Example Use Case

GetAllEmployeesUseCase.kt

package com.example.core.usecases

import com.example.core.model.Employee

import com.example.core.repositories.EmployeeRepository

import com.example.core.utils.ResultData

import kotlinx.coroutines.CoroutineDispatcher

import kotlinx.coroutines.flow.*

class GetAllEmployeesUseCase(

    private val employeeRepository: EmployeeRepository,

    private val dispatcher: CoroutineDispatcher

) {

    sealed class Callback {

        data class OnSuccessfullyFetchedAllEmployees(

            val list: List<Employee>

        ) : Callback()

        object NoEmployeesListed : Callback()

        object NoInternetConnectionError : Callback()

        object UnknownError : Callback()

    }

    operator fun invoke(): Flow<Callback> {

        return employeeRepository.getEmployees().map { result ->

            if (result.isError) {

                when (result.error) {

                    ResultData.Error.NO_CONNECTIVITY -> {

                        Callback.NoInternetConnectionError

                    }

                    else -> {

                        Callback.UnknownError

                    }

                }

            } else {

                val employees = result.data

                if (employees != null && employees.isNotEmpty()) {

                    Callback.OnSuccessfullyFetchedAllEmployees(employees)

                } else {

                    Callback.NoEmployeesListed

                }

            }

        }.flowOn(dispatcher)

    }

}