Redirect process plugin .json file to asset url path

handleRequest.test.ts

@@ -326,6 +326,25 @@ it("tryResolvePluginUrl", async () => {
   );
 });
 
+it("should redirect non-wasm plugins to asset URL", async () => {
+  const { handleRequest } = createRequestHandler();
+  const response = await handleRequest(
+    new Request("https://plugins.dprint.dev/prettier-0.7.0.json"),
+  );
+  expect(response.status).toEqual(302);
+  expect(response.headers.get("location")).toEqual(
+    "https://plugins.dprint.dev/dprint/dprint-plugin-prettier/0.7.0/asset/plugin.json",
+  );
+});
+
+it("should not redirect wasm plugins", async () => {
+  const { handleRequest } = createRequestHandler();
+  const response = await handleRequest(
+    new Request("https://plugins.dprint.dev/typescript-0.62.2.wasm"),
+  );
+  expect(response.status).not.toEqual(302);
+});
+
 it("should return 404 for asset not found", async () => {
   const { handleRequest } = createRequestHandler();
   const response = await handleRequest(

handleRequest.ts

@@ -31,6 +31,14 @@ export function createRequestHandler() {
 
       const githubUrl = await resolvePluginOrSchemaUrl(url);
       if (githubUrl != null) {
+        if (!githubUrl.endsWith(".wasm")) {
+          // redirect non-wasm files to asset URL so relative URLs in
+          // plugin.json files resolve correctly
+          const assetPath = githubUrlToAssetPath(githubUrl);
+          if (assetPath != null) {
+            return Response.redirect(new URL(assetPath, url.origin).href, 302);
+          }
+        }
         return servePlugin(request, githubUrl, ctx);
       }
 
@@ -192,6 +200,19 @@ function createJsonResponse(text: string, request: Request) {
   });
 }
 
+// converts a GitHub release URL to a local asset path
+// e.g. https://github.com/dprint/dprint-plugin-prettier/releases/download/0.7.0/plugin.json
+//   -> /dprint/dprint-plugin-prettier/0.7.0/asset/plugin.json
+const githubReleasePattern = /^https:\/\/github\.com\/([^/]+)\/([^/]+)\/releases\/download\/([^/]+)\/(.+)$/;
+function githubUrlToAssetPath(githubUrl: string) {
+  const match = githubReleasePattern.exec(githubUrl);
+  if (match == null) {
+    return undefined;
+  }
+  const [, username, repo, tag, fileName] = match;
+  return `/${username}/${repo}/${tag}/asset/${fileName}`;
+}
+
 function contentTypeForUrl(url: string) {
   if (url.endsWith(".wasm")) return contentTypes.wasm;
   if (url.endsWith(".json") || url.endsWith(".exe-plugin")) return contentTypes.json;