#!/bin/bash

if [ $# -ne 1 ]; then
  echo
  echo "Usage:"
  echo "  $(basename $0) <date in format YYYY-MM-DD or YYYY/MM/DD>"
  echo
  echo "Example:"
  echo "  $(basename $0) 2017-07-23"
  echo "  $(basename $0) 2017/07/23"
  echo
  exit 1
fi

DATE="${1:-"$(date +'%Y-%m-%d')"}"
DATE_IS_NOT_VALID="0"
CWD="$(dirname "$(readlink -f "$0")")"
E_WRONGDATE=10

if echo $DATE | grep -qwEo '^^[0-9]{4}(-|/)[01][0-9](-|/)[0-9]{2}$$' ;then
  if ! date +'%Y-%m-%d' -d "$DATE" >/dev/null 2>&1 ; then
    DATE_IS_NOT_VALID=1
  fi
else
  DATE_IS_NOT_VALID=1
fi

if [ $DATE_IS_NOT_VALID -eq 1 ]; then
    echo "Error: Invalid format for date"
    exit $E_WRONGDATE
fi