/** 
  * Account Balance and Savings Limit Demonstrator
  * @author Robert J Morton YE572246C
  * @version 25 November 2001 revamped 16 November 2007
  * Converted to a JFramed application Thu 09 Mar 2017  */

/* Open a terminal and change directory to where this file is loacated.
   To compile this program, enter the terminal command: javac savlim.java
   To run this program, enter the terminal command: java savlim */

import javax.swing.*;
import java.awt.Dimension;  // to be able to set the preferred JFrame size
import java.awt.Color;      // to be able to set JFrame background colour

public class savlim extends JFrame {

  private static final long 
    serialVersionUID = 601L;  // what the hell this is for, I don't know!

  private int
    XE = 502,  // Horizontal extent of window and JFrame. 500 + 2
    YE = 375;  // Vertical extent of window and JFrame.   350 + 25

  private static String[] SW = {"-f", "-j", "-s"};
  private static int[] LS = {0, 1, 2};
  private static int ls = 1;

  private static String  // default URL of the class, image and data files 
    cb = "http://localhost/software/java_progs/savlim/"; 

   /* Declare a reference to an instance of the child class. Beware:
   and instance of the child class cannot be created here because 
   this must be done within the invokeAndWait environment. */
   private savlim1 child; 

  public savlim() {  // construct an instance of this extended JFrame

    //set window frame title on title bar
    super("Account Balance and Savings Limit Demonstrator");

    /* Set up the window listener to listen for the window close command which
    occurs when the user clicks on the X control in the window's title bar.*/
    setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

    /* Set the initial size of the extended JFrame. This is the area INSIDE 
    the frame. It does not include the border or the title bar areas. */
    setPreferredSize(new Dimension(XE, YE));

    setBounds(0,0,XE,YE);         // of area inside window frame
    setBackground(Color.black);   // default background colour of JFrame
    child = new savlim1(ls,cb);   // Create new instance of savlim class
    getContentPane().add(child);  // add it to the extended JFrame's pane.
    pack();                       // should automatically pack to fill JFrame
    setVisible(true);             // make this extended JFrame visible
  }


  public static void main(final String[] args) {

    if(argsValid(args)) {

    /* Initiate the creation of a new instance of this extended JFrame then
    wait until the building process has completely finished before giving
    the new instance of the child class permission to commence running. */

    try {
      javax.swing.SwingUtilities.invokeAndWait(
        new Runnable(){public void run(){new savlim();}});
    } catch(Exception e) {
      System.out.println("Couldn't create Swing GUI.");
      System.out.println("There's probably an error in the constructor");
      System.out.println("code of one of this class's child classes.");
      System.out.println(e);
      System.out.println(e.getCause()); 
    }

    /* The above try-catch sequence is necessary for the following reason. 
    The statement "new savlim();" is a request to Swing to create a GUI in-
    stance of this application. It includes, in effect, all the statements
    in the constructor methods of all this class's child classes. All these
    requests are made on this, the main() program thread. 

    However, these requests are carried out [ie the actual constructing is 
    done] by the underlying Swing system on the Event Despatching Thread. 
    The constructing process necessarily takes longer to do than the mere
    task of REQUESTING that the constructing be done. This means that the
    main() thread will set the run() thread in motion before the GUI has 
    finished being constructed. Hence trouble.

    The solution is to force the main() thread to withhold permission for 
    the run() thread to start its job until the Event Despatching Thread 
    has completely finished constructing the GUI.

    NOTE: This class inherits a paint() method from the JFrame class that 
    it extends. This method automatically calls the paint() method of the
    child [extended JPanel] class when necessary. */

     }  // end of if(argsValid)
  }     // end of main()


  private static boolean argsValid(String[] args) {
    int L = args.length;  // number of command-line arguments
    if(L == 0)            // if command line has no arguments
      return true;
    String s = args[0];   // the first command line argument

    if(s.indexOf("help") != -1) {
      System.out.println("This program accepts command line arguments to");
      System.out.println("say from where it should load its data files:");
      System.out.println("-f = load files from local directory.");
      System.out.println("-j = load files from this app's jar file.");
      System.out.println("-s = load files from a specified server.");
      System.out.println("A URL may be entered after the -s switch.");
      System.out.println("If no URL is given, a default URL is used.");
      return false;
    }
    for(int i = 0; i < 3; i++) {
      if(s.equals(SW[i])) {
        ls = i; break;
      }
    }
    if(L < 2)      // no second argument so use default URL
      return true;
    cb = args[1];  // there must be a second arguement [URL]
    if(!cb.startsWith("http://")) {
      System.out.println("URL has absent or invalid protocol.");
      return false;
    }
    return true;
   }
}  //end of savlim class