refactor: Error Handler

src/app.ts

@@ -16,6 +16,7 @@ import indexRoute from "./routes/index";
 import rawHtml from "./routes/raw-html";
 
 import publicConfig from "./publicConfig";
+import errorHandler from "./errors/handler";
 
 class App {
   config: IConfigService;
@@ -56,6 +57,8 @@ class App {
     fastify.register(parseRoute);
     fastify.register(rawHtml);
 
+    fastify.setErrorHandler(errorHandler);
+
     fastify.listen({ port: Number(this.config.get("PORT")) }, (err) => {
       err && console.log(err);
     });

src/errors.ts

@@ -1,3 +0,0 @@
-export class EngineParseError extends Error {}
-export class InvalidParameterError extends Error {}
-export class NotHtmlMimetypeError extends Error {}

src/errors/handler.ts

@@ -0,0 +1,14 @@
+import { FastifyReply, FastifyRequest } from "fastify";
+import { NotHtmlMimetypeError } from "./main";
+
+export default function errorHandler(
+  error: Error,
+  _: FastifyRequest,
+  reply: FastifyReply
+) {
+  if (error instanceof NotHtmlMimetypeError) {
+    return reply.redirect(301, error.url);
+  } else {
+    return error;
+  }
+}

src/errors/main.ts

@@ -0,0 +1,9 @@
+export class EngineParseError extends Error {}
+export class InvalidParameterError extends Error {}
+export class NotHtmlMimetypeError extends Error {
+  url: string;
+  constructor(params: { url: string }) {
+    super();
+    this.url = params?.url;
+  }
+}

src/handlers/google.ts

@@ -1,6 +1,6 @@
 import { DOMWindow } from "jsdom";
 import { IHandlerOutput } from "./handler.interface";
-import { EngineParseError } from "../errors";
+import { EngineParseError } from "../errors/main";
 
 export default async function google(
   window: DOMWindow

src/handlers/main.ts

@@ -8,25 +8,22 @@ import readability from "./readability";
 import google from "./google";
 import { generateProxyUrl } from "../utils";
 
-import { InvalidParameterError, NotHtmlMimetypeError } from "../errors";
+import { InvalidParameterError, NotHtmlMimetypeError } from "../errors/main";
 
 export default async function handlePage(
   url: string,
   requestUrl: URL,
-  engine?: string,
+  engine?: string
 ): Promise<IHandlerOutput> {
-
   if (engine && engineList.indexOf(engine) === -1) {
     throw new InvalidParameterError("Invalid engine");
   }
 
   const response = await axios.get(url);
-  const mime: string | undefined = (
-    response.headers["content-type"]?.toString()
-  );
+  const mime: string | undefined = response.headers["content-type"]?.toString();
 
   if (mime && mime.indexOf("text/html") === -1) {
-    throw new NotHtmlMimetypeError();
+    throw new NotHtmlMimetypeError({ url });
   }
 
   const window = new JSDOM(response.data, { url: url }).window;

src/handlers/readability.ts

@@ -1,7 +1,7 @@
 import { Readability } from "@mozilla/readability";
 import { IHandlerOutput } from "./handler.interface";
 import { DOMWindow } from "jsdom";
-import { EngineParseError } from "../errors";
+import { EngineParseError } from "../errors/main";
 
 export default async function readability(
   window: DOMWindow

src/routes/get.ts

@@ -4,8 +4,6 @@ import { GetSchema, IGetSchema } from "../types/requests";
 import handlePage from "../handlers/main";
 import { generateRequestUrl } from "../utils";
 
-import { NotHtmlMimetypeError } from "../errors";
-
 export default async function getRoute(fastify: FastifyInstance) {
   fastify.get<IGetSchema>(
     "/get",
@@ -14,24 +12,15 @@ export default async function getRoute(fastify: FastifyInstance) {
       const remoteUrl = request.query.url;
       const engine = request.query.engine;
 
-      let parsed;
-      try {
-        parsed = await handlePage(
-          remoteUrl,
-          generateRequestUrl(
-            request.protocol,
-            request.hostname,
-            request.originalUrl
-          ),
-          engine
-        );
-      } catch (err) {
-        if (err instanceof NotHtmlMimetypeError) {
-          return reply.redirect(301, remoteUrl);
-        } else {
-          throw err;
-        }
-      }
+      const parsed = await handlePage(
+        remoteUrl,
+        generateRequestUrl(
+          request.protocol,
+          request.hostname,
+          request.originalUrl
+        ),
+        engine
+      );
 
       if (request.query.format === "text") {
         reply.type("text/plain; charset=utf-8");