Hide 'upload sent messages' setting when Backend doesn't support uploads

app/core/src/main/java/com/fsck/k9/controller/MessagingController.java

@@ -1823,6 +1823,10 @@ public class MessagingController {
         return getBackend(account).getSupportsSearchByDate();
     }
 
+    public boolean supportsUpload(Account account) {
+        return getBackend(account).getSupportsUpload();
+    }
+
     public void checkIncomingServerSettings(Account account) throws MessagingException {
         getBackend(account).checkIncomingServerSettings();
     }

app/ui/src/main/java/com/fsck/k9/ui/settings/account/AccountSettingsFragment.kt

@@ -52,6 +52,7 @@ class AccountSettingsFragment : PreferenceFragmentCompat() {
         initializeIncomingServer()
         initializeComposition()
         initializeManageIdentities()
+        initializeUploadSentMessages(account)
         initializeOutgoingServer()
         initializeQuoteStyle()
         initializeDeletePolicy(account)
@@ -86,6 +87,14 @@ class AccountSettingsFragment : PreferenceFragmentCompat() {
         }
     }
 
+    private fun initializeUploadSentMessages(account: Account) {
+        findPreference(PREFERENCE_UPLOAD_SENT_MESSAGES)?.apply {
+            if (!messagingController.supportsUpload(account)) {
+                remove()
+            }
+        }
+    }
+
     private fun initializeOutgoingServer() {
         findPreference(PREFERENCE_OUTGOING_SERVER)?.onClick {
             AccountSetupOutgoing.actionEditOutgoingSettings(requireActivity(), accountUuid)
@@ -261,6 +270,7 @@ class AccountSettingsFragment : PreferenceFragmentCompat() {
         private const val PREFERENCE_COMPOSITION = "composition"
         private const val PREFERENCE_MANAGE_IDENTITIES = "manage_identities"
         private const val PREFERENCE_OUTGOING_SERVER = "outgoing"
+        private const val PREFERENCE_UPLOAD_SENT_MESSAGES = "upload_sent_messages"
         private const val PREFERENCE_QUOTE_STYLE = "quote_style"
         private const val PREFERENCE_DELETE_POLICY = "delete_policy"
         private const val PREFERENCE_EXPUNGE_POLICY = "expunge_policy"

backend/api/src/main/java/com/fsck/k9/backend/api/Backend.kt

@@ -17,6 +17,7 @@ interface Backend {
     val supportsExpunge: Boolean
     val supportsMove: Boolean
     val supportsCopy: Boolean
+    val supportsUpload: Boolean
     val supportsTrashFolder: Boolean
     val supportsSearchByDate: Boolean
     val isPushCapable: Boolean

backend/imap/src/main/java/com/fsck/k9/backend/imap/ImapBackend.java

@@ -82,6 +82,11 @@ public class ImapBackend implements Backend {
         return true;
     }
 
+    @Override
+    public boolean getSupportsUpload() {
+        return true;
+    }
+
     @Override
     public boolean getSupportsTrashFolder() {
         return true;

backend/pop3/src/main/java/com/fsck/k9/backend/pop3/Pop3Backend.kt

@@ -31,6 +31,7 @@ class Pop3Backend(
     override val supportsExpunge = false
     override val supportsMove = false
     override val supportsCopy = false
+    override val supportsUpload = false
     override val supportsTrashFolder = false
     override val supportsSearchByDate = false
     override val isPushCapable = false

backend/webdav/src/main/java/com/fsck/k9/backend/webdav/WebDavBackend.kt

@@ -35,6 +35,7 @@ class WebDavBackend(
     override val supportsExpunge = true
     override val supportsMove = true
     override val supportsCopy = true
+    override val supportsUpload = true
     override val supportsTrashFolder = true
     override val supportsSearchByDate = false
     override val isPushCapable = false