#!/bin/bash

if [[ $# == 0 ]]
then
	echo "No date input, assuming today's date:" `date +\%d/\%m/\%y`
today=`date +\%d/\%m/\%y`
	if (( `grep -c $today ~/.my_calender` != 0 ))
		then
			echo "There are `grep -c $today ~/.my_calender` events on today:"
			grep $today ~/.my_calender | cut --delimiter=" " -f 2
		else echo "No events today."
	fi

else
	if [[ $# > 1 ]]
	then
		echo "Usage: `basename $0` dd/mm/yy"
	else
		if [[ $1 =~ (^[1-9]|[12][0-9]|3[01])/([1-9]|1[0-2])/[01][0-9]$ ]]
		then
			if (( `grep -c $1 ~/.my_calender` != 0 ))
			then
				echo "There are `grep -c $1 ~/.my_calender` events on $1:"
				grep $1 ~/.my_calender | cut --delimiter=" " -f 2
			else echo "No events on $1."
			fi
		else echo "Not a valid date. Use date of the form dd/mm/yy. Exclude leading zeros."
		fi
	fi
fi