#!/bin/bash

# Will remove oldest unneeded backups one by one unitl there are KEEP_FREE_GIGS gigabytes of space free on device containing STORAGE_DIR.
# Unneeded backups are picked regarding daily/weekly/monthly structure.

echo_with_time()
        {
        cur_time=$( date --rfc-3339=ns )
        echo "$cur_time $1"
        }

alldone()
        {
        echo_with_time "$THIS_SCRIPT_NAME completed"
        echo
        exit 0
        }

THIS_SCRIPT_NAME=$( basename $0 )

LOG_DIR='/opt/gpms/logs'
#DATE_POSTFIX=$( date '+_%Y_%m_%d_%H_%M_%S' )
LOG_FILE="${LOG_DIR}/${THIS_SCRIPT_NAME}${DATE_POSTFIX}.log"
if [ ! -d "$LOG_DIR" ]; then
        mkdir -p "$LOG_DIR"
fi
exec 1>>"$LOG_FILE" 2>&1        # Redirect all output to log

echo_with_time "$THIS_SCRIPT_NAME started ----------------"

KEEP_FREE_GIGS='1200'   # Amount of freee space we need to keep in gigabytes
KEEP_FREE_BYTES=$(( KEEP_FREE_GIGS * 1024 * 1024 * 1024 ))

STORAGE_DIR='/mnt/misc2/storage/backup'

DAILY_APP_STORAGE_DIR="${STORAGE_DIR}/app/daily"
WEEKLY_APP_STORAGE_DIR="${STORAGE_DIR}/app/weekly"
MONTHLY_APP_STORAGE_DIR="${STORAGE_DIR}/app/monthly"

DAILY_DB_STORAGE_DIR="${STORAGE_DIR}/db/daily"
WEEKLY_DB_STORAGE_DIR="${STORAGE_DIR}/db/weekly"
MONTHLY_DB_STORAGE_DIR="${STORAGE_DIR}/db/monthly"

echo "Storage dir is $STORAGE_DIR"

files_for_removal+=$( find "${DAILY_APP_STORAGE_DIR}" -mtime +2 -type f)
files_for_removal+=$'\n'
files_for_removal+=$( find "${WEEKLY_APP_STORAGE_DIR}" -mtime +8 -type f )
files_for_removal+=$'\n'
files_for_removal+=$( find "${MONTHLY_APP_STORAGE_DIR}" -mtime +366 -type f )
files_for_removal+=$'\n'

files_for_removal+=$( find "${DAILY_DB_STORAGE_DIR}" -mtime +2 -type f )
files_for_removal+=$'\n'
files_for_removal+=$( find "${WEEKLY_DB_STORAGE_DIR}" -mtime +8 -type f )
files_for_removal+=$'\n'
files_for_removal+=$( find "${MONTHLY_DB_STORAGE_DIR}" -mtime +366 -type f )
files_for_removal+=$'\n'

files_for_removal=$( echo "$files_for_removal" | xargs stat --format='%Y %s %n' | sort -n )

#free_space_gigs=$( df -P --block-size=1G "$STORAGE_DIR" | tail -n +2 | tr -s ' ' | cut -d ' ' -f 4 )
free_space_gigs=$( df -P --block-size=1G "$STORAGE_DIR" | sed '1d;s/^\(\([^ ]*\)\s\+\)\{4\}.*/\2/' )
free_space_bytes=$( df -P --block-size=1 "$STORAGE_DIR" | sed '1d;s/^\(\([^ ]*\)\s\+\)\{4\}.*/\2/' )

echo "There are $free_space_bytes bytes (${free_space_gigs}G) free on the device"
echo "Should keep $KEEP_FREE_BYTES bytes (${KEEP_FREE_GIGS}G) free"

if [ "$free_space_bytes" -ge "$KEEP_FREE_BYTES" ]; then
        echo "No actions needed"
        alldone
fi

should_free_bytes=$(( KEEP_FREE_BYTES - free_space_bytes ))
echo "Should free $should_free_bytes bytes"

numfiles=0
numfiles=$( echo "$files_for_removal" | wc -l )
numallfiles=$( find "$STORAGE_DIR" -type f | wc -l )
echo "Have $numfiles of $numallfiles files available for deletion"

freed=0
enough=''
numfiles=0
while read timestamp size file; do
        echo "Removing \"$file\" size $size bytes"
        rm "$file"
#       mv "$file" /mnt/misc1/for_removal
        freed=$(( freed + size))
        numfiles=$(( numfiles + 1 ))
        if [ "$freed" -ge "$should_free_bytes" ]; then
                enough='yes'
                break
        fi
done <<< "$files_for_removal"

echo "$numfiles files deleted"
echo "Freed $freed bytes"
if [ -z "$enough" ]; then
        echo 'That is not enough'
else
        echo 'That is enough'
fi

alldone