ChatPlus/src/main/java/cn/revaria/chatplus/util/TextStyleFormatter.java

package cn.revaria.chatplus.util;

#if MC_VER <= MC_1_20
import net.minecraft.text.LiteralTextContent;
#else
import net.minecraft.text.PlainTextContent.Literal;
#endif

import net.minecraft.item.ItemStack;
import net.minecraft.server.network.ServerPlayerEntity;
import net.minecraft.text.MutableText;
import net.minecraft.text.Text;

import java.util.ArrayDeque;
import java.util.Deque;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class TextStyleFormatter {
	public static int MAIN_HAND = -1; // Must be smaller than or equal to 0

	/**
	 * Processes text styling with two key functions:
	 * <p>
	 *     1. Replaces {@code &} with {@code §}, using {@code &&} to escape literal {@code &}<br>
	 *     2. Substitutes {@code [item]} with main-hand item hover text and {@code [item=N]} with Nth slot's hover text
	 * </p>
	 * Recursively processes nested text components.
	 *
	 * @param sourceText Original text to process (supports nested text components)
	 * @param sourcePlayer Player used for item stack references
	 * @return Processed text with styling and item hover elements
	 */
	public static MutableText applyStyle(Text sourceText, ServerPlayerEntity sourcePlayer) {
		MutableText sourceMutableText = sourceText.copy();

		MutableText finalText = Text.empty().setStyle(sourceMutableText.getStyle());

		if (sourceText.getContent() instanceof #if MC_VER <= MC_1_20 LiteralTextContent #else Literal #endif plainTextContent) {
			String changedMessage = plainTextContent.string()
				.replace('&', '§')
				.replace("§§", "&");
			String regex = "\\[item(?:=([1-9]))?\\]";
			String[] messages = changedMessage.split(regex, -1);
			Deque<Integer> itemDeque = new ArrayDeque<>();

			Matcher matcher = Pattern.compile(regex).matcher(changedMessage);
			while (matcher.find()) {
				String digit = matcher.group(1);
				if (digit == null) {
					itemDeque.addLast(MAIN_HAND);
				} else {
					itemDeque.addLast(Integer.parseInt(digit));
				}
			}

			for (String message : messages) {
				finalText.append(Text.literal(message));
				if (!itemDeque.isEmpty()) {
					ItemStack itemStack;
					if (itemDeque.getFirst() == MAIN_HAND) {
						itemStack = sourcePlayer.getMainHandStack();
					} else {
						itemStack = sourcePlayer.getInventory().getStack(itemDeque.getFirst() - 1);
					}
					finalText.append(itemStack.toHoverableText());
					itemDeque.removeFirst();
				}
			}
		}

		List<Text> sourceTexts = sourceMutableText.getSiblings();
		for (Text text : sourceTexts) {
			finalText.append(applyStyle(text, sourcePlayer));
		}

		return finalText;
		}
	
		/**
		 * Simple style application that only replaces color codes.
		 * Used for anvil renaming where [item] tags are not appropriate.
		 *
		 * @param text The text to format
		 * @return Formatted text with § color codes
		 */
		public static String applySimpleStyle(String text) {
			if (text == null) return null;
			return text.replace('&', '§').replace("§§", "&");
		}
	}