What's the difference between these two ways of counting reads

[tafelnl]

In the SDK code base there seem to exists two ways of checking the read count:

1. getReadStatuses

val readStatuses = channel.getReadStatuses(userToIgnore = currentUser)
val readCount = readStatuses.count { it.time >= message.getCreatedAtOrThrow().time }

This one is only used by one of the signatures of MessageReadStatusIcon

2. MessageListController's messageReadBy

This one is calculated in a somewhat more sophisticated way. The snippet would look something like this:

val sortedReads = reads
    .filter { it.user.id != currentUser?.id && !it.belongsToFreshlyAddedMember(membersMap) }
    .sortedBy { it.lastRead }

val channelReadsIndexed = messages
    .withIndex()
    .associate { (index, message) -> message.id to index }
    .let { messageToIndex ->
        sortedReads.mapNotNull { channelUserRead ->
            messageToIndex[channelUserRead.lastReadMessageId]?.let {
                channelUserRead to it
            }
        }
    }

val messageReadBy = channelReadsIndexed
    .filter { it.second >= index }
    .map { it.first }

The resulting value is passed on to MessageItemState.messageReadBy. It's used in ChatComponentFactory.MessageFooterStatusIndicator

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1. What is the difference between the two?
2. Why does this difference exists?
3. Which of the two is the recommended approach of determining the number of reads?