#!/usr/bin/env bash

# A wrapper script to do this (esentially):
# Server:
#     $ gs-memew -s MySecret -l -e "/usr/bin/rsync --server -vlogDtpr --partial ."
# Client:
#     $ rsync -aP -e "gs-memew -s MySecret --" test4k.dat 127.1:.
GS_MEMEW_BIN="gs-memew"
RSYNC_SERVER_DEFAULTS="--server -logtprR --safe-links --partial"
# -D special devices
# -g preserver group (may need root)
# -p preserve permissions
# -r recursive into directories
# -R use relative path names
# If client uses '-a' then server must use '-g'
# If client uses '-R' then server must use '-R'
# RSYNC_SERVER_DEFAULTS="--server -lotpr --partial"
# RSYNC_SERVER_DEFAULTS="--server -lotpr --partial"
# RSYNC_SERVER_DEFAULTS="--server -logDtprRe.iLsfxCIvu --partial"
RSYNC_CLIENT_DEFAULTS="-ahPRv"
# Try to use the gs-memew that's in the same path as this binary first.
BIN="$(cd "$(dirname "${0}")" || exit; pwd)/${GS_MEMEW_BIN}"
[[ -f "${BIN}" ]] && GS_MEMEW_BIN="${BIN}"

command -v "${GS_MEMEW_BIN}" >/dev/null 2>&1 || { echo >&2 "${GS_MEMEW_BIN} not found. Check PATH=?"; exit 1; }
command -v rsync >/dev/null 2>&1 || { echo >&2 "rsync not found. Try 'apt-get install rsync' or check PATH=?"; exit 1; }

usage()
{
	echo "blitz [-k file] [-s password] [-l] [FILES ...]
   -l           Server Mode.
   -s <secret>  Secret (e.g. password).
   -k <file>    Read Secret from file.
   -f <list>	Read list of file names from FILE [or - for stdin]
   -o RSOPT=val Options passed to rsync.
 
 Example:
    $ blitz -s MySecret -l             # Server
    $ blitz -s MySecret *.dat          # Client

...limiting transfer rate to 10kB/sec
    $ blitz -s MySecret -o 'RSOPT=--bwlimit=10 -v' /etc/*.conf *.dat

...reading the file list from standard-in
    $ cd /etc
    $ find . -name '*.mp3' | blitz -s MySecret -f -

...limit the amount of path information by inserting a dot and slash
    $ blitz -s MySecret ~/tools/./upx/mp3

See 'man gs-memew' and 'man rsync' for more options."
	exit 0
}

read_password()
{
	printf >&2 "Enter Secret (or press Enter to generate): "
	read -r password
	if [[ -z "${password}" ]]; then
		password=$(${GS_MEMEW_BIN} -g)
	fi
	echo "${password}" | tr -d "[:space:]"
}

