#!/bin/bash
# weather.sh [-s STATE] [ZONE]

usage() { echo "Usage: $0 [-s STATE] [ZONE]" 1>&2; exit 1; }

STATE="de"
ZONE="001"

while getopts "s:" flag; do
  case "$flag" in
    s) STATE="$OPTARG" ;;
    *) usage ;;
  esac
done
shift $((OPTIND - 1))

# Allow 0 or 1 positional arg (ZONE)
if [ "$#" -gt 1 ]; then
  usage
fi

if [ "$#" -eq 1 ]; then
  if [[ ! "$1" =~ ^[0-9]{3}$ ]]; then
    usage
  fi
  ZONE="$1"
fi

STATE="${STATE,,}"  # lowercase

curl -s "https://tgftp.nws.noaa.gov/data/forecasts/zone/${STATE}/${STATE}z${ZONE}.txt"