Some refactoring, more work on the custom theme generator

Logic/Web/QueryParameters.ts

@@ -0,0 +1,72 @@
+/**
+ * Wraps the query parameters into UIEventSources
+ */
+import {UIEventSource} from "../UIEventSource";
+
+export class QueryParameters {
+
+    private static order: string [] = ["layout","test","z","lat","lon"];
+    private static knownSources = {};
+    private static initialized = false;
+    private static defaults = {}
+    
+    private static addOrder(key){
+        if(this.order.indexOf(key) < 0){
+            this.order.push(key)
+        }
+    }
+
+    private static init() {
+        
+        if(this.initialized){
+            return;
+        }
+        this.initialized = true;
+       
+        if (window?.location?.search) {
+            const params = window.location.search.substr(1).split("&");
+            for (const param of params) {
+                const kv = param.split("=");
+                const key = kv[0];
+                QueryParameters.addOrder(key)
+                const v = kv[1];
+                const source = new UIEventSource<string>(v);
+                source.addCallback(() => QueryParameters.Serialize())
+                QueryParameters.knownSources[key] = source;
+            }
+        }
+    }
+
+    private static Serialize() {
+        const parts = []
+        for (const key of QueryParameters.order) {
+            if (QueryParameters.knownSources[key] === undefined || QueryParameters.knownSources[key].data === undefined) {
+                continue;
+            }
+            if (QueryParameters.knownSources[key].data == QueryParameters.defaults[key]) {
+                continue;
+            }
+            parts.push(encodeURIComponent(key) + "=" + encodeURIComponent(QueryParameters.knownSources[key].data))
+        }
+        history.replaceState(null, "", "?" + parts.join("&"));
+
+    }
+
+    public static GetQueryParameter(key: string, deflt: string): UIEventSource<string> {
+        if(!this.initialized){
+            this.init();
+        }
+        if (deflt !== undefined) {
+            QueryParameters.defaults[key] = deflt;
+        }
+        if (QueryParameters.knownSources[key] !== undefined) {
+            return QueryParameters.knownSources[key];
+        }
+        QueryParameters.addOrder(key);
+        const source = new UIEventSource<string>(deflt);
+        QueryParameters.knownSources[key] = source;
+        source.addCallback(() => QueryParameters.Serialize())
+        return source;
+    }
+
+}