package com.sshmanager.controller;

import com.sshmanager.entity.Connection;
import com.sshmanager.entity.User;
import com.sshmanager.repository.ConnectionRepository;
import com.sshmanager.repository.UserRepository;
import com.sshmanager.service.ConnectionService;
import com.sshmanager.service.SshService;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import java.io.IOException;
import java.io.InputStream;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.atomic.AtomicInteger;

@Component
public class TerminalWebSocketHandler extends TextWebSocketHandler {

    private final ConnectionRepository connectionRepository;
    private final UserRepository userRepository;
    private final ConnectionService connectionService;
    private final SshService sshService;
    private final ExecutorService executor;

    private final AtomicInteger sessionCount = new AtomicInteger(0);
    private final Map<String, SshService.SshSession> sessions = new ConcurrentHashMap<>();
    private final Map<String, Long> lastActivity = new ConcurrentHashMap<>();

    public TerminalWebSocketHandler(ConnectionRepository connectionRepository,
                                    UserRepository userRepository,
                                    ConnectionService connectionService,
                                    SshService sshService,
                                    @Qualifier("terminalWebSocketExecutor") ExecutorService executor) {
        this.connectionRepository = connectionRepository;
        this.userRepository = userRepository;
        this.connectionService = connectionService;
        this.sshService = sshService;
        this.executor = executor;
    }

    @Override
    public void afterConnectionEstablished(WebSocketSession webSocketSession) throws Exception {
        Long connectionId = (Long) webSocketSession.getAttributes().get("connectionId");
        String username = (String) webSocketSession.getAttributes().get("username");

        if (connectionId == null || username == null) {
            webSocketSession.close(CloseStatus.BAD_DATA);
            return;
        }

        User user = userRepository.findByUsername(username).orElse(null);
        if (user == null) {
            webSocketSession.close(CloseStatus.BAD_DATA);
            return;
        }

        Connection conn = connectionRepository.findById(connectionId).orElse(null);
        if (conn == null || !conn.getUserId().equals(user.getId())) {
            webSocketSession.close(CloseStatus.BAD_DATA);
            return;
        }

        String password = connectionService.getDecryptedPassword(conn);
        String privateKey = connectionService.getDecryptedPrivateKey(conn);
        String passphrase = connectionService.getDecryptedPassphrase(conn);

        try {
            SshService.SshSession sshSession = sshService.createShellSession(conn, password, privateKey, passphrase);
            sessions.put(webSocketSession.getId(), sshSession);
            lastActivity.put(webSocketSession.getId(), System.currentTimeMillis());
            sessionCount.incrementAndGet();

            executor.submit(() -> {
                try {
                    InputStream in = sshSession.getOutputStream();
                    byte[] buf = new byte[4096];
                    int n;
                    while (webSocketSession.isOpen() && sshSession.isConnected() && (n = in.read(buf)) >= 0) {
                        String text = new String(buf, 0, n, "UTF-8");
                        webSocketSession.sendMessage(new TextMessage(text));
                    }
                } catch (Exception e) {
                    if (webSocketSession.isOpen()) {
                        try {
                            webSocketSession.sendMessage(new TextMessage("\r\n[Connection closed]\r\n"));
                        } catch (IOException ignored) {
                        }
                    }
                }
            });
        } catch (Exception e) {
            webSocketSession.sendMessage(new TextMessage("\r\n[SSH Error: " + e.getMessage() + "]\r\n"));
        }
    }

    @Override
    protected void handleTextMessage(WebSocketSession webSocketSession, TextMessage message) throws Exception {
        SshService.SshSession sshSession = sessions.get(webSocketSession.getId());
        if (sshSession != null && sshSession.isConnected()) {
            lastActivity.put(webSocketSession.getId(), System.currentTimeMillis());
            sshSession.getInputStream().write(message.asBytes());
            sshSession.getInputStream().flush();
        }
    }

    @Override
    public void afterConnectionClosed(WebSocketSession webSocketSession, CloseStatus status) throws Exception {
        SshService.SshSession sshSession = sessions.remove(webSocketSession.getId());
        lastActivity.remove(webSocketSession.getId());
        if (sshSession != null) {
            sshSession.disconnect();
            sessionCount.decrementAndGet();
        }
    }
}