import path from 'node:path';
import type { NextHandleFunction } from 'connect';
import { pathExists, readFile } from 'fs-extra';
import type { ServerContext } from '../index';

export function indexHtmlMiddleware(serverContext: ServerContext): NextHandleFunction {
  return async (req, res, next) => {
    if (req.url === '/') {
      const { root } = serverContext;
      const indexHtmlPath = path.join(root, 'index.html');
      if (await pathExists(indexHtmlPath)) {
        const rawHtml = await readFile(indexHtmlPath, 'utf8');
        let html = rawHtml;
        for (const plugin of serverContext.plugins) {
          if (plugin.transformIndexHtml) {
            html = await plugin.transformIndexHtml(html);
          }
        }

        res.statusCode = 200;
        res.setHeader('Content-Type', 'text/html');
        return res.end(html);
      }
    }
    return next();
  };
}