feat: year aggregation cloud function

firebase.json

@@ -12,5 +12,19 @@
         "destination": "/index.html"
       }
     ]
-  }
+  },
+  "functions": [
+    {
+      "source": "functions",
+      "codebase": "default",
+      "ignore": [
+        "node_modules",
+        ".git",
+        "firebase-debug.log",
+        "firebase-debug.*.log",
+        "*.local"
+      ],
+      "predeploy": "npm --prefix ./functions run test"
+    }
+  ]
 }

functions/.gitignore

@@ -0,0 +1,2 @@
+node_modules/
+*.local

functions/aggregator.js

@@ -0,0 +1,15 @@
+exports.calculateYearCounts = (publications) => {
+  const yearCounts = {};
+
+  publications.forEach((publication) => {
+    const year = publication.year;
+    if (year) {
+      yearCounts[year] = (yearCounts[year] || 0) + 1;
+    }
+  });
+
+  return Object.entries(yearCounts).map(([label, count]) => ({
+    label,
+    count,
+  }));
+};

functions/functions.test.js

@@ -0,0 +1,45 @@
+const { calculateYearCounts } = require('./aggregator');
+
+describe('calculateYearCounts', () => {
+  test('correctly aggregates counts by year', () => {
+    const testData = [
+      { year: 2021, title: 'Paper 1' },
+      { year: 2021, title: 'Paper 2' },
+      { year: 2022, title: 'Paper 3' },
+      { year: 2023, title: 'Paper 4' },
+      { year: 2024, title: 'Paper 5' },
+      { year: 2024, title: 'Paper 6' },
+    ];
+
+    const result = calculateYearCounts(testData);
+
+    expect(result).toEqual([
+      { label: '2021', count: 2 },
+      { label: '2022', count: 1 },
+      { label: '2023', count: 1 },
+      { label: '2024', count: 2 },
+    ]);
+  });
+
+  test('handles empty input', () => {
+    const result = calculateYearCounts([]);
+    expect(result).toEqual([]);
+  });
+
+  test('handles missing year data', () => {
+    const testData = [
+      { year: 2021, title: 'Paper 1' },
+      { title: 'Paper 2' },
+      { year: 2021, title: 'Paper 3' },
+      { year: null, title: 'Paper 4' },
+      { year: 2023, title: 'Paper 5' },
+    ];
+
+    const result = calculateYearCounts(testData);
+
+    expect(result).toEqual([
+      { label: '2021', count: 2 },
+      { label: '2023', count: 1 },
+    ]);
+  });
+});

functions/index.js

@@ -0,0 +1,42 @@
+const { onDocumentWritten } = require('firebase-functions/v2/firestore');
+const { initializeApp } = require('firebase-admin/app');
+const { getFirestore } = require('firebase-admin/firestore');
+const { calculateYearCounts } = require('./aggregator');
+
+// Initialize Firebase Admin SDK
+initializeApp();
+const db = getFirestore();
+
+// Calculate and save aggregations 
+async function calculateAggregatedCounts() {
+  const publicationsSnapshot = await db.collection('publications').get();
+  const publications = publicationsSnapshot.docs.map(doc => doc.data());
+
+  // Count of docs by year 
+  const aggregatedCounts = calculateYearCounts(publications);
+
+  // Save the aggregation(s)
+  await db.collection('aggregations').doc('publicationCounts').set({
+    counts: aggregatedCounts,
+  });
+}
+
+// onDocumentWritten triggers on create, update, or delete
+exports.aggregatePublicationsOnWrite = onDocumentWritten(
+  'publications/{docId}',
+  async (event) => {
+    try {
+      // log before and after data
+      const beforeData = event.data.before.data();
+      const afterData = event.data.after.data();
+
+      console.log(`Document written: ${event.params.docId}`);
+      console.log('Before data:', beforeData);
+      console.log('After data:', afterData);
+
+      await calculateAggregatedCounts();
+    } catch (error) {
+      console.error('Error recalculating counts on document write:', error);
+    }
+  }
+);