Fix: URL-parameter language disables the language picker, fix #1506

assets/layers/usersettings/usersettings.json

@@ -33,7 +33,16 @@
       "id": "language_picker",
       "render": {
         "*": "{language_picker()}"
+      },
+      "mappings": [
+        {
+          "if": "__url_parameter_initialized:language=yes",
+          "icon": "./assets/layers/usersettings/translate_disabled.svg",
+          "then": {
+            "en": "The language was set via an URL-parameter and cannot be set by the user.²"
           }
+        }
+      ]
     },
     {
       "id": "inbox",

src/Logic/State/UserRelatedState.ts

@@ -15,6 +15,7 @@ import Locale from "../../UI/i18n/Locale"
 import LinkToWeblate from "../../UI/Base/LinkToWeblate"
 import FeatureSwitchState from "./FeatureSwitchState"
 import Constants from "../../Models/Constants"
+import { QueryParameters } from "../Web/QueryParameters"
 
 /**
  * The part of the state which keeps track of user-related stuff, e.g. the OSM-connection,
@@ -93,13 +94,21 @@ export default class UserRelatedState {
             this.osmConnection.GetLongPreference("identity", "mangrove")
         )
 
-        this.language.addCallbackAndRunD((language) => Locale.language.setData(language))
-
         this.installedUserThemes = this.InitInstalledUserThemes()
 
         this.homeLocation = this.initHomeLocation()
 
         this.preferencesAsTags = this.initAmendedPrefs(layout, featureSwitches)
+
+        this.syncLanguage()
+    }
+
+    private syncLanguage() {
+        if (QueryParameters.wasInitialized("language")) {
+            return
+        }
+
+        this.language.addCallbackAndRunD((language) => Locale.language.setData(language))
     }
 
     private static initUserRelatedState(): LayerConfig {
@@ -246,6 +255,10 @@ export default class UserRelatedState {
             amendedPrefs.data["__userjourney_" + key] = Constants.userJourney[key]
         }
 
+        for (const key of QueryParameters.initializedParameters()) {
+            amendedPrefs.data["__url_parameter_initialized:" + key] = "yes"
+        }
+
         const osmConnection = this.osmConnection
         osmConnection.preferencesHandler.preferences.addCallback((newPrefs) => {
             for (const k in newPrefs) {
@@ -268,6 +281,7 @@ export default class UserRelatedState {
         })
         const usersettingsConfig = UserRelatedState.usersettingsConfig
         const translationMode = osmConnection.GetPreference("translation-mode")
+
         Locale.language.mapD(
             (language) => {
                 amendedPrefs.data["_language"] = language

src/Logic/Web/QueryParameters.ts

@@ -71,6 +71,9 @@ export class QueryParameters {
         this.init()
         return QueryParameters._wasInitialized.has(key)
     }
+    public static initializedParameters(): ReadonlyArray<string> {
+        return Array.from(QueryParameters._wasInitialized.keys())
+    }
 
     private static addOrder(key) {
         if (this.order.indexOf(key) < 0) {

src/UI/LanguagePicker.ts

@@ -8,11 +8,16 @@ import Lazy from "./Base/Lazy"
 import Toggle from "./Input/Toggle"
 import LanguageUtils from "../Utils/LanguageUtils"
 import { UIEventSource } from "../Logic/UIEventSource"
+import { QueryParameters } from "../Logic/Web/QueryParameters"
 
 export default class LanguagePicker extends Toggle {
     constructor(languages: string[], assignTo: UIEventSource<string>) {
         console.log("Constructing a language pîcker for languages", languages)
-        if (languages === undefined || languages.length <= 1) {
+        if (
+            languages === undefined ||
+            languages.length <= 1 ||
+            QueryParameters.wasInitialized("language")
+        ) {
             super(undefined, undefined, undefined)
         } else {
             const normalPicker = LanguagePicker.dropdownFor(languages, assignTo ?? Locale.language)

src/UI/i18n/Locale.ts

@@ -39,8 +39,8 @@ export default class Locale {
                     "The language to display MapComplete in.",
                     "The user display language is determined in the following order:",
                     "",
+                    "1. Use the language as set by the URL-parameter `language`. This will _disable_ setting the language by the user",
                     "1. If the user did log in and did set their language before with MapComplete, use this language. This language selection is synchronized accross devices using the openstreetmap.org user preferences.",
-                    "2. Use the language as set by the URL-parameter `language`. This will _disable_ saving the language to localStorage in case a non-logged-in user changes their language",
                     "3. If the user visited MapComplete before and did change their language manually, this changed language will be saved in local storage. Use the language from local storage",
                     "4. Use the navigator-language (if available)",
                     "5. Use English",