#!/bin/bash

# Cron job check the logs

## Executing the script
# bash db_backup_script.sh

## command used to back up
# docker exec DOCKER_CONTAINER pg_dump -U postgres -Fc DATABASE_NAME > BACKUP_FILE.DUMP

## command used to restore
# directory where the backup is saved in in the docker container: /var/lib/postgresql/data
# for example: docker exec postgres pg_restore -U postgres -d vikunja-backup /var/lib/postgresql/data/backup/vikunja-2024-01-31.dump
# docker exec DOCKER_CONTAINER pg_restore -U postgres -d DATABASE_NAME /var/lib/postgresql/data/backup/BACKUP_FILE.DUMP

# Date format
YEAR=$(date +"%Y")
MONTH=$(date +"%m")
DAY=$(date +"%d")
NOW=$(date +"%Y-%m-%d")

BACKUP_DIRECTORY="/home/debian/docker/compose/project/db/postgres/data"

# Docker container with DB to backup
DB_1="postgres"
DB_2="postgres-with-pg-vector"

back_up_db() {

    # sql to list all databases
    DATABASE_NAME=$(docker exec $1 psql -U postgres -t -c 'SELECT datname FROM pg_database WHERE datistemplate = false;')

    # pg_dump command
    PGDUMP="docker exec $1 pg_dump -U postgres -Fc"

    for i in $DATABASE_NAME; do

        # ignoring postgres db
        if [[ "$i" != "postgres" ]]; then

            echo "Backing up database $i"
            # backup path to file
            BACKFILE="$BACKUP_DIRECTORY/backup/$i-$NOW.dump"
            $PGDUMP $i > $BACKFILE

        fi

    done
}

clean_up_backups() {

    echo "Looking for dumps to prune in folder: $BACKUP_DIRECTORY/backup/"

    # keep one backup per year, month and last two days
    BACKUP_YEAR="*-$YEAR-02-01.dump"
    BACKUP_MONTH="*-$YEAR-$MONTH-01.dump"
    BACKUP_DAY="*-$YEAR-$MONTH-$DAY.dump"
    BACKUP_DAY_1="*-$YEAR-$MONTH-$((DAY-1)).dump"
    FILE_TO_DELETE=$(find $BACKUP_DIRECTORY/backup/ -type f \( ! -name $BACKUP_YEAR -a ! -name $BACKUP_MONTH -a ! -name $BACKUP_DAY -a ! -name $BACKUP_DAY_1 \))

    # delete such files
    for i in $FILE_TO_DELETE; do
        echo "Pruning $i"
        rm $i
    done
}

back_up_db $DB_1
back_up_db $DB_2

clean_up_backups