export const BANNED_WORDS_PATH = '/system/banned-words';
export const BANNED_WORD_NEW_PATH = `${BANNED_WORDS_PATH}/new`;
/** 엑셀 업로드 양식 다운로드 — 파일 응답이라 라우트 핸들러가 받는다. */
export const BANNED_WORD_EXCEL_TEMPLATE_PATH = `${BANNED_WORDS_PATH}/excel-template`;

export const BANNED_WORD_PAGE_SIZE_OPTIONS = [10, 30, 50] as const;
export type BannedWordPageSize =
  (typeof BANNED_WORD_PAGE_SIZE_OPTIONS)[number];

export const DEFAULT_BANNED_WORD_PAGE_SIZE: BannedWordPageSize = 10;
const DEFAULT_PAGE = 1;
const MAX_KEYWORD_LENGTH = 100;

export type BannedWordQuery = {
  keyword: string;
  page: number;
  pageSize: BannedWordPageSize;
};

type RawSearchParams = Record<string, string | string[] | undefined>;

function readParam(params: RawSearchParams, key: string): string | undefined {
  const value = params[key];
  return Array.isArray(value) ? value[0] : value;
}

function isBannedWordPageSize(value: number): value is BannedWordPageSize {
  return (BANNED_WORD_PAGE_SIZE_OPTIONS as readonly number[]).includes(value);
}

export function parseBannedWordQuery(
  searchParams: RawSearchParams
): BannedWordQuery {
  const keywordRaw = readParam(searchParams, 'keyword');
  const pageRaw = Number(readParam(searchParams, 'page'));
  const pageSizeRaw = Number(readParam(searchParams, 'pageSize'));

  return {
    keyword: (keywordRaw ?? '').trim().slice(0, MAX_KEYWORD_LENGTH),
    page: Number.isInteger(pageRaw) && pageRaw > 0 ? pageRaw : DEFAULT_PAGE,
    pageSize: isBannedWordPageSize(pageSizeRaw)
      ? pageSizeRaw
      : DEFAULT_BANNED_WORD_PAGE_SIZE,
  };
}

export function buildBannedWordHref(
  query: BannedWordQuery,
  overrides: Partial<BannedWordQuery> = {}
): string {
  const merged = { ...query, ...overrides };
  const params = new URLSearchParams();

  if (merged.keyword) {
    params.set('keyword', merged.keyword);
  }
  if (merged.pageSize !== DEFAULT_BANNED_WORD_PAGE_SIZE) {
    params.set('pageSize', String(merged.pageSize));
  }
  if (merged.page !== DEFAULT_PAGE) {
    params.set('page', String(merged.page));
  }

  const queryString = params.toString();
  return queryString ? `${BANNED_WORDS_PATH}?${queryString}` : BANNED_WORDS_PATH;
}