#!/bin/bash
#set -x

#
#   The script:
#	•	creates a new folder for each backup.  The folder is named with the current date and time
#	•	does an incremental backup 
#	    ⁃	each new run backs up the files that change
#	    ⁃	the excluded items are listed in "exclude_from_list.txt" file
#
#   The USB stick is formatted for “ext4”.
#
#
#   To do list:
#   - Add a check for a near full USB stick
#

#	Check if run as root
if [ $(id -u) -ne 0 ]; then
  printf "Script must be run as root. Try 'sudo script.sh'\n"
  exit 1
fi

LOCK=/tmp/backupemonpilock
if [ -f $LOCK ]; then
    echo;echo "emonPi backup job is running!  Quitting this emonPi Log backup job.";echo
    exit 1
fi

#	get current date in "YYYY-MM-DD_HH.MM.SS" format - used to timestamp backup folders
NOW=$(date "+%Y-%m-%d_%H.%M.%S")
echo;echo "emonPi Log Backup - started on $NOW"

#	check for mounted USB and mount if needed
mountpoint -q /mnt/usb || mount -vt ext4 /dev/sda1 /mnt/usb || exit;

#	Backup Source
SOURCE="/var/log/"							#   SOURCE path MUST end with a "/"
echo;echo "SOURCE = $SOURCE"

#	set path to backups
BACKUPS="/mnt/usb/emonPi_Backups"
if [ ! -d "$BACKUPS" ]; then
	rpi-rw		#	needed for emonPi
	mkdir -v "$BACKUPS" || (rpi-ro && exit);
	rpi-ro		#	needed for emonPi
fi


#	set Backup Destination with timestamp
DESTINATION="$BACKUPS/$NOW" 
echo "DESTINATION = $DESTINATION"
mkdir -v -m 775 "$DESTINATION" || exit;
chown -v pi:root "$DESTINATION" || exit;

#	set path for FLAG file (this FLAG file is the last backup)
FLAGFILE="${BACKUPS}/emonpi_log_flag.txt"
#echo "FLAGFILE = $FLAGFILE"

if [ -f "$FLAGFILE" ];		        #	does the FLAG file exist?
then
    echo;echo "File $FLAGFILE exists"
    FLAGFILECONTENTS="$(<"$FLAGFILE")"
    echo "Last Backup on = $FLAGFILECONTENTS"
    LinkDest="--link-dest=../$FLAGFILECONTENTS"
fi

#   rsync Flags:
#   --archive       archive mode - preserves all file attributes and permissions  
#   --hard-links    preserve hard links
#   --stats         file-transfer stats
#   --link-dest     hardlink to files in DIR when unchanged.  
#   --out-format    output updates using specific format
#   --recursive     recurse into directories
#   --chown         simple username/groupname mapping   =youruser:yourgroup

echo;echo;echo -e "\033[1mRun RSYNC - copy log files from /var/log\033[0m";echo
#echo;echo;echo "Run RSYNC - copy log files from /var/log";echo
rsync --archive --hard-links --stats ${LinkDest} \
    --chown=pi:pi \
    --out-format="%t  %i  %f  %b" \
    "/var/log/" "${DESTINATION}/" || exit;


echo;echo "Run RSYNC - copy log files from /home/pi/data";echo
rsync --archive --hard-links --stats ${LinkDest} \
    --chown=pi:pi \
    --out-format="%t  %i  %f  %b" \
    --include="*.log" --exclude "*" \
    "/home/pi/data/" "${DESTINATION}" || exit;

#	Set FLAG for this backup.  Used for next backup
echo "${NOW}" > "${FLAGFILE}"
echo;echo "emonPi Log Backup - completed at $(date "+%Y-%m-%d_%H.%M.%S")"

#   Done!
exit