fix: replace URLs on the response to self hostname

importmap.json

@@ -1,9 +1,11 @@
 {
   "imports": {
+    "@rollup/plugin-terser": "https://esm.sh/@rollup/plugin-terser",
     "@rollup/plugin-virtual": "https://esm.sh/@rollup/plugin-virtual",
     "rollup": "https://esm.sh/rollup",
     "testing/asserts": "https://deno.land/std/testing/asserts.ts",
     "testing/mock": "https://deno.land/std/testing/mock.ts",
     "http": "https://deno.land/std/http/mod.ts"
+
   }
 }

src/esm-proxy-request-handler.test.ts

@@ -2,24 +2,32 @@ import { assertEquals } from 'testing/asserts';
 import { assertSpyCallArg, returnsNext, stub } from 'testing/mock';
 import { esmProxyRequestHandler } from './esm-proxy-request-handler.ts';
 
-Deno.test('should return an string of code in systemjs format', async () => {
-  const fetchStub = stub(globalThis, 'fetch', returnsNext([
-      Promise.resolve({ text: () => Promise.resolve('export * from "https://esm.sh/stable/vue@3.3.2/es2022/vue.mjs";') } as unknown as Response),
-  ]));
-  const req = new Request('https://systemjs.sh/vue');
-  const res = await esmProxyRequestHandler(req);
-  const systemjsCode = await res.text();
-  assertEquals(systemjsCode.startsWith('System.register('), true);
-  fetchStub.restore();
-});
+Deno.test('esmProxyRequestHandler', async (t) => {
+
+  const ESM_SERVICE_HOST = 'esm.sh';
+  const SELF_HOST = 'systemjs.sh';
+  const fetchReturn = Promise.resolve({ text: () => Promise.resolve(`export * from "https://${ESM_SERVICE_HOST}/stable/vue@3.3.2/es2022/vue.mjs";`) } as unknown as Response);
+  const fetchStub = stub(globalThis, 'fetch', returnsNext([fetchReturn, fetchReturn, fetchReturn]));
+
+  await t.step('should forward the request to ESM_SERVICE_HOST keeping the parameters', async () => {
+    const req = new Request(`https://${SELF_HOST}/foo?bundle`);
+    await esmProxyRequestHandler(req);
+    assertSpyCallArg(fetchStub, 0, 0, `https://${ESM_SERVICE_HOST}/foo?bundle`);
+  });
+
+  await t.step('should return an string of code in systemjs format', async () => {
+    const req = new Request(`https://${SELF_HOST}/vue`);
+    const res = await esmProxyRequestHandler(req);
+    const systemjsCode = await res.text();
+    assertEquals(systemjsCode.startsWith('System.register('), true);
+  });
+
+  await t.step('should replace the ESM_SERVICE_HOST by the self host', async () => {
+    const req = new Request(`https://${SELF_HOST}/vue`);
+    const res = await esmProxyRequestHandler(req);
+    const systemjsCode = await res.text();
+    assertEquals(!!systemjsCode.match(new RegExp(`https://${SELF_HOST}/stable/vue@3.3.2/es2022/vue.mjs`)), true);
+  });
 
-Deno.test('should forward the request to host "esm.sh" keeping the parameters', async () => {
-  const fetchStub = stub(globalThis, 'fetch', returnsNext([
-      Promise.resolve({ text: () => Promise.resolve('export default "foo"') } as unknown as Response),
-  ]));
-  const req = new Request('https://systemjs.sh/foo?bundle');
-  const res = await esmProxyRequestHandler(req);
-  const systemjsCode = await res.text();
-  assertSpyCallArg(fetchStub, 0, 0, 'https://esm.sh/foo?bundle');
   fetchStub.restore();
 });

src/esm-proxy-request-handler.ts

@@ -1,19 +1,14 @@
 import { toSystemjs } from './to-systemjs.ts';
 
+const ESM_SERVICE_HOST = 'esm.sh';
+
 export async function esmProxyRequestHandler(req: Request): Promise<Response | never> {
-  let modifiedUrl: URL;
-  let esmCode: string;
-  try {
-    modifiedUrl = new URL(req.url);
-    modifiedUrl.hostname = 'esm.sh';
-    esmCode = await fetch(modifiedUrl.toString(), { headers: req.headers }).then((res) => res.text());
-    const systemjsCode = await toSystemjs(esmCode);
-    return new Response(systemjsCode);
-  } catch (error) {
-    // @ts-ignore
-    console.log(modifiedUrl?.toString());
-    // @ts-ignore
-    console.log(esmCode);
-    throw error;
-  }
+  const modifiedUrl = new URL(req.url);
+  const selfHost = modifiedUrl.host;
+  modifiedUrl.host = ESM_SERVICE_HOST;
+  const esmCode = await fetch(modifiedUrl.toString(), { headers: req.headers }).then((res) => res.text());
+  const systemjsCode = await toSystemjs(esmCode);
+  return new Response(
+    systemjsCode.replace(new RegExp(`//${ESM_SERVICE_HOST}/`, 'ig'), `//${selfHost}/`)
+  );
 }

src/to-systemjs.ts

@@ -1,6 +1,6 @@
 import { ModuleFormat, rollup } from 'rollup';
+//import terser from '@rollup/plugin-terser';
 import virtual from '@rollup/plugin-virtual';
-//import { minify } from 'npm:rollup-plugin-esbuild';
 
 export const toSystemjs = async (esmCode: string): Promise<string>  => {
 
@@ -9,7 +9,7 @@ export const toSystemjs = async (esmCode: string): Promise<string>  => {
     input: 'esmCode',
     plugins: [
       virtual({ esmCode }),
-      //minify(),
+      //terser(),
     ],
     treeshake: false,
   };
@@ -23,5 +23,5 @@ export const toSystemjs = async (esmCode: string): Promise<string>  => {
   const bundle = await rollup(inputOptions);
   const { output } = await bundle.generate(outputOptions);
   await bundle.close();
-  return output[0].code.replace(/https:\/\/esm\.sh\//g, 'https://systemjs.sh/');
+  return output[0].code;
 }