#!/bin/bash
#
# A service script to backup the web storage of a static website.
# Creates a tarball in $BASE_DIR/storage/backups/tarballs folder
# (by default). Optional parameters may change the source and/or
# target folder.
#
# Author: Kovács Zoltán <kovacsz@marcusconsulting.hu>
# License: GNU/GPL 3+ https://www.gnu.org/licenses/gpl-3.0.en.html
# 2025-01-22 Initial version.

# Accepted environment variables and their defaults.
#
PAR_BASEDIR=${PAR_BASEDIR:-""}                  # Service's base folder
PAR_BACKUPDIR=${PAR_BACKUPDIR:-""}              # Folder to dump within
PAR_SOURCEDIR=${PAR_SOURCEDIR:-""}              # Folder to save

# Messages (maybe overridden by configuration).
#
MSG_MISSINGDEP="Fatal: missing dependency"
MSG_NONREAD="The source directory isn't readable"
MSG_NONWRITE="The target directory isn't writable"

# Other initialisations.
#
BACKUPDIR="storage/backups/tarballs"		# Folder to dump within
SOURCEDIR="storage/volumes/staticweb"		# Folder to backup
USER=${USER:-LOGNAME}                           # Fix for cron enviroment only
YMLFILE="docker-compose.yml"

# Checks the dependencies.
#
TR=$(which tr 2>/dev/null)
if [ -z "$TR" ]; then echo "$MSG_MISSINGDEP tr."; exit 1 ; fi
for item in basename cat cut date dirname hostname pwd tar
do
    if [ -n "$(which $item)" ]
    then export $(echo $item | "$TR" '[:lower:]' '[:upper:]' | "$TR" '-' '_')=$(which $item)
    else echo "$MSG_MISSINGDEP $item." >&2; exit 1; fi
done
# All dependencies are available via "$THECOMMAND" (upper case) call.

# 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" "$SOURCE" )" && echo "$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" "$SOURCE" )" && echo "$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.
BACKUPDIR="${PAR_BACKUPDIR:-$BASE_DIR/$BACKUPDIR}"
SOURCEDIR="${PAR_SOURCEDIR:-$BASE_DIR/$SOURCEDIR}"

# The dump target folder must be writable.
#
[[ ! -w "$BACKUPDIR" ]] \
&& echo "$MSG_NONWRITE: $BACKUPDIR" >&2 && exit 1

# The source folder must be readable.
#
[[ ! -r "$SOURCEDIR" ]] \
&& echo "$MSG_NONREAD: $SOURCEDIR" >&2 && exit 1

# Tries the FS backup.
#
if [ -w "$BACKUPDIR" ]; then
    BACKUP_NAME=$("$BASENAME" "$SOURCEDIR").$("$DATE" '+%Y%m%d_%H%M%S').$("$HOSTNAME")
    (cd $SOURCEDIR; "$TAR" cz . \
     > "$BACKUPDIR/$BACKUP_NAME.tgz" 2>>"$BACKUPDIR/$BACKUP_NAME.log")
fi

# That's all, Folks! :)