UX: more work on a search function

src/Logic/Geocoding/RecentSearch.ts

@@ -0,0 +1,49 @@
+import { Store, UIEventSource } from "../UIEventSource"
+import { Feature } from "geojson"
+import { OsmConnection } from "../Osm/OsmConnection"
+import { GeoCodeResult } from "./GeocodingProvider"
+import { GeoOperations } from "../GeoOperations"
+import LayoutConfig from "../../Models/ThemeConfig/LayoutConfig"
+
+export class RecentSearch {
+
+    private readonly _recentSearches: UIEventSource<string[]>
+    public readonly recentSearches: Store<string[]>
+
+    private readonly _seenThisSession: UIEventSource<GeoCodeResult[]> = new UIEventSource<GeoCodeResult[]>([])
+    public readonly seenThisSession: Store<GeoCodeResult[]> = this._seenThisSession
+
+    constructor(state: { layout: LayoutConfig, osmConnection: OsmConnection, selectedElement: Store<Feature> }) {
+        const longPref = state.osmConnection.preferencesHandler.GetLongPreference("recent-searches")
+        this._recentSearches = longPref.sync(str => !str ? [] : <string[]>JSON.parse(str), [], strs => JSON.stringify(strs))
+        this.recentSearches = this._recentSearches
+
+        state.selectedElement.addCallbackAndRunD(selected => {
+            const [osm_type, osm_id] = selected.properties.id.split("/")
+            const [lon, lat] = GeoOperations.centerpointCoordinates(selected)
+            const entry = <GeoCodeResult> {
+                feature: selected,
+                osm_id, osm_type,
+                description: "Viewed recently",
+                lon, lat
+            }
+            this.addSelected(entry)
+
+        })
+    }
+
+    addSelected(entry: GeoCodeResult) {
+        const arr = [...this.seenThisSession.data.slice(0, 20), entry]
+
+        const seenIds = new Set<string>()
+        for (let i = arr.length - 1; i >= 0; i--) {
+            const id = arr[i].osm_type + arr[i].osm_id
+            if (seenIds.has(id)) {
+                arr.splice(i, 1)
+            } else {
+                seenIds.add(id)
+            }
+        }
+        this._seenThisSession.set(arr)
+    }
+}