# gsu -- the global subcommand utility
# (C) 2006-2007 Andre Noll

gsu_init_errors()
{
	gsu_errors="
GSU_SUCCESS			success
E_GSU_BAD_COMMAND		invalid command
E_GSU_NOT_A_NUMBER		not a number
$gsu_errors
"
	local a b i=0
	while read a b; do
		if test -z "$a"; then
			continue
		fi
		#echo "a:$a,  b: $b"
		gsu_error_txt[i]="$b"
		eval $a=$i
		i=$(($i + 1))
	done << EOF
	$gsu_errors
EOF
}
export -f gsu_init_errors

# check if $1 is a number
gsu_is_a_number()
{
	result="$1"
	if test "$1" -eq "$1" &> /dev/null; then
		ret=$GSU_SUCCESS
	else
		ret=-$E_GSU_NOT_A_NUMBER
	fi
}
export -f gsu_is_a_number

gsu_short_msg()
{
	echo "$1" 1>&2
}
export -f gsu_short_msg

gsu_msg()
{
	gsu_short_msg "$gsu_self: $1"
}
export -f gsu_msg

gsu_date_msg()
{
	gsu_short_msg "$gsu_self $(date): $1"
}
export -f gsu_date_msg

gsu_banner_msg()
{
	local txt="*** $gsu_self --"
	if test -z "$gsu_banner_txt"; then
		txt="$txt set \$gsu_banner_txt to customize this message"
	else
		txt="$txt $gsu_banner_txt"
	fi
	gsu_short_msg "$txt ***"
}
export -f gsu_banner_msg

gsu_err_msg()
{
	local txt="$result" err

	gsu_is_a_number "$ret"
	if test $ret -lt 0; then
		gsu_msg "unknown error ($ret:$txt)"
		exit 1
	fi
	if test $result -ge 0; then
		gsu_msg "unknown error ($result:$txt)"
		exit 1
	fi
	err=$((0 - $result))
	if test -n "$txt"; then
		txt="$txt: ${gsu_error_txt[$err]}"
	else
		txt="${gsu_error_txt[$err]}"
	fi
	gsu_msg "$txt"
}
export -f gsu_err_msg

gsu_usage()
{
	gsu_short_msg "Usage: $gsu_self command [options]"
}
export -f gsu_usage

export gsu_help_txt="
Print online help.

Usage: help [command]

Without arguments, print the list of available commands. Otherwise,
print the help text for the given command."
com_help()
{
	local a b
	if test -z "$1"; then
		gsu_banner_msg
		gsu_usage
		# sed is magic, baby
		grep -A 2 "^com_\([a-zA-Z_0-9]\+\)()" $0 \
			| grep -v -- '--' \
			| sed -e '/^com_\([a-zA-Z_0-9]\+\)()/bs' \
				-e 'H;$!d;x;s/\n//g;b' \
				-e :s \
				-e 'x;s/\n//g;${p;x;}' \
			| sed -e 's/^com_\([a-zA-Z_0-9]\+\)()#*/\1\t/' \
			| sort \
			| while read a b; do
				printf "$a\t"
				if test ${#a} -lt 8; then
					printf "\t"
				fi
				echo "$b"
                        done
		echo
		gsu_msg "Try $gsu_self help <command> for info on <command>."
		ret=$GSU_SUCCESS
		return
	fi
	if test "$1" = "help"; then
		gsu_short_msg "$gsu_help_txt"
		ret=$GSU_SUCCESS
		return
	fi
	ret=$GSU_SUCCESS
	if grep -q "^com_$1()" $0; then
		sed -e "1,/com_$1()/d" -e '/^{/,$d' -e 's/^## *//' $0
		return
	fi
	gsu_print_available_commands
	result="$1"
	ret=-$E_GSU_BAD_COMMAND
}
export -f com_help

gsu_available_commands()
{
	result="$( (echo help; grep "^com_[a-z_]\+()" $0) \
		| sed -e 's/^com_//' -e 's/()//' \
		| sort \
		| tr '\n' ' ')"
	ret=$SUCCESS
}
export -f gsu_available_commands

gsu_print_available_commands()
{(
	local i count
	gsu_short_msg "Available commands:"
	for i in $gsu_cmds; do
		printf "$i"
		count=$(($count + 1))
		if test $(($count % 4)) -eq 0; then
			echo
		else
			printf "\t"
			if test ${#i} -lt 8; then
				printf "\t"
			fi
		fi
	done
	echo
) 2>&1
}
export -f gsu_print_available_commands

gsu()
{
	local i

	gsu_self="$(basename $0)"
	gsu_init_errors
	gsu_available_commands
	gsu_cmds="$result"
	if test $# -eq 0; then
		gsu_usage
		gsu_print_available_commands
		exit 1
	fi
	arg="$1"
	shift
	for i in $gsu_cmds; do
		if test "$arg" = "$i"; then
			com_$arg "$@"
			ret=1
			if test $ret -lt 0; then
				gsu_err_msg
				exit 1
			fi
			exit 0
		fi
	done
	ret=-$E_GSU_BAD_COMMAND
	result="$arg"
	gsu_err_msg
	gsu_print_available_commands
	exit 1
}
# no need to export this