#!/bin/sh

set -e

_DEVICE="${1}"
_DIRECTORY="/boot/extlinux"

# User is unprivileged
if [ "$(id -u)" -ne 0 ]
then
	echo "E: need root privileges"
	exit 1
fi

# Redirect stdout to stderr due Debconf usage
exec 1>&2

# Checking extlinux directory
echo -n "P: Checking for EXTLINUX directory..."

# Creating extlinux directory
if [ ! -e "${_DIRECTORY}" ]
then
	echo " not found."

	echo -n "P: Creating EXTLINUX directory..."
	mkdir -p "${_DIRECTORY}"
	echo " done: ${_DIRECTORY}"
else
	echo " found."
fi

# Reading old default file
if [ -e /etc/default/extlinux ]
then
	. /etc/default/extlinux
fi

# Setting defaults
EXTLINUX_UPDATE="${EXTLINUX_UPDATE:-true}"
EXTLINUX_ALTERNATIVES="${EXTLINUX_ALTERNATIVES:-default recovery}"
EXTLINUX_DEFAULT="${EXTLINUX_DEFAULT:-0}"
EXTLINUX_ENTRIES="${EXTLINUX_ENTRIES:-all}"

if [ -z "${EXTLINUX_MENU_LABEL}" ]
then
	if [ -x "$(which lsb_release 2>/dev/null)" ]
	then
		EXTLINUX_MENU_LABEL="$(lsb_release -i -s) GNU/Linux, kernel"
	else
		EXTLINUX_MENU_LABEL="Debian GNU/Linux, kernel"
	fi
fi

EXTLINUX_PARAMETERS="${EXTLINUX_PARAMETERS:-ro quiet}"

if [ -z "${EXTLINUX_ROOT}" ]
then
	# Find root partition
	while read _LINE
	do

read _FS_SPEC _FS_FILE _FS_VFSTYPE _FS_MNTOPS _FS_FREQ _FS_PASSNO << EOF
${_LINE}
EOF

		if [ "${_FS_SPEC}" != "#" ] && [ "${_FS_FILE}" = "/" ]
		then
			EXTLINUX_ROOT="root=${_FS_SPEC}"
			break
		fi
	done < /etc/fstab
fi

if [ -z "${EXTLINUX_THEME}" ]
then
	# Using default menu if available
	if [ -e /usr/share/syslinux/themes/debian/extlinux ]
	then
		EXTLINUX_THEME="debian"
	else
		EXTLINUX_THEME="none"
	fi
fi

EXTLINUX_TIMEOUT="${EXTLINUX_TIMEOUT:-50}"

# Writing new default file
cat > "/etc/default/extlinux" << EOF
## /etc/default/extlinux - configuration file for extlinux-update(8)

EXTLINUX_UPDATE="${EXTLINUX_UPDATE}"

EXTLINUX_ALTERNATIVES="${EXTLINUX_ALTERNATIVES}"
EXTLINUX_DEFAULT="${EXTLINUX_DEFAULT}"
EXTLINUX_ENTRIES="${EXTLINUX_ENTRIES}"
EXTLINUX_MENU_LABEL="${EXTLINUX_MENU_LABEL}"
EXTLINUX_PARAMETERS="${EXTLINUX_PARAMETERS}"
EXTLINUX_ROOT="${EXTLINUX_ROOT}"
EXTLINUX_THEME="${EXTLINUX_THEME}"
EXTLINUX_TIMEOUT="${EXTLINUX_TIMEOUT}"
EOF

if [ "${EXTLINUX_UPDATE}" != "true" ]
then
	echo "P: extlinux-update is disabled in /etc/default/extlinux."

	exit 0
fi

# Create linux.cfg
cat > "${_DIRECTORY}/linux.cfg" << EOF
## ${_DIRECTORY}/linux.cfg
##
## IMPORTANT WARNING
##
## The configuration of this file is generated automatically.
## Do not edit this file manually, use: extlinux-update


default 0

EOF

# Find linux versions
_VERSIONS="$(cd /boot && ls vmlinuz-* | sed -e 's|vmlinuz-||g' | sort -r)"

if [ "$(stat --printf %d /)" = "$(stat --printf %d /boot)" ]
then
	# / and /boot are on the same filesystem
	_BOOT="/boot"
else
	# / and /boot are not on the same filesystem
	_BOOT=""
fi


for _VERSION in ${_VERSIONS}
do
	echo "P: Writing config for /boot/vmlinuz-${_VERSION}..."

