Proposal to add ability to map data in a proxy

.vscode/launch.json

@@ -0,0 +1,19 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Next.js: debug full stack",
+      "type": "node",
+      "request": "launch",
+      "runtimeExecutable": "${workspaceFolder}/node_modules/.bin/next",
+      "serverReadyAction": {
+        "pattern": "started server on .+, url: (https?://.+)",
+        "uriFormat": "%s",
+        "action": "debugWithChrome"
+      }
+    }
+  ]
+}

src/pages/api/services/proxy.js

@@ -5,6 +5,16 @@ import nzbgetProxyHandler from "utils/proxies/nzbget";
 import npmProxyHandler from "utils/proxies/npm";
 import transmissionProxyHandler from "utils/proxies/transmission";
 
+function simpleArrayMapper(endpoint, targetEndpoint, data, mapper) {
+  if ((data?.length > 0) && (endpoint === targetEndpoint)) {
+    const json = JSON.parse(data.toString());
+    if (json instanceof Array) {
+      return json.map(mapper);
+    }
+  }
+  return data;
+}
+
 const serviceProxyHandlers = {
   // uses query param auth
   emby: genericProxyHandler,
@@ -13,7 +23,9 @@ const serviceProxyHandlers = {
   radarr: genericProxyHandler,
   sonarr: genericProxyHandler,
   lidarr: genericProxyHandler,
-  readarr: genericProxyHandler,
+  readarr: { proxy: genericProxyHandler, mapper: (endpoint, data) =>
+    simpleArrayMapper(endpoint, "book", data, d => ({ statistics: { bookFileCount: d.statistics.bookFileCount } }))
+  },
   bazarr: genericProxyHandler,
   speedtest: genericProxyHandler,
   tautulli: genericProxyHandler,
@@ -42,7 +54,14 @@ export default async function handler(req, res) {
   const serviceProxyHandler = serviceProxyHandlers[type];
 
   if (serviceProxyHandler) {
-    return serviceProxyHandler(req, res);
+    if (serviceProxyHandler instanceof Function) {
+      return serviceProxyHandler(req, res);
+    }
+
+    const { proxy, mapper } = serviceProxyHandler;
+    if (proxy) {
+      return proxy(req, res, mapper);
+    }
   }
 
   return res.status(403).json({ error: "Unkown proxy service type" });

src/utils/proxies/generic.js

@@ -2,7 +2,7 @@ import getServiceWidget from "utils/service-helpers";
 import { formatApiCall } from "utils/api-helpers";
 import { httpProxy } from "utils/http";
 
-export default async function genericProxyHandler(req, res) {
+export default async function genericProxyHandler(req, res, mapper) {
   const { group, service, endpoint } = req.query;
 
   if (group && service) {
@@ -23,13 +23,18 @@ export default async function genericProxyHandler(req, res) {
         headers,
       });
 
+      let resultData = data;
+      if (mapper) {
+        resultData = mapper(endpoint, data);
+      }
+
       if (contentType) res.setHeader("Content-Type", contentType);
 
       if (status === 204 || status === 304) {
         return res.status(status).end();
       }
 
-      return res.status(status).send(data);
+      return res.status(status).send(resultData);
     }
   }