Network utilities for Android.

NetworkRequestError.kt

sealed interface NetworkRequestError {
	data class HttpError(
		val code: Int,
		val message: String?,
	) : NetworkRequestError
	data object IoError : NetworkRequestError
	data object UnknownError : NetworkRequestError
}

NetworkResult.kt

import kotlin.contracts.ExperimentalContracts
import kotlin.contracts.contract

sealed interface NetworkResult<out T : Any> {

	sealed interface Failure : NetworkResult<Nothing>

	data object NoInternetConnection : Failure

	data class RequestError(val error: NetworkRequestError) : Failure

	data class Success<out T : Any>(val data: T) : NetworkResult<T>
}

@OptIn(ExperimentalContracts::class)
fun <T : Any> NetworkResult<T>.isSuccessful(): Boolean {
	contract {
		returns(true) implies (this@isSuccessful is NetworkResult.Success<T>)
		returns(false) implies (this@isSuccessful is NetworkResult.Failure)
	}

	return this is NetworkResult.Success<T>
}

@OptIn(ExperimentalContracts::class)
fun <T : Any> NetworkResult<T>.isFailure(): Boolean {
	contract {
		returns(false) implies (this@isFailure is NetworkResult.Success<T>)
		returns(true) implies (this@isFailure is NetworkResult.Failure)
	}

	return this is NetworkResult.Failure
}

Resource.kt

sealed interface Resource<out D, out E> {
	class Success<out D>(val data: D) : Resource<D, Nothing>
	class Error<out E>(val error: E) : Resource<Nothing, E>

	companion object
}

ResourceExt.kt

import retrofit2.HttpException
import java.io.IOException
import kotlin.coroutines.cancellation.CancellationException

suspend inline fun <D> Resource.Companion.safeApiCall(
	crossinline call: suspend () -> D,
): Resource<D, NetworkRequestError> {
	try {
		val response = call()

		return Resource.Success(response)
	}
	catch (e: CancellationException) {
		throw e
	}
	catch (e: HttpException) {
		e.printStackTrace()
		return Resource.Error(
			NetworkRequestError.HttpError(
				code = e.code(),
				message = e.message().takeIf { it.isNotBlank() },
			)
		)
	}
	catch (e: IOException) {
		e.printStackTrace()
		return Resource.Error(NetworkRequestError.IoError)
	}
	catch (e: Exception) {
		e.printStackTrace()
		return Resource.Error(NetworkRequestError.UnknownError)
	}
}