	_NUMBER="${_NUMBER:-0}"
	_ENTRY="${_ENTRY:-1}"

	if [ -e /boot/initrd.img-${_VERSION} ]
	then
		_INITRD="initrd=${_BOOT}/initrd.img-${_VERSION}"
	else
		_INITRD=""
	fi

	if echo ${EXTLINUX_ALTERNATIVES} | grep -q default
	then

# Writing default entry
cat >> "${_DIRECTORY}/linux.cfg" << EOF

label ${_NUMBER}
	menu label ${EXTLINUX_MENU_LABEL} ${_VERSION}
	kernel ${_BOOT}/vmlinuz-${_VERSION}
	append ${_INITRD} ${EXTLINUX_ROOT} ${EXTLINUX_PARAMETERS}
EOF

	fi

	if echo ${EXTLINUX_ALTERNATIVES} | grep -q live
	then

# Writing live entry
cat >> "${_DIRECTORY}/linux.cfg" << EOF

label ${_NUMBER}l
	menu label ${EXTLINUX_MENU_LABEL} ${_VERSION} (live mode)
	kernel ${_BOOT}/vmlinuz-${_VERSION}
	append ${_INITRD} ${EXTLINUX_ROOT} ${EXTLINUX_PARAMETERS} boot=live plainroot
	text help
   This option boots the system into live mode (non-persistent)
	endtext
EOF

	fi

	if echo ${EXTLINUX_ALTERNATIVES} | grep -q recovery
	then

# Writing recovery entry
cat >> "${_DIRECTORY}/linux.cfg" << EOF

label ${_NUMBER}r
	menu label ${EXTLINUX_MENU_LABEL} ${_VERSION} (recovery mode)
	kernel ${_BOOT}/vmlinuz-${_VERSION}
	append ${_INITRD} ${EXTLINUX_ROOT} $(echo ${EXTLINUX_PARAMETERS} | sed -e 's| quiet||') single
	text help
   This option boots the system into recovery mode (single-user)
	endtext
EOF

	fi

	_NUMBER="$((${_NUMBER} + 1))"

	if [ "${EXTLINUX_ENTRIES}" = "${_ENTRY}" ]
	then
		break
	fi
done

cat > "${_DIRECTORY}/extlinux.conf" << EOF
## ${_DIRECTORY}/extlinux.conf
##
## IMPORTANT WARNING
##
## The configuration of this file is generated automatically.
## Do not edit this file manually, use: extlinux-update


default ${EXTLINUX_DEFAULT}
prompt 1
timeout ${EXTLINUX_TIMEOUT}
EOF

if [ -n "${EXTLINUX_THEME}" ] && [ "${EXTLINUX_THEME}" != "none" ]
then
	if [ ! -e "/usr/share/syslinux/themes/${EXTLINUX_THEME}/extlinux" ]
	then
		echo "E: /usr/share/syslinux/${EXTLINUX_THEME}/extlinux: No such file or directory"
		exit 1
	else
		echo -n "P: Installing ${EXTLINUX_THEME} theme..."
		rm -rf "${_DIRECTORY}/themes/${EXTLINUX_THEME}"

		mkdir -p "${_DIRECTORY}/themes"

		EXTLINUX_THEME_ORIG="$(readlink /usr/share/syslinux/themes/${EXTLINUX_THEME})" || true

		if [ -n "${EXTLINUX_THEME_ORIG}" ]
		then
			cp -aL "/usr/share/syslinux/themes/${EXTLINUX_THEME_ORIG}/extlinux" "${_DIRECTORY}/themes/${EXTLINUX_THEME_ORIG}"
			ln -sf "${EXTLINUX_THEME_ORIG}" "${_DIRECTORY}/themes/${EXTLINUX_THEME}"
		else
			cp -aL "/usr/share/syslinux/themes/${EXTLINUX_THEME}/extlinux" "${_DIRECTORY}/themes/${EXTLINUX_THEME}"
		fi

		echo " done."
	fi

cat >> "${_DIRECTORY}/extlinux.conf" << EOF

include themes/${EXTLINUX_THEME}/theme.cfg
EOF

else

cat >> "${_DIRECTORY}/extlinux.conf" << EOF

display boot.txt
include linux.cfg
EOF

	if [ ! -e "${_DIRECTORY}/boot.txt" ]
	then
		echo "Wait 5 seconds or press ENTER to " > "${_DIRECTORY}/boot.txt"
	fi
fi