What role does UseCase play in the Clean Architecture structure and why is its use preferable?

In Clean Architecture, a UseCase (or use case) represents the application's business logic and acts as an intermediary between interfaces (UI, API) and data layers (Repository).

Role of UseCase:

• Encapsulates specific actions and business rules.
• Ensures the independence of business logic from data storage implementation details.
• Allows easy testing of business logic separately from the database or network.

Why prefer using UseCase over direct access to Repository:

• Repository is responsible only for data access, while UseCase handles the logic of processing this data.
• UseCase controls the sequence of operations, validation, and error handling.
• This improves separation of concerns and facilitates maintenance and extension of the code.

Example:

class GetUserProfileUseCase(private val userRepository: UserRepository) {
    suspend operator fun invoke(userId: String): UserProfile {
        val user = userRepository.getUserById(userId)
        // Additional business logic
        return user.toUserProfile()
    }
}

Thus, the UseCase acts as a link, ensuring architecture purity and application flexibility.