RequestInterceptor.kt

import android.os.SystemClock
import android.util.Log
import okhttp3.Interceptor
import okhttp3.Response
import java.io.IOException

class RequestInterceptor(private val tokenStore: TokenStore) : Interceptor {

    private val oauthService by lazy { ServiceGenerator.createAuthService() }
    private var isRefreshing = false

    @Throws(IOException::class)
    override fun intercept(chain: Interceptor.Chain): Response {
        val response = chain.proceed(chain.request())
        // Checking for unauthorized
        if (response.code() == 401) {
            Log.d(javaClass.simpleName, "Unauthorized request was intercepted")
            // Wait until refresh token is finished
            if (isRefreshing){
                Log.d(javaClass.simpleName, "Token is refreshing ...")
                do {
                    Log.d(javaClass.simpleName, "Sleep for ${SLEEP_TIME/1000} seconds ...")
                    SystemClock.sleep(SLEEP_TIME)
                } while (isRefreshing)
                return chain.proceed(chain.request())
            }

            val refreshToken = tokenStore.getRefreshToken()
            if (!refreshToken.isNullOrEmpty()){
                // Perform synchronous refresh token
                val refreshResponse = refreshToken(refreshToken!!)
                if (refreshResponse != null) {
                    when {
                        // NetworkInterceptor will take care of adding authorization header after refreshing token has finished
                        refreshResponse.code() == 200 -> return chain.proceed(chain.request())
                        refreshResponse.code() == 401 -> logout()
                        else -> return refreshResponse
                    }
                }
            }
        }
        return response
    }

    private fun refreshToken(refreshToken: String): Response? {

        isRefreshing = true
        var failedAttempt = 0
        var response: Response? = null

        do {
            Log.d(javaClass.simpleName, "Refreshing Token")
            val call = oauthService.refreshToken("refresh_token", refreshToken)

            try {
                val requestResponse = call.execute()
                response = requestResponse.raw()

                if (requestResponse.isSuccessful){
                    var accessToken = requestResponse.body()
                    if (accessToken != null){
                        Log.d(javaClass.simpleName, "Refresh Token success")
                        setActiveToken(accessToken.accessToken, accessToken.refreshToken)
                        isRefreshing = false
                        return response
                    }else{
                        failedAttempt += 1
                    }
                }else{
                    failedAttempt += 1
                }
            } catch (e: IOException) {
                failedAttempt += 1
                e.printStackTrace()
            }

        } while (failedAttempt < MAX_ATTEMPT)

        isRefreshing = false
        return response
    }

    private fun setActiveToken(accessToken: String?, refreshToken: String?) {
        if (!accessToken.isNullOrEmpty() && !refreshToken.isNullOrEmpty()) {
            tokenStore.saveToken(accessToken!!)
            tokenStore.saveRefreshToken(refreshToken!!)
            tokenStore.notifiyTokenUpdate(accessToken, refreshToken)
        }
    }



    private fun logout() {
        Log.d(javaClass.simpleName, "Refresh Token failed, perform force logout")
    }

    companion object {
        private const val MAX_ATTEMPT = 3
        private const val SLEEP_TIME: Long = 3*1000 // 3 Seconds
    }
}