#!/bin/bash
###############################
#                             #
#  spapshot script for btrfs  #
#        --- daemon ---       #
#             v0.1            #
#                             #
###############################


## settings ##
export logfile="../var/log/backsnap.log"


function main {

	#foar each hour
	while [ true ]; do

		for volume in `ls ../etc/backsnap/volumes/`; do
			[ -n "`cat "../etc/backsnap/volumes/$volume" | tr [:upper:] [:lower:] | grep enabled=true`" ] && snap_volume "../etc/backsnap/volumes/$volume" &
		done

		sleep 1m
	done

}


## snap_ ##
#snap_volume <conf file>
function snap_volume {
	conf="$1"
	prof="`basename $conf`"
	timestamp="../etc/backsnap/stamps/$prof"
	error=
	
	[ -f "$timestamp" ] || touch "$timestamp"
	chmod +x "$timestamp"
	. "$timestamp"

	#getconf
	for t in years months weeks days hours path_vol path_bak MK MV RM CH; do
		eval "$t=`cat "$conf" | grep -v "#" | tr [:upper:] [:lower:] | grep "$t=" | sed -s 's/'"$t="'/''/g' | tr -d " "`"
		[ -z "${!t}" ] && eval "$t=0"
	done

	#set defaults
	MK="btrfs subvolume snapshot -r"
	MV="mv -v"
	RM="btrfs subvolume delete"
	CH="-d"

	#check conf ...
	#path_vol & path_bak exist (ar not 0 ...)
	#min one time number gt 0

	for t in years months weeks days hours; do
		var="`echo $t | tr -d s`"

		[ "${!t}" -gt 0 ] && [ "`timeget_$var`" != "${!var}" ] && {

			#eigendliches backupen...
			logon echo "$prof: SETTINGS: \"years=$years\" \"months=$months\" \"weeks=$weeks\" \"days=$days\" \"hours=$hours\" \"path_vol=$path_vol\" \"path_bak=$path_bak\""
			logon "$prof: MODE: $var" 

			i=$((--$t))

			#delete oldest if border is reached
			[ $CH "$path_bak$var.$i" ] && {
				logon "$prof: SNAP: DEL: \"$path_bak$var.$i\""
				
				error="`eval $RM "$path_bak$var.$i" 3>&1 1>&2 2>&3`"
				[ -n "$error" ] && { logon "$prof: SNAP: DEL: ERROR: $error"; error=; }
				
				sleep 3
			}

			#move all snaps one back
			while [ $i -ge 1 ]; do
				[ $CH "$path_bak$var.$((--i))" ] && {
					logon "$prof: SNAP: MV: \"$path_bak$var.$i\" \"$path_bak$var.$((i+1))\""

					error="`eval $MV "$path_bak$var.$i" "$path_bak$var.$((i+1))" 3>&1 1>&2 2>&3`"
					[ -n "$error" ] && { logon "$prof: SNAP: MV: ERROR: $error"; error=; }

					sleep 3
				}
			done

			#mk new snap
			logon "$prof: SNAP: MK: \"$path_vol\" \"$path_bak$var.$i\""

			error="`eval $MK "$path_vol" "$path_bak$var.$i" 3>&1 1>&2 2>&3`"
			[ -n "$error" ] && { logon "$prof: SNAP: MK: ERROR: $error"; error=; }

			wr_stamp "$timestamp" "$prof"

			break
		}

	done
}

function timeget_year { date +%Y; }
function timeget_month { date +%m; }
function timeget_week { date +%V; }
function timeget_day { date +%d; }
function timeget_hour { date +%H; }

#wr_stamp <stamp_path> <for>
function wr_stamp {

	timestamp="$1"
	echo $1
	reason="$2"

	echo "## timestamp for $reason ##"  > "$timestamp"
	echo "## `date +%Y-%m-%d_%H-%M` ##" >> "$timestamp"
	echo                                >> "$timestamp"
	echo "year=`timeget_year`"          >> "$timestamp"
	echo "month=`timeget_month`"        >> "$timestamp"
	echo "week=`timeget_week`"          >> "$timestamp"
	echo "day=`timeget_day`"            >> "$timestamp"
	echo "hour=`timeget_hour`"          >> "$timestamp"
}

function logon {
	delimeter="#"
	echo "`date +%Y%m%d%H%M%S` $delimeter `echo $@ | tr -d "$delimeter"`" >> "$logfile"
}

main