fix: Restore Metro Reader Asset Middleware

metro.config.js

@@ -1,7 +1,58 @@
 const { getDefaultConfig } = require('expo/metro-config');
+const fs = require('fs');
+const path = require('path');
 
 const config = getDefaultConfig(__dirname);
+const readerAssetsRoot = path.resolve(__dirname, 'assets', 'reader');
+const readerAssetContentTypes = {
+  '.css': 'text/css; charset=utf-8',
+  '.js': 'text/javascript; charset=utf-8',
+  '.ttf': 'font/ttf',
+};
 
 config.resolver.sourceExts.push('sql');
 
+config.server.enhanceMiddleware = metroMiddleware => {
+  return (request, response, next) => {
+    let pathname;
+
+    try {
+      pathname = decodeURIComponent(
+        new URL(request.url, 'http://localhost').pathname,
+      );
+    } catch {
+      return metroMiddleware(request, response, next);
+    }
+
+    if (!pathname.startsWith('/assets/')) {
+      return metroMiddleware(request, response, next);
+    }
+
+    const assetPath = path.resolve(
+      readerAssetsRoot,
+      pathname.slice('/assets/'.length),
+    );
+    const isReaderAsset =
+      assetPath.startsWith(`${readerAssetsRoot}${path.sep}`) &&
+      fs.existsSync(assetPath) &&
+      fs.statSync(assetPath).isFile();
+
+    if (!isReaderAsset) {
+      return metroMiddleware(request, response, next);
+    }
+
+    response.setHeader(
+      'Content-Type',
+      readerAssetContentTypes[path.extname(assetPath)] ||
+        'application/octet-stream',
+    );
+
+    if (request.method === 'HEAD') {
+      return response.end();
+    }
+
+    fs.createReadStream(assetPath).pipe(response);
+  };
+};
+
 module.exports = config;