AppleTunneler/src/main/java/net/limework/networking/AppleTunneler.java

package net.limework.networking;

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitRunnable;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

public class AppleTunneler extends JavaPlugin {

    private Session sshSession;
    private final JSch jsch = new JSch();

    private synchronized void createNewConnection() throws JSchException {
        if (sshSession != null) {
            sshSession.disconnect();
        }
        sshSession = jsch.getSession(getUsername(), getHost(), getPort());
        sshSession.connect(2000);
        getLogger().info("Ssh connection started successfully!");
        loadRemoteToLocalPortForwarding();
    }

    private void connectionFailedLog(JSchException exception) {
        getLogger().severe("==========================");
        getLogger().severe("failed to start a connection");
        exception.printStackTrace();
        getLogger().severe("==========================");

    }

    private void loadIds() throws JSchException {
        File file = new File(getDataFolder(), "Identities");
        if (file.mkdir()) {
            getLogger().info("created Identities folder.");
        }
        File[] files = file.listFiles();

        if (files == null || files.length == 0) {
            getLogger().warning("no Identities files found, please put them in " + file.getPath());
            throw new RuntimeException("no Identities files found");
        }
        for (File id : files) {
            jsch.addIdentity(id.getPath());
        }
        getLogger().info("Ids were loaded!");
    }

    private void loadRemoteToLocalPortForwarding() throws JSchException {
        for (String line : getConfig().getStringList("ports")) {
            sshSession.setPortForwardingL(line);
            getLogger().info(line);
        }
        getLogger().info("ports has been set!");
    }

    private void loadKnownHostFile() throws FileNotFoundException, JSchException {
        File knownHosts = new File(getDataFolder(), ".known_hosts");
        // check whatever known hosts file is folder somehow if so delete it.
        if (knownHosts.isDirectory()) {
            knownHosts.delete();
        }
        if (!knownHosts.exists()) {
            getLogger().severe("FILE at path: " + knownHosts.getAbsolutePath() + " Does not exists");
            throw new RuntimeException("Known host file does not exists in plugin folder");
        }
        this.jsch.setKnownHosts(new FileInputStream(knownHosts));
        getLogger().info("host file was loaded!");

    }

    @Override
    public void onLoad() {
        this.saveDefaultConfig();
        try {
            loadIds();
            loadKnownHostFile();
        } catch (JSchException | FileNotFoundException e) {
            throw new RuntimeException(e);
        }
        try {
            createNewConnection();
        } catch (JSchException e) {
            connectionFailedLog(e);
        }
    }

    @Override
    public void onEnable() {
        new BukkitRunnable() {
            private boolean isConnecting = false;
            @Override
            public void run() {
                if (isConnecting) {
                    return;
                }
                if (!sshSession.isConnected()) {
                    isConnecting = true;
                    try {
                        createNewConnection();
                    } catch (JSchException e) {
                        connectionFailedLog(e);
                    }
                    isConnecting = false;
                }
            }
        }.runTaskTimerAsynchronously(this, 0, 20);
        getLogger().info("reconnecting task was registered successfully");

    }

    /*
        Currently there is no onDisable because plugin might disable itself before another
        which might causes disconnections and data never saved

     */

    private int getPort() {
        return this.getConfig().getInt("port");
    }

    private String getUsername() {
        return this.getConfig().getString("username");
    }

    private String getHost() {
        return this.getConfig().getString("host");
    }
}