import { defineConfig } from 'vite';
import fs from 'node:fs/promises';
import path from 'node:path';
import serveStatic from 'serve-static';

// Cesium 懒加载：复制静态资源、注入 CSS，但不注入 6MB 的 Cesium.js 脚本——
// 脚本由 CesiumGlobe 首次进入“地理”视图时动态加载，避免阻塞首屏。
const CESIUM_URL = '/cesium/';

function cesiumLazy() {
  let isBuild = false;
  return {
    name: 'cesium-lazy',
    config(_c, { command }) {
      isBuild = command === 'build';
    },
    configureServer({ middlewares }) {
      // dev：直接静态服务 Cesium 资源（未压缩版便于调试）
      const dir = path.join(process.cwd(), 'node_modules/cesium/Build/CesiumUnminified');
      middlewares.use(CESIUM_URL, serveStatic(dir));
    },
    async closeBundle() {
      if (!isBuild) return;
      const src = path.join(process.cwd(), 'node_modules/cesium/Build/Cesium');
      const out = path.join(process.cwd(), 'dist', 'cesium');
      for (const d of ['Assets', 'ThirdParty', 'Workers', 'Widgets']) {
        await fs.cp(path.join(src, d), path.join(out, d), { recursive: true });
      }
      await fs.copyFile(path.join(src, 'Cesium.js'), path.join(out, 'Cesium.js'));
    },
    transformIndexHtml() {
      return [{
        tag: 'link',
        attrs: { rel: 'stylesheet', href: `${CESIUM_URL}Widgets/widgets.css` },
      }];
    },
  };
}

export default defineConfig({
  plugins: [cesiumLazy()],
});