export type CreatePayload = {
  // TODO: define fields
  // example:
  // name: string;
};

export type ReplacePayload = {
  // PUT: typically full replace.
  // Define required fields here.
};

export type UpdatePayload = Partial<ReplacePayload>; // PATCH: partial update

function isObject(v: unknown): v is Record<string, unknown> {
  return typeof v === "object" && v !== null && !Array.isArray(v);
}

export function parseCreatePayload(body: unknown): CreatePayload {
  if (!isObject(body)) throw badReq("Body must be a JSON object");
  // TODO: validate required fields
  return body as CreatePayload;
}

export function parseReplacePayload(body: unknown): ReplacePayload {
  if (!isObject(body)) throw badReq("Body must be a JSON object");
  // TODO: validate required fields for PUT
  return body as ReplacePayload;
}

export function parseUpdatePayload(body: unknown): UpdatePayload {
  if (!isObject(body)) throw badReq("Body must be a JSON object");
  return body as UpdatePayload;
}

function badReq(message: string) {
  const err = new Error(message);
  (err as any).status = 400;
  return err;
}