From 7aad5c5971f9305fd4be7905e38b7d9fd10d12c6 Mon Sep 17 00:00:00 2001
From: Frederic Jacobs <github@fredericjacobs.com>
Date: Sat, 28 Feb 2015 15:27:56 +0100
Subject: [PATCH] Fixing UX issue with unsynchronized clocks.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

 TextSecure messages don’t get assigned a timestamp by the server. All
of it is done end-to-end between both clients. A client could have a
misconfigured clock or might want to forge a timestamp. Therefore, we
address this issue by introducing a new receivedAt timestamp for
incoming messages that will be used to sort the messages.
---
 .../textsecure/Messages/TSIncomingMessage.h   |  3 +-
 .../textsecure/Messages/TSIncomingMessage.m   | 10 +++---
 .../src/textsecure/Storage/TSDatabaseView.m   | 33 ++++++++++++++++++-
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/Signal/src/textsecure/Messages/TSIncomingMessage.h b/Signal/src/textsecure/Messages/TSIncomingMessage.h
index c0ab25a5d..9ceaf33af 100644
--- a/Signal/src/textsecure/Messages/TSIncomingMessage.h
+++ b/Signal/src/textsecure/Messages/TSIncomingMessage.h
@@ -42,9 +42,10 @@
                          inThread:(TSGroupThread*)thread
                          authorId:(NSString*)authorId
                       messageBody:(NSString*)body
-                     attachments:(NSArray*)attachments;
+                      attachments:(NSArray*)attachments;
 
 @property (nonatomic, readonly) NSString *authorId;
 @property (nonatomic, getter = wasRead) BOOL read;
+@property (nonatomic, readonly) NSDate   *receivedAt;
 
 @end
diff --git a/Signal/src/textsecure/Messages/TSIncomingMessage.m b/Signal/src/textsecure/Messages/TSIncomingMessage.m
index a80cd8a5f..1d4012dec 100644
--- a/Signal/src/textsecure/Messages/TSIncomingMessage.m
+++ b/Signal/src/textsecure/Messages/TSIncomingMessage.m
@@ -19,8 +19,9 @@
     self = [super initWithTimestamp:timestamp inThread:thread messageBody:body attachments:attachments];
     
     if (self) {
-        _authorId = authorId;
-        _read     = NO;
+        _authorId   = authorId;
+        _read       = NO;
+        _receivedAt = [NSDate date];
     }
     
     return self;
@@ -34,8 +35,9 @@
     self = [super initWithTimestamp:timestamp inThread:thread messageBody:body attachments:attachments];
     
     if (self) {
-        _authorId = nil;
-        _read     = NO;
+        _authorId   = nil;
+        _read       = NO;
+        _receivedAt = [NSDate date];
     }
     
     return self;
diff --git a/Signal/src/textsecure/Storage/TSDatabaseView.m b/Signal/src/textsecure/Storage/TSDatabaseView.m
index 08bbff3fc..ca59be3a9 100644
--- a/Signal/src/textsecure/Storage/TSDatabaseView.m
+++ b/Signal/src/textsecure/Storage/TSDatabaseView.m
@@ -163,11 +163,42 @@ NSString *TSUnreadDatabaseViewExtensionName  = @"TSUnreadDatabaseViewExtensionNa
             TSInteraction *message1 = (TSInteraction*)object1;
             TSInteraction *message2 = (TSInteraction*)object2;
             
-            return [message1.date compare:message2.date];
+            NSDate *date1 = [self localTimeReceiveDateForInteraction:message1];
+            NSDate *date2 = [self localTimeReceiveDateForInteraction:message2];
+            
+            NSComparisonResult result = [date1 compare:date2];
+            
+            // NSDates are only accurate to the second, we might want finer precision
+            if (result != NSOrderedSame) {
+                return result;
+            }
+            
+            if (message1.timestamp > message2.timestamp) {
+                return NSOrderedDescending;
+            } else if (message1.timestamp < message2.timestamp){
+                return NSOrderedAscending;
+            } else{
+                return NSOrderedSame;
+            }
         }
         
         return NSOrderedSame;
     }];
 }
 
++ (NSDate*)localTimeReceiveDateForInteraction:(TSInteraction*)interaction{
+    NSDate *interactionDate = interaction.date;
+    
+    if ([interaction isKindOfClass:[TSIncomingMessage class]]) {
+        TSIncomingMessage *message = (TSIncomingMessage*)interaction;
+        
+        if (message.receivedAt) {
+            interactionDate = message.receivedAt;
+        }
+        
+    }
+    
+    return interactionDate;
+}
+
 @end