#!/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/socket"; # the directory will be writable by ${VCS_BACKUP_USER}

 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";

 mkdir "$(dirname VCS_BACKUP_CLONE_SOCKET)"

 chown "${VCS_BACKUP_USER}:${VCS_BACKUP_USER}" "$(dirname VCS_BACKUP_CLONE_SOCKET)"

 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"; fi }

 # Environment: server

 # $1 = URL

 urlToRelativeDirectoryPath() {

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

 }

 # Environment: all

 # $1 = optional value (if missing, reads STDIN)

 escapeRecfileValue() { if [[ $# = 0 ]]; then awk '{ if (NR > 1) { printf "+ " } print $_ }'; else echo "${@}" | ${FUNCNAME[0]}; fi }

 # Environment: all

 # $1 = key

 # $2 = value

 printRecfileKeyValue() { echo -n "$1: "; escapeRecfileValue "$2"; }

 # --- 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

 # $4 = "clone" (optional), if present, will also clone the backup locally

 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}/$VCS_BACKUP_CURRENT_DIR/$1/$(urlToRelativeDirectoryPath $2)";

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

 			fi

 		fi

 	else

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

 	fi

 }

 # Environment: server

 # User: $VCS_BACKUP_MANAGER

 # 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"

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

 			cd "$VCS_BACKUP_PUBLIC_DIR";

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

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

 		fi

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

 			callBackSocket=$absolutePath/${VCS_BACKUP_CLONE_CALLBACK_SOCKET}

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

 				echo "Message from the service: $m";

 			done &

 			callBackPID=$!;

 		fi

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

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

 			echo "Waiting for a message from the service on $callBackSocket (PID $callBackPID)";

 			wait -n $callBackPID;

 		fi

 	else

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

 	fi

 }

 # Environment: server

 # User: root

 # 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");

 		if [[ -e "$VCS_BACKUP_CURRENT_DIR/$d" ]]; then

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

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

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

 			fi

 		else

 			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};

 		fi

 	done

 }

 # Environment: server

 # User: $VCS_BACKUP_USER

 # 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 [[ "$vcsType" == "git" ]]; then git clone --mirror "$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

 }

 # Environment: client

 # prints list of repositories in recfile format

 # usage example: vcs-backup.sh clientListRepositories | relpipe-in-recfile | relpipe-out-tabular

 vcs_backup_public_clientListRepositories() {

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

 	${VCS_BACKUP_SSH_COMMAND[@]} vcs-backup.sh serverListRepositories;

 }

 # Environment: server

 # User: $VCS_BACKUP_MANAGER

 vcs_backup_public_serverListRepositories() {

 	echo "%rec: repositories";

 	echo "%type: bytes int";

 	echo "%type: public bool";

 	echo;

 	find "$VCS_BACKUP_CONFIG_DIR" -name url.txt -printf '%P\n' | sort | xargs dirname | while read d; do

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

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

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

 		sizeBytes=$(du -sb "$VCS_BACKUP_CURRENT_DIR/$d" | cut -f1);

 		[[ -e "$VCS_BACKUP_PUBLIC_DIR/$d" ]] && public="true" || public="false";

 		if [[ "$vcsType" == "hg"  ]]; then lastCommit=$(hg log --limit 1 --template '{date|isodatesec}' -R "$VCS_BACKUP_CURRENT_DIR/$d" 2>/dev/null);

 		elif [[ "$vcsType" == "git" ]]; then lastCommit=$(git -C "$VCS_BACKUP_CURRENT_DIR/$d" log --max-count=1 --pretty="%ai"); 

 		else lastCommit=""; fi

 		printRecfileKeyValue "type"            "$vcsType";

 		printRecfileKeyValue "url"             "$url";

 		printRecfileKeyValue "state"           "$state";

 		printRecfileKeyValue "public"          "$public";

 		printRecfileKeyValue "serverPath"      "$VCS_BACKUP_CURRENT_DIR/$d";

 		printRecfileKeyValue "size"            "$sizeBytes";

 		printRecfileKeyValue "lastCommit"      "$lastCommit";

 		echo;

 	done

 }

 # Environment: server

 # User: $VCS_BACKUP_USER

 # should be called from cron (usually every day)

 vcs_backup_public_serverPullCronTask() {

 	echo "%rec: pull";

 	echo "%type: started date";

 	echo "%type: finished date";

 	echo "%type: duration int";

 	echo "%type: resultCode int";

 	find "$VCS_BACKUP_CONFIG_DIR" -name url.txt -printf '%P\n' | sort | xargs dirname | while read d; do

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

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

 		absolutePath="$VCS_BACKUP_CURRENT_DIR/$d";

 		pullStarted=$(date --iso-8601=s);

 		pullStartedMiliseconds=$(($(date +%s%N)/1000000));

 		pullFinished="";

 		pullDuration="";

 		pullResult="";

 		pullResultCode="";

 		if [[ "$state" == "cloned" ]]; then

 			if   [[ "$vcsType" == "hg" ]];  then pullResult=$(hg pull --force --repository "$absolutePath" 2>&1); pullResultCode=$?;

 			elif [[ "$vcsType" == "git" ]]; then pullResult=$(git -C "$absolutePath" fetch 2>&1); pullResultCode=$?;

 			fi

 			pullFinished=$(date --iso-8601=s);

 			pullFinishedMiliseconds=$(($(date +%s%N)/1000000));

 			pullDuration=$(( $pullFinishedMiliseconds - $pullStartedMiliseconds ));

 		fi

 		printRecfileKeyValue "serverPath"      "$absolutePath";

 		printRecfileKeyValue "type"            "$vcsType";

 		printRecfileKeyValue "state"           "$state";

 		printRecfileKeyValue "started"         "$pullStarted";

 		printRecfileKeyValue "finished"        "$pullFinished";

 		printRecfileKeyValue "duration"        "$pullDuration";

 		printRecfileKeyValue "resultCode"      "$pullResultCode";

 		printRecfileKeyValue "message"         "$pullResult";

 		echo;

 	done

 }

 # Environment: server

 # User: root

 # should be called from cron (usually every day) after Pull (see above)

 vcs_backup_public_serverSnapshotCronTask() {

 	return;

 }

 # --- 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}";

 elif [[ $(basename $0) == "vcs-backup-clone-private-hg"  ]]; then "${PUBLIC_FUNCTION_PREFIX}clientSubmitBackupRequest" hg  "$1" private clone;

 elif [[ $(basename $0) == "vcs-backup-clone-private-git" ]]; then "${PUBLIC_FUNCTION_PREFIX}clientSubmitBackupRequest" git "$1" private clone;

 elif [[ $(basename $0) == "vcs-backup-clone-public-hg"   ]]; then "${PUBLIC_FUNCTION_PREFIX}clientSubmitBackupRequest" hg  "$1" public  clone;

 elif [[ $(basename $0) == "vcs-backup-clone-public-git"  ]]; then "${PUBLIC_FUNCTION_PREFIX}clientSubmitBackupRequest" git "$1" public  clone;

 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