#!/bin/bash
#
# very simple restore script
# Usage:
#	restore filename
# where filename can be a part of a filename
# This is not (yet) thought to restore complete directories.

here="`/bin/pwd`"
host="`hostname -f`"

BACK=/backup/md5backup

for a in . md5 log out
do
	t="$BACK/$a"
	if [ ! -d "$t" ]
	then
		echo "directory $t is missing"
		exit 1
	fi
done

for a in log md5
do
	t="$BACK/$a/$host"
	if [ ! -s "$t" ]
	then
		echo "logfile $t is missing"
		exit 1
	fi
done

# fixes old log file type
fixup()
{
# old: YYYY-MM-DD HH:MM:SS md5 MD5SUMHERE 0 /PATH
# new: YYYY-MM-DD HH:MM:SS md5 xKB MD5SUMHERE 0 /PATH
sed 's/^\([^ ]* [^ ]* md5 \)\([0-9a-f]*\) /\1?KB \2 /'
}

# Compare file with the contents of the backup
# Hunt it in all out dirs.
md5cmp()
{
cmpdiff=false
md5t="`expr "$4" : '\(..\)'`/`expr "$4" : '..\(..\)'`/$4.$5.md5"
for a in "$BACK"/out*
do
	[ -d "$a" ] || continue
	[ -f "$a/$md5t" ] || continue
	[ -r "$a/$md5t" ] || continue
	cmp -s "$1" "$a/$md5t" && return
	cmpdiff=:
done
$cmpdiff && return 1
return 2
}

# Compare file with the contents of the backup
# Hunt it in all out dirs.
: md5restore
md5restore()
{
md5t="`expr "$4" : '\(..\)'`/`expr "$4" : '..\(..\)'`/$4.$5.md5"
for a in "$BACK"/out*
do
	[ -d "$a" ] || continue
	[ -f "$a/$md5t" ] || continue
	[ -r "$a/$md5t" ] || continue
	cp --backup=t "$a/$md5t" "$1"
	return
done
echo "$l $md5t not present in archive"
false
}

# Diff file with the contents of the backup
# Hunt it in all out dirs.
: md5diff
md5diff()
{
md5t="`expr "$5" : '\(..\)'`/`expr "$5" : '..\(..\)'`/$5.$6.md5"
for a in "$BACK"/out*
do
	[ -d "$a" ] || continue
	[ -f "$a/$md5t" ] || continue
	[ -r "$a/$md5t" ] || continue
	diff $2 -- "$a/$md5t" "$1" | less
	return
done
echo "$l $md5t not present in archive"
false
}

# Escape the information, such that it is conforming to shell syntax
: escape
escape()
{
sed "
s/'/'\\\\''/g
s/\\\\'''\\\\'/\\\\'\\\\'/g
s/\\\\'''\\\\'/\\\\'\\\\'/g
s/^\\(.*\\)$/'\\1'/
"
}

: escapeargs
escapeargs()
{
for escapes
do
	echo "$escapes"
done |
escape
}

: huntname
huntname()
{
sed -n 's/^[0-9a-f]* \*//p' "$BACK/md5/$host" |
fgrep -- "$1" |
sort -u |
escape
}

getversions()
{
fgrep " $1" "$BACK/log/$host" |
fixup |
while read -r date time what kb md5 nr file
do
	case "$what:$kb" in
	md5:*)		;;
	known:md5)	;;
	*)		continue;;
	esac
	[ ".$1" = ".$file" ] || continue
	echo "'$date $time $md5 $nr'"
done |
awk 'known[$3,$4]	{ next }
{ known[$3,$4]=1; print }'
}

: process
process()
{
echo "$1"
}

echo "+- WARNING!  This is a preliminary script!"
echo "!  Expect BUGs!"
echo "!  And this script is dog slow!  Sorry!"
echo "+- restore script started"
for arg
do
	echo "+- processing $arg"
	declare -a names
	eval names=\(`huntname "$arg"`\)

	if [ -z "${#names[@]}" ]
	then
		echo "OOPS $arg"
		continue
	fi
	if [ 0 -eq ${#names[@]} ]
	then
		echo "!  +- unknown file argument"
		continue
	fi

	declare -i i
	i=-1
	while	let i++
		[ $i -lt ${#names[@]} ]
	do
		echo "!  +- $i/${#names[@]} check versions on ${names[$i]}"
		l='!  !  '
		[ $[$i+1] -ge ${#names[@]} ] && l='!     '
	
		declare -a versions
		eval versions=\(`getversions "${names[$i]}"`\)
		if [ 0 -ge "${#versions[@]}" ]
		then
			echo "$l+- ${names[$i]} is not in the log"
			echo "$l   currently, you must do a manual restore!"
			unset names[$i]
			continue
		fi

		declare -i ok
		ok=0
		if [ ! -f "${names[$i]}" ]
		then
			echo "$l+- file is missing"
		elif [ ! -r "${names[$i]}" ]
		then
			echo "$l+- file is unreadable"
		else
			declare -i j
			j=0
			while	[ $j -lt ${#versions[@]} ]
			do
				echo -n "$l+- comparing version ${versions[$j]}: "
				md5cmp "${names[$i]}" ${versions[$j]}
				case "$?" in
				0)	echo "ok"
					versions[$j]=
					let ok++
					;;
				1)	echo "differ"
					;;
				*)	echo "missing or unreadable"
					versions[$j]=
					let ok++
					;;
				esac
				let j++
			done
			if [ $ok -ge "${#versions[@]}" ]
			then
				echo "$l+- nothing left to do"
				continue
			fi
		fi

		while	echo "$l+- restoreable versions:"
		do
			declare -i j
			j=-1
			while	let j++
				[ $j -lt ${#versions[@]} ]
			do
				[ -n "${versions[$j]}" ] &&
				echo "$l!  +- $j) ${versions[$j]}"
			done
			echo "$l!  \\- target to restore: ${names[$i]}"
			echo -n "$l+- restore which version (N/diff N [args]/EOF to skip)? "
			if ! read -r ans nr args
			then
				echo EOF
				echo "$l+- not restored"
				break
			fi
			if [ diff = "$ans" ]
			then
				if [ -z "${versions[$nr]}" ]
				then
					echo "$l+- wrong input"
					continue
				fi
				[ -z "$args" ] && args="-ub"
				md5diff "${names[$i]}" "$args" ${versions[$ans]}
				continue
			fi

			if [ -z "${versions[$ans]}" ]
			then
				echo "$l+- wrong input"
				continue
			fi

			echo "$l+- restoring ${versions[$ans]}"
			echo "$l+- to ${names[$i]}"
			if	md5restore "${names[$i]}" ${versions[$ans]}
			then
				echo "$l\\- done"
				break
			else
				echo "$l+- failed"
			fi
		done
	done
done
echo "+- restore script finished"