check_number

#!/usr/bin/env bash

# #region Help & Version
function show_help() {
	cat <<_EOF_
Assert that the input is a correctly formatted number.

Usage:	$0 [-idsurk] [-b BASE] NUMBER

Options:
	-i, --integer: must be a integer
	-d, --decimal: must be a decimal
	-s, --signed: must be signed
	-u, --unsigned: must be unsigned (if remove_plus, can be labeled positive)
	-r, --remove_plus: Remove the plus sign from the output if in the input
	-k, --keep_plus: Keep the plus sign from the output if in the input
_EOF_
}
function show_version() {
	cat <<_EOF_
$0 1.0.0

Copyright (C) 2025 Justin Morris
_EOF_
}
# #endregion Help & Version

shopt -s extglob globasciiranges
readonly DECIMAL_MATCHER='[[:digit:]]'
# readonly HEX_MATCHER='[[:xdigit:]]'
# readonly OCTAL_MATCHER='[01234567]'
# readonly PRE_DECIMAL_MATCHER=''
# readonly PRE_HEX_MATCHER='0[xX]'
# readonly PRE_OCTAL_MATCHER='0'
declare pattern='^'
declare pattern_body='MATCH+\.?$'
declare is_decimal='false'
declare is_signed='false'
declare remove_plus='true'
# declare -i allowed_base=10
# declare force_base='false'
while [[ "$1" =~ ^(-[[:alpha:]]|--[[:alpha:]_]+)$ ]]; do
	case "$1" in
		(-i | --integer)
			pattern_body='MATCH+\.?$'
			if ! declare -r is_decimal='false'; then exit 1; fi
			shift
			;;
		(-d | --decimal)
			pattern_body='(MATCH+\.?|MATCH*\.MATCH+)$'
			if ! declare -r is_decimal='true'; then exit 1; fi
			shift
			;;
		(-s | --signed)
			pattern='^(-|\+)?'
			if ! declare -r is_signed='true'; then exit 1; fi
			shift
			;;
		(-u | --unsigned)
			pattern='^'
			if ! declare -r is_signed='false'; then exit 1; fi
			shift
			;;
		(-r | --remove_plus)
			if ! declare -r remove_plus='true'; then exit 1; fi
			shift
			;;
		(-k | --keep_plus)
			if ! declare -r remove_plus='false'; then exit 1; fi
			shift
			;;
		# (-b | --base)
		# 	shift
		# 	case "$1" in
		# 		(decimal)
		# 			if ! declare -r allowed_base=10; then exit 1; fi
		# 			;;
		# 		(hex | hexadecimal)
		# 			if ! declare -r allowed_base=16; then exit 1; fi
		# 			;;
		# 		(oct | octal)
		# 			if ! declare -r allowed_base=8; then exit 1; fi
		# 			;;
		# 		([[:digit:]]+)
		# 			if ! declare -r allowed_base="$1"; then exit 1; fi
		# 			if ((allowed_base < 2 || allowed_base > 64)); then
		# 				echo "Base must be decimal, oct(al), hex(adecimal), or an unsigned integer between 2 & 64 inclusive; was $1" 1>&2
		# 				exit 1
		# 			fi
		# 			;;
		# 		(*)
		# 			echo "Base must be decimal, oct(al), hex(adecimal), or an unsigned integer between 2 & 64 inclusive; was $1" 1>&2
		# 			exit 1
		# 			;;
		# 	esac
		# 	shift
		# 	;;
		(-h | --help)
			show_help
			exit 0
			;;
		(-v | --version)
			show_version
			exit 0
			;;
		(*)
			break;
			;;
	esac
done
pattern+="${pattern_body//MATCH/$DECIMAL_MATCHER}"
declare -r pattern
declare -r text="$*"
if [[ "$text" =~ $pattern ]]; then
	if eval $remove_plus && [ "${text:0:1}" = '+' ]; then
		echo -n "${text:1}"
	else
		echo -n "$text"
	fi
elif eval "$remove_plus" && [ "${text:0:1}" = '+' ] && [[ "${text:1}" =~ $pattern ]]; then
	echo -n "${text:1}"
# elif [ "$text" = '_' ]; then :; # index is last entry
else
	err_msg="must be a"
	if eval $is_signed; then err_msg+=" signed "; else err_msg+="n unsigned "; fi
	if eval $is_decimal; then err_msg+="decimal number"; else err_msg+="integer"; fi
	echo "$err_msg; value was '$text'" 1>&2
	exit 1
fi
exit 0