#!/bin/bash

# VCS Backup

# Copyright © 2019 František Kučera (Frantovo.cz, GlobalCode.info)

#

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program. If not, see <http://www.gnu.org/licenses/>.

# Server-side configuration:

VCS_BACKUP_DATA_DIR="/mnt/data";

VCS_BACKUP_CURRENT_DIR="$VCS_BACKUP_DATA_DIR/current";

VCS_BACKUP_PUBLIC_DIR="$VCS_BACKUP_DATA_DIR/public";

VCS_BACKUP_CONFIG_DIR="$VCS_BACKUP_DATA_DIR/config";

VCS_BACKUP_SNAPSHOT_DIR="$VCS_BACKUP_DATA_DIR/snapshot";

VCS_BACKUP_SUBVOLUME_SOCKET="/run/vcs-backup-subvolume";

VCS_BACKUP_CLONE_SOCKET="/run/vcs-backup-clone";

VCS_BACKUP_CLONE_CALLBACK_SOCKET="clone-callback";

VCS_BACKUP_USER="vcs-backup";

VCS_BACKUP_MANAGER="vcs-backup-manager";

# Installation – check and do it by hand:

# There should be already mounted Btrfs at $VCS_BACKUP_DATA_DIR

installInstructions() {

cp vcs-backup.sh /usr/local/bin/

adduser --disabled-password "$VCS_BACKUP"

adduser --disabled-password "$VCS_BACKUP_MANAGER"

mkdir "$VCS_BACKUP_CURRENT_DIR";

mkdir "$VCS_BACKUP_CONFIG_DIR";

mkdir "$VCS_BACKUP_SNAPSHOT_DIR";

chown "${VCS_BACKUP_USER}:${VCS_BACKUP_USER}" "$VCS_BACKUP_CURRENT_DIR"

chown "${VCS_BACKUP_MANAGER}:${VCS_BACKUP_MANAGER}" "$VCS_BACKUP_CONFIG_DIR"

}

# --- Private functions: ---------------------------------------------------------------------------

# Environment: all

# $1 = VCS type: hg, git

# $2 = URL

isValidTypeAndURL() { ([[ "$1" == "hg" || "$1" == "git" ]]) && [[ $(echo "$2" | wc -l) == 1 ]] && [[ $(echo "$2" | grep -E '^(http|https|ssh)://([a-zA-Z0-9_-][a-zA-Z0-9_-.]*/?)+$' | wc -l) == 1 ]]; }

# Environment: all

# $1 = path to the config file

loadConfigFile() { if [ -f "$1" ]; then . "$1"; else echo "Missing config file: $1" >&2; exit 1; fi }

# Environment: server

# $1 = URL

urlToRelativeDirectoryPath() {

	echo "$1" | sed -E 's@^[^:]+://@@g';

}

# --- Public interface functions: ------------------------------------------------------------------

# Environment: client

# $1 = VCS type: hg, git

# $2 = URL

# $3 = "public" or "private" (default), whether the repository should be available through the public web interface

vcs_backup_public_clientSubmitBackupRequest() {

	if isValidTypeAndURL "$1" "$2"; then

		loadConfigFile ~/.config/vcs-backup/client.cfg

		${VCS_BACKUP_SSH_COMMAND[@]} vcs-backup.sh serverSubmitBackupRequest "$1" "$2" "$3" "$4"

		if [[ "$4" == "clone" ]]; then

			if   [[ "$1" == "hg"  ]]; then  hg clone "ssh://${VCS_BACKUP_SERVER}//mnt/data/current/$1/$(urlToRelativeDirectoryPath $2)";

			elif [[ "$1" == "git" ]]; then git clone "ssh://${VCS_BACKUP_SERVER}//mnt/data/current/$1/$(urlToRelativeDirectoryPath $2)";

			fi

		fi

	else

		echo "Unsupported VCS type: '$1' or URL: '$2'" >&2;

	fi

}

# Environment: server

# has same parameters as clientSubmitBackupRequest (see above)

vcs_backup_public_serverSubmitBackupRequest() {

	if isValidTypeAndURL "$1" "$2"; then

		loadConfigFile "/etc/vcs-backup/server.cfg";

		relativePath=$1/$(urlToRelativeDirectoryPath "$2");

