be more careful with corner cases when mentioning multiple people

3 files changed, 53 insertions, 5 deletions

diff --git a/src/main/java/de/pixart/messenger/entities/Conversation.java b/src/main/java/de/pixart/messenger/entities/Conversation.java
index a3811a751..f654902b4 100644
--- a/src/main/java/de/pixart/messenger/entities/Conversation.java
+++ b/src/main/java/de/pixart/messenger/entities/Conversation.java
@@ -303,6 +303,17 @@ public class Conversation extends AbstractEntity implements Blockable, Comparabl
         return null;
     }
 
+    public boolean hasMessageWithCounterpart(Jid counterpart) {
+        synchronized (this.messages) {
+            for (Message message : this.messages) {
+                if (counterpart.equals(message.getCounterpart())) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
     public void populateWithMessages(final List<Message> messages) {
         synchronized (this.messages) {
             messages.clear();
diff --git a/src/main/java/de/pixart/messenger/ui/ConversationFragment.java b/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
index c94e6f4f0..50b93cf5e 100644
--- a/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
+++ b/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
@@ -44,6 +44,7 @@ import net.java.otr4j.session.SessionStatus;
 
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
 import java.util.List;
@@ -74,6 +75,7 @@ import de.pixart.messenger.ui.adapter.MessageAdapter.OnContactPictureClicked;
 import de.pixart.messenger.ui.adapter.MessageAdapter.OnContactPictureLongClicked;
 import de.pixart.messenger.ui.widget.ListSelectionManager;
 import de.pixart.messenger.utils.GeoHelper;
+import de.pixart.messenger.utils.NickValidityChecker;
 import de.pixart.messenger.utils.UIHelper;
 import de.pixart.messenger.utils.XmppUri;
 import de.pixart.messenger.xmpp.XmppConnection;
@@ -879,13 +881,15 @@ public class ConversationFragment extends Fragment implements EditMessage.Keyboa
                 editable.insert(pos, nick + ": ");
             } else {
                 if (pos > 2 && editable.subSequence(pos - 2, pos).toString().equals(": ")) {
-                    editable.insert(pos - 2, ", " + nick);
-                } else {
-                    editable.insert(pos, (Character.isWhitespace(before) ? "" : " ") + nick + (Character.isWhitespace(after) ? "" : " "));
-                    if (Character.isWhitespace(after)) {
-                        mEditMessage.setSelection(mEditMessage.getSelectionStart() + 1);
+                    if (NickValidityChecker.check(conversation, Arrays.asList(editable.subSequence(0, pos - 2).toString().split(", ")))) {
+                        editable.insert(pos - 2, ", " + nick);
+                        return;
                     }
                 }
+                editable.insert(pos, (Character.isWhitespace(before) ? "" : " ") + nick + (Character.isWhitespace(after) ? "" : " "));
+                if (Character.isWhitespace(after)) {
+                    mEditMessage.setSelection(mEditMessage.getSelectionStart() + 1);
+                }
             }
         }
     }
diff --git a/src/main/java/de/pixart/messenger/utils/NickValidityChecker.java b/src/main/java/de/pixart/messenger/utils/NickValidityChecker.java
new file mode 100644
index 000000000..0b4df771f
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/utils/NickValidityChecker.java
@@ -0,0 +1,33 @@
+package de.pixart.messenger.utils;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.List;
+
+import de.pixart.messenger.entities.Conversation;
+import de.pixart.messenger.xmpp.jid.InvalidJidException;
+import de.pixart.messenger.xmpp.jid.Jid;
+
+public class NickValidityChecker {
+
+    private static boolean check(final Conversation conversation, final String nick) {
+        Jid room = conversation.getJid();
+        try {
+            Jid full = Jid.fromParts(room.getLocalpart(), room.getDomainpart(), nick);
+            return conversation.hasMessageWithCounterpart(full)
+                    || conversation.getMucOptions().findUserByFullJid(full) != null;
+        } catch (InvalidJidException e) {
+            return false;
+        }
+    }
+
+    public static boolean check(final Conversation conversation, final List<String> nicks) {
+        Set<String> previousNicks = new HashSet<>(nicks);
+        for(String previousNick : previousNicks) {
+            if (!NickValidityChecker.check(conversation,previousNick)) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
\ No newline at end of file