#!/bin/bash

REMOTE_HOST=localhost
REMOTE_BASE=/tmp/backmeupscotty
ARCHIVE_KEEPNBACKUPS=30
ARCHIVE_KEEPNDAYS=30

if [ $(pidof -x $(basename $0) | wc -w) -gt 2 ]; then 
    echo BACKMEUPSCOTTY: Another instance of $(basename $0) is already running! >&2
    exit 1
fi

while getopts ":q" opt; do
    case $opt in
	q)
	    exec > /dev/null
	    ;;
    esac
done

function grepbackups {
    ssh $REMOTE_HOST "ls $REMOTE_BASE/$1" | grep -E '[0-9]+-[0-9]+'
}

function scottysync {
    timestamp=$(date +%s)

    echo BACKMEUPSCOTTY: Syncing $1 to $REMOTE_HOST:$REMOTE_BASE/$2 @$timestamp

    dir_current=$REMOTE_BASE/$2/current
    dir_incomplete=$REMOTE_BASE/$2/incomplete
    dir_timestamped=$REMOTE_BASE/$2/$timestamp-$(date -d @$timestamp +%Y%m%d%H%M%S)

    if [ -z $3 ]; then
	rsync_exclude=""
    else
	rsync_exclude=$(eval echo --exclude={$3} | tr -d {})
    fi

    if (ssh $REMOTE_HOST '[ ! -d '$REMOTE_BASE/$2' ]'); then
	echo BACKMEUPSCOTTY: Creating destination directory $REMOTE_HOST:$REMOTE_BASE/$2
	ssh $REMOTE_HOST "mkdir $REMOTE_BASE/$2"
    fi

    if (ssh $REMOTE_HOST '[ -d '$REMOTE_BASE/$2/incomplete' ]'); then
	echo BACKMEUPSCOTTY: Continuing old incomplete backup >&2
    fi

    echo BACKMEUPSCOTTY: Starting rsync
    rsync -e ssh \
	-v -aHAX --numeric-ids --delete --delete-excluded \
	--link-dest=$dir_current \
	$rsync_exclude \
	$1/ $REMOTE_HOST:$dir_incomplete/
    
    if [ $? -eq 0 ]; then
	echo BACKMEUPSCOTTY: Timestamping completed backup and linking to current backup
	ssh $REMOTE_HOST \
	    "mv $dir_incomplete $dir_timestamped && rm -f $dir_current && ln -s $dir_timestamped $dir_current"
    fi

    while [ $(grepbackups $2 | wc -l) -gt $ARCHIVE_KEEPNBACKUPS ]; do
	oldestbackup=$(grepbackups $2 | head -1)
	oldestbackuptstamp=$(echo $oldestbackup | cut -d'-' -f1)

	if [ $oldestbackuptstamp -lt $(( $(date +%s) - $ARCHIVE_KEEPNDAYS*60*60*24 )) ]; then
	    echo BACKMEUPSCOTTY: Removing old backup $oldestbackup
	    ssh $REMOTE_HOST rm -r "$REMOTE_BASE/$2/$oldestbackup"
	else
	    break
	fi
    done
}