NotHtmlMimetype error handling

src/errors/handler.ts

@@ -29,10 +29,6 @@ function apiErrorHandler(error: Error, reply: FastifyReply) {
     });
   }
 
-  if (error instanceof NotHtmlMimetypeError) {
-    return generateResponse(501);
-  }
-
   if (getFastifyError(error)?.statusCode === 400) {
     return generateResponse(400);
   }
@@ -45,10 +41,6 @@ function apiErrorHandler(error: Error, reply: FastifyReply) {
 }
 
 function htmlErrorHandler(error: Error, reply: FastifyReply, url: string) {
-  if (error instanceof NotHtmlMimetypeError) {
-    return reply.redirect(301, error.url);
-  }
-
   if (getFastifyError(error)?.statusCode === 400) {
     return reply.code(400).view("/templates/error.ejs", {
       url,
@@ -62,6 +54,7 @@ function htmlErrorHandler(error: Error, reply: FastifyReply, url: string) {
       url,
       code: error.code,
       description: error.description,
+      proxyBtn: error instanceof NotHtmlMimetypeError,
     });
   }
 

src/errors/main.ts

@@ -3,7 +3,11 @@ export abstract class TxtDotError extends Error {
   name: string;
   description: string;
 
-  constructor(code: number, name: string, description: string) {
+  constructor(
+    code: number,
+    name: string,
+    description: string,
+  ) {
     super(description);
     this.code = code;
     this.name = name;
@@ -13,22 +17,30 @@ export abstract class TxtDotError extends Error {
 
 export class EngineParseError extends TxtDotError {
   constructor(message: string) {
-    super(422, "EngineParseError", `Parse error: ${message}`);
+    super(
+      422,
+      "EngineParseError",
+      `Parse error: ${message}`,
+    );
   }
 }
 
 export class LocalResourceError extends TxtDotError {
   constructor() {
-    super(403, "LocalResourceError", "Proxying local resources is forbidden.");
+    super(
+      403,
+      "LocalResourceError",
+      "Proxying local resources is forbidden.",
+    );
   }
 }
 
-export class NotHtmlMimetypeError extends Error {
-  name: string = "NotHtmlMimetypeError";
-  url: string;
-
-  constructor(url: string) {
-    super();
-    this.url = url;
+export class NotHtmlMimetypeError extends TxtDotError {
+  constructor() {
+    super(
+      421,
+      "NotHtmlMimetypeError",
+      "Received non-HTML content, use proxy",
+    );
   }
 }

src/handlers/main.ts

@@ -32,7 +32,7 @@ export default async function handlePage(
   const mime: string | undefined = response.headers["content-type"]?.toString();
 
   if (mime && mime.indexOf("text/html") === -1) {
-    throw new NotHtmlMimetypeError(url);
+    throw new NotHtmlMimetypeError();
   }
 
   return getFallbackEngine(urlObj.hostname, engine)(

templates/error.ejs

@@ -15,6 +15,14 @@
         <h1>txt<span class="dot-err">.</span></h1>
         <p class="menu">
           <a href="/" class="button">Home</a>
+          <% if (proxyBtn) { %>
+            <a
+              href="/proxy?url=<%= encodeURIComponent(url) %>"
+              class="button secondary"
+            >
+              Proxy
+            </a>
+          <% } %>
           <a href="<%= url %>" class="button secondary">Original page</a>
         </p>
         <p><%= description %></p>