ProfileStoryProgress.kt

// Based on structure in https://gist.github.com/BenHenning/0e3a3c4a798dbe4ffb884144e2b7e592.

private const val CACHE_NAME = "topic_progress_database"
private const val CHAPTER_PROGRESS_ID = "ChapterProgressDataProvider"

class StoryProgressController @Inject constructor(private val persistentCacheStoreFactory: PersistentCacheStore.Factory, private val dataProviders: DataProviders) {
  private val cacheStoreMap = mutableMapOf<ProfileId, PersistentCacheStore<TopicProgressDatabase>>()
  
  fun lookUpChapterProgress(val topicId, val storyId, val explorationId, profileId: ProfileId): DataProvider<ChapterPlayState> {
    return dataProviders.transform(retrieveCacheStore(profileId), CHAPTER_PROGRESS_ID) { database ->
      // Needs error checking & defaulting. Maybe proto does this directly?
      database.getTopicProgressMap()[topicId].getStoreProgressMap()[storyId].getChapterProgressMap()[explorationId]
    }
  }
  
  private fun retrieveCacheStore(profileId: ProfileId): PersistentCacheStore<TopicProgressDatabase> {
    if (profileId in cacheStoreMap) {
      return cacheStoreMap[profileId]
    } else {
      val cacheStore = persistentCacheStoreFactory.createPerProfile(CACHE_NAME, TopicProgressDatabase.getDefaultInstance(), profileId)
      cacheStoreMap[profileId] = cacheStore
      return cacheStore
    }
  }
}

@BenHenning This worked. Thanks