add legacy gradle plugin url redirecting

src/gradle-plugins.ts

@@ -0,0 +1,53 @@
+import { RequestHandler } from 'express';
+import got from 'got';
+
+const gradleApi = 'https://plugins.gradle.org/api/gradle/4.10/plugin/use';
+
+export const LegacyGradlePluginsHandler: RequestHandler = (req, res, next) => {
+  const url = req.originalUrl ?? req.url;
+  if (!url.includes('.gradle.plugin/')) {
+    next();
+  }
+
+  if (req.method !== 'HEAD' && req.method !== 'GET') {
+    return res.sendStatus(403);
+  }
+
+  try {
+    const basePath = /^\/[^/]*(?=\/)/.exec(url)?.[0];
+    const fileName = /[^/]+$/.exec(url)?.[0];
+    const version = /[^/]+$/.exec(url.replace(`/${fileName}`, ''))?.[0];
+    const packageId = fileName?.replace(/\.gradle\.plugin.*$/, '');
+    const endpoint = `${gradleApi}/${packageId}/${version}`;
+    got
+      .get(endpoint)
+      .then((result) => {
+        const info = JSON.parse(result.body) as {
+          id: string;
+          version: string;
+          implementation: {
+            gav: string;
+            repo: string;
+          };
+          implementationType: string;
+          legacy: boolean;
+        };
+        const newId =
+          /(?<=:).+(?=:)/.exec(info.implementation.gav)?.[0] ?? 'new-id';
+        const newFileName = /[^/]+$/.exec(
+          url.replaceAll(`${info.id}.gradle.plugin`, newId)
+        )?.[0];
+        const newUrl = `${basePath}/${/^[\w.]+(?=:)/.exec(info.implementation.gav)?.[0]?.replaceAll('.', '/')}/${newId}/${version}/${newFileName}`;
+        console.log('🔀 [301]', url);
+        req.url = newUrl;
+        next();
+      })
+      .catch(() => {
+        next();
+      });
+  } catch (error) {
+    // eslint-disable-next-line @typescript-eslint/no-unused-expressions
+    error;
+    next();
+  }
+};

src/index.ts

@@ -15,11 +15,12 @@ import {
 } from './config';
 import { getCachedServer, printServedEndpoints } from './utils';
 import { GotDownloader } from './downloader/got';
+import { LegacyGradlePluginsHandler } from './gradle-plugins';
 
 const downloader = new GotDownloader();
 
 const cacheRequestHandler: RequestHandler = (req, res, next) => {
-  const url = (req.originalUrl || req.url).replace(/^\/\w+\//, '/');
+  const url = req.url.replace(/^\/\w+\//, '/');
   if (req.method !== 'HEAD' && req.method !== 'GET') {
     return res.sendStatus(403);
   }
@@ -76,6 +77,7 @@ const app = express();
 if (VERBOSE) {
   app.use(morgan('combined'));
 }
+app.get('*', LegacyGradlePluginsHandler);
 app.get('*', cacheRequestHandler);
 app.listen(PORT, () => {
   console.log('add this ⬇️  in build.gradle');