Show session restore banner

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -162,6 +162,7 @@ typedef enum : NSUInteger {
 @property (nonatomic) NSCache *cellMediaCache;
 @property (nonatomic) ConversationHeaderView *headerView;
 @property (nonatomic, nullable) UIView *bannerView;
+@property (nonatomic, nullable) UIView *restoreSessionBannerView;
 @property (nonatomic, nullable) OWSDisappearingMessagesConfiguration *disappearingMessagesConfiguration;
 
 // Back Button Unread Count
@@ -506,7 +507,7 @@ typedef enum : NSUInteger {
     // Ensure thread instance is up to date
     [self.thread reload];
     // Update UI
-    // TODO: Show banner here
+    [self updateSessionRestoreBanner];
 }
 
 - (void)peekSetup
@@ -960,17 +961,37 @@ typedef enum : NSUInteger {
     return [result copy];
 }
 
+- (void)updateSessionRestoreBanner {
+    BOOL isContactThread = [self.thread isKindOfClass:[TSContactThread class]];
+    BOOL shouldRemoveBanner = !isContactThread;
+    if (isContactThread) {
+        TSContactThread *thread = (TSContactThread *)self.thread;
+        if (thread.sessionRestoreDevices.count > 0) {
+            if (self.restoreSessionBannerView) {
+                // TODO: Create banner here
+            }
+        } else {
+            shouldRemoveBanner = true;
+        }
+    }
+    
+    if (shouldRemoveBanner && self.restoreSessionBannerView) {
+        [self.restoreSessionBannerView removeFromSuperview];
+        self.restoreSessionBannerView = nil;
+    }
+}
+
 - (void)ensureBannerState
 {
     // This method should be called rarely, so it's simplest to discard and
     // rebuild the indicator view every time.
     [self.bannerView removeFromSuperview];
     self.bannerView = nil;
-
+    
     if (self.userHasScrolled) {
         return;
     }
-
+    
     NSArray<NSString *> *noLongerVerifiedRecipientIds = [self noLongerVerifiedRecipientIds];
 
     if (noLongerVerifiedRecipientIds.count > 0) {
@@ -1131,6 +1152,16 @@ typedef enum : NSUInteger {
     }];
 }
 
+- (void)restoreSession {
+    if ([self.thread isKindOfClass:[TSContactThread class]]) {
+        TSContactThread *thread = (TSContactThread *)self.thread;
+        NSArray *devices = thread.sessionRestoreDevices;
+        // TODO: Send session restore to all devices
+        // TODO: Add message saying session restore was sent
+        [thread removeAllRessionRestoreDevicesWithTransaction:nil];
+    }
+}
+
 - (void)noLongerVerifiedBannerViewWasTapped:(UIGestureRecognizer *)sender
 {
     if (sender.state == UIGestureRecognizerStateRecognized) {

SignalServiceKit/src/Messages/OWSMessageDecrypter.m

@@ -689,13 +689,14 @@ NSError *EnsureDecryptError(NSError *_Nullable error, NSString *fallbackErrorDes
                                    transaction:(YapDatabaseReadWriteTransaction *)transaction
 {
     NSString *masterHexEncodedPublicKey = [LKDatabaseUtilities getMasterHexEncodedPublicKeyFor:envelope.source in:transaction];
-    TSThread *contactThread = [TSContactThread getOrCreateThreadWithContactId:masterHexEncodedPublicKey transaction:transaction];
+    NSString *hexEncodedPublicKey = masterHexEncodedPublicKey ?: envelope.source;
+    TSThread *contactThread = [TSContactThread getOrCreateThreadWithContactId:hexEncodedPublicKey transaction:transaction];
        
    // Trigger a session restore prompt if we get specific errors
    if (errorMessage.errorType == TSErrorMessageNoSession ||
        errorMessage.errorType == TSErrorMessageInvalidMessage ||
        errorMessage.errorType == TSErrorMessageInvalidKeyException) {
-       [((TSContactThread *) contactThread) addSessionRestoreDevice:masterHexEncodedPublicKey transaction:transaction];
+       [((TSContactThread *) contactThread) addSessionRestoreDevice:hexEncodedPublicKey transaction:transaction];
    }
 }
 
@@ -704,7 +705,8 @@ NSError *EnsureDecryptError(NSError *_Nullable error, NSString *fallbackErrorDes
                       transaction:(YapDatabaseReadWriteTransaction *)transaction
 {
     NSString *masterHexEncodedPublicKey = [LKDatabaseUtilities getMasterHexEncodedPublicKeyFor:envelope.source in:transaction];
-    TSThread *contactThread = [TSContactThread getOrCreateThreadWithContactId:masterHexEncodedPublicKey transaction:transaction];
+    NSString *hexEncodedPublicKey = masterHexEncodedPublicKey ?: envelope.source;
+    TSThread *contactThread = [TSContactThread getOrCreateThreadWithContactId:hexEncodedPublicKey transaction:transaction];
     [SSKEnvironment.shared.notificationsManager notifyUserForErrorMessage:errorMessage
                                                                    thread:contactThread
                                                               transaction:transaction];