#!/bin/bash
#
# Optional additional backup operation, intended to export an (almost)
# up-to-date downloadable copy for our customers about their data
# handled by us. The script synchronizes some of the existing backup
# files to an export folder that can be downloaded from the web.
#
# Uses the rotate_folder tool to select files to synchronize.
# This tool must be somewhere in the path.
#
# Author: Kovács Zoltán <kovacsz@marcusconsulting.hu>
# License: GNU/GPL v3+ (https://www.gnu.org/licenses/gpl-3.0.en.html)
# 2025-03-06 v0.1 Initial release

# Accepted environment variables and their defaults.
PAR_BASEDIR=${PAR_BASEDIR:-""}                  # Service's base folder
PAR_DUMPDIR=${PAR_DUMPDIR:-""}                  # Absolute path to DB dumps
PAR_EXPORTDIR=${PAR_EXPORTDIR:-""}              # Absolute path to export dir
PAR_RETAINDAYS=${PAR_RETAINDAYS:-"1"}		# Days to retain the copies
PAR_TARBALLDIR=${PAR_TARBALLDIR:-""}            # Absolute path to tgz dumps

# Other initialisations.
CLASSES_PATTERN="^([^.]*)\..*\.$HOSTNAME\.(dmp|sql\.gz|tgz|log)$"
DUMPPATH="storage/backups/dumps"                # Default path to DB dumps
EXPORTPATH="storage/backups/export"             # Default path to export dir
TARBALLPATH="storage/backups/tarballs"          # Default path to tgz dumps
USER=${USER:-LOGNAME}                           # Fix for cron enviroment only
YMLFILE="docker-compose.yml"

# Messages.
MSG_MISSINGDEP="Fatal: missing dependency"
MSG_MISSINGYML="Fatal: didn't find the docker-compose.yml file"
MSG_NONWRITE="The target directory isn't writable"

# Checks the dependencies.
TR=$(which tr 2>/dev/null)
if [ -z "$TR" ]; then echo "$MSG_MISSINGDEP tr."; exit 1 ; fi
for item in cp cut date dirname grep hostname readlink rotate_folder tar
do
    if [ -n "$(which $item)" ]
    then export $(echo $item | "$TR" '[:lower:]' '[:upper:]' | "$TR" '-' '_')=$(which $item)
    else echo "$MSG_MISSINGDEP $item." >&2; exit 1; fi
done

# Where I'm?
# https://gist.github.com/TheMengzor/968e5ea87e99d9c41782
SOURCE="$0"
while [ -h "$SOURCE" ]; do
    # resolve $SOURCE until the file is no longer a symlink
    SCRPATH="$( cd -P "$("$DIRNAME" "$SOURCE" )" && pwd )" #"
    SOURCE="$("$READLINK" "$SOURCE")"
    # if $SOURCE was a relative symlink, we need to resolve it
    # relative to the path where the symlink file was located
    [[ $SOURCE != /* ]] && SOURCE="$SCRPATH/$SOURCE"
done; SCRPATH="$( cd -P "$("$DIRNAME" "$SOURCE" )" && pwd )" #"

# Searches the base folder, containing a docker-compose.yml file.
# Called from the base folder (./)?
BASE_DIR="$PAR_BASEDIR"
TEST_DIR="$SCRPATH"
[[ -z "$BASE_DIR" ]] && [[ -r "$TEST_DIR/$YMLFILE" ]] && BASE_DIR="$TEST_DIR"
# Called from ./tools?
TEST_DIR="$("$DIRNAME" "$TEST_DIR")"
[[ -z "$BASE_DIR" ]] && [[ -r "$TEST_DIR/$YMLFILE" ]] && BASE_DIR="$TEST_DIR"
# Called from ./tools/*.d?
TEST_DIR="$("$DIRNAME" "$TEST_DIR")"
[[ -z "$BASE_DIR" ]] && [[ -r "$TEST_DIR/$YMLFILE" ]] && BASE_DIR="$TEST_DIR"
# On failure gives it up here.
if [ -z "$BASE_DIR" -o ! -r "$BASE_DIR/$YMLFILE" ]; then
    echo "$MSG_MISSINGYML" >&2; exit 1
fi
# Sets the absolute paths.
DUMPDIR="${PAR_DUMPDIR:-$BASE_DIR/$DUMPPATH}"
EXPORTDIR="${PAR_EXPORTDIR:-$BASE_DIR/$EXPORTPATH}"
TARBALLDIR="${PAR_TARBALLDIR:-$BASE_DIR/$TARBALLPATH}"

# Exits silently if EXPORTDIR isn't present.
[[ ! -e "$EXPORTDIR" ]] && exit 0
# EXPORTDIR must be writable.
[[ ! -w "$EXPORTDIR" ]] \
&& echo "$MSG_NONWRITE: $BACKUPDIR" >&2 && exit 1

# Let's select and copy the appropriate backup files.
#
# We'll call rotate_folder (dry run) with CLASSES_PATTERN and PAR_RETAINDAYS
# set above to select relevant files created in the backup folders within last
# PAR_RETAINDAYS days. These files are synchronized with the cp -u statement.
#
# Enumerates the folders.
for folder in "$DUMPDIR" "$TARBALLDIR"
do
    # Selects the appropriate files (which have the "DR" - daily retain - tag).
    for filename in $((export CLASSES_PATTERN="$CLASSES_PATTERN" \
                              RETAIN_DAYS="$PAR_RETAINDAYS" RETAIN_WEEKS=0 RETAIN_MONTHS=0; \
                       "$ROTATE_FOLDER" --noconf -f "$folder") | \
                      "$GREP" '^DR ' | "$CUT" -d' ' -f2) ""
    do
	# Updates the current file.
	if [ -n "$filename" ]; then
	    "$CP" -u "$folder/$filename" "$EXPORTDIR/" 2>/dev/null
	fi
    done
done

# That's all, Folks! :)