Further stabilization of wikipedia box

Logic/ImageProviders/WikidataImageProvider.ts

@@ -23,7 +23,10 @@ export class WikidataImageProvider extends ImageProvider {
     }
 
     public async ExtractUrls(key: string, value: string): Promise<Promise<ProvidedImage>[]> {
-        const entity = await Wikidata.LoadWikidataEntry(value)
+        const entity = await Wikidata.LoadWikidataEntryAsync(value)
+        if(entity === undefined){
+            return []
+        }
        
         const allImages : Promise<ProvidedImage>[] = []
         // P18 is the claim 'depicted in this image'
@@ -32,7 +35,7 @@ export class WikidataImageProvider extends ImageProvider {
             allImages.push(...promises)
         }
         
-        const commons =entity.wikisites.get("commons")
+        const commons = entity.commons
         if (commons !== undefined) {
             const promises = await WikimediaImageProvider.singleton.ExtractUrls(undefined , commons)
             allImages.push(...promises)

Logic/Osm/Overpass.ts

@@ -18,7 +18,8 @@ export class Overpass {
     private _relationTracker: RelationsTracker;
 
 
-    constructor(filter: TagsFilter, extraScripts: string[],
+    constructor(filter: TagsFilter,
+                extraScripts: string[],
                 interpreterUrl: string,
                 timeout: UIEventSource<number>,
                 relationTracker: RelationsTracker,

Logic/UIEventSource.ts

@@ -1,4 +1,5 @@
 import {Utils} from "../Utils";
+import * as Events from "events";
 
 export class UIEventSource<T> {
 
@@ -32,14 +33,14 @@ export class UIEventSource<T> {
         return [];
     }
 
-    public static flatten<X>(source: UIEventSource<UIEventSource<X>>, possibleSources: UIEventSource<any>[]): UIEventSource<X> {
+    public static flatten<X>(source: UIEventSource<UIEventSource<X>>, possibleSources?: UIEventSource<any>[]): UIEventSource<X> {
         const sink = new UIEventSource<X>(source.data?.data);
 
         source.addCallback((latestData) => {
             sink.setData(latestData?.data);
         });
 
-        for (const possibleSource of possibleSources) {
+        for (const possibleSource of possibleSources ?? []) {
             possibleSource?.addCallback(() => {
                 sink.setData(source.data?.data);
             })
@@ -186,6 +187,25 @@ export class UIEventSource<T> {
         }
     }
 
+    /**
+     * Monadic bind function
+     */
+    public bind<X>(f: ((t: T) => UIEventSource<X>)): UIEventSource<X>{
+        const sink = new UIEventSource<X>( undefined )
+        const seenEventSources = new Set<UIEventSource<X>>();
+        this.addCallbackAndRun(data => {
+            const eventSource = f(data)
+            if(eventSource === undefined){
+                sink.setData(undefined)
+            }else if(!seenEventSources.has(eventSource)){
+                eventSource.addCallbackAndRun(mappedData => sink.setData(mappedData))
+                seenEventSources.add(eventSource)
+            }
+        })
+        
+        return sink;
+    } 
+
     /**
      * Monoidal map:
      * Given a function 'f', will construct a new UIEventSource where the contents will always be "f(this.data)'

Logic/Web/Wikidata.ts

@@ -1,4 +1,5 @@
 import {Utils} from "../../Utils";
+import {UIEventSource} from "../UIEventSource";
 
 
 export interface WikidataResponse {
@@ -62,15 +63,23 @@ export default class Wikidata {
         }
     }
 
-    /**
-     * Loads a wikidata page
-     * @returns the entity of the given value
-     */
-    public static async LoadWikidataEntry(value: string | number): Promise<WikidataResponse> {
-        const wikidataUrl = "https://www.wikidata.org/wiki/"
-        if (typeof value === "number") {
-            value = "Q" + value
+    private static readonly _cache = new Map<number, UIEventSource<{success: WikidataResponse} | {error: any}>>()
+    public static LoadWikidataEntry(value: string | number): UIEventSource<{success: WikidataResponse} | {error: any}> {
+        const key = this.ExtractKey(value)
+        const cached = Wikidata._cache.get(key)
+        if(cached !== undefined){
+            return cached
         }
+        const src = UIEventSource.FromPromiseWithErr(Wikidata.LoadWikidataEntryAsync(key))
+        Wikidata._cache.set(key, src)
+        return src;
+    }
+    
+    private static ExtractKey(value: string | number) : number{
+        if (typeof value === "number") {
+           return value
+        }
+        const wikidataUrl = "https://www.wikidata.org/wiki/"
         if (value.startsWith(wikidataUrl)) {
             value = value.substring(wikidataUrl.length)
         }
@@ -78,12 +87,30 @@ export default class Wikidata {
             // Probably some random link in the image field - we skip it
             return undefined
         }
-        if (!value.startsWith("Q")) {
-            value = "Q" + value
+        if (value.startsWith("Q")) {
+            value = value.substring(1)
         }
-        const url = "https://www.wikidata.org/wiki/Special:EntityData/" + value + ".json";
+        const n = Number(value)
+        if(isNaN(n)){
+            return undefined
+        }
+        return n;
+    }
+
+    /**
+     * Loads a wikidata page
+     * @returns the entity of the given value
+     */
+    public static async LoadWikidataEntryAsync(value: string | number): Promise<WikidataResponse> {
+        const id = Wikidata.ExtractKey(value)
+        if(id === undefined){
+            console.warn("Could not extract a wikidata entry from", value)
+            return undefined;
+        }
+        console.log("Requesting wikidata with id", id)
+        const url = "https://www.wikidata.org/wiki/Special:EntityData/Q" + id + ".json";
         const response = await Utils.downloadJson(url)
-        return Wikidata.ParseResponse(response.entities[value]);
+        return Wikidata.ParseResponse(response.entities["Q" + id])
     }
 
 }

Logic/Web/Wikipedia.ts

@@ -61,7 +61,6 @@ export default class Wikipedia {
 
         const links = Array.from(content.getElementsByTagName("a"))
 
-        console.log("Links are", links)
         // Rewrite relative links to absolute links + open them in a new tab
         links.filter(link => link.getAttribute("href")?.startsWith("/") ?? false).
         forEach(link => {