import express from 'express';
import { WebSocketServer } from 'ws';
import { createServer } from 'http';
import os from 'os';
import path from 'path';
import { fileURLToPath } from 'url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const app = express();
const PORT = process.env.PORT || 3002;

// Middleware
app.use(express.json({ limit: '50mb' }));
app.use(express.text({ type: '*/*' }));

// Terminal sessions storage
const terminalSessions = new Map();
let sessionIdCounter = 1;

// Get shell based on platform
function getShell() {
  if (process.platform === 'win32') {
    // Use PowerShell on Windows
    return 'powershell.exe';
  }
  return process.env.SHELL || '/bin/bash';
}

// Create terminal session
async function createTerminalSession(cwd, cols = 80, rows = 24) {
  const pty = await import('node-pty');
  const shell = getShell();

  // Validate working directory
  let workingDir = cwd || os.homedir();
  try {
    const fs = await import('fs');
    if (!fs.existsSync(workingDir)) {
      workingDir = os.homedir();
    }
  } catch {
    workingDir = os.homedir();
  }

  const ptyProcess = pty.spawn(shell, [], {
    name: 'xterm-256color',
    cols,
    rows,
    cwd: workingDir,
    env: process.env,
  });

  return ptyProcess;
}

// Generate session ID
function generateSessionId() {
  return `term-${Date.now()}-${sessionIdCounter++}`;
}

// API: Create terminal session
app.post('/api/terminal/create', async (req, res) => {
  try {
    const { cwd, cols, rows } = req.body;

    const sessionId = generateSessionId();
    const ptyProcess = await createTerminalSession(cwd, cols || 80, rows || 24);

    const session = {
      id: sessionId,
      pty: ptyProcess,
      cwd: ptyProcess.cwd,
      cols: cols || 80,
      rows: rows || 24,
      createdAt: Date.now(),
    };

    terminalSessions.set(sessionId, session);

    // Handle PTY data
    ptyProcess.onData((data) => {
      // Data will be sent via SSE or WebSocket
    });

    ptyProcess.onExit(({ exitCode, signal }) => {
      console.log(`Terminal exited: session=${sessionId} code=${exitCode} signal=${signal}`);
      terminalSessions.delete(sessionId);
    });

    res.json({
      sessionId,
      cols: session.cols,
      rows: session.rows,
      capabilities: {
        input: {
          preferred: 'http',
          transports: ['ws', 'http'],
          ws: {
            path: '/api/terminal/input-ws',
          },
        },
      },
    });
  } catch (error) {
    console.error('Failed to create terminal:', error);
    res.status(500).json({ error: error.message });
  }
});

// SSE: Terminal output stream
app.get('/api/terminal/:sessionId/stream', (req, res) => {
  const { sessionId } = req.params;
  const session = terminalSessions.get(sessionId);

  if (!session) {
    return res.status(404).json({ error: 'Terminal session not found' });
  }

  // Set SSE headers
  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');
  res.flushHeaders();

  const clientId = Date.now();
  const dataHandler = (data) => {
    res.write(`data: ${JSON.stringify({ type: 'data', data })}\n\n`);
  };

  const exitHandler = ({ exitCode, signal }) => {
    res.write(`data: ${JSON.stringify({ type: 'exit', exitCode, signal })}\n\n`);
    res.end();
  };

  session.pty.onData(dataHandler);
  session.pty.onExit(exitHandler);

  // Send initial connection event
  res.write(`data: ${JSON.stringify({ type: 'connected' })}\n\n`);

  // Handle client disconnect
  req.on('close', () => {
    session.pty.offData(dataHandler);
    session.pty.offExit(exitHandler);
    console.log(`Client disconnected: session=${sessionId} client=${clientId}`);
  });
});

// HTTP: Send terminal input
app.post('/api/terminal/:sessionId/input', (req, res) => {
  const { sessionId } = req.params;
  const session = terminalSessions.get(sessionId);

  if (!session) {
    return res.status(404).json({ error: 'Terminal session not found' });
  }

  try {
    const data = req.body;
    session.pty.write(data);
    res.status(204).send();
  } catch (error) {
    console.error('Failed to write to terminal:', error);
    res.status(500).json({ error: 'Failed to write to terminal' });
  }
});

