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Use streamSSEResponse to stream server sent events #113

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Use streamSSEResponse to stream server sent events #113

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85 changes: 66 additions & 19 deletions src/treaty2/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -112,28 +112,75 @@ const processHeaders = (
}
}

export async function* streamResponse(response: Response) {
const body = response.body

if (!body) return

const reader = body.getReader()
const decoder = new TextDecoder()

try {
while (true) {
const { done, value } = await reader.read()
if (done) break
interface SSEEvent {
event: string;
data: string;
id?: string;
}

const data = decoder.decode(value)
export async function* streamSSEResponse(response: Response): AsyncGenerator<SSEEvent> {
const body = response.body;
if (!body) return;

const reader = body.getReader();
const decoder = new TextDecoder();
let buffer = '';

try {
while (true) {
const { done, value } = await reader.read();
if (done) break;

buffer += decoder.decode(value, { stream: true });

let eventEnd: number;
while ((eventEnd = buffer.indexOf('\n\n')) >= 0) {
const eventData = buffer.slice(0, eventEnd);
buffer = buffer.slice(eventEnd + 2);

const event = parseEvent(eventData);
if (event) {
yield event;
}
}
}

if (buffer.trim()) {
const event = parseEvent(buffer);
if (event) {
yield event;
}
}
} finally {
reader.releaseLock();
}
}

yield parseStringifiedValue(data)
}
} finally {
reader.releaseLock()
}
function parseEvent(eventData: string): SSEEvent | null {
let event: string = 'message';
let data: string[] = [];
let id: string | undefined;

const lines = eventData.split('\n');
for (const line of lines) {
if (line.startsWith('event:')) {
event = line.slice(6).trim();
} else if (line.startsWith('data:')) {
data.push(line.slice(5));
} else if (line.startsWith('id:')) {
id = line.slice(3).trim();
}
}

if (data.length > 0) {
const dataString = data.join('\n');
return { event, data: dataString, id };
}

return null;
}


const createProxy = (
domain: string,
config: Treaty.Config,
Expand Down Expand Up @@ -407,7 +454,7 @@ const createProxy = (
response.headers.get('Content-Type')?.split(';')[0]
) {
case 'text/event-stream':
data = streamResponse(response)
data = streamSSEResponse(response)
break

case 'application/json':
Expand Down