#!/bin/sh -efu
### This file is covered by the GNU General Public License
### version 2 or later.
###
### Copyright (C) 2019  ALT Linux Team
### Author: Leonid Krivoshein <klark@altlinux.org>

numbers_only=0
titles_only=0
search_item=
progname="${0##*/}"
grubmenu="/boot/grub/grub.cfg"


show_help() {
	cat <<-EOF
$progname - Show default or specified grub menu.

Usage: $progname [options]

Options:
  -f, --config=  Specify path to the grub config.
  -n, --numbers  Show only numbers of the items.
  -t, --titles   Show only titles of the items.
  -c, --check=   Specify item name to validate.
  -V, --version  Show script version and exit.
  -h, --help     Show this help message and exit.
EOF
	exit 0
}

show_version() {
	cat <<-EOF
$progname version 0.9
Copyright (C) 2019, ALT Linux Team
EOF
	exit 0
}

show_usage() {
	[ -z "$*" ] || echo "$*" 1>&2
	echo "Try '$progname --help' for more information." 1>&2
	exit 1
}

parse_args() {
	local opts="+f:,n,t,c:,V,h"
	local longopts="config:,numbers,titles,check:,version,help"

	opts=$(getopt -n "$progname" -o "$opts" -l "$longopts" -- "$@") ||
		show_usage "Invalid command-line arguments."
	eval set -- "$opts"
	while [ $# -gt 0 ]; do
		case "$1" in
		-f|--config)	shift; grubmenu="$1";;
		-n|--numbers)	numbers_only=1; titles_only=0;;
		-t|--titles)	numbers_only=0; titles_only=1;;
		-c|--check)	shift; search_item="$1";;
		-V|--version)	show_version;;
		-h|--help)	show_help;;
		--)		shift; break;;
		-*)		show_usage "Unrecognized option: '$1'";;
		*)		break;;
		esac
		shift
	done
	[ $# -eq 0 ] || show_usage "Unrecognized arguments: '$*'"
}

show_menu() {
	local mode title number prefix entry=0 itemno=0

	cat "$grubmenu" | sed \
		-re '/^\s*(menuentry\s+|submenu\s+|})/!d' \
		-re "s/^\s*menuentry\s+'([^']+)'.*\$/M\t\1/g" \
		-re 's/^\s*menuentry\s+"([^"]+)".*$/M\t\1/g' \
		-re "s/^\s*submenu\s+'([^']+)'.*\$/S\t\1/g" \
		-re 's/^\s*submenu\s+"([^"]+)".*$/S\t\1/g' \
		-re "s/^\s*}\s*\$/E\t-/g" |
	while read mode title; do
		case "$mode" in
		M)	if [ $numbers_only -ne 0 ]; then
				echo -e "${number}${itemno}"
			elif [ $titles_only -ne 0 ]; then
				echo -e "${prefix}${title}"
			else
				echo -e "${number}${itemno}\t${prefix}${title}"
			fi
			itemno=$(($itemno + 1))
			entry=1
			;;
		S)	number="${number}${itemno}>"
			prefix="${prefix}${title}>"
			itemno=0
			;;
		*)	if [ $entry -ne 0 ]; then
				entry=0
			elif [ -n "$number" ]; then
				number="${number%>}"
				prefix="${prefix%>}"
				case "$number" in
				*">"*)	itemno="${number##*>}"
					number="${number%>*}>"
					prefix="${prefix%>*}>"
					itemno=$(($itemno + 1))
					;;
				*)	itemno=$number
					itemno=$(($itemno + 1))
					prefix=
					number=
					;;
				esac
			fi
			;;
		esac
	done
}

check_item() {
	local cnt

	numbers_only=1
	titles_only=0
	cnt=$(show_menu | grep -swc "$search_item" ||:)
	[ "$cnt" != "1" ] || exit 0

	numbers_only=0
	titles_only=1
	cnt=$(show_menu | grep -swc "$search_item" ||:)
	[ "$cnt" != "1" ] || exit 0

	if [ $cnt -eq 0 ]; then
		echo "$search_item: menu item not found." 1>&2
	else
		echo "$search_item: duplicate items found." 1>&2
	fi
	exit 1
}


parse_args "$@"
[ -r "$grubmenu" ] || show_usage "$grubmenu: config file not found."
[ -z "$search_item" ] || check_item
show_menu