'use strict';
const express = require('express');
const { WebSocketServer } = require('ws');
const pty = require('node-pty');
const http = require('http');
const https = require('https');
const fs = require('fs');
const path = require('path');
const os = require('os');
const { execSync } = require('child_process');

const app = express();
const PORT = process.env.PORT || 3333;

// セッションログ保存ディレクトリ
const SESSIONS_DIR = path.join(os.homedir(), 'posimai-dev-sessions');
if (!fs.existsSync(SESSIONS_DIR)) fs.mkdirSync(SESSIONS_DIR, { recursive: true });

app.use(express.json());
app.use(express.static(path.join(__dirname)));

// セッション一覧 API
app.get('/api/sessions', (req, res) => {
  const files = fs.readdirSync(SESSIONS_DIR)
    .filter((f) => f.endsWith('.log'))
    .map((f) => {
      const stat = fs.statSync(path.join(SESSIONS_DIR, f));
      return { id: f.replace('.log', ''), size: stat.size, mtime: stat.mtime };
    })
    .sort((a, b) => new Date(b.mtime) - new Date(a.mtime));
  res.json(files);
});

// セッション内容 API
app.get('/api/sessions/:id', (req, res) => {
  const file = path.join(SESSIONS_DIR, req.params.id + '.log');
  if (!fs.existsSync(file)) return res.status(404).json({ error: 'not found' });
  res.type('text/plain').send(fs.readFileSync(file, 'utf8'));
});

// ── ヘルス & メトリクス API (/api/health) ──────────────────────
// Atlas など外部から参照される。CORS ヘッダーを付与して Vercel 上の Atlas からも取得可能にする
function getCpuSample() {
  return os.cpus().map((c) => {
    const total = Object.values(c.times).reduce((a, b) => a + b, 0);
    return { total, idle: c.times.idle };
  });
}

app.get('/api/health', (req, res) => {
  res.setHeader('Access-Control-Allow-Origin', '*');

  const mem   = os.freemem();
  const total = os.totalmem();

  // CPU: 100ms 間隔の2サンプルで実使用率を計算
  const s1 = getCpuSample();
  setTimeout(() => {
    const s2 = getCpuSample();
    const cpuPct = s1.reduce((sum, c1, i) => {
      const c2    = s2[i];
      const dIdle = c2.idle  - c1.idle;
      const dTotal = c2.total - c1.total;
      return sum + (dTotal > 0 ? (1 - dIdle / dTotal) * 100 : 0);
    }, 0) / s1.length;

    // Disk usage
    let disk = null;
    try {
      const dfOut = execSync('df -B1 / 2>/dev/null', { timeout: 2000 }).toString();
      const parts = dfOut.trim().split('\n')[1].split(/\s+/);
      const totalB = parseInt(parts[1]);
      const usedB  = parseInt(parts[2]);
      disk = {
        total_gb: Math.round(totalB / 1e9 * 10) / 10,
        used_gb:  Math.round(usedB  / 1e9 * 10) / 10,
        use_pct:  Math.round(usedB / totalB * 100),
      };
    } catch (_) {}

    // Load average (1 / 5 / 15 min) and CPU count
    const loadAvg   = os.loadavg();
    const cpuCount  = os.cpus().length;

    res.json({
      ok: true,
      hostname: os.hostname(),
      uptime_s: Math.floor(os.uptime()),
      cpu_pct: Math.round(cpuPct),
      cpu_count: cpuCount,
      load_avg: loadAvg.map(l => Math.round(l * 100) / 100),
      mem_used_mb: Math.round((total - mem) / 1024 / 1024),
      mem_total_mb: Math.round(total / 1024 / 1024),
      disk,
      active_sessions: wss.clients ? wss.clients.size : 0,
      node_version: process.version,
      platform: os.platform(),
      timestamp: new Date().toISOString(),
    });
  }, 100);
});

// Tailscale証明書を自動検出
function findCert() {
  const home = os.homedir();
  const crt = fs.readdirSync(home).find((f) => f.endsWith('.crt'));
  if (!crt) return null;
  const key = crt.replace('.crt', '.key');
  if (!fs.existsSync(path.join(home, key))) return null;
  return { cert: fs.readFileSync(path.join(home, crt)), key: fs.readFileSync(path.join(home, key)) };
}

const tlsOpts = findCert();
const server = tlsOpts ? https.createServer(tlsOpts, app) : http.createServer(app);
const proto = tlsOpts ? 'https' : 'http';

const wss = new WebSocketServer({ server, path: '/terminal' });

wss.on('connection', (ws) => {
  // セッションID・ログファイル作成
  const sessionId = new Date().toISOString().replace(/[:.]/g, '-').slice(0, 19);
  const logPath = path.join(SESSIONS_DIR, `${sessionId}.log`);
  const logStream = fs.createWriteStream(logPath, { flags: 'a' });
  logStream.write(`=== posimai-dev session ${sessionId} ===\n`);

  // セッションID をブラウザに通知
  ws.send(JSON.stringify({ type: 'session', id: sessionId }));

  const shell = process.env.SHELL || '/bin/bash';
  const ptyProc = pty.spawn(shell, [], {
    name: 'xterm-256color',
    cols: 80,
    rows: 24,
    cwd: path.join(os.homedir(), 'posimai-project'),
    env: { ...process.env, PATH: `${os.homedir()}/.npm-global/bin:${process.env.PATH}` }
  });

  // 起動時に posimai-project へ自動移動（cwd で指定済みだが source bashrc も通す）
  setTimeout(() => ptyProc.write(`source ~/.bashrc\n`), 300);

  ptyProc.onData((data) => {
    logStream.write(data);
    if (ws.readyState === 1) ws.send(JSON.stringify({ type: 'output', data }));
  });

  ws.on('message', (raw) => {
    try {
      const msg = JSON.parse(raw.toString());
      if (msg.type === 'input') {
        logStream.write(msg.data);
        ptyProc.write(msg.data);
      }
      if (msg.type === 'resize') ptyProc.resize(Number(msg.cols), Number(msg.rows));
    } catch {}
  });

  ws.on('close', () => {
    logStream.end(`\n=== session end ===\n`);
    try { ptyProc.kill(); } catch {}
  });
  ptyProc.onExit(() => { try { ws.close(); } catch {} });
});

server.listen(PORT, '0.0.0.0', () => {
  console.log(`posimai-dev running on ${proto}://0.0.0.0:${PORT}`);
});