fix: 2.7 dev start

utils/openai/fetch-sse.ts

@@ -0,0 +1,89 @@
+import { createParser } from 'eventsource-parser'
+
+import * as types from './types'
+import { fetch as nodefetch } from 'node-fetch'
+import { streamAsyncIterable } from './stream-async-iterable'
+
+export async function fetchSSE(
+    url: string,
+    options: Parameters<typeof fetch>[1] & {
+        onMessage: (data: string) => void
+        onError?: (error: any) => void
+    },
+    fetch: types.FetchFn = nodefetch
+) {
+    const { onMessage, onError, ...fetchOptions } = options
+    const res = await fetch(url, fetchOptions)
+    if (!res.ok) {
+        let reason: string
+
+        try {
+            reason = await res.text()
+        } catch (err) {
+            reason = res.statusText
+        }
+
+        const msg = `ChatGPT error ${res.status}: ${reason}`
+        const error = new types.ChatGPTError(msg, { cause: res })
+        error.statusCode = res.status
+        error.statusText = res.statusText
+        throw error
+    }
+
+    const parser = createParser((event) => {
+        if (event.type === 'event') {
+            onMessage(event.data)
+        }
+    })
+
+    // handle special response errors
+    const feed = (chunk: string) => {
+        let response = null
+
+        try {
+            response = JSON.parse(chunk)
+        } catch {
+            // ignore
+        }
+
+        if (response?.detail?.type === 'invalid_request_error') {
+            const msg = `ChatGPT error ${response.detail.message}: ${response.detail.code} (${response.detail.type})`
+            const error = new types.ChatGPTError(msg, { cause: response })
+            error.statusCode = response.detail.code
+            error.statusText = response.detail.message
+
+            if (onError) {
+                onError(error)
+            } else {
+                console.error(error)
+            }
+
+            // don't feed to the event parser
+            return
+        }
+
+        parser.feed(chunk)
+    }
+
+    if (!res.body.getReader) {
+        // Vercel polyfills `fetch` with `node-fetch`, which doesn't conform to
+        // web standards, so this is a workaround...
+        const body: NodeJS.ReadableStream = res.body as any
+
+        if (!body.on || !body.read) {
+            throw new types.ChatGPTError('unsupported "fetch" implementation')
+        }
+
+        body.on('readable', () => {
+            let chunk: string | Buffer
+            while (null !== (chunk = body.read())) {
+                feed(chunk.toString())
+            }
+        })
+    } else {
+        for await (const chunk of streamAsyncIterable(res.body)) {
+            const str = new TextDecoder().decode(chunk)
+            feed(str)
+        }
+    }
+}