refactor: share responses input handling

src/gateway/http-common.ts

@@ -0,0 +1,57 @@
+import type { IncomingMessage, ServerResponse } from "node:http";
+
+import { readJsonBody } from "./hooks.js";
+
+export function sendJson(res: ServerResponse, status: number, body: unknown) {
+  res.statusCode = status;
+  res.setHeader("Content-Type", "application/json; charset=utf-8");
+  res.end(JSON.stringify(body));
+}
+
+export function sendText(res: ServerResponse, status: number, body: string) {
+  res.statusCode = status;
+  res.setHeader("Content-Type", "text/plain; charset=utf-8");
+  res.end(body);
+}
+
+export function sendMethodNotAllowed(res: ServerResponse, allow = "POST") {
+  res.setHeader("Allow", allow);
+  sendText(res, 405, "Method Not Allowed");
+}
+
+export function sendUnauthorized(res: ServerResponse) {
+  sendJson(res, 401, {
+    error: { message: "Unauthorized", type: "unauthorized" },
+  });
+}
+
+export function sendInvalidRequest(res: ServerResponse, message: string) {
+  sendJson(res, 400, {
+    error: { message, type: "invalid_request_error" },
+  });
+}
+
+export async function readJsonBodyOrError(
+  req: IncomingMessage,
+  res: ServerResponse,
+  maxBytes: number,
+): Promise<unknown> {
+  const body = await readJsonBody(req, maxBytes);
+  if (!body.ok) {
+    sendInvalidRequest(res, body.error);
+    return undefined;
+  }
+  return body.value;
+}
+
+export function writeDone(res: ServerResponse) {
+  res.write("data: [DONE]\n\n");
+}
+
+export function setSseHeaders(res: ServerResponse) {
+  res.statusCode = 200;
+  res.setHeader("Content-Type", "text/event-stream; charset=utf-8");
+  res.setHeader("Cache-Control", "no-cache");
+  res.setHeader("Connection", "keep-alive");
+  res.flushHeaders?.();
+}