import java.util.*;

import java.io.*;

import java.util.concurrent.atomic.AtomicLong;

/**

* @author Ikonija Bogojevic

* @author Sandra Weber

* @author Miguel Perez

*

* This is the main Client class, which spawns ClientThreads which connect to the server. This class

* includes methods for obtaining the user's commands and validating them.

*/

public class Client {

private static String hostName;

// create a variable to initialize new threads with

private static Thread thrd = null;

// the threads are kept track of with a linked list

private static LinkedList<Thread> list = new LinkedList<Thread>();

// AtomicLong is a class that is synchronized, and can be used across

// multiple threads. Here it is used for benchmarking, to store the sum

// of the command completion times for all threads

private static AtomicLong totalTime = new AtomicLong(0);

// this AtomicLong is used to keep track of the current # of running threads

private static AtomicLong runningThreads = new AtomicLong(0);

private static boolean printOutput = true;

public static void main(String[] args) {

int menuSelection = 0;

int numProcesses = 1;

// if no hostname is provided, quit

if (args.length == 0) {

System.out.println("User did not enter a host name. Client program exiting.");

System.exit(1);

}

// until the user selects 8, the Exit option, keep looping and

// offering the menu again after running the queries to the server

else while (menuSelection != 8) {

// display the menu and get the user's choice

menuSelection = mainMenu();

// if 8, exit program

if (menuSelection == 8) {

System.out.println("Quitting.");

System.exit(0);

}

// if 7, ask which command should be run in the benchmark mode

// and how many connections to create

if (menuSelection == 7) {

printOutput = false;

menuSelection = benchmarkMenu();

numProcesses = numProcessesMenu();

}

// create threads. since numProcesses is initialized to 1 and gets reset

// at the end of this loop, if the user has not selected to benchmark

// a command, this loop will only create one process

totalTime.set(0);

runningThreads.set(numProcesses);

for (int i = 0; i < numProcesses; i++) {

// make a new thread, tell it the hostname to connect to

// and the command to run. It is also passed the totalTime object,

// so it can record how much time its command took to complete

thrd = new Thread(new ClientThread(args[0], menuSelection, totalTime, printOutput, runningThreads));

thrd.start(); // start the thread

list.add(thrd); // add the thread to the end of the linked list

}

// wait for all of the threads to complete before going to the top

// of the loop again. This ensures that all threads complete before the

// menu is shown again

for (int i = 0; i < numProcesses; i++) {

try {

// wait for the thread to finish

list.get(i).join();

} catch (InterruptedException e) {

// if the join interrupts the thread, print an error

e.printStackTrace();

}

}

// while runningThreads is not 0, there are still clients waiting for the server

// to send a response, so keep looping (waiting) until they are finished

while (runningThreads.get() != 0) {}

System.out.println("Average response time: " + (totalTime.get() / numProcesses) + " ms\n");

numProcesses = 1;

printOutput = true;

}

}

//----------------------------------------------------------------------------

/**

* Function to prompt the user for a command to run

* @return command number 1-8

*/

public static int mainMenu() {

int menuSelection = 0;

// loop (and prompt again) until the user's input is an integer between 1 and 8

while ((menuSelection <= 0) || (menuSelection > 8)) {

System.out.println("The menu provides the following choices to the user: ");

System.out.println("1. Host current Date and Time \n2. Host uptime\n"

+ "3. Host memory use \n4. Host Netstat \n5. Host current users "

+ "\n6. Host running processes \n7. Benchmark (measure mean response time)\n8. Quit ");

System.out.print("Please provide number corresponding to the action you want to be performed: ");

Scanner sc = new Scanner(System.in);

if (sc.hasNextInt()) menuSelection = sc.nextInt();

}

return menuSelection;

}

/**

* Function to prompt the user for a benchmark command to run

* @return command number 1-6

*/

public static int benchmarkMenu() {

int menuSelection = 0;

// loop (and prompt again) until the user's input is an integer between 1 and 6

while ((menuSelection <= 0) || (menuSelection > 6)) {

System.out.println("Which command would you like to benchmark? ");

System.out.println("1. Host current Date and Time \n2. Host uptime\n"

+ "3. Host memory use \n4. Host Netstat \n5. Host current users "

+ "\n6. Host running processes");

System.out.print("Please provide number corresponding to the action you want to be performed: ");

Scanner sc = new Scanner(System.in);

if (sc.hasNextInt()) menuSelection = sc.nextInt();

}

return menuSelection;

}

/**

* Function to prompt the user for how many connections to make (for measuring the mean response time)

* @return number 1-100

*/

public static int numProcessesMenu() {

int menuSelection = 0;

// loop (and prompt again) until the user's input is an integer between 1 and 100

while ((menuSelection <= 0) || (menuSelection > 100)) {

System.out.print("How many connections to the server would you like to open? [1-100]: ");

Scanner sc = new Scanner(System.in);

if (sc.hasNextInt()) menuSelection = sc.nextInt();

}

return menuSelection;

}

}