/*
 * JobServServer
 *
 * v1.0
 *
 * May 18, 2019
 */

package JobServ;

import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.netty.GrpcSslContexts;
import io.grpc.netty.NettyServerBuilder;
import io.netty.handler.ssl.ClientAuth;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.SslContextBuilder;
import io.netty.handler.ssl.SslProvider;
import javax.net.ssl.SSLException;
import java.util.InputMismatchException;
import java.io.File;
import java.io.IOException;
import java.util.logging.Logger;

/*
 * The JobServServer class implements the JobServ protobuf API
 * It does this by extending the gRPC stub code.
 * Additionally, JobServServer starts and manages a daemon
 * Which accepts incoming connections from client.
 */
public class JobServServer {
    private static final Logger logger = Logger.getLogger(JobServServer.class.getName());

    private Server server;

    /*
     * Constructor
     * builds server object
     */
    public JobServServer(SslContext ssl, int port) throws IOException {
	this.server = NettyServerBuilder.forPort(port)
	    .addService(new ShellServerService())
	    .sslContext(ssl)
	    .build()
	    .start();
    }

    /*
     * start()
     * this initializes the server
     */
    private void start() throws IOException {
        // TODO: this should be passed in from a configuration manager
        server.start();
        logger.info("Server initialized!");

        Runtime.getRuntime().addShutdownHook(new Thread() {
                @Override
                public void run() {
                    logger.info("Shutting down server");
                    JobServServer.this.stop();
                }
            });
    }

    /*
     * stop()
     * This is called when ctrl+c is pressed
     */
    private void stop() {
        if (server != null) {
            server.shutdown();
        }
    }

    /*
     * blockUntilShutdown()
     * This is more or less the main loop of the server.
     * It spins until shutdown is called.
     */
    private void blockUntilShutdown() throws InterruptedException {
        if (server != null) {
            server.awaitTermination();
        }
    }

    /*
     * main()
     * Entrypoint of hte server
     * parses args and initializes a server object.
     * calls server main loop.
     */
    public static void main(String[] args) throws IOException, InterruptedException {
        // TODO: port and key/cert files should be handled by a config manager
        if(args.length < 4) {
            System.out.println("Usage: ./jobserv-server port cert privatekey truststore");
            return;
        }

        JobServServer server;

        try {
	    SslContextBuilder sslContextBuilder = SslContextBuilder.forServer(new File(args[1]), new File(args[2]));
	    
	    // Mutual TLS trust store and require client auth
	    sslContextBuilder.trustManager(new File(args[3]));
	    sslContextBuilder.clientAuth(ClientAuth.REQUIRE);

	    server = new JobServServer(GrpcSslContexts.configure(sslContextBuilder).build(),
				       Integer.parseInt(args[0]));

        } catch (InputMismatchException e) {
            System.out.println("Invalid port!");
            return;

        } catch (SSLException e) {
            System.out.println(e.getMessage());
            return;
	    
        } catch (IOException e) {
	    System.out.println(e.getMessage());
	    return;
	}

        server.blockUntilShutdown();
    }
}