#!/bin/bash
# rsyncshot

# Craig Jennings craigmartinjennings@gmail.com
# Inspired by Mike Rubel: http://www.mikerubel.org/computers/rsync_snapshots/

# Debugging

# uncomment next 4 lines for debugging output
# exec 5> >(logger -t $0)
# BASH_XTRACEFD="5"
# PS4='$LINENO: '
# set -x

# Default Locations For Setup

SCRIPTLOC=/usr/local/bin/rsyncshot;
DESTINATION=/media/backup;

INSTALLHOME=/etc/rsyncshot
LOGHOME=/var/log/rsyncshot.log;

INCLUDES="$INSTALLHOME/include.txt";
EXCLUDES="$INSTALLHOME/exclude.txt";

# Default Cron Job Entries
# CRON_H = hourly on minute 0 from 1am to 11pm
# CRON_D = daily at midnight, Monday - Saturday
# CRON_W = weekly at midnight on Sundays

CRON_H="0 1-23 * * * $SCRIPTLOC hourly 22";
CRON_D="0 0 * * 1-6 $SCRIPTLOC daily 6";
CRON_W="0 0 * * 7 $SCRIPTLOC weekly 51";

# Help

help()
{
    echo ""
    echo "rsyncshot - compact snapshots on Linux using rsync and hard links."
    echo ""
    echo "rsyncshot must be run as root"
    echo ""
    echo "Usage: "
    echo "rsyncshot <name> <number of backups to retain>"
    echo "          setup (installs rsyncshot and cron jobs)"
    echo "          help  (prints this info)"
    echo "Notes:"
    echo "- install and log locations defined in script."

# Error

error()
{
    echo "ERROR: $0: $@" 1>&2;
    echo "See \"rsyncshot help\" for usage."
    exit 1;
}

# Setup

setup()
{
    # copy this file to directory on path
    cp -f $0 /usr/local/bin
    echo "$0 copied to /usr/local/bin"
    
    # make install home if it doesn't exist;
    if [ ! -d $INSTALLHOME ]; then
	mkdir -p $INSTALLHOME;
	"Created install home at $INSTALLHOME.";
    fi

    # create includes file and add default entries
    if [ -f $INCLUDES ]; then rm $INCLUDES; fi
    printf "/home /etc /usr/local/bin" >> $INCLUDES;
    echo "modify include file at $INCLUDES";

    # create excludes file and add default entries
    if [ -f $EXCLUDES ]; then rm $EXCLUDES; fi
    printf "*.pyc\n*.pyo\n*.class\n*.elc\n*.o\n*.tmp\n.cache*" >>  $EXCLUDES;
    echo "modify exclude file at $EXCLUDES";

    # write out current crontab, append default entries, and install
    crontab -l > crontemp;
    echo "$CRON_H >> $LOGHOME 2>&1" >> crontemp;
    echo "$CRON_D >> $LOGHOME 2>&1" >> crontemp;
    echo "$CRON_W >> $LOGHOME 2>&1">> crontemp;
    crontab crontemp;
    rm crontemp;
    echo "hourly, daily, and weekly cron jobs installed.";
}

# Check Help Option

if [ "$TYPE" = "HELP" ]; then help; exit; fi

# Ensure Root

if [ "$EUID" -ne 0 ]; then error "This script must be run as root."; fi

# Display How Script Was Started

echo "rsyncshot invoked on `date -u` with: $0 $1 $2";

# Parameter Validation

if ! [[ $1 =~ [a-zA-Z] ]]; then error "snapshot type not recognized."; fi
TYPE=$(tr '[a-z]' '[A-Z]' <<< $1);
if [ "$TYPE" = "SETUP" ]; then setup; exit; fi

# Validate Max Snapshots

if ! [[ $2 =~ [0-9] ]]; then error "max snapshots not a number."; fi
MAX=$(($2-1));

# Validate Include File (Source Directories) Exist

if [ ! -f "$INCLUDES" ]; then error "include file $INCLUDES not found."; fi
SOURCES=$(<$INCLUDES);
for SOURCE in $SOURCES
do
    if [ ! -d "$SOURCE" ]; then error "source $SOURCE not found"; fi
done

# Validate Exclude File (Exclusion Patterns) Exist

if [ ! -f "$EXCLUDES" ]; then error "Exclude file $EXCLUDES not found."; fi

# Sync Each Directory In Turn

for SOURCE in $SOURCES
do
    rsync -avh -i --times \
    	  --delete  --delete-excluded \
    	  --exclude-from=$EXCLUDES \
    	  --update $SOURCE $DESTINATION/latest ;
done

# Delete Max+1 Snapshot If Exists

if [ -d $DESTINATION/$TYPE.$MAX ]; then
    rm -rf $DESTINATION/$TYPE.$MAX;
fi

# Rotate Snapshots Descending

for (( start=$(($MAX)); start>=0; start--)); do
    end=$(($start+1));
	if [ -d $DESTINATION/$TYPE.$start ]; then
	    mv $DESTINATION/$TYPE.$start $DESTINATION/$TYPE.$end;
	fi
done

# Reset Directory Timestamp

touch $DESTINATION/latest

# Hard Link Only Copy to Destination

cp -al $DESTINATION/latest $DESTINATION/$TYPE.0;

# Make Directory Type Read-Only

chmod -w $DESTINATION/$TYPE.0

# Print Time and Exit

echo "rsyncshot completed `date -u` ";
exit 0;