Add FileService class to parse CSV data from a given URL and return a stream for download

src/routes/index.js

@@ -1,9 +1,24 @@
 var express = require('express');
 var router = express.Router();
 
+const FileService = require('../services/file');
+
 /* GET home page. */
-router.get('/', function(req, res, next) {
-  res.render('index', { title: 'Express' });
+router.get('/', async function(req, res, next) {
+  const url = 'https://bodacc-datadila.opendatasoft.com/api/explore/v2.1/catalog/datasets/annonces-commerciales/exports/csv?lang=fr&refine=publicationavis%3A%22A%22&refine=publicationavis_facette%3A%22Bodacc%20A%22&refine=familleavis_lib%3A%22Ventes%20et%20cessions%22&timezone=Asia%2FBaghdad&use_labels=true&delimiter=%3B';
+
+  const columns = ['id', 'region_code', 'listepersonnes.personne.typePersonne', 'listepersonnes.personne.denomination', 'listeetablissements.etablissement.adresse', 'listeprecedentproprietaire.personne.nom', 'listeprecedentproprietaire.personne.prenom'];
+
+  const fileService = new FileService();
+  const stream = await fileService.parseFromUrl(url, columns);
+
+  if ( !stream ) {
+    return res.status(500).send('Invalid stream');
+  }
+
+  stream.pipe(res);
+
+  // res.render('index', { title: 'Express' });
 });
 
 module.exports = router;

src/services/file.js

@@ -0,0 +1,40 @@
+const EventEmitter = require('events');
+const csv = require('csv-parser');
+
+const File = require('../models/File');
+
+// Create a class FileService that extends EventEmitter
+class FileService extends EventEmitter {
+
+
+  async parseFromUrl(url, columns) {
+    this.emit('parseFromUrl.start', { url, columns });
+
+    // Check if url is valid
+    if (!url) {
+      this.emit('parseFromUrl.error', { url, columns, error: 'Invalid url' });
+      return Promise.reject(new Error('Invalid url'));
+    }
+
+    // Check columns
+    if (!columns || !Array.isArray(columns) || columns.length === 0) {
+      this.emit('parseFromUrl.error', { url, columns, error: 'Invalid columns' });
+      return Promise.reject(new Error('Invalid columns'));
+    }
+
+    // Create a new File instance
+    const file = new File(url);
+    const filepath = await file.download();
+
+    const stream = file.parse(columns);
+    if ( !stream ) {
+      this.emit('parseFromUrl.error', { url, columns, error: 'Invalid stream' });
+      return Promise.reject(new Error('Invalid stream'));
+    }
+
+    this.emit('parseFromUrl.end', { url, columns, filepath });
+    return Promise.resolve(stream);
+  }
+}
+
+module.exports = FileService;