AutomaticLogDeleter/src/main/java/net/limework/automaticlogdeleter/AutomaticLogDeleter.java

package net.limework.automaticlogdeleter;

import org.bukkit.configuration.file.FileConfiguration;
import org.bukkit.plugin.java.JavaPlugin;

import java.io.File;
import java.util.logging.Level;

public class AutomaticLogDeleter extends JavaPlugin {

    @Override
    public void onEnable() {
        new Thread(() -> {
            this.saveDefaultConfig();
            deleteLogs();
        }).start();
    }

    @Override
    public void onDisable() {
        FileConfiguration config = getConfig();
        if (config.getBoolean("also-delete-logs-on-shutdown")) {

            //we aren't using separate thread here, so it has time to finish before server shutdowns

            deleteLogs();
        }
    }

    public void deleteLogs() {
        File path = new File("logs");

        File[] files = path.listFiles();
        if (files == null) { return; }
        FileConfiguration config = getConfig();

        //maximum file age allowed

        long maxOldMillis = config.getLong("delete-logs-older-than-seconds") * 1000;
        String fileName;

        for (File file : files) {
            if (file.isFile()) {
                fileName = file.getName();

                //if file is not a log file
                //using contains to make it more likely to catch different types of logging systems
                if (!fileName.contains(".log") && !fileName.contains("log.")) {
                    continue;
                }

                //if file is older than configured time
                if ((System.currentTimeMillis() - file.lastModified()) < maxOldMillis) {
                    continue;
                }

                if (!file.delete()) {
                    getLogger().log(Level.WARNING, "[AutomaticLogDeleter] Failed to delete server log file! Are you sure the file permissions are correct?");
                } else {
                    getLogger().log(Level.INFO, "[AutomaticLogDeleter] Deleted log file " + fileName);
                }
            }
        }
    }
}