// Illustrating inheritance and simple terminal I/O in Java

import java.io.*;

class StudentDB
{

  public static void main (String args[]) throws IOException
  {
    Database D1 = new Database(100);
    String m, inputstring;
    String sn;
    int y;
    String com;

    BufferedReader din = new BufferedReader(new InputStreamReader(System.in));

    System.out.print("Enter command: ");
    com = din.readLine();
    while (! com.equalsIgnoreCase("QUIT"))
      {
	if (com.equalsIgnoreCase("ADD"))
	  {
	    String student_type = null;
	    boolean legal_type = false;
	    while (! legal_type)
	      {
		System.out.print("Enter student type: (Grad or Student): ");
		student_type = din.readLine();
		if (student_type.equalsIgnoreCase("graduate") ||
		    student_type.equalsIgnoreCase("student"))
		  legal_type = true;
		else System.out.println("Illegal type of Student");
	      }

	    System.out.print("Enter ssn: ");
	    sn = din.readLine();
	    System.out.print("Enter name: ");
	    m = din.readLine();
	    System.out.print("Enter age: ");
	    inputstring = din.readLine();
	    y = Integer.parseInt(inputstring);
	    if (student_type.equalsIgnoreCase("graduate"))
	      {
		System.out.print("Enter thesis: ");
		String thes = din.readLine();
		System.out.print("Enter advisor: ");
		String adv = din.readLine();
		D1.add_Student(new Graduate(sn, thes, m, y, adv));
	      }
	    else D1.add_Student(new Student(sn, m, y));
	  }
	else if (com.equalsIgnoreCase( "REMOVE"))
	  {
	    System.out.print("Enter ssn: ");
	    sn = din.readLine();
	    D1.remove_Student(sn);
	  }

	else if (com.equalsIgnoreCase("DISPLAY"))
	  {
	    System.out.print("Enter ssn: ");
	    sn = din.readLine();
	    D1.display_Student(sn);
	  }

	else if (com.equalsIgnoreCase("SHOWALL"))
	  {
	    D1.display_all();
	  }

	else
	  System.out.println("Error case");

	System.out.print("Enter next command: ");
	com = din.readLine();
	
      }
  }
}