#!/bin/bash
BACKUP_LIST="$(readlink -e ~/)/.backup.lst"

if [ -n "$BACKUP_LIST" ]
then
 touch $BACKUP_LIST
fi

add() {
	local add_to_backup=$(readlink -m "$OPTARG")
	touch $BACKUP_LIST || exit

	if ! grep -Fxq $add_to_backup $BACKUP_LIST
	then
	echo $add_to_backup >> $BACKUP_LIST
	fi
}

remove() {
	grep -v $(readlink -m "$OPTARG") $BACKUP_LIST > remove; mv remove $BACKUP_LIST
	find $BACKUP_LIST -size 0 -delete
}

backup() {
	local current_time=`date '+%Y-%m-%d-%H-%M-%S'`
	local latest_backup_date="$(readlink -e ~/)/.latest_backup_date"
    local rsync_path="mkdir -p $REMOTE_OR_LOCAL_DEST && rsync" 
    
	if [ -n "$1" ] && [ -s "$latest_backup_date" ]
	then
	 local latest_backup="$BACKUP_PATH/$(cat $latest_backup_date)"
	 rsync -Rrtu / --rsync-path="$rsync_path" --compare-dest="$latest_backup" --files-from="$BACKUP_LIST" "$BACKUP_PATH/$current_time"
    else 
     rsync -Rrt / --rsync-path="$rsync_path" --files-from="$BACKUP_LIST" "$BACKUP_PATH/$current_time"
    fi
     
    echo "$current_time" > "$latest_backup_date"
}

do_backup() {
	if [ -n "$DO_UPDATED_BACKUP" ]
	then
	 backup true
	else
	 backup
	fi
}

help() {
local AUTHOR=$'Author: \u2605 Patryk Zdunowski\u2605'
local DESC="Description: Simple script for backup your data."
local OPTIONS="
* -a - add new file to defined backup list
* -r - remove file from defined list
* -b - send defined files to remote server / local folder
* -u - update defined files which has differences against latest created backup
* -h - help
"
echo "$AUTHOR"
echo $DESC
printf "$OPTIONS"

}
while getopts "a:r:b:uh" opt; do
  case $opt in
    a)
      add
      ;;
    r)
      remove
      ;;
    b)
      #check if backup path from remote server (bad but only for student project)
      if [[ $OPTARG == *[:]* ]]
      then
       BACKUP_PATH=$OPTARG
       REMOTE_OR_LOCAL_DEST=$(echo $OPTARG | cut -f2 -d:)
       
      else
       BACKUP_PATH=$(readlink -m "$OPTARG")
       REMOTE_OR_LOCAL_DEST=$BACKUP_PATH
       mkdir -p $REMOTE_OR_LOCAL_DEST
      fi
      ;;
    u)
      DO_UPDATED_BACKUP=true
      ;;
    h)
      SHOW_HELP=true
      ;;
  esac
done

if [ -n "$BACKUP_PATH" ]
then
 do_backup 
fi

if [ -n "$SHOW_HELP" ]
then
 help 
fi