, date: string) => {
+            if (currency === 'USD') return { price_pln: '2' };
+            return { price_pln: '4' };
+        });
+
+        const result = getExchangeRate('USD', 'EUR', '2022-01-01');
+        expect(result).toEqual(0.5);
+    });
+});

src/currency/getExchangeRate.ts

@@ -0,0 +1,7 @@
+import { currencyStore } from "./repository";
+
+export const getExchangeRate = (fromCurrency: string, toCurrency: string, date: string) => {
+    const fromCurrencyPrice =  currencyStore.getCurrencyPrice(fromCurrency, date);
+    const toCurrencyPrice = currencyStore.getCurrencyPrice(toCurrency, date);
+    return fromCurrencyPrice && toCurrencyPrice ? +fromCurrencyPrice.price_pln / +toCurrencyPrice.price_pln : null;
+};

src/currency/repository.ts

@@ -0,0 +1,41 @@
+import { CurrencyPrice } from "./types";
+
+class CurrencyStore {
+    private store: Map<string, Map<string, CurrencyPrice>>;
+
+    constructor() {
+        this.store = new Map();
+    }
+
+    addCurrencyPrice(currencyPrice: CurrencyPrice) {
+        let currencyData = this.store.get(currencyPrice.date);
+        if (!currencyData) {
+            currencyData = new Map();
+            this.store.set(currencyPrice.date, currencyData);
+        }
+        currencyData.set(currencyPrice.currency, currencyPrice);
+    }
+
+    getCurrencyPrice(currency: string, date: string): CurrencyPrice | undefined {
+        if (currency === "PLN") {
+            return {
+                currency: "PLN",
+                price_pln: "1",
+                date: date
+            };
+        }
+        const currencyData = this.store.get(date);
+        return currencyData ? currencyData.get(currency) : undefined;
+    }
+
+    flush() {
+        this.store.clear();
+    }
+
+    getCurrencies(): CurrencyPrice[] {
+        const currencies = Array.from(this.store.values()).flatMap(dateMap => Array.from(dateMap.values()));
+        return currencies.sort((a, b) => a.currency.localeCompare(b.currency));
+    }
+}
+
+export const currencyStore = new CurrencyStore();

src/currency/router.ts

@@ -0,0 +1,57 @@
+import express, { Request, Response } from 'express';
+import {
+    CurrencyExchangeRequest,
+    CurrencyExchangeResponse,
+    CurrencyPriceRequest,
+    CurrencyPriceResponse
+} from "./types";
+import { currencyStore } from "./repository";
+import { getExchangeRate } from "./getExchangeRate";
+const router = express.Router();
+
+
+router.post('/currencyExchange', (req: Request, res: Response<CurrencyExchangeResponse | { message: string, error: true }>) => {
+    const { from_currency, to_currency, amount, date }: CurrencyExchangeRequest = req.body;
+
+    const exchangeRate = getExchangeRate(from_currency, to_currency, date);
+
+    if (exchangeRate === null) {
+        res.status(404).send({ error: true, message: 'Exchange rate for the given date is not available' });
+        return;
+    }
+
+    const value = +amount * exchangeRate;
+
+    res.send({
+        currency: to_currency,
+        value: value,
+        date: date
+    });
+});
+
+router.post('/currency', (req: Request, res: Response) => {
+    const { currencies }: CurrencyPriceRequest = req.body;
+    currencies.forEach((currency) => {
+        currencyStore.addCurrencyPrice(currency);
+    });
+
+    res.status(201).send({ message: 'Currency data has been successfully saved.' });
+});
+
+router.get('/currency', (req: Request, res: Response) => {
+    const currencies = currencyStore.getCurrencies();
+
+    const response: CurrencyPriceResponse = {
+        currencies: currencies
+    };
+
+    res.send(response);
+});
+
+router.post('/currencyFlush', (req: Request, res: Response) => {
+    currencyStore.flush();
+
+    res.send({ message: 'Currency store has been successfully flushed.' });
+});
+
+export default router;

src/currency/types.ts

@@ -0,0 +1,26 @@
+export interface CurrencyExchangeRequest {
+    from_currency: string;
+    to_currency: string;
+    amount: number;
+    date: string;
+}
+
+export interface CurrencyExchangeResponse {
+    currency: string;
+    value: number;
+    date: string;
+}
+
+export interface CurrencyPrice {
+    currency: string;
+    price_pln: string;
+    date: string;
+}
+
+export interface CurrencyPriceRequest {
+    currencies: CurrencyPrice[];
+}
+
+export interface CurrencyPriceResponse {
+    currencies: CurrencyPrice[];
+}

src/index.ts

@@ -2,15 +2,20 @@
 import express, { Express, Request, Response } from "express";
 import dotenv from "dotenv";
 
+import currencyRouter from "./currency/router";
+
 dotenv.config();
 const app: Express = express();
+app.use(express.json());
 
 const port = process.env.PORT || 3000;
 
 app.get("/health-check", (req: Request, res: Response) => {
   res.send("health check OK");
 });
 
+app.use(currencyRouter);
+
 /* Start the Express app and listen
  for incoming requests on the specified port */
 app.listen(port, () => {

test.http

@@ -1,3 +1,17 @@
+###
+POST http://localhost:3000/currencyFlush
+Content-Type: application/json
+
+{}
+
+> {%
+    client.test('should add new rates to existing rates',
+        () => {
+            console.log(response.status);
+            client.assert(response.status === 200);
+        });
+%}
+
 ###
 GET http://localhost:3000/health-check
 
@@ -145,7 +159,7 @@ GET http://localhost:3000/currency
                         },
                         {
                             "currency": "EUR",
-                            "price_pln": "4.5",
+                            "price_pln": "4.50",
                             "date": "2023-01-02"
                         },
                         {
@@ -155,7 +169,7 @@ GET http://localhost:3000/currency
                         },
                         {
                             "currency": "USD",
-                            "price_pln": "4",
+                            "price_pln": "4.00",
                             "date": "2023-01-02"
                         }
                     ]