#!/bin/bash
# Copyright (c) 2017 Synology Inc. All rights reserved.
# prerm script for synology-active-backup-for-business package

DATTOBD="synosnap"
DATTOBD_MODULE="synosnap"
APP_NAME="synosnap"

main()
{
	action="$1"

	case "${action}" in
		remove)
			action_remove $@
		;;
		upgrade)
			action_upgrade $@
		;;
		deconfigure)
			action_deconfigure $@
		;;
		failed-upgrade)
			action_failed_upgrade $@
		;;
		*)
			echo "prerm called with unknown arguemnts '$1'" >&2
			return 1
		;;
	esac

	return $?
}

TEXT_COLOR='\033[0;31m' #Red
BG_COLOR='\033[43m' # Yellow background
NC='\033[0m' # No Color

function echo_highlight() {
    echo -e "${TEXT_COLOR}${BG_COLOR}$1${NC}"
}


update_initrd()
{
	# 1. remove modprobe synosnap & reload script in initrd for all kernels that installed synosnap
	# 2. try to remove backup initrd for all kernels that installed synosnap

	dkms_output=$(dkms status | grep synosnap | grep install)
	if [ -z "$dkms_output" ]; then
		echo "No synosnap modules installed in dkms."
		return 0
	fi

	kernel_versions=()
	while IFS=',/' read -r -a line_array; do
		kernel_version=$(echo "${line_array[2]}" | tr -d '[:space:]')
		kernel_versions+=("$kernel_version")
	done <<< "$dkms_output"

	echo "Found synosnap installed by dkms in the following kernel versions: ${kernel_versions[@]}"
	echo "Start updating initrd and try to remove backup initrd for these kernel versions..."

	# if not found the proper initrd name, intrd will be empty string
	for kernel_version in "${kernel_versions[@]}"; do
		for initrd in "initrd.img-$kernel_version" "initramfs-$kernel_version.img" "initrd-$kernel_version.img" "initrd-$kernel_version" ''; do
			[[ $initrd && -f /boot/$initrd ]] && break
		done

		if ! [[ $initrd ]]; then 
			continue 
		fi

		# get the size (MB) of the initrd
		initrd_size=$(du -m /boot/$initrd | cut -f1)

		if type "update-initramfs" &> /dev/null; then
			echo "Configuring update-initramfs for $kernel_version, please wait..."
			update-initramfs -u -k $kernel_version
		elif type "mkinitrd" &> /dev/null; then
			echo "Configuring initrd for $kernel_version, please wait..."
			mkinitrd -f /boot/$initrd $kernel_version
		fi

		if [ $? -ne 0 ]; then
			echo_highlight "Failed to update /boot/$initrd"
			echo_highlight "One possible cause is insufficient free space on the /boot volume (at least $initrd_size MB required)."
			echo_highlight "Please manually update the initrd for the kernel- $kernel_version later."
		fi

		backup_initrd="/boot/$initrd.old-syno"
		if [[ -f $backup_initrd ]]; then
			echo "Removing old backup initrd $backup_initrd"
			rm -fv $backup_initrd
		fi


	done
	
	return 0
}


action_remove()
{
	in_favour_package_name="$3"
	new_version="$4"
	dattobd_version="$(dpkg-query --show --showformat='${Version}' synosnap)"

	rmmod ${DATTOBD_MODULE}
	rm -rf /etc/synosnap/
	rm -fv /usr/share/initramfs-tools/hooks/synosnap
	rm -fv /usr/share/initramfs-tools/scripts/init-premount/synosnap
	rm -fv /lib/systemd/system-shutdown/synosnap.shutdown
	update_initrd
	dkms remove ${DATTOBD}/${dattobd_version} --all

	return 0
}

action_upgrade()
{
	new_version="$2"
	installed_version=$(dpkg-query --show --showformat='${Version}' ${APP_NAME})

	dpkg --compare-versions "${new_version}" "ge" "${installed_version}"

	if [ $? -ne 0 ]; then
		echo "installed ${APP_NAME} version is newer or equal"
		return 1
	fi

	return 0
}

action_deconfigure()
{
	in_favour_package_name="$3"
	in_favour_package_version="$4"
	conflicting_package_name="$6"
	conflicting_package_version="$7"

	return 0
}

action_failed_upgrade()
{
	old_version="$2"

	return 0
}

main $@
exit $?