Nothing outside of TSThread should know about legacy colors

SignalMessaging/appearance/OWSConversationColor.h

@@ -76,9 +76,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 @property (class, readonly, nonatomic) NSArray<NSString *> *conversationColorNames;
 
-+ (NSString *)defaultConversationColorName;
-+ (OWSConversationColor *)defaultConversationColor;
-
 @end
 
 NS_ASSUME_NONNULL_END

SignalMessaging/appearance/OWSConversationColor.m

@@ -5,6 +5,7 @@
 #import "OWSConversationColor.h"
 #import "Theme.h"
 #import "UIColor+OWS.h"
+#import <SignalServiceKit/TSThread.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -314,56 +315,29 @@ NS_ASSUME_NONNULL_BEGIN
     return colorMap;
 }
 
-+ (NSDictionary<NSString *, NSString *> *)ows_legacyConversationColorMap
-{
-    static NSDictionary<NSString *, NSString *> *colorMap;
-    static dispatch_once_t onceToken;
-    dispatch_once(&onceToken, ^{
-        colorMap = @{
-            @"red" : @"crimson",
-            @"deep_orange" : @"crimson",
-            @"orange" : @"vermilion",
-            @"amber" : @"vermilion",
-            @"brown" : @"burlap",
-            @"yellow" : @"burlap",
-            @"pink" : @"plum",
-            @"purple" : @"violet",
-            @"deep_purple" : @"violet",
-            @"indigo" : @"indigo",
-            @"blue" : @"blue",
-            @"light_blue" : @"blue",
-            @"cyan" : @"teal",
-            @"teal" : @"teal",
-            @"green" : @"forest",
-            @"light_green" : @"wintergreen",
-            @"lime" : @"wintergreen",
-            @"blue_grey" : @"taupe",
-            @"grey" : @"steel",
-        };
-    });
-
-    return colorMap;
-}
-
 + (NSArray<NSString *> *)conversationColorNames
 {
     NSMutableArray<NSString *> *names = [NSMutableArray new];
     for (OWSConversationColor *conversationColor in self.allConversationColors) {
         [names addObject:conversationColor.name];
     }
+#ifdef DEBUG
+    NSSet<NSString *> *colorNameSet = [NSSet setWithArray:names];
+    // These constants are duplicated in two places. So this canary exists to make sure they stay in sync.
+    NSSet<NSString *> *threadColorNameSet = [NSSet setWithArray:TSThread.conversationColorNames];
+    OWSAssertDebug([colorNameSet isEqual:threadColorNameSet]);
+#endif
     return [names copy];
 }
 
 + (nullable OWSConversationColor *)conversationColorForColorName:(NSString *)conversationColorName
 {
-    NSString *_Nullable mappedColorName = self.ows_legacyConversationColorMap[conversationColorName.lowercaseString];
-    if (mappedColorName) {
-        conversationColorName = mappedColorName;
-    } else {
-        OWSAssertDebug(self.conversationColorMap[conversationColorName] != nil);
-    }
+    OWSConversationColor *_Nullable result = self.conversationColorMap[conversationColorName];
+
+    // Any mapping to colorNames should be done in TSThread before this method is called.
+    OWSAssertDebug(result != nil);
 
-    return self.conversationColorMap[conversationColorName];
+    return result;
 }
 
 + (OWSConversationColor *)conversationColorOrDefaultForColorName:(NSString *)conversationColorName
@@ -375,16 +349,9 @@ NS_ASSUME_NONNULL_BEGIN
     return [self defaultConversationColor];
 }
 
-+ (NSString *)defaultConversationColorName
-{
-    NSString *conversationColorName = @"steel";
-    OWSAssert([self.conversationColorNames containsObject:conversationColorName]);
-    return conversationColorName;
-}
-
 + (OWSConversationColor *)defaultConversationColor
 {
-    return [self conversationColorForColorName:self.defaultConversationColorName];
+    return [self conversationColorForColorName:kTSThread_DefaultConversationColorName];
 }
 
 @end

SignalMessaging/utils/OWSContactAvatarBuilder.m

@@ -76,9 +76,7 @@ NS_ASSUME_NONNULL_BEGIN
     OWSAssertDebug(localNumber.length > 0);
     OWSAssertDebug(diameter > 0);
 
-    NSString *colorName = [OWSConversationColor defaultConversationColorName];
-
-    return [self initWithSignalId:localNumber colorName:colorName diameter:diameter];
+    return [self initWithSignalId:localNumber colorName:kTSThread_DefaultConversationColorName diameter:diameter];
 }
 
 #pragma mark - Dependencies

SignalServiceKit/src/Contacts/TSThread.h

@@ -10,10 +10,11 @@ NS_ASSUME_NONNULL_BEGIN
 @class TSInteraction;
 @class TSInvalidIdentityKeyReceivingErrorMessage;
 
+extern NSString *const kTSThread_DefaultConversationColorName;
+
 /**
  *  TSThread is the superclass of TSContactThread and TSGroupThread
  */
-
 @interface TSThread : TSYapDatabaseObject
 
 // YES IFF this thread has ever had a message.
@@ -37,6 +38,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)updateConversationColorName:(NSString *)colorName transaction:(YapDatabaseReadWriteTransaction *)transaction;
 + (NSString *)stableColorNameForNewConversationWithString:(NSString *)colorSeed;
+@property (class, nonatomic, readonly) NSArray<NSString *> *conversationColorNames;
 
 /**
  * @returns

SignalServiceKit/src/Contacts/TSThread.m

@@ -19,6 +19,8 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+NSString *const kTSThread_DefaultConversationColorName = @"steel";
+
 @interface TSThread ()
 
