#!/usr/bin/zsh
# uncomment to debug
# set -x
#
BIKE_DELIVERY_DATE='24 aug 2006'

_message () {
    echo "Your bike $3 service is due."
    echo "Get done between " `date --date="$1" '+%d %B %Y'` \
" and " `date --date="$2" '+%d %B %Y.'`
exit 0
}

service () {
    sdate1=`date --date="$BIKE_DELIVERY_DATE $1 days" ` #--rfc-3339='date'`
    sdate2=`date --date="$BIKE_DELIVERY_DATE $2 days" ` #--rfc-3339='date'`
    if [[ "`date`" < "$sdate2" ]]
        then
        _message $sdate1 $sdate2 $3
    fi
}

# if asked for delivery date with option -d, print it and return
while getopts d opt; do
    case $opt in
        d)
            print $BIKE_DELIVERY_DATE
            return;
            ;;
    esac
done

# service 30 45 "first"
# service 75 90 "second"
# service 165 180 "third"
# service 255 270 "fourth"
# service 350 365 "fifth"
service 435 450 "sixth"