#!/bin/sh
# gsu -- the global subcommand utility
# (C) 2006-2009 Andre Noll

_gsu_init_errors()
{
	gsu_errors="
GSU_SUCCESS			success
E_GSU_BAD_COMMAND		invalid command
E_GSU_NOT_A_NUMBER		not a number
E_GSU_SOURCE			error in config file
E_GSU_CONFIG			bad/missing config file option
$gsu_errors
"
	local a b i=0
	while read a b; do
		if test -z "$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

_gsu_available_commands()
{
	result="$( (printf "help\nman\n"; grep "^com_[a-z_]\+()" $0) \
		| sed -e 's/^com_//' -e 's/()//' \
		| sort \
		| tr '\n' ' ')"
	ret=$GSU_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

export gsu_man_txt="
Print the manual.

Usage: man"

com_man()
{
	local equal_signs="=================================================="
	local minus_signs="--------------------------------------------------"
        local com num

	echo "$_gsu_self (_${gsu_banner_txt}_) manual"
	echo "${equal_signs:0:${#_gsu_self} + ${#gsu_banner_txt} + 16}"
	echo

        sed -e '1,/^#\{70,\}/d' -e '/^#\{70,\}/,$d' $0 -e 's/^# *//'
	echo "----"
        echo
	echo "$_gsu_self usage"
	echo "${minus_signs:0:${#_gsu_self} + 6}"
	printf "\t"
	_gsu_usage 2>&1
	echo "Each command has its own set of options as described below."
	echo
	echo "----"
	echo
	echo "Available commands:"

	_gsu_available_commands
        for com in $result; do
		num=${#com}
		if test $num -lt 4; then
			num=4
		fi
                echo "${minus_signs:0:$num}"
                echo "$com"
                echo "${minus_signs:0:$num}"
                $0 help $com
		echo
        done
        ret=$GSU_SUCCESS
}
export -f com_man

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 "$1"; then
		_gsu_banner_msg 2>&1
		_gsu_usage 2>&1
		# sed is magic, baby
		(printf "com_help()\n$gsu_help_txt" | head -n 4; echo "--"
		printf "com_man()\n$gsu_man_txt" | head -n 4; echo "--"

		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
		echo "Try $_gsu_self help <command> for info on <command>."
		ret=$GSU_SUCCESS
		return
	fi
	if test "$1" = "help"; then
		echo "$gsu_help_txt"
		ret=$GSU_SUCCESS
		return
	fi
	if test "$1" = "man"; then
		echo "$gsu_man_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_init_config()
{
	local name val default_val required ty comment

	# set default values
	while read name default_val required ty comment; do
		if test -z "$name"; then
			continue
		fi
		eval ${gsu_self}_$name="$default_val"
	done << EOF
	$gsu_config_vars
EOF
	result="$HOME/.${gsu_self}rc"
	# overwrite by custom configuration
	if [ -r "$result" ]; then
		ret=-$E_GSU_SOURCE
		if ! . "$result"; then
			gsu_err_msg
			exit 1
		fi
	fi
	while read name default_val required ty comment; do
		[ -z "$name" ] && continue
		eval val="\$$name"
		# abort if any required config var remains unset
		ret=-$_E_GSU_CONFIG
		if [ "$val" = "-" -a "$required" = "required" ]; then
			result="$name"
			gsu_err_msg
			exit 1
		fi
		if [ $ty == "number" ]; then
			gsu_is_a_number "$val"
			if [ $ret -lt 0];  then
				gsu_err_msg
				exit 1
			fi
		fi
		eval export ${gsu_self}_$name
	done << EOF
	$config_vars
EOF
}
export -f _gsu_init_config

gsu()
{
	local i

	_gsu_self="$(basename $0)"
	_gsu_init_errors
	_gsu_init_config
	_gsu_available_commands
	gsu_cmds="$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 "$@"
			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
}
export -f gsu