import moment from 'moment'

/**
 * @param {number} workingDays - to subtract
 * @param {date|moment} [date] - date of reference
 * @return {date} result - of subtracting workingDays from date
 */
export const subtractWorkingDays = (workingDays, date = moment()) => {
  const m = moment(date)
  // if we have more than 5 days to reduce, subtract as much weeks
  // as we can, asuming a week contains 5 business days
  if (workingDays > 5) {
              // ~~ is faster than parseInt or Math.floor
    m.subtract(~~(workingDays/5), 'week')
    workingDays = workingDays % 5
  }
  if (workingDays - (m.get('day') - 1/*monday*/) > 0) workingDays = workingDays + 2
  return m.subtract(workingDays, 'day').toDate()
}