From 1f81697069ea882a3523490e88aa551f07b0272e Mon Sep 17 00:00:00 2001
From: Max Leiter <max.leiter@vercel.com>
Date: Sun, 11 Jun 2023 18:24:23 -0700
Subject: [PATCH 1/2] ai-stream: fix trimStartOfStreamHelper

---
 packages/core/streams/ai-stream.ts | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/packages/core/streams/ai-stream.ts b/packages/core/streams/ai-stream.ts
index 89fecf0..d6ac79f 100644
--- a/packages/core/streams/ai-stream.ts
+++ b/packages/core/streams/ai-stream.ts
@@ -12,13 +12,17 @@ export interface AIStreamCallbacks {
 }
 
 export interface AIStreamParser {
-  (data: string): string | void
+  (data: string, isStream: boolean): string | void
 }
 
 export function createEventStreamTransformer(customParser: AIStreamParser) {
   const decoder = new TextDecoder()
   let parser: EventSourceParser
 
+  let isSSE = false;
+  let isFirstChunk = true;
+
+
   return new TransformStream<Uint8Array, string>({
     async start(controller): Promise<void> {
       function onParse(event: ParsedEvent | ReconnectInterval) {
@@ -29,7 +33,12 @@ export function createEventStreamTransformer(customParser: AIStreamParser) {
             return
           }
 
-          const message = customParser(data)
+          if (isFirstChunk) {
+            isFirstChunk = false;
+            isSSE = data.startsWith('data: ');
+          }
+
+          const message = customParser(data, isSSE)
           if (message) controller.enqueue(message)
         }
       }
@@ -76,13 +85,17 @@ export function createCallbacksTransformer(
 // If we're still at the start of the stream, we want to trim the leading
 // `\n\n`. But, after we've seen some text, we no longer want to trim out
 // whitespace.
+
 export function trimStartOfStreamHelper() {
-  let start = true
+  let start = true;
   return (text: string) => {
-    if (start) text = text.trimStart()
-    if (text) start = false
-    return text
-  }
+    let trimmedText = text;
+    if (start) {
+      trimmedText = text.trimStart();
+      start = trimmedText.length > 0;
+    }
+    return trimmedText;
+  };
 }
 
 export function AIStream(
@@ -90,6 +103,7 @@ export function AIStream(
   customParser: AIStreamParser,
   callbacks?: AIStreamCallbacks
 ): ReadableStream {
+  console.log('res.body', res.body)
   const stream =
     res.body ||
     new ReadableStream({

From 380f340492e1aa4b3afb5ed86bcea8f17ddbd480 Mon Sep 17 00:00:00 2001
From: Max Leiter <max.leiter@vercel.com>
Date: Sun, 11 Jun 2023 18:27:39 -0700
Subject: [PATCH 2/2] undo change

---
 packages/core/streams/ai-stream.ts | 27 ++++++++-------------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/packages/core/streams/ai-stream.ts b/packages/core/streams/ai-stream.ts
index d6ac79f..311c69b 100644
--- a/packages/core/streams/ai-stream.ts
+++ b/packages/core/streams/ai-stream.ts
@@ -12,17 +12,13 @@ export interface AIStreamCallbacks {
 }
 
 export interface AIStreamParser {
-  (data: string, isStream: boolean): string | void
+  (data: string): string | void
 }
 
 export function createEventStreamTransformer(customParser: AIStreamParser) {
   const decoder = new TextDecoder()
   let parser: EventSourceParser
 
-  let isSSE = false;
-  let isFirstChunk = true;
-
-
   return new TransformStream<Uint8Array, string>({
     async start(controller): Promise<void> {
       function onParse(event: ParsedEvent | ReconnectInterval) {
@@ -33,12 +29,7 @@ export function createEventStreamTransformer(customParser: AIStreamParser) {
             return
           }
 
-          if (isFirstChunk) {
-            isFirstChunk = false;
-            isSSE = data.startsWith('data: ');
-          }
-
-          const message = customParser(data, isSSE)
+          const message = customParser(data)
           if (message) controller.enqueue(message)
         }
       }
@@ -85,17 +76,16 @@ export function createCallbacksTransformer(
 // If we're still at the start of the stream, we want to trim the leading
 // `\n\n`. But, after we've seen some text, we no longer want to trim out
 // whitespace.
-
 export function trimStartOfStreamHelper() {
-  let start = true;
+  let start = true
   return (text: string) => {
-    let trimmedText = text;
+    let trimmedText = text
     if (start) {
-      trimmedText = text.trimStart();
-      start = trimmedText.length > 0;
+      trimmedText = text.trimStart()
+      start = trimmedText.length > 0
     }
-    return trimmedText;
-  };
+    return trimmedText
+  }
 }
 
 export function AIStream(
@@ -103,7 +93,6 @@ export function AIStream(
   customParser: AIStreamParser,
   callbacks?: AIStreamCallbacks
 ): ReadableStream {
-  console.log('res.body', res.body)
   const stream =
     res.body ||
     new ReadableStream({