v1.0.23

src/lib/server/sse-parser.ts

@@ -0,0 +1,89 @@
+/**
+ * Pure SSE parsing utilities — no server dependencies.
+ * Can be safely imported in unit tests and client code.
+ */
+
+/**
+ * Check if the client prefers JSON over SSE.
+ * Returns true when Accept header includes application/json but NOT text/event-stream.
+ */
+export function prefersJSON(request?: Request): boolean {
+	const accept = request?.headers.get('accept') || '';
+	return accept.includes('application/json') && !accept.includes('text/event-stream');
+}
+
+/**
+ * Wrap an SSE Response for JSON-preferring clients.
+ *
+ * Consumes the SSE stream using proper event framing (blank-line delimited,
+ * multi-line data joined with \n, CRLF stripped). Returns the `result` event
+ * data as a JSON response, or a fallback if no result event was emitted.
+ *
+ * Usage:
+ *   if (prefersJSON(request)) return sseToJSON(buildSSEResponse());
+ *   return buildSSEResponse();
+ */
+export async function sseToJSON(sseResponse: Response): Promise<Response> {
+	const reader = sseResponse.body!.getReader();
+	const decoder = new TextDecoder();
+	let buffer = '';
+	let eventType = '';
+	let dataLines: string[] = [];
+	let resultData: unknown = null;
+
+	const dispatch = () => {
+		const data = dataLines.join('\n');
+		const type = eventType || 'message';
+		eventType = '';
+		dataLines = [];
+		if (type === 'result' && data) {
+			try {
+				resultData = JSON.parse(data);
+			} catch {
+				// keep previous resultData
+			}
+		}
+	};
+
+	const parseLine = (rawLine: string) => {
+		const line = rawLine.endsWith('\r') ? rawLine.slice(0, -1) : rawLine;
+		if (line.startsWith(':')) return;
+		if (line === '') { dispatch(); return; }
+		const colon = line.indexOf(':');
+		const field = colon === -1 ? line : line.slice(0, colon);
+		let val = colon === -1 ? '' : line.slice(colon + 1);
+		if (val.startsWith(' ')) val = val.slice(1);
+		if (field === 'event') eventType = val || 'message';
+		else if (field === 'data') dataLines.push(val);
+	};
+
+	try {
+		while (true) {
+			const { done, value } = await reader.read();
+			if (done) break;
+
+			buffer += decoder.decode(value, { stream: true });
+			const lines = buffer.split('\n');
+			buffer = lines.pop() || '';
+
+			for (const line of lines) parseLine(line);
+		}
+
+		// Flush remaining bytes and process trailing content
+		buffer += decoder.decode();
+		if (buffer) {
+			for (const line of buffer.split('\n')) parseLine(line);
+		}
+		// Final dispatch for servers missing trailing blank line
+		if (dataLines.length > 0) dispatch();
+	} catch {
+		// stream error, return what we have
+	} finally {
+		reader.releaseLock();
+	}
+
+	const body = resultData ?? { success: false, error: 'No result' };
+	return new Response(JSON.stringify(body), {
+		headers: { 'content-type': 'application/json' }
+	});
+}