feat: add stream support

app/api/chat-stream/route.ts

@@ -0,0 +1,64 @@
+import type { ChatRequest } from "../chat/typing";
+import { createParser } from "eventsource-parser";
+import { NextRequest } from "next/server";
+
+const apiKey = process.env.OPENAI_API_KEY;
+
+async function createStream(payload: ChatRequest) {
+  const encoder = new TextEncoder();
+  const decoder = new TextDecoder();
+
+  console.log("[ChatStream]", payload);
+
+  const res = await fetch("https://api.openai.com/v1/chat/completions", {
+    headers: {
+      "Content-Type": "application/json",
+      Authorization: `Bearer ${apiKey}`,
+    },
+    method: "POST",
+    body: JSON.stringify(payload),
+  });
+
+  const stream = new ReadableStream({
+    async start(controller) {
+      function onParse(event: any) {
+        if (event.type === "event") {
+          const data = event.data;
+          // https://beta.openai.com/docs/api-reference/completions/create#completions/create-stream
+          if (data === "[DONE]") {
+            controller.close();
+            return;
+          }
+          try {
+            const json = JSON.parse(data);
+            const text = json.choices[0].delta.content;
+            const queue = encoder.encode(text);
+            controller.enqueue(queue);
+          } catch (e) {
+            controller.error(e);
+          }
+        }
+      }
+
+      const parser = createParser(onParse);
+      for await (const chunk of res.body as any) {
+        parser.feed(decoder.decode(chunk));
+      }
+    },
+  });
+  return stream;
+}
+
+export async function POST(req: NextRequest) {
+  try {
+    const body = (await req.json()) as ChatRequest;
+    const stream = await createStream(body);
+    return new Response(stream);
+  } catch (error) {
+    console.error(error);
+  }
+}
+
+export const config = {
+  runtime: "edge",
+};

app/api/chat/route.ts

@@ -2,8 +2,7 @@ import { OpenAIApi, Configuration } from "openai";
 import { ChatRequest } from "./typing";
 
 const isProd = process.env.NODE_ENV === "production";
-
-let apiKey = process.env.OPENAI_API_KEY;
+const apiKey = process.env.OPENAI_API_KEY;
 
 const openai = new OpenAIApi(
   new Configuration({