Refactor linker

src/neo4j-linker.ts

 import {v1 as neo4j} from 'neo4j-driver';
-import builder from 'geolinker-common/dist/uri-builder';
-import nconf = require('nconf');
-import logger from 'geolinker-common/dist/logger';
 
-/**
- * Load config for the streamer
- */
-nconf.argv()
-  .env()
-  .file({file: './config.json'});
+export class Linker {
+  private nconf;
+  private logger;
+  private driver;
+  private uriBuilder;
 
-const driver = neo4j.driver(
-  nconf.get('neo4j:config:uri'),
-  neo4j.auth.basic(
-    nconf.get('neo4j:config:user'),
-    nconf.get('neo4j:config:password'),
-  ),
-);
+  constructor(nconf, logger, uriBuilder) {
+    this.nconf = nconf;
+    this.logger = logger;
+    this.uriBuilder = uriBuilder;
+    this.driver = neo4j.driver(
+      nconf.get('neo4j:config:uri'),
+      neo4j.auth.basic(
+        nconf.get('neo4j:config:user'),
+        nconf.get('neo4j:config:password'),
+      ),
+    );
+
+  }
 
-export default {
   /**
    * Create a new node in the db if they do not exists
    * @param node
    * @returns {Result}
    */
-  newNode: (node) => {
+  newNode(node) {
     // todo: from topic!
     const provider = 'geonames';
-    const uri = builder.geoname(node.id);
-    return driver.session().run(`MERGE (n:Place { uri: '${uri}'})
+    const uri = this.uriBuilder.geoname(node.id);
+    return this.driver.session().run(`MERGE (n:Place { uri: '${uri}'})
         ON CREATE SET n.id: '${node.id}', n.provider: ${provider}
         ON MATCH SET n.id: '${node.id}', n.provider: ${provider}`);
-  },
+  }
 
   /**
    * Write connection int the db. Create nodes if they do not exists
    * @param connection
    */
-  connect: (connection) => {
-    let query = `MERGE (o:Place {uri:'${connection.from}'}) `;
-    connection.to.forEach((current, i) => {
-      query += ` MERGE (t${i}:Place {uri:'${current}'}) `;
-      query += ` MERGE (o)-[:${connection.relation.type} {author:'${connection.relation.author}'}]->(t${i}) `;
-    });
-    driver.session().run(query).then((err) => {
-      logger.error('Error while saving a connection to neo4j');
-      logger.error(JSON.stringify(err));
+  connect(connection) {
+    return new Promise( (resolve, reject) => {
+      let query = `MERGE (o:Place {uri:'${connection.from}'}) `;
+      connection.to.forEach((current, i) => {
+        query += ` MERGE (t${i}:Place {uri:'${current}'}) `;
+        query += ` MERGE (o)-[:${connection.relation.type} {author:'${connection.relation.author}'}]->(t${i}) `;
+      });
+      // get a new session
+      const session = this.driver.session();
+      this.logger.info('Try to build network');
+      session.run(query).then(() => {
+        session.close();
+        resolve();
+      }).catch((err) => {
+        session.close();
+        reject(`Error while saving a connection to neo4j ${JSON.stringify(err)}`);
+      });
     });
-  },
-};
+
+  }
+}