#!/bin/bash
#
# backup-script system for cloning systems using rsync
# Copyright (c)2008-2016 Alexander Barton, alex@barton.de
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# Please read the file COPYING, README and AUTHORS for more information.
#

NAME=$(basename "$0")

VERBOSE=0
QUIET=0

export LC_ALL=C

# Default settings, can be overwritten in backup-script.conf:
[ -d "/usr/local/etc/backup-script.d" ] \
	&& conf_d="/usr/local/etc/backup-script.d" \
	|| conf_d="/etc/backup-script.d"

default_backup_type="rsync"
default_files="running-config"
default_generations=0
default_target="/var/backups"

# Search configuration file (last one is used as default!)
for conf in \
	"/usr/local/etc/backup-script.conf" \
	"/etc/backup-script.conf" \
	"${conf_d}/backup-script.conf" \
	"/usr/local/etc/backup-script.conf" \
; do
	if [ -r "$conf" ]; then
		# shellcheck source=/dev/null
		source "$conf"
		break
	fi
done

Usage() {
	echo "Usage: $NAME [-q|--quiet] [-v|--verbose] [<system> [<system> [...]]]"
	echo "       $NAME <-d|--dirs> <dir1> <dir2>"
	echo
	exit 2
}

BeginDiff() {
	echo "Differences in $*:"
}

PipeDiff() {
	local line
	IFS=
	while read -r line; do
		echo -e "     | $line"
	done
}

EndDiff() {
	:
}

HandleSystem() {
	local fname="$1"

	# Set global defaults
	local backup_type="$default_backup_type"
	local files="$default_files"
	local generations="$default_generations"
	local local=0
	local system="$fname"
	local target="$default_target"

	# Read in system configuration file
	# shellcheck source=/dev/null
	source "$f"

	target="$target/$(basename "$f")"

	[[ -d "$target" ]] || return 0

	# System name
	[[ "$system" == "$fname" ]] \
		&& systxt="\"$system\"" \
		|| systxt="\"$fname\" [\"$system\"]"
	[[ "$local" -eq 0 ]] \
		&& echo "Checking $systxt ..." \
		|| echo "Checking $systxt (local system) ..."

	# Check if job is disabled
	if [[ "$backup_type" == "disabled" ]]; then
		echo "Job is DISABLED and will be skipped."
		echo; return 0
	fi

	if [ $generations -lt 1 ]; then
		echo "No generations configured, nothing to compare, skipping system!"
		echo; return 1
	fi

	local latest_d="$target/latest"
	if [[ ! -d "$latest_d" || ! -r "$latest_d/.stamp" ]]; then
		echo "Failed to access latest backup generation in \"$latest_d\", skipping system!"
		echo; return 1
	fi
	echo "Found latest generation in \"$latest_d\"."

	declare -i code=-1
	# shellcheck source=/dev/null
	source "$latest_d/.stamp"

	if [[ $code -ne 0 && $code -ne 24 ]]; then
		echo "Last backup generation has errors, skipping system!"
		echo; return 1
	fi

	# Search previous generation without errors
	local previous_d=""
	# shellcheck disable=SC2045
	for d in $(ls -1dt "$target/"[0-9]*-[0-9]* 2>/dev/null); do
		[[ -d "$d" && -r "$d/.stamp" ]] || return 0

		declare -i code=-1
		# shellcheck source=/dev/null
		source "$d/.stamp"

		if [[ $code -eq 0 || $code -eq 24 ]]; then
			previous_d="$d"
			break
		fi
	done
	if [[ -z "$previous_d" || ! -d "$previous_d" || ! -r "$previous_d/.stamp" ]]; then
		echo "Failed to find previous successfull backup generation, skipping system!"
		echo; return 1
	fi
	echo "Comparing with generation in $previous_d ..."

