import { addDays, format, getDayOfYear, parse } from 'date-fns';

export const EMPTY_GUID = '00000000-0000-0000-0000-000000000000';

export function groupBy<T, K extends keyof any>(
  list: T[],
  getKey: (item: T) => K
) {
  return list.reduce((previous, currentItem) => {
    const group = getKey(currentItem);
    if (!previous[group]) previous[group] = [];
    previous[group].push(currentItem);
    return previous;
  }, {} as Record<K, T[]>);
}

export function toDate(strDate: string) {
  try {
    return parse(strDate.substr(0, 10), 'yyyy-MM-dd', new Date());
  } catch {
    return null;
  }
}

export function toFormattedDate(strDate: string) {
  try {
    const dt = toDate(strDate);
    return dt ? format(dt, 'dd MMM yyyy') : '';
  } catch {
    return null;
  }
}

export function addDaysToDate(dt: Date, d: number) {
  return addDays(dt, d);
}

export function getDayIndex(dt: Date) {
  return getDayOfYear(dt);
}

export function isSameDate(sDate: Date, eDate: Date) {
  return (
    sDate.getFullYear() === eDate.getFullYear() &&
    sDate.getMonth() === eDate.getMonth() &&
    sDate.getDate() === eDate.getDate()
  );
}