#!/bin/sh

#version 2
#iansun2 2022/7/14


#config (without "/"  eg. /DISKI/Backup)
source_dir=
output_dir=
backup_count_max=


#init
year=$(date +"%Y") #get year
month=$(date +"%m") #get month
date=$(date +"%d") #get date

file_name=${year}"_"${month}"_"${date}".7z" #new backup file name  eg. 2022_2_2.7z
backup_count=$(find ${output_dir} -type f -iname "*.7z" -print | wc -l) #count file in $output_dir with name *.7z as $backup_count


#check src/out dir
if [ -d $source_dir ]
then
	echo "source dir found, ok"
else
	echo "source dir not found, exit"
	exit 0
fi


if [ -d $output_dir ]
then
	echo "output dir found, enter"
	cd $output_dir
else
        echo "output dir not found, exit"
	exit 0
fi


#log dir
if [ -d "log" ] #check log dir exist?
then
	echo "log dir exist"
else
	mkdir "log"
	echo "log dir not exist, create"
fi

echo ${year}"_"${month}"_"${date} >> ${output_dir}"/log/backup_record" #save backup time in ${output_dir}/log/backup_record


#clear old backup
echo "check old backup"
echo "old backup count: "${backup_count}
while [ ${backup_count} -gt ${backup_count_max} ] #while $backup_count > $backup_count_max
do
	oldest_file=$(find ${output_dir} -type f -iname "*.7z" -print | sort -n | head -n 1) #find oldest *.7z file by name
	rm $oldest_file
	echo "remove "${oldest_file}
	backup_count=$((backup_count-1))
done

find ${output_dir} -empty -type d -delete #delete empty dir


#year dir
if [ -d $year ]
then
	cd $year
	echo "year dir exist, enter!"
else
	mkdir $year
	cd $year
	echo "year dir not exist, create!"
fi


#month dir
if [ -d $month ]
then
	cd $month
	echo "month dir exist, enter!"
else
	mkdir $month
	cd $month
	echo "month dir not exist, create!"
fi



echo "create backup"
7z a ${file_name} ${source_dir}"/" -mx9


#echo "[debug]"
#find ${output_dir} -type f -print | sort -n

#echo $backup_count
#echo $source_dir
#echo $file_name