export type VehicleDetailRangeKey = 'context' | 'last15' | 'month' | 'quarter';

export interface VehicleDetailDateRange {
  start: string;
  end: string;
}

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

function fmtYmd(date: Date): string {
  const year = date.getFullYear();
  const month = String(date.getMonth() + 1).padStart(2, '0');
  const day = String(date.getDate()).padStart(2, '0');
  return `${year}-${month}-${day}`;
}

function validDate(value?: string): string | null {
  if (!value) return null;
  const match = DATE_PATTERN.exec(value);
  if (!match) return null;
  const date = new Date(Number(match[1]), Number(match[2]) - 1, Number(match[3]));
  return fmtYmd(date) === value ? value : null;
}

export function normalizeVehicleDetailContext(
  startDate?: string,
  endDate?: string,
): VehicleDetailDateRange | null {
  const start = validDate(startDate);
  const end = validDate(endDate);
  if (!start || !end) return null;
  return start <= end ? { start, end } : { start: end, end: start };
}

export function resolveVehicleDetailRange(
  key: VehicleDetailRangeKey,
  context: VehicleDetailDateRange | null,
  now = new Date(),
): VehicleDetailDateRange {
  if (key === 'context' && context) return context;

  const today = new Date(now.getFullYear(), now.getMonth(), now.getDate());
  const end = fmtYmd(today);
  if (key === 'month') {
    return { start: fmtYmd(new Date(today.getFullYear(), today.getMonth(), 1)), end };
  }
  if (key === 'quarter') {
    const quarterStartMonth = Math.floor(today.getMonth() / 3) * 3;
    return { start: fmtYmd(new Date(today.getFullYear(), quarterStartMonth, 1)), end };
  }

  const start = new Date(today);
  start.setDate(today.getDate() - 14);
  return { start: fmtYmd(start), end };
}

export function vehicleDetailContextLabel(context: VehicleDetailDateRange): string {
  if (context.start === context.end) {
    return `${Number(context.start.slice(5, 7))}月${Number(context.start.slice(8, 10))}日`;
  }
  return '所选区间';
}

export function includeCurrentDayInVehicleDetail(key: VehicleDetailRangeKey): boolean {
  return key === 'context';
}