/**
 * Project: Java Basic Math Tools
 * Developer: Molla Samser
 * Designer & Tester: Rima Khatun
 * Website: https://rskworld.in
 * Year: 2026
 */

package com.rskworld.mathtools.utils;

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

public class HistoryManager {
    private static HistoryManager instance;
    private final List<String> history;
    private static final int MAX_HISTORY = 100;

    private HistoryManager() {
        history = new ArrayList<>();
    }

    public static synchronized HistoryManager getInstance() {
        if (instance == null) {
            instance = new HistoryManager();
        }
        return instance;
    }

    public void addEntry(String entry) {
        if (history.size() >= MAX_HISTORY) {
            history.remove(0);
        }
        history.add(entry);
    }

    public List<String> getHistory() {
        return new ArrayList<>(history);
    }

    public void clearHistory() {
        history.clear();
    }
}