#!/bin/bash

#_INCLUDE_START_
# Default config values

# Be verbose
VERBOSE=1

# Be extra verbose
DEBUG=0

# Don't actually do anything, just print the commands
DRY_RUN=0

# Force synchronization, even when the target already exist
FORCE_SYNC=0

# Log file (if empty, print to stdout/err)
LOG_FILE=

# Where to find the configuration of the hosts to backup
CONFIG_PATH=/etc/bacap/hosts

# Name of the local host (so no ssh would be used with this host)
LOCALHOST=$HOSTNAME

# Where to put the backups
BACKUP_PATH=/backup

# Date format used for backed up directories (passed to the date command)
DATE_FMT="%Y-%m-%d"

# Ping remote hosts to check if they are up (set to 0 if your hosts don't
# reply to ICMP pings).
PING_CHECK=1

# rsync flags to use
RSYNC_FLAGS="-aAHSXx --numeric-ids"

# rsync flags to use when in verbose mode
RSYNC_VERBOSE_FLAGS="-v --stats"

# rsync remote shell to use
RSYNC_RSH="ssh"

#_INCLUDE_END_

SCRIPT_DIR=$(dirname `readlink -f $0`)
BACAPRC=$1

# Load configuration files
load_config() {
	extra_config=$1
	source "/etc/bacaprc" 2> /dev/null
	source "/etc/bacap/bacaprc" 2> /dev/null
	source "$SCRIPT_DIR/bacaprc" 2> /dev/null
	test -n "$BACAPRC" && source "$BACAPRC"
	test -n "$extra_config" && source "$1" 2> /dev/null

	run=
	[ $DRY_RUN -eq 1 ] &&
		run=echo
	[ $VERBOSE -eq 1 ] &&
		RSYNC_FLAGS="$RSYNC_FLAGS $RSYNC_VERBOSE_FLAGS"
	[ $DEBUG -eq 1 ] &&
		V=-v
	exec 3>&2
	[ -n "$LOG_FILE" ] &&
		exec 1>>"$LOG_FILE" &&
		exec 2>>"$LOG_FILE"

	export RSYNC_RSH
}

error() {
	echo "$@" >&3
}

log() {
	[ $VERBOSE -eq 1 ] &&
		echo "$@"
}

logerr() {
	echo "$@" >&2
}

ping_host() {
	ping -c1 "$1" > /dev/null 2>&1
}

load_config

if ! test -d "$BACKUP_PATH"
then
	error "BACKUP_PATH=$BACKUP_PATH doesn't exist!"
	exit 1
fi

date=`date "+$DATE_FMT"`
log
log
log "========================================================================="
log "Starting backup for $date at `date '+%Y-%m-%d %H:%M:%S'`"
log "========================================================================="
ret=0
for host_path in "$CONFIG_PATH"/*
do
	saved_ret=$ret
	# Load default config and override config if correspond
	load_config "$host_path/bacaprc"
	host=`basename "$host_path"`
	host_backup_path="$BACKUP_PATH/$host"
	mkdir -p $host_backup_path
	dst="$BACKUP_PATH/$host/$date"
	src=`cat "$host_path/paths"`
	[ "$host" != "$LOCALHOST" ] &&
		src=`awk "{print \"$host:\"\\$1}" "$host_path/paths"`
	exclude="$host_path/excludes"
	include="$host_path/includes"
	current_link="$host_backup_path/current"
	current_dir="$host_backup_path/`readlink \"$current_link\"`"
	extra_flags=
	log "-----------------------------------------------------------------"
	log "Backup for host $host started at `date '+%Y-%m-%d %H:%M:%S'`"
	log "-----------------------------------------------------------------"
	log "Source:      $src"
	log "Destination: $dst"
	log "Last:        $current_dir"
	log
	[ -d "$dst" ] && [ "$FORCE_SYNC" -ne 1 ] &&
		logerr "$dst already exists, skipping..." &&
		continue
	[ "$PING_CHECK" -eq 1 ] && ! ping_host $host &&
		logerr "$host is down, skipping..." &&
		continue
	[ -r "$exclude" ] &&
		extra_flags="--exclude-from=$exclude"
	[ -r "$include" ] &&
		extra_flags="$extra_flags --include-from=$include"
	log "Running rsync..."
	$run rsync $RSYNC_FLAGS $extra_flags \
				--link-dest="$current_dir" $src "$dst/"
	rsync_ret=$?
	case $rsync_ret in
		0)
			# Normal return
			;;
		24)
			# Ignore error 24 from rsync ("Partial transfer due to
			# vanished source files") which is somewhat expected
			# since we don't do a snapshot
			;;
		*)
			# Any other error is important enough
			ret=$(($ret+1))
			;;
	esac

	if [ $ret -eq $saved_ret ]
	then
		# Only move current if rsync did not fail, to avoid dangling
		# symlinks
		log "Moving current..."
		$run rm -f $V "$current_link" ||
		ret=$(($ret+1))
		$run ln -s $V "$date" "$current_link" ||
		ret=$(($ret+1))
	else
		ERROR_HOSTS="$ERROR_HOSTS $host"
	fi
done

log "========================================================================="
log "Backup for $date finished at `date '+%Y-%m-%d %H:%M:%S'`"
log "========================================================================="

if [ $ret -ne 0 ]
then
	error
	error "There were some errors when running the backup on: $ERROR_HOSTS"
	error
	if [ -n "$LOG_FILE" ]
	then
		error "Please take a look at the log: $LOG_FILE"
		error
	fi
fi

exit $ret