More refactoring: using a decent, configurable datapipeline now

Logic/FeatureSource/FilteringFeatureSource.ts

@@ -0,0 +1,52 @@
+import FeatureSource from "./FeatureSource";
+import {UIEventSource} from "../UIEventSource";
+import LayerConfig from "../../Customizations/JSON/LayerConfig";
+import Loc from "../../Models/Loc";
+
+export default class FilteringFeatureSource implements FeatureSource {
+    public features: UIEventSource<{ feature: any; freshness: Date }[]> = new UIEventSource<{ feature: any; freshness: Date }[]>([]);
+
+    constructor(layers: {
+                    isDisplayed: UIEventSource<boolean>,
+                    layerDef: LayerConfig
+                }[],
+                location: UIEventSource<Loc>,
+                upstream: FeatureSource) {
+
+        const layerDict = {};
+       
+        const self = this;
+        
+        function update() {
+            console.log("UPdating...")
+            const features: { feature: any, freshness: Date }[] = upstream.features.data;
+            const newFeatures = features.filter(f => {
+                const layerId = f.feature.properties._matching_layer_id;
+                if (layerId === undefined) {
+                    console.error(f)
+                    throw "feature._matching_layer_id is undefined"
+                }
+                const layer: {
+                    isDisplayed: UIEventSource<boolean>,
+                    layerDef: LayerConfig
+                } = layerDict[layerId];
+                if (layer === undefined) {
+                    throw "No layer found with id " + layerId;
+                }
+                return layer.isDisplayed.data && (layer.layerDef.minzoom <= location.data.zoom);
+            });
+            self.features.setData(newFeatures);
+        }
+        for (const layer of layers) {
+            layerDict[layer.layerDef.id] = layer;
+            layer.isDisplayed.addCallback(update)
+        }
+        upstream.features.addCallback(update);
+        location.map(l => l.zoom).addCallback(update);
+
+
+    }
+
+
+
+}