import java.util.Scanner;

/* QueueTester.java
** This Java application is for the purpose of testing a class that
** implements the Queue interface. 
**
** Author: R. McCloskey
** Date: October 2025
*/

public class QueueTester {

   private static boolean keepGoing;
   private static Scanner keyboard = new Scanner(System.in);

   public static void main(String[] args) {
      System.out.println("Welcome to the QueueViaLink1Circ Tester!");

      // For our current purposes, the class to be tested is QueueViaLink1Circ.
      Queue<String> queue = new QueueViaLink1Circ<String>();

      testQueue(queue);
   }

   public static void testQueue(Queue<String> queue) {
      keepGoing = true;
      while (keepGoing) {
         String command;
         // Prompt user until a non-empty string is entered
         do {
            System.out.print("\n> ");
            command = keyboard.nextLine().trim();
         }
         while (command.length() == 0);

         // Having received a non-empty command, try to perform it.
         try {
            performCommand(queue, command);
         }
         catch (Exception e) {
            e.printStackTrace(System.out);
            System.out.println("\n Something went wrong; try again");
         }
      }
      System.out.println("Goodbye.");
   }

   private static final String QUIT = "q";
   private static final String HELP = "h";
   private static final String SIZE = "#";
   private static final String FRONT = "f";
   private static final String ENQUEUE = "e";
   private static final String DEQUEUE = "d";
   private static final String PRINT = "p";

   /* Applies the command described by the second parameter to the queue
   ** given by the first.
   */
   private static void performCommand(Queue<String> queue, String command) {
      Scanner comScanner = new Scanner(command);
      String commandCode = comScanner.next().toLowerCase();
      String insertWarning = "Need to specify a string to insert!";
      
      if (commandCode.equals(QUIT)) {
         keepGoing = false;
      } 
      else if (commandCode.equals(HELP)) { 
         printHelp();
      }
      else if (commandCode.equals(SIZE)) { 
         System.out.printf("Size of queue is %s\n", queue.sizeOf());
      }
      else if (commandCode.equals(FRONT)) { 
         System.out.printf("Front item is %s\n", queue.frontOf());
      }
      else if (commandCode.equals(ENQUEUE)) {    // insert item at rear
         if (!comScanner.hasNext()) {
            System.out.println(insertWarning);
         }
         else {
            String item = comScanner.next();
            System.out.printf("Inserting \"%s\" at rear...\n", item);
            queue.enqueue(item);
            printContents(queue);
         }
      }
      else if (commandCode.equals(DEQUEUE)) {  // remove item at front
         System.out.println("Removing item at front...");
         queue.dequeue();
         printContents(queue);
      }
      else if (commandCode.equals(PRINT)) { 
         printContents(queue);
      }
      else {
         System.out.println("Unrecognized command.");
      }
   }

   private static void printHelp() {
      System.out.println(QUIT + ": to quit");
      System.out.println(HELP + ": for help");
      System.out.println(SIZE + ": to print size of queue");
      System.out.println(FRONT + ": to print item at front of queue");
      System.out.println(ENQUEUE + " x: to enqueue x at rear");
      System.out.println(DEQUEUE + ": dequeue (remove item from front)");
      System.out.println(PRINT + ": to print contents of queue");
   }

   private static void printContents(Queue d) {
      System.out.println("Contents of queue: " + d);
   }

}