Extend support for useFileOutput to stream (#309)

* Break stream on done event without enqueuing it

* Fix doc comment for fetch parameter

* Transform URLs in streaming responses when useFileOutput is enabled

* Revert 'Break stream on done event without enqueuing it'

* Default to useFileOutput = true for readable streams

Author: mattt

lib/stream.js

@@ -48,15 +48,18 @@ class ServerSentEvent {
  * @param {string} config.url The URL to connect to.
  * @param {typeof fetch} [config.fetch] The URL to connect to.
  * @param {object} [config.options] The EventSource options.
+ * @param {boolean} [config.options.useFileOutput] Whether to use the file output stream.
  * @returns {ReadableStream<ServerSentEvent> & AsyncIterable<ServerSentEvent>}
  */
 function createReadableStream({ url, fetch, options = {} }) {
+  const { useFileOutput = true, headers = {}, ...initOptions } = options;
+
   return new ReadableStream({
     async start(controller) {
       const init = {
-        ...options,
+        ...initOptions,
         headers: {
-          ...options.headers,
+          ...headers,
           Accept: "text/event-stream",
         },
       };
@@ -84,9 +87,15 @@ function createReadableStream({ url, fetch, options = {} }) {
           break;
         }
 
-        controller.enqueue(
-          new ServerSentEvent(event.event, event.data, event.id)
-        );
+        let data = event.data;
+        if (
+          useFileOutput &&
+          typeof data === "string" &&
+          (data.startsWith("https:") || data.startsWith("data:"))
+        ) {
+          data = createFileOutput({ data, fetch });
+        }
+        controller.enqueue(new ServerSentEvent(event.event, data, event.id));
 
         if (event.event === "done") {
           break;
@@ -104,7 +113,7 @@ function createReadableStream({ url, fetch, options = {} }) {
  *
  * @param {object} config
  * @param {string} config.url The URL to connect to.
- * @param {typeof fetch} [config.fetch] The URL to connect to.
+ * @param {typeof fetch} [config.fetch] The fetch function.
  * @returns {ReadableStream<Uint8Array>}
  */
 function createFileOutput({ url, fetch }) {