CometSkyBlock/plugin/src/main/java/com/alttd/cometskyblock/util/StringUtil.java

package com.alttd.cometskyblock.util;

import java.util.*;
import java.util.stream.Collectors;

public class StringUtil {

    /**
     * Splits a mini message string into smaller chunks. It re-opens any unclosed tags it encounters for
     * each part of the string added to the list
     *
     * @param string the mini message string to split
     * @return a list of the split strings
     */
    public static List<String> splitMiniMessageString(String string) {
        Set<String> tags = findTags(string);
        List<String> splitString = new ArrayList<>();
        Stack<String> openTags = new Stack<>();
        Stack<String> previousOpenTags = new Stack<>();
        int startCurString = 0;
        int len = 0;
        int i = 0;
        for (; i < string.length(); i++) {
            while (string.charAt(i) == '<') {
                i = skipTags(i, string, openTags, tags);
            }
            len++;
            if (len != 30) {
                continue;
            }
            while (i < string.length() && !Character.isWhitespace(string.charAt(i))) {
                while (string.charAt(i) == '<') {
                    i = skipTags(i, string, openTags, tags);
                }
                if (Character.isWhitespace(string.charAt(i))) {
                    break;
                }
                i++;
            }
            String prependTags = previousOpenTags.stream().map(str -> "<" + str + ">").collect(Collectors.joining(""));
            splitString.add(prependTags + string.substring(startCurString, i));
            previousOpenTags.clear();
            previousOpenTags.addAll(openTags);
            startCurString = ++i;
            len = 0;
        }
        if (startCurString < string.length()) {
            String prependTags = previousOpenTags.stream().map(str -> "<" + str + ">").collect(Collectors.joining(""));
            splitString.add(prependTags + string.substring(startCurString));
        }
        return splitString;
    }

    private static int skipTags(int i, String string, Stack<String> openTags, Set<String> tags) {
        StringBuilder tagBuilder = new StringBuilder();
        i++;
        for (; i < string.length() && string.charAt(i) != '>'; i++) {
            tagBuilder.append(string.charAt(i));
        }
        String tagString = tagBuilder.toString();
        if (!tagString.isEmpty() && tagString.charAt(0) == '/') {
            if (!openTags.isEmpty() && openTags.peek().contentEquals(tagString.substring(1))) {
                openTags.pop();
            }
        } else if (tags.contains(tagString)) {
            openTags.add(tagString);
        }
        tagBuilder.setLength(0);
        return Math.min(++i, string.length() - 1);
    }

    public static Set<String> findTags(String string) {
        List<String> tags = new ArrayList<>();
        HashSet<String> closedTags = new HashSet<>();
        StringBuilder tag = new StringBuilder();
        boolean tagFound = false;

        for (int i = 0; i < string.length(); i++) {
            if (string.charAt(i) == '<') {
                tagFound = true;
                continue;
            }

            if (string.charAt(i) == '>') {
                tagFound = false;

                if (tag.charAt(0) != '/') {
                    tags.add(tag.toString());
                } else {
                    String closingTag = tag.substring(1);
                    if (tags.contains(closingTag)) {
                        tags.remove(closingTag);
                        closedTags.add(closingTag);
                    }
                }

                tag.setLength(0);
                continue;
            }

            if (tagFound) {
                tag.append(string.charAt(i));
            }
        }

        return closedTags;
    }

}