import type { IncomingMessage } from "node:http";

const MAX_BODY = 1_048_576;

export const readJsonBody = async (req: IncomingMessage): Promise<unknown> => {
  const chunks: Buffer[] = [];
  let total = 0;
  for await (const chunk of req) {
    const buf = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk);
    total += buf.length;
    if (total > MAX_BODY) {
      throw new Error("Request body too large");
    }
    chunks.push(buf);
  }
  const raw = Buffer.concat(chunks).toString("utf8").trim();
  if (raw.length === 0) {
    return {};
  }
  try {
    return JSON.parse(raw) as unknown;
  } catch (cause) {
    throw new Error("Invalid JSON body", { cause });
  }
};