An offline interceptor to cache requests when there is no network connection. It checks if a specific header is present before caching.

OfflineCacheInterceptorWithHeader.kt

open class OfflineCacheInterceptorWithHeader : Interceptor {
    override fun intercept(chain: Interceptor.Chain): Response {
        var request = chain.request()
        val header = request.headers["Cacheable"]

        if (header != null) {
            /* check if this request has the [Cacheable] header */
            if (header == "true" &&
                !PaymentApp.instance!!.isNetworkConnected()
            ) {
                Timber.d("CACHE Header: called.::%s", header)

                // prevent caching when network is on. For that we use the "networkInterceptor"
                Timber.d("cache interceptor: called.")
                val cacheControl = CacheControl.Builder()
                    .maxStale(7, TimeUnit.DAYS)
                    .build()

                request = request.newBuilder()
                    .removeHeader(HEADER_PRAGMA)
                    .removeHeader(HEADER_CACHE_CONTROL)
                    .cacheControl(cacheControl)
                    .build()
            } else {
                Timber.d("cache interceptor: not called.")
            }
        }
        return chain.proceed(request)
    }
}