feat: fallback to unsplash cover when article contains no image

lib/helpers.ts

@@ -31,19 +31,54 @@ export const fixRenderedMarkdown = (content: string) => {
     });
 };
 
-export async function fetchStream(url: string, cb: (chunk: string) => void) {
-  const response = await fetch(url);
-  const reader = response?.body?.getReader();
-  if (reader) {
-    while (true) {
-      const { done, value } = await reader.read();
-      if (done) return;
-      const data = new TextDecoder().decode(value);
-      data
-        .split("$")
-        .filter((d) => d && d.length)
-        .map((d) => cb(Array.isArray(d) ? d[0] : d));
-    }
+type StreamMessage = {
+  type: "info";
+  message: string;
+} | {
+  type: "error";
+  message: string;
+} | {
+  type: "warning";
+  message: string;
+} | {
+  type: "finished";
+  url: string;
+};
+
+export async function fetchStream(
+  url: string,
+  cb: (chunk: StreamMessage) => void,
+  init?: RequestInit,
+) {
+  const res = await fetch(url, init);
+  if (!res.body) return;
+
+  let buffer = "";
+  const reader = res.body
+    .pipeThrough(new TextDecoderStream())
+    .pipeThrough(
+      new TransformStream<string, string>({
+        transform(chunk, controller) {
+          buffer += chunk;
+          let idx;
+          while ((idx = buffer.indexOf("\n")) >= 0) {
+            const line = buffer.slice(0, idx).trim();
+            buffer = buffer.slice(idx + 1);
+            if (line) controller.enqueue(line);
+          }
+        },
+        flush(controller) {
+          const line = buffer.trim();
+          if (line) controller.enqueue(line);
+        },
+      }),
+    )
+    .getReader();
+
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) break;
+    cb(JSON.parse(value));
   }
 }
 
@@ -58,32 +93,53 @@ export function hashString(message: string) {
 }
 
 export const createStreamResponse = () => {
-  let controller: ReadableStreamController<ArrayBufferView>;
-  const body = new ReadableStream({
-    start(cont) {
-      controller = cont;
+  const encoder = new TextEncoder();
+  let controller: ReadableStreamDefaultController<Uint8Array>;
+
+  const body = new ReadableStream<Uint8Array>({
+    start(c) {
+      controller = c;
     },
   });
 
   const response = new Response(body, {
     headers: {
-      "content-type": "text/plain",
+      // newline-delimited JSON
+      "content-type": "application/x-ndjson; charset=utf-8",
+      // prevent intermediaries from buffering/transforming
+      "cache-control": "no-cache, no-transform",
       "x-content-type-options": "nosniff",
+      // nginx hint to disable proxy buffering
+      "x-accel-buffering": "no",
+      // if you control compression, keep it off for streams
+      // "content-encoding": "identity",
     },
   });
 
-  function cancel() {
-    controller.close();
+  const send = (obj: unknown) => {
+    controller.enqueue(encoder.encode(JSON.stringify(obj) + "\n")); // ← delimiter
+  };
+  const cancel = () => controller.close();
+
+  function info(message: string) {
+    return send({ type: "info", message });
   }
 
-  function enqueue(chunk: string) {
-    controller?.enqueue(new TextEncoder().encode("$" + chunk));
+  function error(message: string) {
+    return send({ type: "error", message });
+  }
+
+  function warning(message: string) {
+    return send({ type: "warning", message });
   }
 
   return {
     response,
     cancel,
-    enqueue,
+    send,
+    info,
+    error,
+    warning,
   };
 };