import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.io.*;
import java.net.URL;

class TutorPage
{
	public TutorPage back;
	public TutorPage next;
	public String passcode;
	public StringBuffer str;
	public TutorPage wrong;
	
	public static String wrongAnswer = new String("Whoops, that was the wrong answer, click back to try again.");
	
	public TutorPage(TutorPage b)
	{
		back = b;
		next = null;
		str = new StringBuffer();
		passcode = "N";
		wrong = new TutorPage(this,wrongAnswer);
	}
	
	public TutorPage(TutorPage b, String st)
	{
		back =b;
		next = null;
		str = new StringBuffer(st);
		passcode = "N";
	}
	
	public void setNext(TutorPage n)
	{
		next = n;
	}
	
	public void append(char ch)
	{
		str.append(ch);
	}
	
	public String getText()
	{
		return str.toString();
	}
}

class OutputPanel extends Panel
{
	private Image i=null;
			 
	public void setImage(Image im)
	{
		i = im;
	}
	
	public void update(Graphics g)
	{
		paint(g);
	}
	
	public void paint(Graphics g)
	{
		Dimension d = getSize();
		int leftx = d.width-175;
		int lefty = d.height-175;
		if (i != null)
			g.drawImage(i,(int)leftx/2,(int)lefty/2,this);
	}
}

public class tutor extends Frame
{
	Panel leftPanel,buttonPanel;
	Button back,next;
	Label page;
	protected int pageNum = 1;
	protected TextArea text;
	private FileReader fr;
    private BufferedReader myInput;
	private String readstr = new String();
	private boolean gotime = false;
	private TutorPage first = null;
	private Checkbox A,B,C;
	private CheckboxGroup group;
	protected OutputPanel OP;

	public void parse()
	{
	}
	

	public tutor(String filename)
	{
		super("Java TA");
		setSize(410,260);
		setResizable(false);
		setBackground(Color.white);
		setFont(new Font("Serif",Font.PLAIN,12));
		this.addWindowListener(new WindowAdapter()
			{
				public void windowActivated(WindowEvent e)
				{  repaint();  }
		
				public void windowClosing(WindowEvent e)
				{  dispose();  }
		
				public void windowDeiconified(WindowEvent e)
				{  repaint();  }
		
				public void windowOpened(WindowEvent e)
				{  repaint();  } 
			}
							   );
		setLayout(new GridLayout(0,2,0,0)); 
		leftPanel = new Panel(new BorderLayout(0,0));
		buttonPanel = new Panel();
		back = new Button("Back");
		back.addActionListener(new ActionListener()
			{
				public void actionPerformed(ActionEvent e)
				{
					if (gotime)
					{
						if (first.back != null)
						{
							first = first.back;
							text.setText(first.getText());
							pageNum--;
							page.setText("PAGE "+pageNum);
							group.setSelectedCheckbox(null);
							parse();
						}
					}
				}
			}
							   );
		next = new Button("Next");
		next.addActionListener(new ActionListener()
			{
				public void actionPerformed(ActionEvent e)
				{
					if (gotime)
					{
						//setTitle(group.getSelectedCheckbox().getLabel());
						if (first.next != null)
						{
							boolean passed = true;
							if (!first.passcode.equals("N"))
							{
								Checkbox box = group.getSelectedCheckbox();
								if (box == null)
									passed = false;
								else if (!box.getLabel().equals(first.passcode))
									passed =false;
							}	
							if (passed)
							{
								first = first.next;
								text.setText(first.getText());
								pageNum++;
								page.setText("PAGE "+pageNum);
								group.setSelectedCheckbox(null);
								parse();
							}
							else
							{
								TutorPage wrong = new TutorPage(first,TutorPage.wrongAnswer);
								first = wrong;
								text.setText(first.getText());
								pageNum++;
								page.setText("PAGE "+pageNum);
								group.setSelectedCheckbox(null);
							}
						}		
					}
				}
			}
							   );
		page = new Label("PAGE 1",Label.CENTER);
		buttonPanel.add(back);
		buttonPanel.add(page);
		buttonPanel.add(next);
		leftPanel.add(buttonPanel,"South");
		OP = new OutputPanel();
		leftPanel.add(OP,"Center");
		add(leftPanel);
		Panel RightPanel = new Panel(new BorderLayout(0,0));
		text = new TextArea("Loading Java TA, please wait...",20,10,TextArea.SCROLLBARS_VERTICAL_ONLY);
		text.setEditable(false);
		RightPanel.add(text,"Center");
		group = new CheckboxGroup();
		A = new Checkbox("A",false,group);
		B = new Checkbox("B",false,group);
		C = new Checkbox("C",false,group);
		Panel CheckBoxPanel = new Panel(new FlowLayout(FlowLayout.CENTER));
		CheckBoxPanel.add(A);
		CheckBoxPanel.add(B);
		CheckBoxPanel.add(C);					
		RightPanel.add(CheckBoxPanel,"South");
		add(RightPanel);
		show();
		ReadFile(filename);
	}
	
	public void ReadFile(String filename)
	{
			int size =0;
			char[] data = null;
			try
			{
				URL url = new URL(filename);
				Reader fr = new InputStreamReader(url.openStream());
				int check = 0, stuff_read = 0;
				size = 20000;
				data = new char[size];
				while (check != -1)
				{
					try
					{
						check = fr.read(data,stuff_read,size);
					}
					catch (IOException ie)
					{
						text.append("ieeeee!");
					}
					if (check != -1) 	stuff_read+=check;
			}
				size = stuff_read;
			}
			catch (IOException fe)
			{
				text.append("Big IOEx you!");
			}
			int start = 0;
			TutorPage last = null;
			TutorPage temp = new TutorPage(last);
			first = temp;
			while (start < size)
			{		  
				if (data[start] != '@')
				{
					temp.append(data[start]);
				}
				else
				{	
					start++;
					last = temp;
					last.passcode = ""+data[start];
					temp = new TutorPage(last);
					last.setNext(temp);
				}
				start++;
			}
			text.setText(first.getText());
			gotime = true;
	}
	
	class TutorWindowAdapter extends WindowAdapter
	{
		private tutor KingTut;
		public TutorWindowAdapter(tutor t)
		{ KingTut = t;}
		public void windowActivated(WindowEvent e)
		{
			KingTut.repaint();
		}
		
		public void windowClosed(WindowEvent e)
		{
			KingTut.dispose();
			KingTut = null;
		}
		
		public void windowDeiconified(WindowEvent e)
		{
			KingTut.repaint();
		}
		
		public void windowOpened(WindowEvent e)
		{
			KingTut.repaint();
		}
	}
}