refactoring

Logic/FeatureSource/Actors/TileLocalStorage.ts

@@ -0,0 +1,63 @@
+import { IdbLocalStorage } from "../../Web/IdbLocalStorage"
+import { UIEventSource } from "../../UIEventSource"
+
+/**
+ * A class which allows to read/write a tile to local storage.
+ *
+ * Does the heavy lifting for LocalStorageFeatureSource and SaveFeatureToLocalStorage
+ */
+export default class TileLocalStorage<T> {
+    private static perLayer: Record<string, TileLocalStorage<any>> = {}
+    private readonly _layername: string
+    private readonly cachedSources: Record<number, UIEventSource<T>> = {}
+
+    private constructor(layername: string) {
+        this._layername = layername
+    }
+
+    public static construct<T>(layername: string): TileLocalStorage<T> {
+        const cached = TileLocalStorage.perLayer[layername]
+        if (cached) {
+            return cached
+        }
+
+        const tls = new TileLocalStorage<T>(layername)
+        TileLocalStorage.perLayer[layername] = tls
+        return tls
+    }
+
+    /**
+     * Constructs a UIEventSource element which is synced with localStorage
+     * @param layername
+     * @param tileIndex
+     */
+    public getTileSource(tileIndex: number): UIEventSource<T> {
+        const cached = this.cachedSources[tileIndex]
+        if (cached) {
+            return cached
+        }
+        const src = UIEventSource.FromPromise(this.GetIdb(tileIndex))
+        src.addCallbackD((data) => this.SetIdb(tileIndex, data))
+        this.cachedSources[tileIndex] = src
+        return src
+    }
+
+    private SetIdb(tileIndex: number, data): void {
+        try {
+            IdbLocalStorage.SetDirectly(this._layername + "_" + tileIndex, data)
+        } catch (e) {
+            console.error(
+                "Could not save tile to indexed-db: ",
+                e,
+                "tileIndex is:",
+                tileIndex,
+                "for layer",
+                this._layername
+            )
+        }
+    }
+
+    private GetIdb(tileIndex: number): Promise<any> {
+        return IdbLocalStorage.GetDirectly(this._layername + "_" + tileIndex)
+    }
+}