first commit

.dockerignore

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+.docker*
+.git*
+.vscode/
+coverage/
+node_modules/
+test/
+.eslintrc.js
+*.yml
+Dockerfile*
+*.md

.eslintrc.js

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+module.exports = {
+  env: {
+    commonjs: true,
+    es6: true,
+    node: true,
+    jest: true
+  },
+  extends: [
+    'standard'
+  ],
+  globals: {
+    Atomics: 'readonly',
+    SharedArrayBuffer: 'readonly'
+  },
+  parserOptions: {
+    ecmaVersion: 2018
+  },
+  rules: {}
+}

.gitignore

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+.docker/
+coverage/
+node_modules/

.vscode/launch.json

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+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "app",
+      "type": "node",
+      "request": "attach",
+      "port": 9229,
+      "address": "localhost",
+      "localRoot": "${workspaceFolder}",
+      "remoteRoot": "/usr/src/app",
+      "protocol": "inspector"
+    },
+    {
+      "type": "node",
+      "request": "launch",
+      "name": "test",
+      "program": "${workspaceFolder}/node_modules/.bin/jest",
+      "args": ["--runInBand"],
+      "console": "integratedTerminal",
+      "internalConsoleOptions": "neverOpen",
+      "disableOptimisticBPs": true,
+      "windows": {
+        "program": "${workspaceFolder}/node_modules/jest/bin/jest",
+      }
+    }
+  ]
+}

Dockerfile

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+FROM node:10
+
+WORKDIR /usr/src/app
+
+COPY ["package.json", "yarn.lock", "./"]
+
+RUN yarn install --production
+
+COPY . .
+
+ENTRYPOINT [ "yarn", "start" ]

README.md

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+# Instructions
+
+## Run
+
+Run with docker compose:
+
+```bash
+$ docker-compose up -d
+```
+
+## API call examples
+
+```bash
+$ curl "localhost:8080/convert?amount=100&src_currency=GBP&dest_currency=USD&reference_date=2020-03-25"
+$ curl "localhost:8080/convert?amount=200&src_currency=AUD&dest_currency=CAD"
+```
+
+## Run the tests
+
+Install dependencies then run with npm:
+
+```bash
+$ npm i
+$ npm test
+````
+
+or yarn:
+
+```bash
+$ yarn
+$ yarn test
+```

docker-compose.debug.yml

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+version: "3.7"
+services:
+  app:
+    build: .
+    depends_on:
+    - redis
+    entrypoint: yarn debug
+    environment:
+    - CRONTZ=Europe/Rome
+    - RATES_API=https://www.ecb.europa.eu/stats/eurofxref/eurofxref-hist-90d.xml
+    - REDIS_HOST=redis
+    - REDIS_TTL=120
+    - REF_CURRENCY=EUR
+    ports:
+    - 8080:8080
+    - 9229:9229
+    restart: always
+
+  redis:
+    image: redis:5
+    container_name: redis
+    command: redis-server --appendonly yes
+    restart: always
+    volumes:
+    - $PWD/.docker/redis-debug:/data
+
+  redis-commander:
+    image: rediscommander/redis-commander:latest
+    container_name: redis-commander
+    hostname: redis-commander
+    environment:
+    - REDIS_HOSTS=local:redis:6379
+    ports:
+    - 8081:8081
+    restart: always

docker-compose.yml

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+version: "3.7"
+services:
+  app:
+    build: .
+    depends_on:
+    - redis
+    environment:
+    - "CRON=5 16 * * 1-5"
+    - CRONTZ=Europe/Rome
+    - RATES_API=https://www.ecb.europa.eu/stats/eurofxref/eurofxref-hist-90d.xml
+    - REDIS_HOST=redis
+    - REDIS_TTL=90000
+    - REF_CURRENCY=EUR
+    ports:
+    - 8080:8080
+    restart: always
+
+  redis:
+    image: redis:5
+    container_name: redis
+    command: redis-server --appendonly yes
+    restart: always
+    volumes:
+    - $PWD/.docker/redis:/data

index.js

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+const cron = require('node-cron')
+const Redis = require('ioredis')
+
+const getRedisClient = require('./src/lib/redis')
+const apiFactory = require('./src/services/api')
+const parserFactory = require('./src/services/parser')
+
+const redis = getRedisClient(Redis)
+const api = apiFactory(redis)
+const parse = parserFactory(redis)
+
+const HOST = '0.0.0.0'
+const PORT = 8080
+
+parse()
+  .then(() => cron.schedule(
+    process.env.CRON || '* * * * *',
+    parse,
+    { timezone: process.env.CRONTZ || 'Europe/London' }
+  ))
+
+api.listen(PORT, HOST)
+
+console.log(`${new Date().toISOString()} INFO listening on http://${HOST}:${PORT}`)

