#!/bin/sh

PROGNAME="update-evobackup-canary"
REPOSITORY="https://gitea.evolix.org/evolix/evobackup"

VERSION="22.06"
readonly VERSION

# base functions

show_version() {
    cat <<END
${PROGNAME} version ${VERSION}

Copyright 2022 Evolix <info@evolix.fr>,
               Jérémy Lecour <jlecour@evolix.fr>,
               and others.

${REPOSITORY} 

${PROGNAME} comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to redistribute it under certain conditions.
See the GNU General Public License v3.0 for details.
END
}
show_help() {
    cat <<END
${PROGNAME} is updating a canary file for evobackup.

Usage: ${PROGNAME} [OPTIONS]

Main options
 -w, --who      who has updated the file (default: logname())
 -f, --file     path of the canary file (default: /zzz_evobackup_canary)
 -V, --version  print version and exit
 -h, --help     print this message and exit
END
}

main() {
    if [ -z "${who:-}" ]; then
        who=$(logname)
    fi
    if [ -z "${canary_file:-}" ]; then
        canary_file="/zzz_evobackup_canary"
    fi
    # This option is supported both on OpenBSD which does not use GNU date and on Debian
    date=$(date "+%FT%T%z")

    printf "%s %s\n" "${date}" "${who}" >> "${canary_file}"
}

# parse options
# based on https://gist.github.com/deshion/10d3cb5f88a21671e17a
while :; do
    case $1 in
        -h|-\?|--help)
            show_help
            exit 0
            ;;
        -V|--version)
            show_version
            exit 0
            ;;

        -w|--who)
            # with value separated by space
            if [ -n "$2" ]; then
                who=$2
                shift
            else
                printf 'ERROR: "-w|--who" requires a non-empty option argument.\n' >&2
                exit 1
            fi
            ;;
        --who=?*)
            # with value speparated by =
            who=${1#*=}
            ;;
        --who=)
            # without value
            printf 'ERROR: "--who" requires a non-empty option argument.\n' >&2
            exit 1
            ;;

        -f|--file)
            # with value separated by space
            if [ -n "$2" ]; then
                canary_file=$2
                shift
            else
                printf 'ERROR: "-f|--file" requires a non-empty option argument.\n' >&2
                exit 1
            fi
            ;;
        --file=?*)
            # with value speparated by =
            canary_file=${1#*=}
            ;;
        --file=)
            # without value
            printf 'ERROR: "--file" requires a non-empty option argument.\n' >&2
            exit 1
            ;;

        --)
            # End of all options.
            shift
            break
            ;;
        -?*)
            # ignore unknown options
            printf 'WARN: Unknown option : %s\n' "$1" >&2
            exit 1
            ;;
        *)
            # Default case: If no more options then break out of the loop.
            break
            ;;
    esac

    shift
done

export LC_ALL=C

set -u

main