AdvancedScripts/src/main/java/de/zonlykroks/advancedscripts/lexer/ExpressionColorizer.java

package de.zonlykroks.advancedscripts.lexer;

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

public class ExpressionColorizer {

    private ExpressionColorizer() {
        throw new IllegalStateException("Utility class");
    }

    public static List<Token> colorize(String expression) {
        List<String> parts = tokenize(expression);
        List<Token> tokens = new ArrayList<>();
        for (int i = 0; i < parts.size(); i++) {
            String part = parts.get(i);
            if ("{".equals(part) || "}".equals(part)) {
                tokens.add(new Token(part, TokenTypeColors.OTHER));
                continue;
            }
            if ("true".equalsIgnoreCase(part) || "false".equalsIgnoreCase(part)) {
                tokens.add(new Token(part, TokenTypeColors.BOOLEAN));
                continue;
            }
            try {
                Double.parseDouble(part);
                tokens.add(new Token(part, TokenTypeColors.NUMBER));
                continue;
            } catch (NumberFormatException ignored) {
            }
            try {
                Long.parseLong(part);
                tokens.add(new Token(part, TokenTypeColors.NUMBER));
                continue;
            } catch (NumberFormatException ignored) {
            }
            if (part.contains(".")) {
                String[] split = part.split("\\.");
                if (split.length == 1) {
                    tokens.add(new Token(part, TokenTypeColors.VARIABLE));
                    continue;
                }
                if (VariablePrefixes.RPEFIXES.contains(split[0])) {
                    tokens.add(new Token(split[0], TokenTypeColors.OTHER));
                    tokens.add(new Token(".", TokenTypeColors.OTHER));
                    split = Arrays.copyOfRange(split, 1, split.length);
                }
                tokens.add(new Token(split[0], TokenTypeColors.VARIABLE));
                for (int j = 1; j < split.length; j++) {
                    String s = split[j];
                    tokens.add(new Token(".", TokenTypeColors.OTHER));
                    if (VariableSuffixes.SUFFIXES.contains(s)) {
                        tokens.add(new Token(s, TokenTypeColors.OTHER));
                    } else {
                        tokens.add(new Token(s, TokenTypeColors.ERROR));
                    }
                }
                continue;
            }
            if (Operators.OPERATORS.contains(part)) {
                String previous = get(parts, i, -1);
                String next = get(parts, i, 1);
                if (previous == null || next == null) {
                    tokens.add(new Token(part, TokenTypeColors.ERROR));
                    continue;
                }
                if (Operators.OPERATORS.contains(previous) || Operators.OPERATORS.contains(next)) {
                    tokens.add(new Token(part, TokenTypeColors.ERROR));
                    continue;
                }
                if ("{".equals(previous) || "}".equals(next)) {
                    tokens.add(new Token(part, TokenTypeColors.ERROR));
                    continue;
                }
                tokens.add(new Token(part, TokenTypeColors.OTHER));
                continue;
            }
            if (part.matches("[+\\-*/%^&|<>=!]+")) {
                tokens.add(new Token(part, TokenTypeColors.ERROR));
                continue;
            }
            tokens.add(new Token(part, TokenTypeColors.VARIABLE));
        }
        return tokens;
    }

    private static String get(List<String> parts, int index, int direction) {
        for (int i = index + direction; i >= 0 && i < parts.size(); i += direction) {
            String part = parts.get(i);
            if (!part.isBlank()) return part;
        }
        return null;
    }

    private static List<String> tokenize(String s) {
        List<String> tokens = new ArrayList<>();
        StringBuilder token = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (c == '{' || c == '}' || c == ' ') {
                if (token.length() > 0) {
                    tokens.add(token.toString());
                    token = new StringBuilder();
                }
                tokens.add(c + "");
                continue;
            }
            StringBuilder op = new StringBuilder();
            for (int j = i; j < s.length(); j++) {
                char k = s.charAt(j);
                if (k == '+' || k == '-' || k == '*' || k == '/' || k == '%' || k == '^' || k == '&' || k == '|' || k == '>' || k == '<' || k == '=' || k == '!') {
                    op.append(k);
                } else {
                    break;
                }
            }
            if (op.length() > 0) {
                if (token.length() > 0) {
                    tokens.add(token.toString());
                    token = new StringBuilder();
                }
                tokens.add(op.toString());
                i += op.length() - 1;
                continue;
            }
            token.append(c);
        }
        if (token.length() > 0) {
            tokens.add(token.toString());
        }
        return tokens;
    }
}