Discussion on: Authenticator in Retrofit Android

[ayoub anbara 🇲🇦]

If refresh token is expired also, and request refresh token return 401, how to handle this case?

[Mohit Rajput]

Here is the complete code which I used in one project:

package one.projectname.sdk.network

import kotlinx.coroutines.delay
import kotlinx.coroutines.runBlocking
import okhttp3.Authenticator
import okhttp3.Request
import okhttp3.Response
import okhttp3.Route

/**
 * Created by Mohit Rajput on 09/03/22.
 */
class TokenAuthenticator(
    private val tokenManager: TokenManager
) : Authenticator {
    override fun authenticate(route: Route?, response: Response): Request {
        synchronized(this) {
            val sessionData = if (isRefreshNeeded(response)) {
                runBlocking { getUpdatedSessionData() }
            } else {
                getExistingSessionData()
            }

            return response.request.newBuilder()
                .header(HeaderKeys.SESSION_ID, sessionData.sessionId)
                .header(HeaderKeys.REFRESH_ID, sessionData.refreshId)
                .build()
        }
    }

    private fun isRefreshNeeded(response: Response): Boolean {
        val oldSessionId = response.request.header(HeaderKeys.SESSION_ID)
        val oldRefreshId = response.request.header(HeaderKeys.REFRESH_ID)

        val updatedSessionId = tokenManager.getSessionId()
        val updatedRefreshId = tokenManager.getRefreshId()

        return (oldSessionId == updatedSessionId && oldRefreshId == updatedRefreshId)
    }

    private fun getExistingSessionData(): ApiResponse.SessionData {
        val updatedSessionId = tokenManager.getSessionId()
        val updatedRefreshId = tokenManager.getRefreshId()
        return ApiResponse.SessionData(
            sessionId = updatedSessionId,
            refreshId = updatedRefreshId
        )
    }

    private suspend fun getUpdatedSessionData(): ApiResponse.SessionData {
        val refreshTokenRequest =
            ApiResponse.RefreshSessionRequest(tokenManager.getRefreshId())
        return when (val result =
            getResult { userApiService().refreshSession(refreshTokenRequest) }) {
            is ApiResult.Success -> {
                val sessionData = result.data.data
                tokenManager.saveSessionId(sessionData.sessionId)
                tokenManager.saveRefreshId(sessionData.refreshId)
                delay(50)
                sessionData
            }
            is ApiResult.Error -> {
                MySdk.instance().mySdkListeners?.onSessionExpired()
                return ApiResponse.SessionData()
            }
        }
    }

    private class CustomNetworkStateChecker : NetworkStateChecker {
        override fun isNetworkAvailable() = true
    }

    private fun userApiService(): UserApiService {
        val retrofit = RetrofitHelper.provideRetrofit(
            RetrofitHelper.provideOkHttpClient(CustomNetworkStateChecker(), tokenManager)
        )
        return retrofit.create(UserApiService::class.java)
    }
}