#!/bin/bash

export PATH='/sbin:/usr/sbin:/bin:/usr/bin'
typeset -r usbstick_mountpoint='/media/usb0'

typeset -r backupscript_version='V2.0.6'

printf '#\n'
printf '# Quantron backup script STARTING...\n'

# stop codesys application
# we assume this returns only after codesys is no longer running
systemctl stop 'codesys3-rt.service'

# send all output to the quantron framebuffer console
export TERM='linux'
exec 0<>'/dev/tty0' 1>&0 2>&0
clear

# NASTY HACK:
# systemd/udev has a timeout running which will send SIGKILL to
# all processes in a cggroup. Since this backup script is interactive
# the only way to avoid getting killed by that timeout is to move
# the current shell process into another cggroup.
# This hack is WRONG on so many levels that it hurts, but given
# the time constraints and the stupidity how our system is currently
# designed there was to other way.
# We do this here, after redirecting output to the framebuffer terminal,
# so that we can see whether this fails or not.
printf '%d' $$ >'/sys/fs/cgroup/systemd/system/cgroup.procs'

color_printf()
{
	typeset color=$1
	shift
	typeset ttycmd=''

	case "$color" in
		'black')	ttycmd=$'\E[30m' ;;
		'red')		ttycmd=$'\E[31m' ;;
		'green')	ttycmd=$'\E[32m' ;;
		'yellow')	ttycmd=$'\E[33m' ;;
		'blue')		ttycmd=$'\E[34m' ;;
		'magenta')	ttycmd=$'\E[35m' ;;
		'cyan')		ttycmd=$'\E[36m' ;;
		'white')	ttycmd=$'\E[37m' ;;
	esac

	printf '%s' "$ttycmd"
	printf "$@"
	printf '%s' $'\E[0m'
}


is_usbstick_mounted()
{
	grep -q -E \
		"[[:space:]]+${usbstick_mountpoint}[[:space:]]+(fat|vfat|ntfs|ext4)[[:space:]]+(rw|ro)," \
		'/proc/self/mounts'
	return $?
}

disable_console_screensaver()
{
	# make sure the framebuffer console screenblanker is NOT active
	printf '0\n' >'/sys/devices/platform/imx21-fb.0/graphics/fb0/blank'

	# disable screen blanking (we have to do this via terminal codes
	# since /sys/module/kernel/parameters/consoleblank is read-only)
	printf '\E[9;0]'

	return 0
}

do_menu()
{
	typeset key

	#
	# main menu
	#
	printf '\n#\n'
	printf '# Welcome to the '
	color_printf 'red' 'QUANTRON'
	printf ' /var/dyn\n# backup tool (version %s)!\n' "${backupscript_version}"
	printf '#\n\n'

	color_printf 'yellow' ' * Menu:\n'
	color_printf 'yellow' ' - Press <ESC> key for abort\n\t(system shutdown)\n'	# key="A"
	color_printf 'yellow' ' - Press <T> key for backup\n'				# key="C"
	color_printf 'yellow' ' - Press <L%%/R%%> key for restore\n'			# key="D"

	for ((;;)) ; do
		disable_console_screensaver

		key=''

		#
		# wait for a key press...
		#
		# (warning: Quantron V3.1.9 has bash3.2.48 which does
		# NOT support -N, only -n is supported!)
		#
		IFS='' read -e -r -u0 -n1 key

		case "$key" in
			'A')
				color_printf 'cyan' '#### Aborting, system shutting down...\n'
				sleep 3
				reboot -p
				exit 0
				;;
			'C')
				color_printf 'cyan' '#### Starting backup...\n'
				sleep 3
				do_backup
				exit 0
				;;
			'D')
				color_printf 'cyan' '#### Starting restore...\n'
				sleep 3
				do_restore
				exit 0
				;;
			*)
				# beep ?
				;;
		esac
	done

	# notreached
}

do_backup()
{
	typeset -i backuperr=0

	if ! is_usbstick_mounted ; then
		color_printf 'red' '# ERROR: No USB stick mounted, aborting\n'
		return 1
	fi

	if ! /sbin/eag_usbstick mount_writeable ; then
		color_printf 'red' '# ERROR: Cannot mount stick writeable, aborting\n'
		return 1
	fi

	mkdir -p "${usbstick_mountpoint}/quantron_backup"
	rm -f "${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2.md5sum"

	color_printf 'cyan' '\n# Saving files...\n'
	set -o pipefail

	(cd / && tar -cvf - var/dyn/* ) | \
		bzip2 -9 | \
		tee \
			>(md5sum '/dev/stdin' | sed 's/\/dev\/stdin/quantron_var_dyn_backup.tar.bz2/' >"${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2.md5sum") \
			>"${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2"
	(( backuperr+=$? ))

	sync ; sync # UNIX tradition!

	/sbin/eag_usbstick mount_readonly
	(( backuperr+=$? ))

	# verifying backup
	color_printf 'cyan' '\n# Verifying backup data...\n'
	(cd "${usbstick_mountpoint}/quantron_backup" && md5sum -c 'quantron_var_dyn_backup.tar.bz2.md5sum')
	if (( $? != 0 )) ; then
		(( backuperr++ ))
		color_printf 'red' '# ERROR: Wrong MD5 hash sum of written data\n'

		# remove backup archive so the user cannot restore broken data
		/sbin/eag_usbstick mount_writeable >'/dev/null' 2>&1
		rm -f \
			"${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2" \
			"${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2.md5sum"
		/sbin/eag_usbstick mount_readonly >'/dev/null' 2>&1
	fi

	if (( backuperr == 0 )) ; then
		color_printf 'green' '\n#\n# Backup success.\n#\n'
	else
		color_printf 'red' '\n#\n# Backup FAILED!!\n#\n'
	fi

	disable_console_screensaver

	color_printf 'yellow' '\n\nPlease remove USB stick and reboot...\n'
	return $(( backuperr?1:0 ))
}

do_restore()
{
	typeset -i restoreerr=0

	if [[ ! -r "${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2" ]] ; then
		color_printf 'red' '# ERROR: Cannot read backup file %s\n' "${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2"
		return 1
	fi

	color_printf 'cyan' '\n# Verifying backup data...\n'
	(cd "${usbstick_mountpoint}/quantron_backup" && md5sum -c 'quantron_var_dyn_backup.tar.bz2.md5sum')
	if (( $? != 0 )) ; then
		color_printf 'red' '# ERROR: Backup archive does not have the correct hash sum.\n'
		color_printf 'red' '\n#\n# Restore FAILED!!\n#\n'
		return 1
	fi

	color_printf 'cyan' '\n# Restoring files...\n'
	set -o pipefail
	bunzip2 -c <"${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2" |
		(cd / && tar -xvf -)
	(( restoreerr+=$? ))

	sync ; sync # UNIX tradition!

	if (( restoreerr == 0 )) ; then
		color_printf 'green' '\n#\n# Restore success.\n#\n'
	else
		color_printf 'red' '\n#\n# Restore FAILED!!\n#\n'
	fi

	disable_console_screensaver

	color_printf 'yellow' '\n\nPlease remove USB stick and reboot...\n'
	return $(( restoreerr?1:0 ))
}

# main
do_menu

# EOF.