import http from 'node:http';
import { existsSync } from 'node:fs';
import { cp, mkdir } from 'node:fs/promises';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';
import { WebSocketServer } from 'ws';
import * as pty from 'node-pty';

const __dirname = dirname(fileURLToPath(import.meta.url));
const isDocker = existsSync('/opt/terminal-templates/.zshrc');

const templateDir = isDocker ? '/opt/terminal-templates' : join(__dirname, 'templates');
const ohMyZshSource = isDocker ? '/opt/oh-my-zsh' : null;

const port = Number(process.env.TERMINAL_PTY_PORT ?? '5337');
const host = process.env.TERMINAL_PTY_HOST ?? '127.0.0.1';

const BUFFER_MAX = 50 * 1024;

/** @type {Map<string, { term: import('node-pty').IPty, buffer: string, cols: number, rows: number, ws: import('ws').WebSocket | null, initConfig: object }>} */
const sessions = new Map();

const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('terminal-sidecar');
});

const wss = new WebSocketServer({ server });

const sendJson = (ws, msg) => {
  try {
    ws.send(JSON.stringify(msg));
  } catch {
    // ignore
  }
};

const ensureUserFiles = async (homeDir) => {
  await mkdir(homeDir, { recursive: true });
  await mkdir(join(homeDir, '.config'), { recursive: true });
  await mkdir(join(homeDir, '.local', 'bin'), { recursive: true });

  const zshrcPath = join(homeDir, '.zshrc');
  if (!existsSync(zshrcPath)) {
    await cp(join(templateDir, '.zshrc'), zshrcPath);
  }

  const tmuxconfPath = join(homeDir, '.tmux.conf');
  if (!existsSync(tmuxconfPath)) {
    await cp(join(templateDir, '.tmux.conf'), tmuxconfPath);
  }

  const starshipPath = join(homeDir, '.config', 'starship-officer.toml');
  if (!existsSync(starshipPath)) {
    await cp(join(templateDir, 'starship-officer.toml'), starshipPath);
  }

  const ohMyZshPath = join(homeDir, '.oh-my-zsh');
  if (!existsSync(ohMyZshPath)) {
    if (ohMyZshSource && existsSync(ohMyZshSource)) {
      await cp(ohMyZshSource, ohMyZshPath, { recursive: true });
    } else {
      const proc = Bun.spawn({
        cmd: ['git', 'clone', '--depth=1', 'https://github.com/ohmyzsh/ohmyzsh.git', ohMyZshPath],
        stdout: 'ignore',
        stderr: 'ignore',
      });
      await proc.exited;
    }
  }

  if (!isDocker) {
    const starshipBin = join(homeDir, '.local', 'bin', 'starship');
    if (!existsSync(starshipBin)) {
      const installProc = Bun.spawn({
        cmd: ['sh', '-c', 'curl -sS https://starship.rs/install.sh | sh -s -- -y -b "$HOME/.local/bin"'],
        env: { ...process.env, HOME: homeDir },
        stdout: 'ignore',
        stderr: 'ignore',
      });
      await installProc.exited;
    }
  }
};

const appendBuffer = (session, data) => {
  session.buffer += data;
  if (session.buffer.length > BUFFER_MAX) {
    session.buffer = session.buffer.slice(-BUFFER_MAX);
  }
};

wss.on('connection', (ws) => {
  let currentSessionId = null;

  ws.on('message', async (data) => {
    let msg;
    try {
      msg = JSON.parse(typeof data === 'string' ? data : data.toString());
    } catch {
      return;
    }

    if (msg.type === 'init') {
      const sessionId = msg.sessionId;
      if (!sessionId) return;

      currentSessionId = sessionId;
      const existing = sessions.get(sessionId);

      console.log(`[sidecar] init sessionId=${sessionId} existing=${!!existing} total=${sessions.size}`);

      if (existing) {
        // Evict old WS if still attached
        if (existing.ws && existing.ws !== ws) {
          sendJson(existing.ws, { type: 'detached' });
          try {
            existing.ws.close();
          } catch {
            // ignore
          }
        }

        existing.ws = ws;

        // Replay buffer
        if (existing.buffer.length > 0) {
          sendJson(ws, { type: 'output', data: existing.buffer });
        }

        // Resize PTY to new client dimensions
        const cols = msg.cols ?? existing.cols;
        const rows = msg.rows ?? existing.rows;
        if (cols > 0 && rows > 0 && (cols !== existing.cols || rows !== existing.rows)) {
          existing.cols = cols;
          existing.rows = rows;
          try {
            existing.term.resize(cols, rows);
          } catch {
            // ignore
          }
        }

        return;
      }

      // New session — spawn PTY
      const shell = msg.shell ?? { command: '/bin/bash', args: ['-i'] };
      const cwd = msg.cwd ?? process.cwd();
      const homeDir = msg.homeDir ?? process.cwd();
      const userLabel = msg.userLabel ?? 'officer';
      const prompt = `${userLabel} in %~ %# `;
      const bashPrompt = `${userLabel} \\w \\$ `;
      const cols = msg.cols ?? 80;
      const rows = msg.rows ?? 24;

      try {
        await ensureUserFiles(homeDir);
      } catch {
        // ignore
      }

      let term;
      try {
        term = pty.spawn(shell.command, shell.args ?? [], {
          name: 'xterm-256color',
          cols,
          rows,
          cwd,
          env: {
            ...process.env,
            HOME: homeDir,
            ZDOTDIR: homeDir,
            ZSH: `${homeDir}/.oh-my-zsh`,
            SHELL: shell.command,
            USER: userLabel,
            LOGNAME: userLabel,
            OFFICER_TERMINAL_USER: userLabel,
            PROMPT: prompt,
            PS1: bashPrompt,
            TERM: 'xterm-256color',
          },
        });
      } catch (err) {
        const message = err instanceof Error ? err.message : 'Failed to start terminal';
        sendJson(ws, { type: 'output', data: `\r\n[Terminal error] ${message}\r\n` });
        sendJson(ws, { type: 'exit' });
        return;
      }

      const session = {
        term,
        buffer: '',
        cols,
        rows,
        ws,
        initConfig: { shell, cwd, homeDir, userLabel },
      };
      sessions.set(sessionId, session);

      term.onData((output) => {
        appendBuffer(session, output);
        if (session.ws) {
          sendJson(session.ws, { type: 'output', data: output });
        }
      });

      term.onExit(() => {
        if (session.ws) {
          sendJson(session.ws, { type: 'exit' });
        }
        sessions.delete(sessionId);
      });

      return;
    }

    // Route other messages to current session
    if (!currentSessionId) return;
    const session = sessions.get(currentSessionId);
    if (!session) return;

    switch (msg.type) {
      case 'input':
        session.term.write(msg.data ?? '');
        break;
      case 'resize':
        if (msg.cols > 0 && msg.rows > 0) {
          session.cols = msg.cols;
          session.rows = msg.rows;
          session.term.resize(msg.cols, msg.rows);
        }
        break;
      case 'cwd':
        if (msg.path) session.term.write(`cd ${JSON.stringify(msg.path)}\r`);
        break;
    }
  });

  ws.on('close', () => {
    // Detach WS from session — do NOT kill PTY
    if (currentSessionId) {
      const session = sessions.get(currentSessionId);
      if (session && session.ws === ws) {
        session.ws = null;
      }
    }
  });
});

server.listen(port, host, () => {
  console.log(`[terminal-sidecar] listening on ${host}:${port}`);
});