Auto extend sync period

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

@@ -47,7 +47,7 @@ import io.requery.android.database.sqlite.RequerySQLiteOpenHelperFactory;
 // https://developer.android.com/topic/libraries/architecture/room.html
 
 @Database(
-        version = 28,
+        version = 29,
         entities = {
                 EntityIdentity.class,
                 EntityAccount.class,
@@ -366,6 +366,13 @@ public abstract class DB extends RoomDatabase {
                         }
                     }
                 })
+                .addMigrations(new Migration(28, 29) {
+                    @Override
+                    public void migrate(SupportSQLiteDatabase db) {
+                        Log.i("DB migration from version " + startVersion + " to " + endVersion);
+                        db.execSQL("ALTER TABLE `folder` ADD COLUMN `last_sync` INTEGER");
+                    }
+                })
                 .build();
     }
 

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

@@ -191,6 +191,9 @@ public interface DaoFolder {
     @Query("UPDATE folder SET initialize = 0 WHERE id = :id")
     int setFolderInitialized(long id);
 
+    @Query("UPDATE folder SET last_sync = :last_sync WHERE id = :id")
+    int setFolderSync(long id, long last_sync);
+
     @Query("UPDATE folder SET tbc = 0 WHERE id = :id")
     int resetFolderTbc(long id);
 

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

@@ -91,6 +91,7 @@ public class EntityFolder implements Serializable {
     public String state;
     public String sync_state;
     public String error;
+    public Long last_sync;
 
     static final String INBOX = "Inbox";
     static final String OUTBOX = "Outbox";
@@ -197,7 +198,8 @@ public class EntityFolder implements Serializable {
                     (this.tbd == null ? other.tbd == null : this.tbd.equals(other.tbd)) &&
                     (this.state == null ? other.state == null : this.state.equals(other.state)) &&
                     (this.sync_state == null ? other.sync_state == null : this.sync_state.equals(other.sync_state)) &&
-                    (this.error == null ? other.error == null : this.error.equals(other.error)));
+                    (this.error == null ? other.error == null : this.error.equals(other.error)) &&
+                    (this.last_sync == null ? other.last_sync == null : this.last_sync.equals(other.last_sync)));
         } else
             return false;
     }

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

@@ -92,9 +92,18 @@ public class EntityOperation {
 
     static void sync(DB db, long fid) {
         if (db.operation().getOperationCount(fid, EntityOperation.SYNC) == 0) {
+
             EntityFolder folder = db.folder().getFolder(fid);
+
+            int sync_days = folder.sync_days;
+            if (folder.last_sync != null) {
+                int ago_days = (int) ((new Date().getTime() - folder.last_sync) / (24 * 3600 * 1000L)) + 1;
+                if (ago_days > sync_days)
+                    sync_days = ago_days;
+            }
+
             JSONArray jargs = new JSONArray();
-            jargs.put(folder.initialize ? Math.min(EntityFolder.DEFAULT_INIT, folder.keep_days) : folder.sync_days);
+            jargs.put(folder.initialize ? Math.min(EntityFolder.DEFAULT_INIT, folder.keep_days) : sync_days);
             jargs.put(folder.keep_days);
             jargs.put(folder.download);
 

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

@@ -2248,6 +2248,7 @@ public class ServiceSynchronize extends LifecycleService {
 
             if (state.running)
                 db.folder().setFolderInitialized(folder.id);
+            db.folder().setFolderSync(folder.id, new Date().getTime());
 
             db.folder().setFolderError(folder.id, null);
         } finally {