##### backup_all.sh

# for use with cron, eg:
# 0 3 * * * postgres /var/db/db_backup.sh foo_db

DATABASES=(myvfw_production ptgolf_production our_books_production);

for DATABASE in "${DATABASES[@]}"
do
    # echo $DATABASE
    /home/rails/backups/apps/db_backup.sh "$DATABASE"
done

##### db_backup.sh

#!/bin/bash

if [[ -z "$1" ]]; then
    echo "Usage: $0 <db_name> [pg_dump args]"
    exit 1
fi

DB="$1"; shift
DUMP_ARGS=$@
# DIR="/home/rails/backups/$DB"
suffix="_production"
dbname=${DB%$suffix}
DIR="/home/rails/backups/apps/databases/$dbname"
echo $DIR
# exit 1

KEEP_DAILY=7
KEEP_WEEKLY=5
KEEP_MONTHLY=12

function rotate {
    rotation=$1
    fdate=`date +%Y-%m-%d -d $date`
    file=$DIR/daily/*$fdate*.gz
    mkdir -p $DIR/$rotation/ || abort
    if [ -f $file ]; then
        cp $file $DIR/$rotation/ || abort
    else
        echo
    fi
}

function prune {  
    dir=$DIR/$1
    keep=$2
    ls $dir | sort -rn | awk " NR > $keep" | while read f; do rm $dir/$f; done
}

function abort {
    echo "aborting..."
    exit 1
}

mkdir -p $DIR/daily || abort
mkdir -p $DIR/weekly || abort
mkdir -p $DIR/monthly || abort
mkdir -p $DIR/yearly || abort

date=`date +%Y-%m-%d` || abort
day=`date -d $date +%d` || abort
weekday=`date -d $date +%w` || abort
month=`date -d $date +%m` || abort

# Do the daily backup
/usr/bin/pg_dump $DB $DUMP_ARGS | gzip > $DIR/daily/${DB}_$date.sql.gz
test ${PIPESTATUS[0]} -eq 0 || abort

# Perform rotations
if [[ "$weekday" == "0" ]]; then
    rotate weekly
fi
if [[ "$day" == "01" ]]; then
    rotate monthly
fi
if [[ "$month/$day" == "01/01" ]]; then
    rotate yearly
fi

prune daily $KEEP_DAILY
prune weekly $KEEP_WEEKLY
prune monthly $KEEP_MONTHLY

class PgBackup
  require "date"
  require 'fileutils'
  # example crontab files. should write error to a log file in dir
    # cron staging 00 2 * * * /home/developer/.rbenv/shims/ruby /home/developer/apps/backup/pg_gzip_backup.rb >> /home/developer/apps/backup/log 2>&1
    # cron local   14 12 * * * /Users/xxx/.rbenv/shims/ruby /Users/xxx/work/common/backup/pg_gzip_backup.rb >> /Users/salex/work/common/backup/log 2>&1 
    # rsync --rsh="ssh -p8611" -a --delete /home/rails/backups/apps/databases/  post@myrepo.us:/home/post/backups/databases

  attr_accessor :dir, :apps, :today

  def initialize
    # puts ARGV[0]
    # ARGV[0].present? @stage = ARGV[0] : @stage = 'production'
    # config local paths for stage, dir, pgdump, gzip and an array of databases/apps
    @stage = "development" # normally production but set to development or staging for testing
    @dir = "/Users/salex/work/common/pg_backup"
    # find path of gzip and pg_dump with `which app` and set class vars
    @pgdump = "/opt/homebrew/bin/pg_dump"
    @gzip = "/usr/bin/gzip"
    @apps = %w[myusers myvfw ptgolf our_books] # array of app names
    # go to work and generate the pg dumps
    @today = Date.today  # current date used in filename of dumps
    set_backup_folders # check or create a dump folder structure for each app
    gzip_dumps# get the dumps and gzip them
  end

  def gzip_dumps
    apps.each do |app|
      db = "#{app}_#{@stage}" # create the rails/pg database name
      file_name = db+"_#{today.to_s}.sql" # create the dump name
      file_path = "#{dir}#{app}/daily/#{file_name}" # always dump daily
      `pg_dump #{db} > #{file_path}`
      `#{@gzip} -f #{file_path}`
      # daily period is now zipped, copy and prune if needed
      @zipped_file_path = file_path+'.gz'
      copy_period('weekly') if is_eow?
      copy_period('monthly') if is_eom?
      copy_period('yearly') if is_eoy?
      prune("#{dir}#{app}/daily/",7)
      prune("#{dir}#{app}/weekly/",5)
      prune("#{dir}#{app}/monthly/",12)
    end
  end

  def copy_period(period) # if it's the end of a period, copy daily
    period_file_path = @zipped_file_path.sub('daily',period)
    FileUtils.copy(@zipped_file_path,period_file_path)
  end

  def is_eow?
    today.sunday? # It's Sunday
  end
  def is_eom?
    today.month != (today + 1).month # It's the last day of the month
  end
  def is_eoy? 
    today.year != (today + 1).year # It's the last day of the year
  end

  def prune(dir,size)
    curr_files = Dir.children(dir).sort.reverse # reverse in case of a .file in folder
    if curr_files.size > size
      File.delete(dir + curr_files[size]) # delete the oldest file
    end
  end

  private

  def set_backup_folders
    File.write(@dir+"/log", "") if !File.exist?(@dir+"/log")
    File.write(@dir+"/log", "script opened #{Time.now}\n", mode: 'a+')
    if !Dir.exist?(@dir+"/pg_dumps/")
      # create all app dumps
      Dir.mkdir(@dir+"/pg_dumps/")
      apps.each{|a| make_new_app_set(a)}
    else
      # create any new app dumps added to the apps array after initial creation
      apps.each do |a|
        if !Dir.exist?(@dir+"/pg_dumps/#{a}/")
          make_new_app_set(a)
        end
      end
    end
    @dir = @dir+"/pg_dumps/"
  end

  def make_new_app_set(app)
    Dir.mkdir(@dir+"/pg_dumps/#{app}/")
    Dir.mkdir(@dir+"/pg_dumps/#{app}/daily/")
    Dir.mkdir(@dir+"/pg_dumps/#{app}/weekly/")
    Dir.mkdir(@dir+"/pg_dumps/#{app}/monthly")
    Dir.mkdir(@dir+"/pg_dumps/#{app}/yearly")
  end
  # fire this ruby script
  PgBackup.new
end