ScoreboardTest.java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;

import org.bukkit.Bukkit;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scoreboard.DisplaySlot;
import org.bukkit.scoreboard.Objective;
import org.bukkit.scoreboard.Score;
import org.bukkit.scoreboard.Scoreboard;

import net.kyori.adventure.text.Component;
import net.md_5.bungee.api.ChatColor;

/*
 * Plugin to test the consistency of the display of custom data in
 * the scoreboard’s sidebar, beteen Java client and Bedrock client (using Geyser).
 * 
 * The code provides 2 implementations of the way to update the scorebard.
 * Change the method used at line 53-54. Both methods, with their documentations,
 * Are implemented below in this file.
 * 
 * Dependency : paper-api 1.17.1-R0.1-SNAPSHOT
 */
public class ScoreboardTest extends JavaPlugin {
  
	
	@Override
	public void onEnable() {
		scoreboard = Bukkit.getScoreboardManager().getMainScoreboard();
		
		Bukkit.getScheduler().runTaskTimer(this, this::update, 100, 100);
	}
	
	
	final String[] linePrefixes = new String[] { "1st ", "2nd ", "3rd ", "4th ",
			"5th ", "6th ", "7th ", "8th ", "9th ", "10th " };
	final int count = linePrefixes.length;
	final int[] counters = new int[count];
	final Random rnd = new Random();
	Scoreboard scoreboard;
	
	
	private void update() {
		counters[rnd.nextInt(count)]++;
		
		String[] lines = new String[count];
		for (int i = 0; i < count; i++) {
			lines[i] = linePrefixes[i] + counters[i];
		}

		//ScoreBoardUtil.updateScoreboardSidebarInADumbWay(scoreboard, Component.text("This is a test"), lines);
		ScoreBoardUtil.updateScoreboardSidebar(scoreboard, Component.text("This is a test"), lines);
	}
	
	
}




class ScoreBoardUtil {

	/**
	 * Update the sidebar of the provided scoreboard, with the given title and lines.
	 * 
	 * Compared to {@link #updateScoreboardSidebar(Scoreboard, Component, String[])}, this method
	 * is less intelligent, since it reset the objective values at every updates and resend every lines.
	 * @param scBrd the scoreboard
	 * @param title the title of the sidebar
	 * @param lines the lines that have to be displayed. Null values are treated as empty lines.
	 *              The lines support legacy formatting only, and will be truncated to 40 characters.
	 *              Lines present multiple times will have hidden characters appended to make them different.
	 *              Vanilla Java Edition clients only display the 15 first lines.
	 */
	public static void updateScoreboardSidebarInADumbWay(Scoreboard scBrd, Component title, String[] lines) {
		
		Objective obj = scBrd.getObjective("sidebar_autogen");
		if (obj != null) {
			obj.unregister();
		}
		obj = scBrd.registerNewObjective("sidebar_autogen", "dummy", title);
		obj.displayName(title);
		obj.setDisplaySlot(DisplaySlot.SIDEBAR);
		
		filterLines(lines);

		int boardPos = lines.length;
		for (String line : lines) {
			obj.getScore(line).setScore(boardPos--);
		}
		
		
	}
	
	
	
	/**
	 * Update the sidebar of the provided scoreboard, with the given title and lines.
	 *
	 * @param scBrd the scoreboard
	 * @param title the title of the sidebar
	 * @param lines the lines that have to be displayed. Null values are treated as empty lines.
	 *              The lines support legacy formatting only, and will be truncated to 40 characters.
	 *              Lines present multiple times will have hidden characters appended to make them different.
	 *              Vanilla Java Edition clients only display the 15 first lines.
	 * @implNote The implementation makes sure that the minimum amount of data is transmitted to the client,
	 *           to reduce bandwith usage and avoid the sidebar flickering.
	 *           <ul>
	 *           <li>If a provided line is already present in the sidebar, and at the same line number, it will not be updated.
	 *           <li>If a provided line is already present but at another position, only the score (i.e. the line number) is updated.
	 *           <li>If a provided line was not present before, it is added as a new score entry in the scoreboard.
	 *           <li>If a line that was already present is not in the provided lines, it is removed from the scoreboard.
	 *           <li>The title is only updated if it has actually changed.
	 */
	public static void updateScoreboardSidebar(Scoreboard scBrd, Component title, String[] lines) {
		if (scBrd == null) throw new IllegalArgumentException("scBrd doit être non null");
		if (lines == null) lines = new String[0];
		
		Objective obj = scBrd.getObjective("sidebar_autogen");
		if (obj != null && !obj.getCriteria().equalsIgnoreCase("dummy")) {
			// objective present but with wrong criteria, removing it
			obj.unregister();
			obj = null;
		}
		
		
		if (obj == null) {
			obj = scBrd.registerNewObjective("sidebar_autogen", "dummy", title);
			obj.setDisplaySlot(DisplaySlot.SIDEBAR);
		}
		else {
			// only update title if needed
			if (!title.equals(obj.displayName()))
				obj.displayName(title);
			// fix display slot if someone else changed it
			if (DisplaySlot.SIDEBAR != obj.getDisplaySlot())
				obj.setDisplaySlot(DisplaySlot.SIDEBAR);
		}
		
		
		filterLines(lines);
		
		List<String> listLines = Arrays.asList(lines);
		
		// remove lines from the scoreboard that are not in the provided array
		Objective fObj = obj;
		scBrd.getEntries().stream()
				.filter(e -> !listLines.contains(e))
				.filter(e -> fObj.getScore(e).isScoreSet())
				.forEach(scBrd::resetScores);

		// add and update others lines
		int boardPos = lines.length;
		for (String line : lines) {
			Score score = obj.getScore(line);
			
			if (score.getScore() != boardPos)
				score.setScore(boardPos);
			
			boardPos--;
		}
	}
	
	
	
	
	@SuppressWarnings("deprecation")
	private static void filterLines(String[] lines) {
		List<String> previous = new ArrayList<>();
		for (int i = 0; i < lines.length; i++) {
			String line = lines[i] == null ? "" : truncateAtLengthWithoutReset(lines[i], 40);
			if (previous.contains(line)) {
				for (ChatColor c : ChatColor.values()) {
					line = truncateAtLengthWithoutReset(lines[i], 38) + c;
					if (!previous.contains(line)) {
						break;
					}
				}
			}
			lines[i] = line;
			previous.add(lines[i]);
		}
	}
	
	
	
	
	private static String truncateAtLengthWithoutReset(String text, int l) {
		if (text.length() > l) {
			text = text.substring(0, l);
			if (text.endsWith("§"))
				text = text.substring(0, text.length()-1);
		}
		return text;
	}
	

}