use server timestamp to show the message time in open groups

SignalServiceKit/src/Loki/API/Open Groups/PublicChatPoller.swift

@@ -174,6 +174,7 @@ public final class PublicChatPoller : NSObject {
                     envelope.setSource(senderPublicKey)
                     envelope.setSourceDevice(OWSDevicePrimaryDeviceId)
                     envelope.setContent(try! content.build().serializedData())
+                    envelope.setServerTimestamp(message.serverTimestamp)
                     try! Storage.writeSync { transaction in
                         transaction.setObject(senderDisplayName, forKey: senderPublicKey, inCollection: publicChat.id)
                         let messageServerID = message.serverID

SignalServiceKit/src/Messages/Interactions/TSInteraction.h

@@ -42,6 +42,10 @@ NSString *NSStringFromOWSInteractionType(OWSInteractionType value);
 /// 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;
 
+- (void)setServerTimestampAsReceiveTimestamp:(uint64_t)receivedAtTimestamp;
+
+- (uint64_t)timestamp;
+
 - (NSDate *)receivedAtDate;
 
 - (OWSInteractionType)interactionType;

SignalServiceKit/src/Messages/Interactions/TSInteraction.m

@@ -41,6 +41,8 @@ NSString *NSStringFromOWSInteractionType(OWSInteractionType value)
 
 @implementation TSInteraction
 
+@synthesize timestamp = _timestamp;
+
 + (NSArray<TSInteraction *> *)interactionsWithTimestamp:(uint64_t)timestamp
                                                 ofClass:(Class)clazz
                                         withTransaction:(YapDatabaseReadTransaction *)transaction
@@ -175,11 +177,27 @@ NSString *NSStringFromOWSInteractionType(OWSInteractionType value)
 
 #pragma mark Date operations
 
+- (uint64_t)timestamp
+{
+    if (self.thread.isGroupThread) {
+        TSGroupThread *thread = (TSGroupThread *)self.thread;
+        if (thread.isPublicChat) {
+            return _receivedAtTimestamp;
+        }
+    }
+    return _timestamp;
+}
+
 - (uint64_t)timestampForLegacySorting
 {
     return self.timestamp;
 }
 
+- (void)setServerTimestampAsReceiveTimestamp:(uint64_t)receivedAtTimestamp
+{
+    _receivedAtTimestamp = receivedAtTimestamp;
+}
+
 - (NSDate *)receivedAtDate
 {
     return [NSDate ows_dateWithMillisecondsSince1970:self.receivedAtTimestamp];

SignalServiceKit/src/Messages/OWSMessageManager.m

@@ -1417,6 +1417,11 @@ NS_ASSUME_NONNULL_BEGIN
                                                                 serverTimestamp:serverTimestamp
                                                                 wasReceivedByUD:wasReceivedByUD];
                 
+                //For open group messages, use server timestamp as the receive timestamp
+                if (oldGroupThread.isPublicChat) {
+                    [incomingMessage setServerTimestampAsReceiveTimestamp:(uint64_t)envelope.serverTimestamp];
+                }
+                
                 // Loki: Set open group server ID if needed
                 if (dataMessage.publicChatInfo != nil && dataMessage.publicChatInfo.hasServerID) {
                     incomingMessage.openGroupServerMessageID = dataMessage.publicChatInfo.serverID;