package dorkbox.netUtil

import dorkbox.executor.Executor
import java.io.BufferedWriter
import java.io.File
import java.io.FileWriter
import java.io.IOException

/**
 *
 */
object Dns {
    /**
     * @throws IOException if the DNS resolve.conf file cannot be read
     */
    fun setDNSServers(dnsServersString: String) {
        if (Common.OS_LINUX) {
            val dnsServers = dnsServersString.split(",");
            val dnsFile = File("/etc/resolvconf/resolv.conf.d/head");

             if (!dnsFile.canRead()) {
                 throw IOException("Unable to initialize dns server file. Something is SERIOUSLY wrong");
             }

            BufferedWriter(FileWriter(dnsFile)).use {
                it.write("# File location: /etc/resolvconf/resolv.conf.d/head\n");
                it.write("# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)\n");

                dnsServers.forEach { dns ->
                    it.write("nameserver $dns\n");
                }

                it.flush();
            }

            Executor().command("resolvconf", "-u").startBlocking()
        } else {
            throw RuntimeException("NOT IMPL.")
        }
    }
}