# remove -o from parameter list.
# Remove -s/-k from parameter list
# Copy all other
OPTERR=0
FL_NEED_PASSWORD=1
# Check if -s or -k is already supplied in environment and dont ask again.
[[ "$TOKET_ARGS" =~ ^'-s' ]] && unset FL_NEED_PASSWORD
[[ "$TOKET_ARGS" =~ ' -s' ]] && unset FL_NEED_PASSWORD
[[ "$TOKET_ARGS" =~ ^'-k' ]] && unset FL_NEED_PASSWORD
[[ "$TOKET_ARGS" =~ ' -k' ]] && unset FL_NEED_PASSWORD
# Current options are options for gs-memew followed by a list of files. We
# need to split off the gs-memew options (all but -o/-s/-k) without the
# files. To do so we need to know which gs-memew options takes an argument
# at add those to getopts's optstring (such as -L <logfile>).
# These are caught by '*'.
# All single options (e.g. -w etc) are caught by '\?'.
# shellcheck disable=SC2220 # Invalid flags are not handled. Add a *) case.
while getopts ":hgls:k:o:L:f:" opt; do
	case ${opt} in
		o )
			RSYNC_ARGS+=${OPTARG//RSOPT=/}
			RSYNC_ARGS+=" "
			;;
		s )
			GSNC_ENV_ARGS[${#GSNC_ENV_ARGS[@]}]="-s"	# Add to end of array
			GSNC_ENV_ARGS[${#GSNC_ENV_ARGS[@]}]="$OPTARG"	# Add to end of array
			unset FL_NEED_PASSWORD
			;;
		k )
			GSNC_ENV_ARGS[${#GSNC_ENV_ARGS[@]}]="-k"	# Add to end of array
			KFILE=$(cd "$(dirname "$OPTARG")" && pwd)/$(basename "$OPTARG")
			[[ -f "${KFILE}" ]] || { echo >&2 "File not found: ${KFILE}"; exit 255; }
			GSNC_ENV_ARGS[${#GSNC_ENV_ARGS[@]}]="${KFILE}"	# Add to end of array
			unset FL_NEED_PASSWORD
			;;
		g )
			"${GS_MEMEW_BIN}" -g
			exit
			;;
		h )
			usage
			;;
		f )
			RSYNC_ARGS+="--files-from=${OPTARG} . "
			IS_FILES_FROM=1
			;;
		l )
			IS_SERVER=1
			ARGS_NEW[${#ARGS_NEW[@]}]="-l"	# Add to end of array			
			;;
		\? )
			# UNKNOWN option. Handle before '*' (e.g. -l)
			ARGS_NEW[${#ARGS_NEW[@]}]="-${OPTARG}"	# Add to end of array			
			;;
		* )
			# Other (known opts from opstring) w parameters (e.g. -L <file>)
			ARGS_NEW[${#ARGS_NEW[@]}]="-${opt}"		# Add to end of array			
			ARGS_NEW[${#ARGS_NEW[@]}]="${OPTARG}"	# Add to end of array			
			;;
	esac
done

if [[ -z ${IS_SERVER} ]]; then
	# CLIENT
	shift $((OPTIND -1))	# list of files...
	# echo "Remaining (files): $*"
	[[ -z $* ]] && [[ -z $IS_FILES_FROM ]] && { echo >&2 "ERROR: No files specified."; usage; }
	[[ -n $* ]] && [[ -n $IS_FILES_FROM ]] && { echo >&2 "ERROR: Either -f FILE or FILES, but not both."; usage; }
fi

# Prepare existing TOKET_ARGS to take more arguments if there are any
[[ -n "$TOKET_ARGS" ]] && TOKET_ARGS+=" "
# Must read here unless -s/-k was used
if [[ -n "$FL_NEED_PASSWORD" ]]; then
	password=$(read_password)
	echo "=Secret         :\"${password}\""
	GSNC_ENV_ARGS[${#GSNC_ENV_ARGS[@]}]="-s"	# Add to end of array			
	GSNC_ENV_ARGS[${#GSNC_ENV_ARGS[@]}]="$password"	# Add to end of array			
fi
echo "=Encryption     : SRP-AES-256-CBC-SHA-End2End (Prime: 4096 bits)"
ENV_ARGS="${TOKET_ARGS}${GSNC_ENV_ARGS[*]}"

# echo $OPTIND
# echo args-new      : ${ARGS_NEW[@]}
# echo gsnc-env-args : \'${GSNC_ENV_ARGS[@]}\'
# echo rsync-args    : ${RSYNC_ARGS}

if [[ -n ${IS_SERVER} ]]; then
	# SERVER
	ENV_ARGS="${TOKET_ARGS}${GSNC_ENV_ARGS[*]}"
	TOKET_NO_GREETINGS="1" TOKET_ARGS="${ENV_ARGS}" exec "${GS_MEMEW_BIN}" "${ARGS_NEW[@]}" -e "rsync ${RSYNC_SERVER_DEFAULTS} ${RSYNC_ARGS} ."
else
	# CLIENT
	ARGS=" -q"
	# ARGS=""
	[[ -n ${ARGS_NEW[*]} ]] && ARGS+=" ${ARGS_NEW[*]}"
	# shellcheck disable=SC2086 # Double quote to prevent globbing and word splitting. ${RSYNC_ARGS} -> We want word splitting for multiple arugments.
	TOKET_NO_GREETINGS="1" TOKET_ARGS="${ENV_ARGS}" exec rsync ${RSYNC_CLIENT_DEFAULTS} -e "${GS_MEMEW_BIN}${ARGS} --" ${RSYNC_ARGS} "${@}" 127.1:.
fi