// HTTP: Resize terminal
app.post('/api/terminal/:sessionId/resize', (req, res) => {
  const { sessionId } = req.params;
  const session = terminalSessions.get(sessionId);

  if (!session) {
    return res.status(404).json({ error: 'Terminal session not found' });
  }

  try {
    const { cols, rows } = req.body;
    session.pty.resize(cols, rows);
    session.cols = cols;
    session.rows = rows;
    res.status(204).send();
  } catch (error) {
    console.error('Failed to resize terminal:', error);
    res.status(500).json({ error: 'Failed to resize terminal' });
  }
});

// HTTP: Close terminal session
app.delete('/api/terminal/:sessionId', (req, res) => {
  const { sessionId } = req.params;
  const session = terminalSessions.get(sessionId);

  if (!session) {
    return res.status(404).json({ error: 'Terminal session not found' });
  }

  try {
    session.pty.kill();
    terminalSessions.delete(sessionId);
    res.status(204).send();
  } catch (error) {
    console.error('Failed to close terminal:', error);
    res.status(500).json({ error: 'Failed to close terminal' });
  }
});

// Restart terminal session
app.post('/api/terminal/:sessionId/restart', async (req, res) => {
  const { sessionId } = req.params;
  const session = terminalSessions.get(sessionId);

  if (!session) {
    return res.status(404).json({ error: 'Terminal session not found' });
  }

  try {
    const { cwd, cols, rows } = req.body;

    // Kill existing session
    session.pty.kill();
    terminalSessions.delete(sessionId);

    // Create new session
    const newSessionId = generateSessionId();
    const ptyProcess = await createTerminalSession(cwd, cols || 80, rows || 24);

    const newSession = {
      id: newSessionId,
      pty: ptyProcess,
      cwd: ptyProcess.cwd,
      cols: cols || 80,
      rows: rows || 24,
      createdAt: Date.now(),
    };

    terminalSessions.set(newSessionId, newSession);

    ptyProcess.onExit(({ exitCode, signal }) => {
      terminalSessions.delete(newSessionId);
    });

    res.json({
      sessionId: newSessionId,
      cols: newSession.cols,
      rows: newSession.rows,
      capabilities: {
        input: {
          preferred: 'http',
          transports: ['ws', 'http'],
          ws: {
            path: '/api/terminal/input-ws',
          },
        },
      },
    });
  } catch (error) {
    console.error('Failed to restart terminal:', error);
    res.status(500).json({ error: 'Failed to restart terminal' });
  }
});

// Force kill terminal
app.post('/api/terminal/force-kill', (req, res) => {
  const { sessionId, cwd } = req.body;

  let killedCount = 0;

  if (sessionId) {
    const session = terminalSessions.get(sessionId);
    if (session) {
      session.pty.kill();
      terminalSessions.delete(sessionId);
      killedCount = 1;
    }
  } else if (cwd) {
    for (const [id, session] of terminalSessions) {
      if (session.cwd === cwd) {
        session.pty.kill();
        terminalSessions.delete(id);
        killedCount++;
      }
    }
  }

  res.json({ killed: killedCount });
});

// WebSocket for terminal input
const server = createServer(app);
const wss = new WebSocketServer({ server, path: '/api/terminal/input-ws' });

wss.on('connection', (ws, req) => {
  console.log('WebSocket connected for terminal input');

  let boundSessionId = null;

  ws.on('message', (message) => {
    try {
      const data = new Uint8Array(message);
      // Control frame: JSON
      if (data[0] === 0x01) {
        const jsonStr = new TextDecoder().decode(data.slice(1));
        const payload = JSON.parse(jsonStr);

        // Bind session
        if (payload.t === 'b' && payload.s) {
          boundSessionId = payload.s;
          console.log(`WebSocket bound to session: ${boundSessionId}`);
        }

        // Ping
        if (payload.t === 'p') {
          ws.send(Buffer.from([0x01, ...new TextEncoder().encode(JSON.stringify({ t: 'po' }))]));
        }
        return;
      }

      // Regular input data
      const text = new TextDecoder().decode(message);
      if (boundSessionId) {
        const session = terminalSessions.get(boundSessionId);
        if (session) {
          session.pty.write(text);
        }
      }
    } catch (error) {
      console.error('WebSocket message error:', error);
    }
  });

  ws.on('close', () => {
    console.log('WebSocket disconnected');
  });
});

server.listen(PORT, () => {
  console.log(`Terminal server running on http://localhost:${PORT}`);
});