src/game/java/net/minecraft/client/CommandHistory.java

package net.minecraft.client;

import com.google.common.base.Charsets;
import com.mojang.logging.LogUtils;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Collection;
import net.minecraft.util.ArrayListDeque;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;
import org.slf4j.Logger;

@OnlyIn(Dist.CLIENT)
public class CommandHistory {
    private static final Logger LOGGER = LogUtils.getLogger();
    private static final int MAX_PERSISTED_COMMAND_HISTORY = 50;
    private static final String PERSISTED_COMMANDS_FILE_NAME = "command_history.txt";
    private final Path commandsPath;
    private final ArrayListDeque<String> lastCommands = new ArrayListDeque<>(50);

    public CommandHistory(Path p_298502_) {
        this.commandsPath = p_298502_.resolve("command_history.txt");
        if (Files.exists(this.commandsPath)) {
            try (BufferedReader bufferedreader = Files.newBufferedReader(this.commandsPath, Charsets.UTF_8)) {
                this.lastCommands.addAll(bufferedreader.lines().toList());
            } catch (Exception exception) {
                LOGGER.error("Failed to read {}, command history will be missing", "command_history.txt", exception);
            }
        }
    }

    public void addCommand(String p_298813_) {
        if (!p_298813_.equals(this.lastCommands.peekLast())) {
            if (this.lastCommands.size() >= 50) {
                this.lastCommands.removeFirst();
            }

            this.lastCommands.addLast(p_298813_);
            this.save();
        }
    }

    private void save() {
        try (BufferedWriter bufferedwriter = Files.newBufferedWriter(this.commandsPath, Charsets.UTF_8)) {
            for (String s : this.lastCommands) {
                bufferedwriter.write(s);
                bufferedwriter.newLine();
            }
        } catch (IOException ioexception) {
            LOGGER.error("Failed to write {}, command history will be missing", "command_history.txt", ioexception);
        }
    }

    public Collection<String> history() {
        return this.lastCommands;
    }
}