#!/bin/sh
set -e -o pipefail
bootdir="$1"
file="$2"

if [ -z "$bootdir" -o -z "$file" ]; then
	die "Usage: $0 /boot /boot/grub/grub.cfg"
fi

reset_entry() {
	name=""
	kexectype="elf"
	kernel=""
	initrd=""
	modules=""
	append=""
}

filedir=`dirname $file`
bootdir="${bootdir%%/}"
bootlen="${#bootdir}"
appenddir="${filedir:$bootlen}"

fix_path() {
	path="$@"
	if [ "${path:0:1}" != "/" ]; then
		path="$appenddir/$path"
	fi
}

echo_entry() {
	if [ "$kexectype" = "elf" ]; then
		if [ -z "$kernel" ]; then return; fi

		fix_path $kernel
		entry="$name|$kexectype|kernel $path"
		if [ -n "$initrd" ]; then
			fix_path $initrd
			entry="$entry|initrd $path"
		fi
		if [ -n "$append" ]; then
			entry="$entry|append $append"
		fi

		echo $(eval "echo \"$entry\"")
	fi
	if [ "$kexectype" = "multiboot" -o "$kexectype" = "xen" ]; then
		if [ -z "$kernel" ]; then return; fi

		fix_path $kernel
		echo $(eval "echo \"$name|$kexectype|kernel $path$modules\"")
	fi
}

search_entry() {
	case $line in
		menuentry* | MENUENTRY* )
			state="grub"
			reset_entry
			name=`echo $line | tr "'" "\"" | cut -d\" -f 2`
			;;

		label* | LABEL* )
			state="syslinux"
			reset_entry
			name=`echo $line | cut -c6- `
	esac
}

grub_entry() {
	if [ "$line" = "}" ]; then
		echo_entry
		state="search"
		return
	fi

	# add info to menuentry
	trimcmd=`echo $line | tr '\t ' ' ' | tr -s ' '`
	cmd=`echo $trimcmd | cut -d\  -f1`
	val=`echo $trimcmd | cut -d\  -f2-`
	case $cmd in
		multiboot*)
			# TODO: differentiate between Xen and other multiboot kernels
			kexectype="xen"
			kernel="$val"
			;;
		module*)
			case $val in
				--nounzip*) val=`echo $val | cut -d\  -f2-` ;;
			esac
			fix_path $val
			modules="$modules|module $path"
			;;
		linux*)
			kernel=`echo $trimcmd | cut -d\  -f2`
			append=`echo $trimcmd | cut -d\  -f3-`
			;;
		initrd*)
			initrd="$val"
			;;
	esac
}

syslinux_end() {
	# finish menuentry

	# attempt to parse out of append if missing initrd
	if [ -z "$initrd" ]; then
		newappend=""
		for param in $append; do
			case $param in
				initrd=*)
					initrd=`echo $param | cut -d\= -f2`
					;;
				*) newappend="$newappend $param" ;;
			esac
		done
		append="${newappend##' '}"
	fi

	echo_entry
	state="search"
}

syslinux_multiboot_append() {
	splitval=`echo "${val// --- /|}" | tr '|' '\n'`
	while read line
	do
		if [ -z "$kernel" ]; then
			kernel="$line"
		else
			fix_path $line
			modules="$modules|module $path"
		fi
	done << EOF
$splitval
EOF
}

syslinux_entry() {
	case $line in
		"")
			syslinux_end
			return
			;;
		label* | LABEL* )
			syslinux_end
			search_entry
			return
			;;
	esac

	# add info to menuentry
	trimcmd=`echo $line | tr '\t ' ' ' | tr -s ' '`
	cmd=`echo $trimcmd | cut -d\  -f1`
	val=`echo $trimcmd | cut -d\  -f2-`
	case $trimcmd in
		menu* | MENU* )
			cmd2=`echo $trimcmd | cut -d \  -f2`
			if [ "$cmd2" = "label" -o "$cmd2" = "LABEL" ]; then
				name=`echo $trimcmd | cut -c11- | tr -d '^'`
			fi
			;;
		linux* | LINUX* | kernel* | KERNEL* )
			case $val in
				# TODO: differentiate between Xen and other multiboot kernels
				*mboot.c32) kexectype="xen" ;;
				*.c32)
					# skip this entry
					state="search"
					;;
				*)
					kernel="${val#"$bootdir"}"
			esac
			;;
		initrd* | INITRD* )
			initrd="${val#"$bootdir"}"
			;;
		append* | APPEND* )
			if [ "$kexectype" = "multiboot" -o "$kexectype" = "xen" ]; then
				syslinux_multiboot_append
			else
				append="$val"
			fi
			;;
	esac
}

state="search"
while read line
do
	case $state in
		search)
			search_entry
			;;
		grub)
			grub_entry
			;;
		syslinux)
			syslinux_entry
			;;
	esac
done < "$file"

# handle EOF case
if [ "$state" = "syslinux" ]; then
	syslinux_end
fi