// CopyCat
//
// Continuously scrolling message board for permanent and temporary messages.
//
// Author  Matthew Caryl
// Created 16.4.96
//
// SUGGESTIONS FOR NEXT TIME
// Try making an array of characters to represent the message window.
// One system would handle these characters, the other would push
// characters in at the far end.  Character system would not have to
// use cliprect and would not have to think about old messages.	 The
// other system would deal with revolving messages.	 To update messages
// may use another id system and retyping of previous messages.
// Messages have to be prioritised so that new messages come up first.
// What about constant rate scrolling independant of frame update.

package CopyCat;

import java.awt.*;

final class MessageBoard {
	private static int	MESSAGE_TIME_ALLOWANCE = 2000;
	private String[]	messageStrings = new String[0];
	private boolean[]	messagePermanent = new boolean[0];
	private int			messageCurrent = -1;
	private int			messageLast = -1;
	private boolean		messageLost;
	private int			messageScroll = 0;
	private long		messageExpiry;
	private Font		messageFont = new Font("Courier", Font.PLAIN, 14);
	private int			characterHeight;
	private int			characterWidth;
	private int			messageWidth;
	private boolean		dirty;
	private int			width;
	private int			height;
	private Image		image;
	private Graphics	graphics;
	
	private void expand() {
		String[] ms = new String[messageStrings.length + 1];
		for (int i = messageStrings.length - 1; i >= 0; i--)
			ms[i] = messageStrings[i];
		messageStrings = ms;
		boolean[] mp = new boolean[messagePermanent.length + 1];
		for (int i = messagePermanent.length - 1; i >= 0; i--)
			mp[i] = messagePermanent[i];
		messagePermanent = mp;
		}
	
	private int spare() {
		for (int i = messageStrings.length - 1; i >= 0; i--)
			if (messageStrings[i] == null)
				return i;
		expand();
		return messageStrings.length - 1;
		}
	
	private int next() {
		for (int i = messageCurrent - 1; i >= 0; i--)
			if (messageStrings[i] != null)
				return i;
		int stop = Math.max(messageCurrent, 0);
		for (int i = messageStrings.length - 1; i >= stop; i--)
			if (messageStrings[i] != null)
				return i;
		return -1;
		}
	
	private void scroll() {
		messageLast = messageCurrent;
		if (messageLast >= 0 && !messagePermanent[messageLast])
			messageStrings[messageLast] = null;
		messageCurrent = next();
		messageExpiry = System.currentTimeMillis() + MESSAGE_TIME_ALLOWANCE;
		if (messageCurrent != messageLast) {
			messageScroll = messageWidth;
			dirty = true;
			}
		}
	
	protected void finalize() throws Throwable {
		if (graphics != null)
			graphics.dispose();
		super.finalize();
		}
	
	public MessageBoard(Graphics g, int W, int H, Component C) {
		width = W;
		height = H;
		FontMetrics m = g.getFontMetrics(messageFont);
		characterHeight = m.getHeight();
		characterWidth = m.charWidth(' ');
		messageWidth = width / characterWidth;
		dirty = true;
		image = C.createImage(W, H);
		graphics = image.getGraphics();
		}
	
	public int post(String message, boolean permanent) {
		int spare = spare();
		messageStrings[spare] = message;
		messagePermanent[spare] = permanent;
		if (messageCurrent < 0)
			scroll();
		return spare;
		}
	
	public int post(String message) {
		return post(message, false);
		}
	
	public void update(int id, String message) {
		messageStrings[id] = message;
		if (id == messageCurrent | id == messageLast)
			dirty = true;
		}
	
	public void delete(int id) {
		messageStrings[id] = null;
		if (id == messageLast)
			messageLost = true;
		if (id == messageCurrent)
			scroll();
		}
	
	public void paint(Graphics g, int X, int Y) {
		g.drawImage(image, X, Y, null);
		}
	
	public boolean dirty() {
		if (messageScroll > 0) {
			messageScroll--;
			dirty = true;
			}
		else if (System.currentTimeMillis() >= messageExpiry)
			scroll();
		if (dirty) {
			graphics.setColor(Color.black);
			graphics.fillRect(0, 0, width, height);
			if (messageCurrent >= 0) {
				graphics.setColor(Color.white);
				graphics.setFont(messageFont);
				graphics.drawString(messageStrings[messageCurrent], 2 + messageScroll * characterWidth, (height + characterHeight) / 2 - 2);
				}
			dirty = false;
			return true;
			}
		else
			return false;
		}
	}