Fix public chat message deletion

Signal/src/Models/MessageActions.swift

@@ -116,6 +116,8 @@ class ConversationViewItemActions: NSObject {
     class func mediaActions(conversationViewItem: ConversationViewItem, shouldAllowReply: Bool, delegate: MessageActionsDelegate) -> [MenuAction] {
         var actions: [MenuAction] = []
 
+        let isGroup = conversationViewItem.isGroupThread;
+        
         if shouldAllowReply {
             let replyAction = MessageActionBuilder.reply(conversationViewItem: conversationViewItem, delegate: delegate)
             actions.append(replyAction)
@@ -132,8 +134,10 @@ class ConversationViewItemActions: NSObject {
             }
         }
 
-        let deleteAction = MessageActionBuilder.deleteMessage(conversationViewItem: conversationViewItem, delegate: delegate)
-        actions.append(deleteAction)
+        if !isGroup || conversationViewItem.userCanDeleteGroupMessage {
+            let deleteAction = MessageActionBuilder.deleteMessage(conversationViewItem: conversationViewItem, delegate: delegate)
+            actions.append(deleteAction)
+        }
 
         let showDetailsAction = MessageActionBuilder.showDetails(conversationViewItem: conversationViewItem, delegate: delegate)
         actions.append(showDetailsAction)

Signal/src/ViewControllers/ConversationView/ConversationViewItem.m

@@ -1269,13 +1269,13 @@ NSString *NSStringForOWSMessageCellType(OWSMessageCellType cellType)
     }];
     if (publicChat == nil) return false;
     
-    // Only allow deletion on incoming messages if the user has moderation permission
     if (interationType == OWSInteractionType_IncomingMessage) {
-        BOOL isModerator = [LKPublicChatAPI isUserModerator:self.userHexEncodedPublicKey forGroup:publicChat.channel onServer:publicChat.server];
-        if (!isModerator) return false;
+        // Only allow deletion on incoming messages if the user has moderation permission
+        return [LKPublicChatAPI isUserModerator:self.userHexEncodedPublicKey forGroup:publicChat.channel onServer:publicChat.server];
+    } else {
+        // Only allow deletion on outgoing messages if the user was the sender (i.e. it was not sent from another linked device)
+        return [self.interaction.actualSenderHexEncodedPublicKey isEqual:self.userHexEncodedPublicKey];
     }
-
-    return true;
 }
 
 @end

SignalServiceKit/src/Loki/API/Public Chat/LokiPublicChatPoller.swift

@@ -147,17 +147,18 @@ public final class LokiPublicChatPoller : NSObject {
                 signalLinkPreview = nil
             }
             let body = (message.body == message.timestamp.description) ? "" : message.body // Workaround for the fact that the back-end doesn't accept messages without a body
-            let message = TSOutgoingMessage(outgoingMessageWithTimestamp: message.timestamp, in: thread, messageBody: body, attachmentIds: NSMutableArray(array: attachmentIDs), expiresInSeconds: 0,
+            let signalMessage = TSOutgoingMessage(outgoingMessageWithTimestamp: message.timestamp, in: thread, messageBody: body, attachmentIds: NSMutableArray(array: attachmentIDs), expiresInSeconds: 0,
                 expireStartedAt: 0, isVoiceMessage: false, groupMetaMessage: .deliver, quotedMessage: signalQuote, contactShare: nil, linkPreview: signalLinkPreview)
+            signalMessage.actualSenderHexEncodedPublicKey = message.hexEncodedPublicKey
             storage.dbReadWriteConnection.readWrite { transaction in
-                message.update(withSentRecipient: publicChat.server, wasSentByUD: false, transaction: transaction)
-                message.saveGroupChatServerID(messageServerID, in: transaction)
-                guard let messageID = message.uniqueId else { return print("[Loki] Failed to save public chat message.") }
+                signalMessage.update(withSentRecipient: publicChat.server, wasSentByUD: false, transaction: transaction)
+                signalMessage.saveGroupChatServerID(messageServerID, in: transaction)
+                guard let messageID = signalMessage.uniqueId else { return print("[Loki] Failed to save public chat message.") }
                 storage.setIDForMessageWithServerID(UInt(messageServerID), to: messageID, in: transaction)
             }
             DispatchQueue.main.async {
                 if let linkPreviewURL = OWSLinkPreview.previewUrl(forMessageBodyText: message.body, selectedRange: nil) {
-                    message.generateLinkPreviewIfNeeded(fromURL: linkPreviewURL)
+                    signalMessage.generateLinkPreviewIfNeeded(fromURL: linkPreviewURL)
                 }
             }
         }

SignalServiceKit/src/Messages/Interactions/TSInteraction.h

@@ -39,6 +39,9 @@ NSString *NSStringFromOWSInteractionType(OWSInteractionType value);
 @property (nonatomic, readonly) uint64_t timestamp;
 @property (nonatomic, readonly) uint64_t sortId;
 @property (nonatomic, readonly) uint64_t receivedAtTimestamp;
+/// Used for public chats where a message sent from a slave device is interpreted as having been sent from the master device.
+@property (nonatomic) NSString *actualSenderHexEncodedPublicKey;
+
 - (NSDate *)receivedAtDate;
 
 - (OWSInteractionType)interactionType;