Limit synchronizing folders to 25

.idea/misc.xml

@@ -30,7 +30,7 @@
       </value>
     </option>
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_7" project-jdk-name="1.8" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">

app/src/main/java/eu/faircode/email/DaoFolder.java

@@ -90,6 +90,10 @@ public interface DaoFolder {
             " WHERE account = :account AND type = :type")
     EntityFolder getFolderByType(long account, String type);
 
+    @Query("SELECT COUNT(folder.id) FROM folder" +
+            " WHERE account = :account AND `synchronize`")
+    int getFolderSyncCount(long account);
+
     // For debug/crash info
     @Query("SELECT folder.* FROM folder" +
             " JOIN account ON account.id = folder.account" +

app/src/main/java/eu/faircode/email/FragmentFolder.java

@@ -61,6 +61,8 @@ public class FragmentFolder extends FragmentEx {
     private long id = -1;
     private long account = -1;
 
+    private static final int MAX_FOLDER_SYNC = 25;
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -295,14 +297,13 @@ public class FragmentFolder extends FragmentEx {
             private boolean once = false;
 
             @Override
-            public void onChanged(@Nullable EntityFolder folder) {
+            public void onChanged(@Nullable final EntityFolder folder) {
                 if (once)
                     return;
                 once = true;
 
                 if (savedInstanceState == null) {
                     etRename.setText(folder == null ? null : folder.name);
-                    cbSynchronize.setChecked(folder == null ? true : folder.synchronize);
                     cbUnified.setChecked(folder == null ? false : folder.unified);
                     etAfter.setText(Integer.toString(folder == null ? EntityFolder.DEFAULT_USER_SYNC : folder.after));
                 }
@@ -311,9 +312,27 @@ public class FragmentFolder extends FragmentEx {
                 pbWait.setVisibility(View.GONE);
                 Helper.setViewsEnabled(view, true);
                 etRename.setEnabled(folder == null || EntityFolder.USER.equals(folder.type));
+                cbSynchronize.setEnabled(false);
                 btnSave.setEnabled(true);
                 ibDelete.setEnabled(true);
                 ibDelete.setVisibility(folder == null ? View.GONE : View.VISIBLE);
+
+                Bundle args = new Bundle();
+                args.putLong("account", folder == null ? account : folder.account);
+
+                new SimpleTask<Integer>() {
+                    @Override
+                    protected Integer onLoad(Context context, Bundle args) {
+                        long account = args.getLong("account");
+                        return DB.getInstance(context).folder().getFolderSyncCount(account);
+                    }
+
+                    @Override
+                    protected void onLoaded(Bundle args, Integer count) {
+                        cbSynchronize.setChecked((folder == null || folder.synchronize) && count < MAX_FOLDER_SYNC);
+                        cbSynchronize.setEnabled(count < MAX_FOLDER_SYNC);
+                    }
+                }.load(FragmentFolder.this, args);
             }
         });
     }