Make OkHttpClient with cache

OkHttpClient.kt

val cacheSize = (5 * 1024 * 1024).toLong()
val cache = Cache(context.cacheDir, cacheSize)

// Source https://medium.com/mindorks/caching-with-retrofit-store-responses-offline-71439ed32fda
val okHttpClient = OkHttpClient.Builder()
  // Specify the cache we created earlier.
  .cache(cache)
  // Add an Interceptor to the OkHttpClient.
  .addInterceptor { chain ->

    // Get the request from the chain.
    var request = chain.request()

    /**  Leveraging the advantage of using Kotlin,
     *  we initialize the request and change its header depending on whether
     *  the device is connected to Internet or not.
     */
    request = if (context.isConnected())
    /**  If there is Internet, get the cache that was stored 5 seconds ago.
     *  If the cache is older than 5 seconds, then discard it,
     *  and indicate an error in fetching the response.
     *  The 'max-age' attribute is responsible for this behavior.
     */
      request.newBuilder().header("Cache-Control", "public, max-age=" + 5).build()
    else
    /** If there is no Internet, get the cache that was stored 7 days ago.
     *  If the cache is older than 7 days, then discard it,
     *  and indicate an error in fetching the response.
     *  The 'max-stale' attribute is responsible for this behavior.
     *  The 'only-if-cached' attribute indicates to not retrieve new data; fetch the cache only instead.
     */
      request.newBuilder().header(
        "Cache-Control",
        "public, only-if-cached, max-stale=" + 60 * 60 * 24 * 7
      ).build()
    // End of if-else statement

    // Add the modified request to the chain.
    chain.proceed(request)
  }
  .addInterceptor(HttpLoggingInterceptor().setLevel(Level.BODY))
  .build()