From f6cbb44454b8dd020208abfd331280172ef95746 Mon Sep 17 00:00:00 2001
From: pietervdvn <pietervdvn@posteo.net>
Date: Mon, 10 May 2021 23:42:01 +0200
Subject: [PATCH] Add a contributor counting actor

---
 Logic/ContributorCount.ts | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 Logic/ContributorCount.ts

diff --git a/Logic/ContributorCount.ts b/Logic/ContributorCount.ts
new file mode 100644
index 000000000..9c954bdfb
--- /dev/null
+++ b/Logic/ContributorCount.ts
@@ -0,0 +1,21 @@
+/// Given a feature source, calculates a list of OSM-contributors who mapped the latest versions
+import FeatureSource from "./FeatureSource/FeatureSource";
+import {UIEventSource} from "./UIEventSource";
+
+export default class ContributorCount {
+
+    public readonly Contributors: UIEventSource<Map<string, number>>;
+
+    constructor(featureSource: FeatureSource) {
+        this.Contributors = featureSource.features.map(features => {
+            const hist = new Map<string, number>();
+            for (const feature of features) {
+                const contributor = feature.feature.properties["_last_edit:contributor"]
+                const count = hist.get(contributor) ?? 0;
+                hist.set(contributor, count + 1)
+            }
+            return hist;
+        })
+    }
+
+}
\ No newline at end of file