TokenAuthenticator.kt

class TokenAuthenticator @Inject constructor(
  private val api: Api,
  private val tokenStore: TokenStore,
  private val logoutTrigger: LogoutTrigger
) : Authenticator {

  companion object {
    const val AUTH_HEADER_NAME = "Authorization"
    const val AUTH_HEADER_VALUE_FORMAT = "Bearer %s"
  }

  override fun authenticate(route: Route?, response: Response): Request? {
    Timber.i("Attempting to refresh token.")

    if (response.request.url.encodedPath.endsWith("access_token")) {
      Timber.e("Failed to refresh token.")
      logoutTrigger.run()
      return null
    }

    val refreshToken = tokenStore.refreshToken()
    if (refreshToken == null) {
      Timber.e("Refresh token is not available.")
      logoutTrigger.run()
      return null
    }

    runCatching {
      val accessToken = runBlocking { api.accessToken(AccessTokenPayload(refreshToken)).accessToken }
      tokenStore.saveAccessToken(accessToken)
      return response.request.newBuilder()
        .header(AUTH_HEADER_NAME, AUTH_HEADER_VALUE_FORMAT.format(accessToken))
        .build()
    }.onFailure {
      Timber.e(it, "Failed to refresh token.")
    }

    logoutTrigger.run()
    return null
  }
}