Added option to group by sender/subject

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

@@ -421,6 +421,12 @@ public interface DaoMessage {
             " AND inreplyto = :inreplyto")
     List<EntityMessage> getMessagesByInReplyTo(long account, String inreplyto);
 
+    @Query("SELECT * FROM message" +
+            " WHERE account = :account" +
+            " AND sender = :sender" +
+            " AND subject = :subject")
+    List<EntityMessage> getMessagesBySubject(long account, String sender, String subject);
+
     @Query("SELECT message.* FROM message" +
             " LEFT JOIN message AS base ON base.id = :id" +
             " WHERE message.account = :account" +

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

@@ -82,6 +82,7 @@ public class FragmentOptionsSynchronize extends FragmentBase implements SharedPr
     private SwitchCompat swDeleteUnseen;
     private SwitchCompat swSyncKept;
     private SwitchCompat swGmailThread;
+    private SwitchCompat swSubjectThreading;
     private SwitchCompat swSyncFolders;
     private SwitchCompat swSyncFoldersPoll;
     private SwitchCompat swSyncSharedFolders;
@@ -103,7 +104,8 @@ public class FragmentOptionsSynchronize extends FragmentBase implements SharedPr
     private final static String[] RESET_OPTIONS = new String[]{
             "enabled", "poll_interval", "auto_optimize", "schedule", "schedule_start", "schedule_end",
             "sync_quick_imap", "sync_quick_pop",
-            "sync_nodate", "sync_unseen", "sync_flagged", "delete_unseen", "sync_kept", "gmail_thread_id",
+            "sync_nodate", "sync_unseen", "sync_flagged", "delete_unseen", "sync_kept",
+            "gmail_thread_id", "subject_threading",
             "sync_folders", "sync_folders_poll", "sync_shared_folders", "subscriptions",
             "check_authentication", "check_reply_domain", "check_mx", "check_blocklist", "use_blocklist",
             "tune_keep_alive"
@@ -149,6 +151,7 @@ public class FragmentOptionsSynchronize extends FragmentBase implements SharedPr
         swDeleteUnseen = view.findViewById(R.id.swDeleteUnseen);
         swSyncKept = view.findViewById(R.id.swSyncKept);
         swGmailThread = view.findViewById(R.id.swGmailThread);
+        swSubjectThreading = view.findViewById(R.id.swSubjectThreading);
         swSyncFolders = view.findViewById(R.id.swSyncFolders);
         swSyncFoldersPoll = view.findViewById(R.id.swSyncFoldersPoll);
         swSyncSharedFolders = view.findViewById(R.id.swSyncSharedFolders);
@@ -325,6 +328,14 @@ public class FragmentOptionsSynchronize extends FragmentBase implements SharedPr
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
                 prefs.edit().putBoolean("gmail_thread_id", checked).apply();
+                swSubjectThreading.setEnabled(!checked);
+            }
+        });
+
+        swSubjectThreading.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
+                prefs.edit().putBoolean("subject_threading", checked).apply();
             }
         });
 
@@ -493,6 +504,8 @@ public class FragmentOptionsSynchronize extends FragmentBase implements SharedPr
         swDeleteUnseen.setChecked(prefs.getBoolean("delete_unseen", false));
         swSyncKept.setChecked(prefs.getBoolean("sync_kept", true));
         swGmailThread.setChecked(prefs.getBoolean("gmail_thread_id", false));
+        swSubjectThreading.setChecked(prefs.getBoolean("subject_threading", false));
+        swSubjectThreading.setEnabled(!swGmailThread.isChecked());
         swSyncFolders.setChecked(prefs.getBoolean("sync_folders", true));
         swSyncFoldersPoll.setChecked(prefs.getBoolean("sync_folders_poll", false));
         swSyncFoldersPoll.setEnabled(swSyncFolders.isChecked());

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

@@ -1274,9 +1274,10 @@ public class MessageHelper {
     }
 
     String getThreadId(Context context, long account, long folder, long uid) throws MessagingException {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+
         if (imessage instanceof GmailMessage) {
             // https://developers.google.com/gmail/imap/imap-extensions#access_to_the_gmail_thread_id_x-gm-thrid
-            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
             boolean gmail_thread_id = prefs.getBoolean("gmail_thread_id", false);
             if (gmail_thread_id) {
                 long thrid = ((GmailMessage) imessage).getThrId();
@@ -1330,6 +1331,21 @@ public class MessageHelper {
                 db.message().updateMessageThread(message.account, message.thread, thread);
             }
 
+        boolean subject_threading = prefs.getBoolean("subject_threading", false);
+        if (subject_threading) {
+            String sender = getSortKey(getFrom());
+            String subject = getSubject();
+            if (!TextUtils.isEmpty(sender) && !TextUtils.isEmpty(subject)) {
+                List<EntityMessage> subjects = db.message().getMessagesBySubject(account, sender, subject);
+                for (EntityMessage message : subjects)
+                    if (!thread.equals(message.thread)) {
+                        Log.w("Updating subject thread from " + message.thread + " to " + thread);
+                        db.message().updateMessageThread(message.account, message.thread, thread);
+                    }
+            }
+        }
+
+
         return thread;
     }
 

app/src/main/res/layout/fragment_options_synchronize.xml

@@ -577,6 +577,18 @@
                     app:layout_constraintStart_toStartOf="parent"
                     app:layout_constraintTop_toBottomOf="@id/swGmailThread" />
 
+                <androidx.appcompat.widget.SwitchCompat
+                    android:id="@+id/swSubjectThreading"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_marginStart="12dp"
+                    android:layout_marginTop="12dp"
+                    android:text="@string/title_advanced_subject_threading"
+                    app:layout_constraintEnd_toEndOf="parent"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toBottomOf="@id/tvGmailThreadHint"
+                    app:switchPadding="12dp" />
+
                 <androidx.appcompat.widget.SwitchCompat
                     android:id="@+id/swSyncFolders"
                     android:layout_width="0dp"
@@ -586,7 +598,7 @@
                     android:text="@string/title_advanced_sync_folders"
                     app:layout_constraintEnd_toEndOf="parent"
                     app:layout_constraintStart_toStartOf="parent"
-                    app:layout_constraintTop_toBottomOf="@id/tvGmailThreadHint"
+                    app:layout_constraintTop_toBottomOf="@id/swSubjectThreading"
                     app:switchPadding="12dp" />
 
                 <eu.faircode.email.FixedTextView

app/src/main/res/values/strings.xml

@@ -351,6 +351,7 @@
     <string name="title_advanced_delete_unseen">Delete old unread messages</string>
     <string name="title_advanced_kept_removed">Check if old messages were removed from the server</string>
     <string name="title_advanced_gmail_thread">Gmail message grouping style for Gmail accounts</string>
+    <string name="title_advanced_subject_threading">Group messages by sender and subject</string>
     <string name="title_advanced_sync_folders">Synchronize folder list</string>
     <string name="title_advanced_sync_folders_poll">Actively synchronize folder list</string>
     <string name="title_advanced_sync_shared_folders">Synchronize shared folder lists</string>