DefaultSessionAndUserEventRepository.kt

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
class DefaultSessionAndUserEventRepository(
    private val userEventDataSource: UserEventDataSource,
    private val sessionRepository: SessionRepository
) : SessionAndUserEventRepository {

    override fun getObservableUserEvent(
        userId: String?,
        eventId: SessionId
    ): Flow<Result<LoadUserSessionUseCaseResult>> {
        // Handles null userId

        // Observes the user events and merges them with session data
        return userEventDataSource.getObservableUserEvent(userId, eventId).map { userEventResult ->
            // lambda of the map operator that can call suspend functions
            val event = sessionRepository.getSession(eventId)

            // Merges session with user data and emits the result
            val userSession = UserSession(
                event,
                userEventResult.userEvent ?: createDefaultUserEvent(event)
            )
            Result.Success(LoadUserSessionUseCaseResult(userSession))
        }
    }
}

ViewModel