package.json

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+{
+  "name": "currency-converter",
+  "version": "1.0.0",
+  "scripts": {
+    "start": "node index.js",
+    "debug": "node --inspect-brk=0.0.0.0 index.js",
+    "test": "jest --coverage --verbose=true test"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/k33rs/currency-converter.git"
+  },
+  "author": "Michele Chersich",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/k33rs/currency-converter/issues"
+  },
+  "homepage": "https://github.com/k33rs/currency-converter#readme",
+  "dependencies": {
+    "@hapi/joi": "^17.1.1",
+    "@hapi/joi-date": "^2.0.1",
+    "axios": "^0.19.2",
+    "bignumber.js": "^9.0.0",
+    "celebrate": "^12.0.1",
+    "express": "^4.17.1",
+    "ioredis": "^4.16.0",
+    "node-cron": "^2.0.3",
+    "xml2json": "^0.12.0"
+  },
+  "devDependencies": {
+    "eslint": "^6.8.0",
+    "eslint-config-standard": "^14.1.1",
+    "eslint-plugin-import": "^2.20.1",
+    "eslint-plugin-node": "^11.0.0",
+    "eslint-plugin-promise": "^4.2.1",
+    "eslint-plugin-standard": "^4.0.1",
+    "jest": "^25.1.0"
+  }
+}

src/controllers/convert.js

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+/* eslint-disable camelcase */
+
+const convertFactory = (convertLib) => async (req, res) => {
+  try {
+    const {
+      query: {
+        amount: src_amount,
+        src_currency,
+        dest_currency: currency,
+        reference_date
+      }
+    } = req
+
+    const amount = await convertLib(
+      src_amount,
+      src_currency,
+      currency,
+      reference_date
+    )
+
+    res.status(200).json({ amount, currency })
+    return Promise.resolve()
+  } catch (error) {
+    console.log(`${new Date().toISOString()} ERROR ${error}`)
+
+    switch (error.constructor.name) {
+      case 'NotFoundError':
+        res.status(404).json({
+          statusCode: 404,
+          error: error.message
+        })
+        break
+      default:
+        res.status(500).json({
+          statusCode: 500,
+          error: 'Internal Server Error'
+        })
+    }
+
+    return Promise.reject(error)
+  }
+}
+
+module.exports = convertFactory

src/controllers/validate.js

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+const { celebrate } = require('celebrate')
+const Joi = require('@hapi/joi')
+  .extend(require('@hapi/joi-date'))
+
+const validate = celebrate({
+  query: Joi.object({
+    amount: Joi.number().required(),
+    src_currency: Joi.string().pattern(/^[A-Z]{3}$/).required(),
+    dest_currency: Joi.string().pattern(/^[A-Z]{3}$/).required(),
+    reference_date: Joi.date().format('YYYY-MM-DD').raw()
+  })
+})
+
+module.exports = validate

src/lib/convert.js

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+const BigNumber = require('bignumber.js')
+
+const convertLibFactory = (redis) => async (
+  amount,
+  srcCurrency,
+  dstCurrency,
+  date = new Date().toISOString().replace(/T.*Z/, '')
+) => {
+  const srcRate = await redis.getRate(date, srcCurrency)
+  const dstRate = await redis.getRate(date, dstCurrency)
+
+  const amountBN = BigNumber(amount)
+    .div(srcRate)
+    .times(dstRate)
+    .dp(2, BigNumber.ROUND_HALF_DOWN)
+
+  return amountBN.toNumber()
+}
+
+module.exports = convertLibFactory

src/lib/errors.js

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+class NotFoundError extends Error {}
+
+module.exports = { NotFoundError }

src/lib/rates.js

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+const parser = require('xml2json')
+
+const getRatesFactory = (client) => async () => {
+  const response = await client.get(
+    process.env.RATES_API || 'https://www.ecb.europa.eu/stats/eurofxref/eurofxref-hist-90d.xml'
+  )
+
+  const { data } = response
+  const dataStr = parser.toJson(data)
+  const dataJson = JSON.parse(dataStr)
+
+  const {
+    'gesmes:Envelope': {
+      Cube: {
+        Cube: rates
+      }
+    }
+  } = dataJson
+
+  return rates
+}
+
+const compactRates = (rates) => {
+  return rates.map(rate => {
+    const kvpairs = rate.Cube.map(elem => ({ [elem.currency]: elem.rate }))
+
+    rate.Cube = { [process.env.REF_CURRENCY || 'EUR']: '1' }
+    const [rate1, ...rate2toN] = kvpairs
+    Object.assign(rate.Cube, rate1, ...rate2toN)
+
+    return rate
+  })
+}
+
+module.exports = { getRatesFactory, compactRates }