	DiffGenerations "$backup_type" "$previous_d" "$latest_d" "$files"
	return_code=$?

	echo
	return $return_code
}

DiffGenerations() {
	local backup_type="$1"
	local gen1_d="$2"
	local gen2_d="$3"
	local files="$4"

	local return_code=0

	if [[ "$backup_type" == "rsync" ]]; then
		# rsync Backup Type

		for file in \
			/etc/passwd \
			/etc/shadow \
			/etc/group \
			/etc/gshadow \
			\
			/etc/fstab \
			/etc/hostname \
			/etc/hosts \
			/etc/machine-id \
			/etc/modules \
			/etc/network/interfaces \
			/etc/networks \
		; do
			[[ -r "${gen1_d}${file}" ]] || continue

			[[ $VERBOSE -ne 0 ]] && echo "Checking \"$file\" ..."
			diff -U 3 "${gen1_d}${file}" "${gen2_d}${file}" >"$tmp_diff"
			if [[ $? -ne 0 ]]; then
				BeginDiff "\"$file\""
				tail -n +3 "$tmp_diff" | PipeDiff
				EndDiff
				return_code=1
			fi
		done

		if [[ -d "${gen1_d}/var/lib/dpkg/info" && -d "${gen2_d}/var/lib/dpkg/info" ]]; then
			[[ $VERBOSE -ne 0 ]] && echo "Checking list of installed packages ..."
			chroot "${gen1_d}" dpkg --get-selections >"$tmp_1" || return 2
			chroot "${gen2_d}" dpkg --get-selections >"$tmp_2" || return 2
			diff -U 0 "$tmp_1" "$tmp_2" >"$tmp_diff"
			if [[ $? -ne 0 ]]; then
				BeginDiff "list of installed packages"
				tail -n +3 "$tmp_diff" | grep -v '^@@ ' | PipeDiff
				EndDiff
				return_code=1
			fi
		fi
	elif [[ "$backup_type" == "scp" ]]; then
		# scp Backup type
		file=$(basename "$files")
		[[ $VERBOSE -ne 0 ]] && echo "Checking \"$file\" ..."
		diff -U 3 "${gen1_d}/${file}" "${gen2_d}/${file}" >"$tmp_diff"
		if [[ $? -ne 0 ]]; then
			BeginDiff "\"$file\""
			tail -n +3 "$tmp_diff" | PipeDiff
			EndDiff
			return_code=1
		fi
	else
		echo "Backup type \"$backup_type\" undefined, \"$system\" skipped!"
		echo; return 2
	fi

	return $return_code
}

MkTempFiles() {
	tmp_1=$(mktemp "/tmp/$NAME.XXXXXX") || exit 1
	tmp_2=$(mktemp "/tmp/$NAME.XXXXXX") || exit 1
	tmp_diff=$(mktemp "/tmp/$NAME.XXXXXX") || exit 1
	tmp_out=$(mktemp "/tmp/$NAME.XXXXXX") || exit 1
}

CleanUp() {
	rm -f "$tmp_1" "$tmp_2" "$tmp_diff" "$tmp_out"
}

while [[ $# -gt 0 ]]; do
	case "$1" in
	  "-d"|"--dirs")
		shift
		[[ $# -eq 2 ]] || Usage
		MkTempFiles
		DiffGenerations "$default_backup_type" "$1/" "$2/" "$default_files"
		return_code=$?
		CleanUp
		exit $return_code
		;;
	  "-q"|"--quiet")
		QUIET=1; shift
		;;
	  "-v"|"--verbose")
		VERBOSE=1; shift
		;;
	  "-"*)
		Usage
		;;
	  *)
		break
	esac
done

if [[ $# -ge 1 ]]; then
	for s in "$@"; do
		if [ ! -r "${conf_d}/$s" ]; then
			echo "$NAME: Can' read \"${conf_d}/$s\"!"
			exit 1
		fi
		sys+=("${conf_d}/$s")
	done
else
	sys=("${conf_d}/"*)
fi

MkTempFiles
for f in "${sys[@]}"; do
	[[ -r "$f" && -f "$f" ]] || continue

	fname=$(basename "$f")
	case "$fname" in
		"backup-script.conf"|*.sh)
			continue
			;;
	esac

	HandleSystem "$fname" >"$tmp_out" 2>&1
	[[ $QUIET -eq 0 || $? -ne 0 ]] && cat "$tmp_out"
done
CleanUp

# -eof-