Filter deltas: Add rdflib.js and class Delta

Class Delta from:
https://github.com/lblod/toezicht-flattened-form-data-generator/blob/v1.3.0/lib/delta.js

app.js

@@ -1,6 +1,10 @@
+// eslint-disable-next-line no-unused-vars
+import { NamedNode, triple } from 'rdflib';
 import bodyParser from 'body-parser';
 import { LOG_INCOMING_DELTA } from './config';
 import { app, query, errorHandler } from 'mu';
+// eslint-disable-next-line no-unused-vars
+import { Delta } from './lib/delta';
 
 app.get('/', function (req, res) {
   res.send('Hello from virus-scanner-service');
@@ -31,7 +35,7 @@ app.post(
         console.log(`Receiving delta : ${JSON.stringify(body)}`);
       }
 
-      //await processDelta(body);
+      // ...
 
       res.status(202).send();
     } catch (error) {

lib/delta.js

@@ -0,0 +1,32 @@
+import { NamedNode, triple } from 'rdflib';
+
+export class Delta {
+  constructor(delta) {
+    this.delta = delta;
+  }
+
+  get inserts() {
+    return this.delta.map((changeSet) => changeSet.inserts).flat();
+  }
+
+  getInsertsFor(trigger) {
+    return this.inserts
+      .filter((triple) => this.isTriggerTriple(triple, trigger))
+      .map(this.mapToRdfTriple);
+  }
+
+  isTriggerTriple(triple, trigger) {
+    return (
+      triple.predicate.value === trigger.predicate.value &&
+      triple.object.value === trigger.object.value
+    );
+  }
+
+  mapToRdfTriple(t) {
+    return triple(
+      new NamedNode(t.subject.value),
+      new NamedNode(t.predicate.value),
+      new NamedNode(t.object.value),
+    );
+  }
+}