Implemented the redirector

src/index.ts

@@ -1,18 +1,69 @@
-/**
- * Welcome to Cloudflare Workers! This is your first worker.
- *
- * - Run `npm run dev` in your terminal to start a development server
- * - Open a browser tab at http://localhost:8787/ to see your worker in action
- * - Run `npm run deploy` to publish your worker
- *
- * Bind resources to your worker in `wrangler.toml`. After adding bindings, a type definition for the
- * `Env` object can be regenerated with `npm run cf-typegen`.
- *
- * Learn more at https://developers.cloudflare.com/workers/
- */
+interface Headers {
+  [key: string]: string;
+}
 
 export default {
-    async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
-        return new Response('Hello World!');
-    },
+  async fetch(
+    request: Request,
+    // @ts-ignore
+    env: Env,
+    ctx: ExecutionContext
+  ): Promise<Response> {
+    const referer = request.headers.get('Referer');
+
+    let headers: Headers = {
+      // 'Link': '<data:>; rel=icon', // it doesn't work
+      'Content-Security-Policy': "default-src 'self'; img-src 'none';", // disable favicon requests
+      'X-Robots-Tag': 'noindex, nofollow, noarchive, nosnippet'
+    };
+
+    if (referer) {
+      try {
+        const url = new URL(request.url);
+        const destination = url.pathname;
+
+        const refererUrl = new URL(referer);
+        const hostname = refererUrl.hostname;
+        let path = refererUrl.pathname
+
+        if (url.searchParams.has('base')) {
+          switch (url.searchParams.get('base')) {
+            case 'root':
+              path = '';
+              break;
+            case 'path':
+              path = refererUrl.pathname;
+              break;
+            case 'repo':
+              path = refererUrl.pathname.split("/", 3).join("/");
+              break;
+            default:
+              return new Response('Invalid base option', { status: 400 });
+          }
+        } else {
+          switch (hostname) {
+            case 'github.com':
+              path = refererUrl.pathname.split("/", 3).join("/");
+              break;
+          }
+        }
+
+        const targetUrl = `https://${hostname}${path}${destination}`;
+        headers = {
+          ...headers,
+          'Location': targetUrl,
+          'Cache-Control': 'no-store, no-cache, must-revalidate, proxy-revalidate',
+          'Surrogate-Control': 'no-store',
+          'Pragma': 'no-cache',
+          'Expires': '0'
+        };
+
+        return new Response(null, { status: 302, headers });
+      } catch (error) {
+        return new Response('Invalid referer URL', { status: 400, headers });
+      }
+    } else {
+      return new Response('Referer header is missing or invalid', { status: 400, headers });
+    }
+  }
 };