Prevent duplicate attachment sequence numbers

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

@@ -34,10 +34,10 @@ public interface DaoAttachment {
             " ORDER BY sequence")
     LiveData<List<EntityAttachment>> liveAttachments(long message);
 
-    @Query("SELECT COUNT(id)" +
+    @Query("SELECT ifnull(MAX(sequence), 0)" +
             " FROM attachment" +
             " WHERE message = :message")
-    int getAttachmentCount(long message);
+    int getAttachmentSequence(long message);
 
     @Query("SELECT COUNT(id)" +
             " FROM attachment" +

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

@@ -578,7 +578,7 @@ public class FragmentCompose extends FragmentEx {
                         try {
                             db.beginTransaction();
 
-                            int seq = db.attachment().getAttachmentCount(id);
+                            int seq = db.attachment().getAttachmentSequence(id);
 
                             attachment1.message = id;
                             attachment1.sequence = seq + 1;
@@ -868,7 +868,7 @@ public class FragmentCompose extends FragmentEx {
             Log.i(Helper.TAG, "Attaching to id=" + id);
 
             attachment.message = draft.id;
-            attachment.sequence = db.attachment().getAttachmentCount(draft.id) + 1;
+            attachment.sequence = db.attachment().getAttachmentSequence(draft.id) + 1;
             attachment.name = name;
 
             String extension = Helper.getExtension(attachment.name);