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

export async function readBody(req: IncomingMessage): Promise<Buffer> {
  const chunks: Buffer[] = [];
  for await (const c of req) chunks.push(c as Buffer);
  return Buffer.concat(chunks);
}

export interface MultipartPart {
  name: string;
  filename?: string;
  data: Buffer;
}

/** 极简 multipart/form-data 解析,仅供 mock 使用。 */
export function parseMultipart(body: Buffer, contentType: string): MultipartPart[] {
  const m = /boundary=(?:"([^"]+)"|([^;]+))/i.exec(contentType);
  if (!m) return [];
  const boundary = Buffer.from(`--${m[1] ?? m[2]}`);
  const parts: MultipartPart[] = [];
  let pos = body.indexOf(boundary);
  while (pos >= 0) {
    const start = pos + boundary.length;
    if (body.subarray(start, start + 2).toString() === "--") break;
    const next = body.indexOf(boundary, start);
    if (next < 0) break;
    const chunk = body.subarray(start + 2, next - 2); // 去掉起始 CRLF 与结尾 CRLF
    const sep = chunk.indexOf("\r\n\r\n");
    const head = chunk.subarray(0, sep).toString();
    const data = chunk.subarray(sep + 4);
    const name = /name="([^"]*)"/.exec(head)?.[1] ?? "";
    const filename = /filename="([^"]*)"/.exec(head)?.[1];
    parts.push({ name, ...(filename !== undefined ? { filename } : {}), data });
    pos = next;
  }
  return parts;
}

export function parseCookies(header: string | undefined): Record<string, string> {
  const out: Record<string, string> = {};
  for (const p of (header ?? "").split(";")) {
    const i = p.indexOf("=");
    if (i > 0) out[p.slice(0, i).trim()] = p.slice(i + 1).trim();
  }
  return out;
}