## Some default values of important variables

## Settings
GPG_RECIPIENT="robin.oburka@nic.cz"

## Style
TIME_FMT="\nBackup took:\t%E"

## Internal variables - backup process
NAME=""
REMOTE=""
GENERATE=""
COMMAND=""
PLACES=""
EXCLUDE=""
STORE=""
AFTER=""

## Pipeline variables
PID_GENERATE=""
PID_STORE=""
PID_FILE="pids"
STAGE="0"

## Internal variables - program logic
PERSN_FILE_NAME=".backuper.sh.per"

## Output helpers
title() {
	TXT="$1"
	printf "\n%s\n==========================================\n" "$TXT"
}

get_size() {
	FILE="$1"
	du -h "$FILE" | awk '{ print $1 }'
}

## Getting data helpers
get_home() {
	CURRENT_USER="$(id --real --user --name)"
	CU_HOME="$(getent passwd "$CURRENT_USER" | cut -d: -f6)"
	echo "$CU_HOME"
}

result_file() {
	if [ -n "$DST" ]; then
		echo "$DST"/"$FILENAME_ENC"
	else
		echo "$FILENAME_ENC"
	fi
}

## Program control
error() {
	echo "ERROR: $1" >&2
	exit 1
}

die() {
	if [ -n "$1" ]; then
		echo "DIE: $1" >&2
	fi
	## -6 ~ SIGABRT
	## This is the only SIGNAL that cleanup doesn't reset
	kill -6 "$$"
}

## Interface functions
name() {
	NAME="$1"
	compute_variables
}

remote() {
	REMOTE="$1"
}

generate() {
	GENERATE="$1"
}

cmd() {
	COMMAND="$1"
}

places() {
	PLACES="$1"
	[ "$#" -gt 1 ] && error "Specify places as string"
}

exclude() {
	STR=""
	for EXC in "$@"; do
		STR="$STR --exclude=$EXC"
	done
	EXCLUDE="$STR"
}

store() {
	STORE="$1"
}

after() {
	AFTER="$1"
}

run() {
	title "Run command"
	echo "$@"
	echo $@ | $REMOTE sh -s
	printf "\n"
}

store_file() {
	[ -z "$1" ] && error "Specify destination"
	store "sh -c 'cat > ${1}/${FILENAME_ENC}'"
}

## Internal functions
test_input() {
	[ -z "$NAME" ] && error "Specify backup name"
	[ -z "$COMMAND" -a -z "$PLACES" ] && error "Specify backup subject"
	[ -n "$COMMAND" -a -n "$PLACES" ] && error "Do not specify two types of backup at once"
	[ -z "$STORE" ] && error "Specify store command"
}

compute_variables() {
	UTS="$(date +"%s")"
	TS="$(date +"%Y-%m-%d_%H-%M-%S")"
	FILENAME="backup_"$NAME"_"$TS".tar"
	FILENAME_ENC="${FILENAME}.bz2.gpg"
	RUNDIR="/tmp/backuper_run_dir_$$_$UTS"
}

prepare() {
	trap 'error_handler' EXIT INT QUIT TERM ABRT HUP ILL TRAP BUS FPE SEGV
	mkdir -p "$RUNDIR"
}

error_handler() {
	cleanup
	exit 42
}

cleanup() {
	trap - EXIT INT QUIT TERM HUP ILL TRAP BUS FPE SEGV

	for PID in $(cat "$RUNDIR"/"$PID_FILE"); do
		if ps --ppid $$ | grep -q "$PID"; then
			kill "$PID"
		fi
	done

	[ -n "$PID_GENERATE" ] && if ps --ppid $$ | grep -q "$PID_GENERATE"; then
		kill "$PID_GENERATE"
	fi

	[ -n "$PID_STORE" ] && if ps --ppid $$ | grep -q "$PID_STORE"; then
		kill "$PID_STORE"
	fi

	if [ -d "$RUNDIR" ]; then
		rm -rf "$RUNDIR"
	fi
}

backup_done() {
	if [ -n "$AFTER" ]; then
		title "After backup hook"
		echo "$AFTER" | sh -s || die "After-backup hook failed"
	fi
}

personalization() {
	HOME="$(get_home)"
	[ -f "$HOME"/"$PERSN_FILE_NAME" ] && . "$HOME"/"$PERSN_FILE_NAME"
}

add_stage() {
	## Prepare pipes
	NEXTSTAGE="$((STAGE+1))"
	[ ! -p "$RUNDIR"/fifo_"$STAGE" ] && mkfifo "$RUNDIR"/fifo_"$STAGE"
	[ ! -p "$RUNDIR"/fifo_"$NEXTSTAGE" ] && mkfifo "$RUNDIR"/fifo_"$NEXTSTAGE"

	## Run requested command and store PID
	$@ > "$RUNDIR"/fifo_"$NEXTSTAGE" < "$RUNDIR"/fifo_"$STAGE" || die &
	echo "$!" >> "$RUNDIR"/"$PID_FILE"

	## Process started - increment
	STAGE="$NEXTSTAGE"
}

start_store() {
	STORE="$STORE < "$RUNDIR"/fifo_"$NEXTSTAGE""
	echo "$STORE" | sh -s
}

start_command() {
	title "Create backup"
	if [ -n "$COMMAND" ]; then
		echo "$COMMAND" | /usr/bin/time -f "$TIME_FMT" $REMOTE $GENERATE sh -s > "$RUNDIR"/fifo_0
	else
		## Exclude keep without quotes
		/usr/bin/time -f "$TIME_FMT" $REMOTE $GENERATE tar c --preserve-permissions $EXCLUDE "$PLACES" > "$RUNDIR"/fifo_0
	fi
}

start_pipeline() {
	add_stage "mbuffer -q -m 100M"
	add_stage "pbzip2"
	add_stage "mbuffer -q -m 100M"
	add_stage "gpg -z0 -r robin.oburka@nic.cz -e"
	## OK, this is strange. If store command fail, mbuffer forks itself with
	## PID that I'm not able to get (event from list of children).
	## ... and it takes 100% CPU. So, for now: Do not use mbuffer as the last one.
	#add_stage "mbuffer -q -m 100M"

	start_store || die &
	PID_STORE=$!

	start_command || die &
	PID_GENERATE=$!

	wait "$PID_STORE" "$PID_GENERATE"
	for PID in $(cat "$RUNDIR"/"$PID_FILE"); do
		wait "$PID"
	done
}

backup() {
	test_input
	prepare
	personalization
	start_pipeline
	backup_done
	cleanup
}