feat: add luxify function for converting traditional middleware (#183)

src/index.js

@@ -3,3 +3,5 @@ export { default as Logger } from './packages/logger';
 export { default as Controller } from './packages/controller';
 export { default as Serializer } from './packages/serializer';
 export { default as Application } from './packages/application';
+
+export { default as luxify } from './packages/luxify';

src/packages/luxify/index.js

@@ -0,0 +1,35 @@
+// @flow
+import createResponseProxy from './utils/create-response-proxy';
+import type { IncomingMessage, ServerResponse } from 'http';
+
+/**
+ * Convert traditional node HTTP server middleware into a lux compatible
+ * function for use in Controller#beforeAction.
+ */
+export default function luxify(
+  middleware: (
+    req: IncomingMessage,
+    res: ServerResponse,
+    next: (err?: Error) => void
+  ) => void
+): (req: IncomingMessage, res: ServerResponse) => Promise<void|mixed> {
+  const result = function (req, res) {
+    return new Promise((resolve, reject) => {
+      res = createResponseProxy(res, resolve);
+
+      middleware.call(null, req, res, (err) => {
+        if (err && err instanceof Error) {
+          reject(err);
+        } else {
+          resolve();
+        }
+      });
+    });
+  };
+
+  Object.defineProperty(result, 'name', {
+    value: middleware.name
+  });
+
+  return result;
+}

src/packages/luxify/utils/create-response-proxy.js

@@ -0,0 +1,21 @@
+// @flow
+import type { ServerResponse } from 'http';
+
+export default function createResponseProxy(
+  res: ServerResponse,
+  resolve: (result: mixed) => void
+): ServerResponse {
+  return new Proxy(res, {
+    get(target: ServerResponse, key: string, receiver: Proxy): ?mixed | void {
+      switch (key) {
+        case 'end':
+        case 'send':
+        case 'json':
+          return resolve;
+
+        default:
+          return target[key];
+      }
+    }
+  });
+}