import { createError } from "h3";

function parsePositiveInt(raw: string | undefined, fallback: number, label: string): number {
  if (raw === undefined || raw === "") {
    return fallback;
  }
  const n = Number(raw);
  if (!Number.isInteger(n) || n < 1) {
    throw createError({ statusCode: 400, statusMessage: `${label} 须为正整数` });
  }
  return n;
}

const ALLOWED_PAGE_SIZES = new Set([10, 20, 50]);
const MAX_SEARCH_LEN = 200;

export function parseMeMediaAssetsQuery(q: { page?: string; pageSize?: string; search?: string }): {
  page: number;
  pageSize: number;
  search: string | null;
} {
  const page = parsePositiveInt(q.page, 1, "page");
  const pageSizeRaw = parsePositiveInt(q.pageSize, 20, "pageSize");
  if (!ALLOWED_PAGE_SIZES.has(pageSizeRaw)) {
    throw createError({ statusCode: 400, statusMessage: "pageSize 须为 10、20 或 50" });
  }
  let search: string | null = null;
  if (typeof q.search === "string") {
    const s = q.search.trim();
    if (s.length > MAX_SEARCH_LEN) {
      throw createError({ statusCode: 400, statusMessage: `search 最多 ${MAX_SEARCH_LEN} 个字符` });
    }
    search = s.length ? s : null;
  }
  return { page, pageSize: pageSizeRaw, search };
}