export type EtcDetailView = 'records' | 'bills';

export interface EtcDrillContext {
  view: EtcDetailView;
  startDate: string;
  endDate: string;
  search: string;
  page: number;
}

interface LocationParts {
  pathname: string;
  search: string;
  hash: string;
}

const DATE_PATTERN = /^\d{4}-\d{2}-\d{2}$/;

function validDate(value: string | null): string {
  if (!value || !DATE_PATTERN.test(value)) return '';
  const [year, month, day] = value.split('-').map(Number);
  const date = new Date(Date.UTC(year, month - 1, day));
  return date.getUTCFullYear() === year
    && date.getUTCMonth() === month - 1
    && date.getUTCDate() === day
    ? value
    : '';
}

function validPage(value: string | null): number {
  if (!value || !/^\d+$/.test(value)) return 1;
  const parsed = Number(value);
  return Number.isSafeInteger(parsed) && parsed > 0 ? parsed : 1;
}

export function parseEtcDrillContext(search: string): EtcDrillContext {
  const params = new URLSearchParams(search);
  const rawSearch = params.get('etcSearch')?.trim() ?? '';
  const firstDate = validDate(params.get('etcStart'));
  const secondDate = validDate(params.get('etcEnd'));
  const startDate = firstDate && secondDate && firstDate > secondDate ? secondDate : firstDate;
  const endDate = firstDate && secondDate && firstDate > secondDate ? firstDate : secondDate;
  return {
    view: params.get('etcView') === 'bills' ? 'bills' : 'records',
    startDate,
    endDate,
    search: rawSearch.length <= 128 ? rawSearch : '',
    page: validPage(params.get('etcPage')),
  };
}

export function buildEtcDrillUrl(location: LocationParts, context: EtcDrillContext): string {
  const params = new URLSearchParams(location.search);
  for (const key of ['etcView', 'etcStart', 'etcEnd', 'etcSearch', 'etcPage']) params.delete(key);
  params.set('etcView', context.view);
  if (context.startDate) params.set('etcStart', context.startDate);
  if (context.endDate) params.set('etcEnd', context.endDate);
  const search = context.search.trim();
  if (search && search.length <= 128) params.set('etcSearch', search);
  if (context.page > 1) params.set('etcPage', String(context.page));
  const query = params.toString();
  return `${location.pathname}${query ? `?${query}` : ''}${location.hash}`;
}