/**
 * mini-user H5 本地预览：
 * Taro Vite `--watch` 在本机易 OOM（峰值 >8GB），改为：
 * 1) 先完整 build（约 30s）
 * 2) 静态托管 dist + /api 代理
 * 3) 监听 src 变更后防抖重建
 */
import { spawn } from 'node:child_process';
import fs from 'node:fs';
import http from 'node:http';
import https from 'node:https';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const APP_ROOT = path.resolve(__dirname, '../apps/mini-user');
const DIST = path.resolve(APP_ROOT, 'dist');
const PORT = Number(process.env.PORT || 5177);
const API_ORIGIN = (process.env.VITE_API_TARGET ?? 'https://dkapi.runxian.top').replace(/\/$/, '');
const TARO_BIN = path.resolve(APP_ROOT, 'node_modules/@tarojs/cli/bin/taro');

const MIME = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'application/javascript; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.svg': 'image/svg+xml',
  '.ico': 'image/x-icon',
  '.woff': 'font/woff',
  '.woff2': 'font/woff2',
  '.map': 'application/json',
};

function runBuild() {
  return new Promise((resolve, reject) => {
    const child = spawn(
      process.execPath,
      ['--max-old-space-size=8192', TARO_BIN, 'build', '--type', 'h5'],
      {
        cwd: APP_ROOT,
        stdio: 'inherit',
        env: process.env,
      },
    );
    child.on('exit', (code) => {
      if (code === 0) resolve();
      else reject(new Error(`taro build failed with code ${code}`));
    });
  });
}

function sendFile(res, filePath) {
  const ext = path.extname(filePath).toLowerCase();
  res.writeHead(200, { 'Content-Type': MIME[ext] || 'application/octet-stream' });
  fs.createReadStream(filePath).pipe(res);
}

function proxyApi(req, res) {
  const target = new URL(req.url || '/', API_ORIGIN);
  const lib = target.protocol === 'https:' ? https : http;
  const headers = { ...req.headers, host: target.host };
  delete headers['accept-encoding'];
  const upstream = lib.request(
    {
      protocol: target.protocol,
      hostname: target.hostname,
      port: target.port || undefined,
      path: target.pathname + target.search,
      method: req.method,
      headers,
    },
    (up) => {
      res.writeHead(up.statusCode || 502, up.headers);
      up.pipe(res);
    },
  );
  upstream.on('error', (err) => {
    res.writeHead(502, { 'Content-Type': 'text/plain; charset=utf-8' });
    res.end(`API proxy error: ${err.message}`);
  });
  req.pipe(upstream);
}

function startServer() {
  const server = http.createServer((req, res) => {
    const urlPath = decodeURIComponent((req.url || '/').split('?')[0]);
    if (urlPath.startsWith('/api')) {
      proxyApi(req, res);
      return;
    }

    const candidates = [
      path.join(DIST, urlPath),
      path.join(DIST, urlPath, 'index.html'),
      path.join(DIST, 'index.html'),
    ];
    const file = candidates.find((p) => fs.existsSync(p) && fs.statSync(p).isFile());
    if (!file) {
      res.writeHead(404, { 'Content-Type': 'text/plain; charset=utf-8' });
      res.end('Not Found');
      return;
    }
    sendFile(res, file);
  });

  server.listen(PORT, '0.0.0.0', () => {
    console.log(`\n mini-user H5 preview: http://localhost:${PORT}`);
    console.log(` API proxy -> ${API_ORIGIN}`);
    console.log(' Watching apps/mini-user/src for changes...\n');
  });
}

function watchSrc() {
  const srcDir = path.join(APP_ROOT, 'src');
  let timer = null;
  let building = false;
  let queued = false;

  const schedule = () => {
    if (timer) clearTimeout(timer);
    timer = setTimeout(async () => {
      if (building) {
        queued = true;
        return;
      }
      building = true;
      try {
        console.log('\n[dev] src changed, rebuilding...');
        await runBuild();
        console.log('[dev] rebuild done — refresh browser');
      } catch (e) {
        console.error('[dev] rebuild failed:', e instanceof Error ? e.message : e);
      } finally {
        building = false;
        if (queued) {
          queued = false;
          schedule();
        }
      }
    }, 800);
  };

  fs.watch(srcDir, { recursive: true }, (_event, filename) => {
    if (!filename) return;
    if (/\.(tsx?|jsx?|css|scss|json|png|jpg|svg)$/i.test(filename)) {
      schedule();
    }
  });
}

async function main() {
  if (!fs.existsSync(TARO_BIN)) {
    throw new Error(`Taro CLI not found: ${TARO_BIN}`);
  }
  console.log('[dev] initial H5 build...');
  await runBuild();
  startServer();
  watchSrc();
}

main().catch((e) => {
  console.error(e);
  process.exit(1);
});