 @property (nonatomic) NSDate *creationDate;
@@ -69,12 +71,25 @@ NS_ASSUME_NONNULL_BEGIN
     }
     
     if (_conversationColorName.length == 0) {
-        NSString *_Nullable contactId = self.contactIdentifier;
-        if (contactId.length > 0) {
+        NSString *_Nullable colorSeed = self.contactIdentifier;
+        if (colorSeed.length > 0) {
+            // group threads
+            colorSeed = self.uniqueId;
+        }
+
         // To be consistent with colors synced to desktop
-            _conversationColorName = [self.class stableColorNameForLegacyConversationWithString:contactId];
+        NSString *colorName = [self.class stableColorNameForLegacyConversationWithString:colorSeed];
+        OWSAssertDebug(colorName);
+
+        _conversationColorName = colorName;
+    } else if (![[[self class] conversationColorNames] containsObject:_conversationColorName]) {
+        // If we'd persisted a non-mapped color name
+        NSString *_Nullable mappedColorName = self.class.legacyConversationColorMap[_conversationColorName];
+        if (mappedColorName) {
+            _conversationColorName = mappedColorName;
         } else {
-            _conversationColorName = [self.class stableColorNameForLegacyConversationWithString:self.uniqueId];
+            OWSFailDebug(@"failure: unexpected unmappable conversationColorName: %@", _conversationColorName);
+            _conversationColorName = kTSThread_DefaultConversationColorName;
         }
     }
 
@@ -459,6 +474,11 @@ NS_ASSUME_NONNULL_BEGIN
     ];
 }
 
++ (NSArray<NSString *> *)conversationColorNames
+{
+    return [self.colorNamesForNewConversation arrayByAddingObject:kTSThread_DefaultConversationColorName];
+}
+
 + (NSString *)stableConversationColorNameForString:(NSString *)colorSeed colorNames:(NSArray<NSString *> *)colorNames
 {
     NSData *contactData = [colorSeed dataUsingEncoding:NSUTF8StringEncoding];
@@ -481,11 +501,20 @@ NS_ASSUME_NONNULL_BEGIN
     return [self stableConversationColorNameForString:colorSeed colorNames:self.colorNamesForNewConversation];
 }
 
-// After introducing new conversation colors, we want to try to maintain as close
-// as possible to the old color for an existing thread.
+// After introducing new conversation colors, we want to try to maintain as close as possible to the old color for an
+// existing thread.
 + (NSString *)stableColorNameForLegacyConversationWithString:(NSString *)colorSeed
 {
-    return [self stableConversationColorNameForString:colorSeed colorNames:self.legacyConversationColorNames];
+    NSString *legacyColorName =
+        [self stableConversationColorNameForString:colorSeed colorNames:self.legacyConversationColorNames];
+    NSString *mappedColorName = self.class.legacyConversationColorMap[legacyColorName];
+
+    if (!mappedColorName) {
+        OWSFailDebug(@"failure: unexpected unmappable legacyColorName: %@", legacyColorName);
+        return kTSThread_DefaultConversationColorName;
+    }
+
+    return mappedColorName;
 }
 
 + (NSArray<NSString *> *)legacyConversationColorNames
@@ -504,6 +533,37 @@ NS_ASSUME_NONNULL_BEGIN
     ];
 }
 
++ (NSDictionary<NSString *, NSString *> *)legacyConversationColorMap
+{
+    static NSDictionary<NSString *, NSString *> *colorMap;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        colorMap = @{
+            @"red" : @"crimson",
+            @"deep_orange" : @"crimson",
+            @"orange" : @"vermilion",
+            @"amber" : @"vermilion",
+            @"brown" : @"burlap",
+            @"yellow" : @"burlap",
+            @"pink" : @"plum",
+            @"purple" : @"violet",
+            @"deep_purple" : @"violet",
+            @"indigo" : @"indigo",
+            @"blue" : @"blue",
+            @"light_blue" : @"blue",
+            @"cyan" : @"teal",
+            @"teal" : @"teal",
+            @"green" : @"forest",
+            @"light_green" : @"wintergreen",
+            @"lime" : @"wintergreen",
+            @"blue_grey" : @"taupe",
+            @"grey" : @"steel",
+        };
+    });
+
+    return colorMap;
+}
+
 - (void)updateConversationColorName:(NSString *)colorName transaction:(YapDatabaseReadWriteTransaction *)transaction
 {
     [self applyChangeToSelfAndLatestCopy:transaction

SignalServiceKit/src/Devices/OWSGroupsOutputStream.m

@@ -27,6 +27,7 @@ NS_ASSUME_NONNULL_BEGIN
     [groupBuilder setName:group.groupName];
     [groupBuilder setMembers:group.groupMemberIds];
     [groupBuilder setColor:groupThread.conversationColorName];
+    OWSAssertDebug([TSThread.conversationColorNames containsObject:groupThread.conversationColorName]);
 
     if ([OWSBlockingManager.sharedManager isGroupIdBlocked:group.groupId]) {
         [groupBuilder setBlocked:YES];

SignalServiceKit/src/Messages/DeviceSyncing/OWSSyncContactsMessage.m

@@ -108,6 +108,7 @@ NS_ASSUME_NONNULL_BEGIN
             conversationColorName = [TSThread stableColorNameForNewConversationWithString:signalAccount.recipientId];
         }
 
+        OWSAssertDebug([TSThread.conversationColorNames containsObject:conversationColorName]);
         [contactsOutputStream writeSignalAccount:signalAccount
                                recipientIdentity:recipientIdentity
                                   profileKeyData:profileKeyData