Simplify TasksAppManager and TasksAppWatcher

app/src/main/kotlin/at/bitfire/davdroid/settings/Settings.kt

@@ -38,10 +38,10 @@ object Settings {
     const val PREFERRED_THEME_DEFAULT = AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM
 
     /**
-     * Selected tasks app. When at least one tasks app is installed, this setting is set to its authority.
+     * Selected tasks app. When at least one tasks app is installed, this setting is set to its sync authority.
      * In case of multiple available tasks app, the user can choose one and this setting will reflect the selected one.
      *
-     * If no tasks app is available, this setting is not set.
+     * This setting may even be set if the corresponding tasks app is not installed because it only reflects the user's choice.
      */
     const val SELECTED_TASKS_PROVIDER = "preferred_tasks_provider"
 

app/src/main/kotlin/at/bitfire/davdroid/startup/TasksAppWatcher.kt

@@ -60,20 +60,14 @@ class TasksAppWatcher @Inject constructor(
 
         if (currentProvider == null) {
             // Iterate through all supported providers and select one, if available.
-            var providerSelected = false
-            for (provider in TaskProvider.ProviderName.entries) {
-                val available = context.packageManager.resolveContentProvider(provider.authority, 0) != null
-                if (available) {
-                    logger.info("Selecting new tasks provider: $provider")
-                    manager.selectProvider(provider)
-                    providerSelected = true
-                    break
+            var newProvider = TaskProvider.ProviderName.entries
+                .firstOrNull { provider ->
+                    context.packageManager.resolveContentProvider(provider.authority, 0) != null
                 }
-            }
 
-            if (!providerSelected)
-                // no provider available (anymore), also clear setting and sync
-                manager.selectProvider(null)
+            // Select provider or clear setting and sync if now provider available
+            logger.info("Selecting new tasks provider: $newProvider")
+            manager.selectProvider(null)
         }
     }
 

app/src/main/kotlin/at/bitfire/davdroid/sync/TasksAppManager.kt

@@ -46,13 +46,13 @@ class TasksAppManager @Inject constructor(
 ) {
 
     /**
-     * Gets the currently selected tasks app.
+     * Gets the currently selected tasks app, if installed.
      *
      * @return currently selected tasks app (when installed), or `null` if no tasks app is selected or the selected app is not installed
      */
     fun currentProvider(): ProviderName? {
-        val preferredAuthority = settingsManager.getString(Settings.SELECTED_TASKS_PROVIDER) ?: return null
-        return preferredAuthorityToProviderName(preferredAuthority)
+        val authority = settingsManager.getString(Settings.SELECTED_TASKS_PROVIDER) ?: return null
+        return authorityToProviderName(authority)
     }
 
     /**
@@ -61,22 +61,19 @@ class TasksAppManager @Inject constructor(
     fun currentProviderFlow(): Flow<ProviderName?> {
         return settingsManager.getStringFlow(Settings.SELECTED_TASKS_PROVIDER).map { preferred ->
             if (preferred != null)
-                preferredAuthorityToProviderName(preferred)
+                authorityToProviderName(preferred)
             else
                 null
         }
     }
 
-    private fun preferredAuthorityToProviderName(preferredAuthority: String): ProviderName? {
-        val packageManager = context.packageManager
-        ProviderName.entries.toTypedArray()
-            .sortedByDescending { it.authority == preferredAuthority }
-            .forEach { providerName ->
-                if (packageManager.resolveContentProvider(providerName.authority, 0) != null)
-                    return providerName
-            }
-        return null
-    }
+    /**
+     * Converts an authority to a [ProviderName], if the authority is known and the provider is installed.
+     */
+    private fun authorityToProviderName(authority: String): ProviderName? =
+        ProviderName.entries
+            .firstOrNull { it.authority == authority }
+            .takeIf { context.packageManager.resolveContentProvider(authority, 0) != null }
 
 
     /**