		absolutePath="$VCS_BACKUP_CONFIG_DIR/$relativePath";

		mkdir -p "$absolutePath";

		echo "$2" > "$absolutePath/url.txt"

		echo "submited" > "$absolutePath/state.txt"

		setfacl -m u:${VCS_BACKUP_USER}:r  "$absolutePath/url.txt"

		setfacl -m u:${VCS_BACKUP_USER}:rw "$absolutePath/state.txt"

		echo "$relativePath" | socat -u - unix-send:${VCS_BACKUP_SUBVOLUME_SOCKET};

		if [[ "$3" == "public" ]]; then

			cd "$VCS_BACKUP_PUBLIC_DIR";

			mkdir -p "$(dirname $relativePath)";

			ln -rs "../current/$relativePath" "$(dirname $relativePath)";

		fi

		if [[ "$4" == "clone" ]]; then

			socat -u "unix-recvfrom:$absolutePath/${VCS_BACKUP_CLONE_CALLBACK_SOCKET},mode=777" - | while read m; do # TODO: ,group=${VCS_BACKUP_USER} and no 777

				echo "Message from the clone service: $m";

			done;

		fi

	else

		echo "Unsupported VCS type: '$1' or URL: '$2'" >&2;

	fi

}

# Environment: server

# Should be started as a systemd/init service.

# - reads messages from from the subvolume socket – message contains the relative directory path

# - creates a subvolume for given repository + necesary parent directories

# - sends a message to the clone service → start cloning into the created subvolume

vcs_backup_public_serverStartSubvolumeService() {

	socat -u "unix-recv:${VCS_BACKUP_SUBVOLUME_SOCKET},group=${VCS_BACKUP_MANAGER},mode=770" - | while read d; do

		mkdir -p $(dirname "$VCS_BACKUP_CURRENT_DIR/$d");

		btrfs subvolume create "$VCS_BACKUP_CURRENT_DIR/$d" && \

		echo "subvolumeCreated" > "$VCS_BACKUP_CONFIG_DIR/$d/state.txt" && \

		chown "${VCS_BACKUP_USER}:${VCS_BACKUP_USER}" "$VCS_BACKUP_CURRENT_DIR/$d" && \

		echo "$d" | socat -u - unix-send:${VCS_BACKUP_CLONE_SOCKET};

	done

}

# Environment: server

# should be started as a systemd/init service

vcs_backup_public_serverStartCloneService() {

	socat -u "unix-recv:${VCS_BACKUP_CLONE_SOCKET},mode=700" - | while read d; do

		vcsType=$(echo "$d" | sed 's@/.*@@g');

		url=$(cat "$VCS_BACKUP_CONFIG_DIR/$d/url.txt");

		if isValidTypeAndURL "$vcsType" "$url"; then

			if   [[ "$vcsType" == "hg"  ]]; then  hg clone -U     "$url" "$VCS_BACKUP_CURRENT_DIR/$d";

			elif [[ "$vcsType" == "git" ]]; then git clone --bare "$url" "$VCS_BACKUP_CURRENT_DIR/$d";

			fi && echo "cloned" > "$VCS_BACKUP_CONFIG_DIR/$d/state.txt";

		else

			echo "Unsupported VCS type: '$vcsType' or URL: '$url'" >&2;

		fi

		callBackSocket="$VCS_BACKUP_CONFIG_DIR/$d/$VCS_BACKUP_CLONE_CALLBACK_SOCKET";

		if [[ -e "$callBackSocket" ]]; then

			echo "done" | socat -u - unix-send:"$callBackSocket";

		fi

	done

}

# --- Single entry-point: --------------------------------------------------------------------------

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin";

PUBLIC_FUNCTION_PREFIX="vcs_backup_public_";

if type -t "$PUBLIC_FUNCTION_PREFIX$1" > /dev/null; then

	"$PUBLIC_FUNCTION_PREFIX${@:1}";

else

	echo "Unsupported sub-command: $1" >&2

	echo "Available sub-commands:" >&2

	declare -F | grep "$PUBLIC_FUNCTION_PREFIX" | sed "s/.*$PUBLIC_FUNCTION_PREFIX/  /g" >&2

	exit 1;

fi