Refactoring: move all code files into a src directory

src/Logic/FeatureSource/Sources/FeatureSourceMerger.ts

@@ -0,0 +1,91 @@
+import { Store, UIEventSource } from "../../UIEventSource"
+import { FeatureSource, IndexedFeatureSource } from "../FeatureSource"
+import { Feature } from "geojson"
+import { Utils } from "../../../Utils"
+
+/**
+ *
+ */
+export default class FeatureSourceMerger implements IndexedFeatureSource {
+    public features: UIEventSource<Feature[]> = new UIEventSource([])
+    public readonly featuresById: Store<Map<string, Feature>>
+    private readonly _featuresById: UIEventSource<Map<string, Feature>>
+    private readonly _sources: FeatureSource[] = []
+    /**
+     * Merges features from different featureSources.
+     * In case that multiple features have the same id, the latest `_version_number` will be used. Otherwise, we will take the last one
+     */
+    constructor(...sources: FeatureSource[]) {
+        this._featuresById = new UIEventSource<Map<string, Feature>>(new Map<string, Feature>())
+        this.featuresById = this._featuresById
+        const self = this
+        sources = Utils.NoNull(sources)
+        for (let source of sources) {
+            source.features.addCallback(() => {
+                self.addData(sources.map((s) => s.features.data))
+            })
+        }
+        this.addData(sources.map((s) => s.features.data))
+        this._sources = sources
+    }
+
+    public addSource(source: FeatureSource) {
+        if (!source) {
+            return
+        }
+        this._sources.push(source)
+        source.features.addCallbackAndRun(() => {
+            this.addData(this._sources.map((s) => s.features.data))
+        })
+    }
+
+    protected addData(featuress: Feature[][]) {
+        featuress = Utils.NoNull(featuress)
+        let somethingChanged = false
+        const all: Map<string, Feature> = new Map()
+        const unseen = new Set<string>()
+        // We seed the dictionary with the previously loaded features
+        const oldValues = this.features.data ?? []
+        for (const oldValue of oldValues) {
+            all.set(oldValue.properties.id, oldValue)
+            unseen.add(oldValue.properties.id)
+        }
+
+        for (const features of featuress) {
+            for (const f of features) {
+                const id = f.properties.id
+                unseen.delete(id)
+                if (!all.has(id)) {
+                    // This is a new feature
+                    somethingChanged = true
+                    all.set(id, f)
+                    continue
+                }
+
+                // This value has been seen already, either in a previous run or by a previous datasource
+                // Let's figure out if something changed
+                const oldV = all.get(id)
+                if (oldV == f) {
+                    continue
+                }
+                all.set(id, f)
+                somethingChanged = true
+            }
+        }
+
+        somethingChanged ||= unseen.size > 0
+        unseen.forEach((id) => all.delete(id))
+
+        if (!somethingChanged) {
+            // We don't bother triggering an update
+            return
+        }
+
+        const newList = []
+        all.forEach((value, key) => {
+            newList.push(value)
+        })
+        this.features.setData(newList)
+        this._featuresById.setData(all)
+    }
+}