#!/bin/sh

#############
# CONSTANTS #
#############

# commands
this_exe="$(command -v "${0}")"
ionice_exe="$(command -v ionice)"
duplicity_exe="$(command -v duplicity)"

# files
duplicity_secrets_file='/root/duplicity_secrets'

#############
# FUNCTIONS #
#############

append_options() {
    ao_cmdline="${1}"
    ao_options="${2}"
    shift 1

    if [ -n "${ao_cmdline}" ] && [ -n "${ao_options}" ]; then
        # if both are given, stitch together with a space
        echo "${ao_cmdline} ${ao_options}"
    elif [ -n "${ao_options}" ]; then
        # if only options are given, output them
        echo "${ao_options}"
    else
        # if at most a cmdline is given, output that
        echo "${ao_cmdline}"
    fi
}

print_command() {
    pc_task="${1}"
    shift 1

    pc_cmdline="${ionice_exe} -c 3 ${duplicity_exe}"
    pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_ALL}" )"

    case "${pc_task}" in
        backup)
            pc_cmdline="$( append_options "${pc_cmdline}" "--allow-source-mismatch" )"
            pc_cmdline="$( append_options "${pc_cmdline}" "--volsize ${BACKUP_VOLSIZE}" )"
            pc_cmdline="$( append_options "${pc_cmdline}" "--full-if-older-than ${FULL_BACKUP_FREQUENCY}" )"
            pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_BACKUP}" )"
            pc_cmdline="$( append_options "${pc_cmdline}" "/backup/source" )"
            ;;
        
        cleanup)
            pc_cmdline="$( append_options "${pc_cmdline}" "cleanup --force" )"
            pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_CLEAN}" )"
            ;;
        
        rmfull)
            pc_cmdline="$( append_options "${pc_cmdline}" "remove-older-than ${BACKUP_RETENTION_TIME} --force" )"
            pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_RMFULL}" )"
            ;;
        
        rmincr)
            pc_cmdline="$( append_options "${pc_cmdline}" "remove-all-inc-of-but-n-full ${KEEP_NUM_FULL_CHAINS} --force" )"
            pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_RMINCR}" )"
            ;;
    esac

    pc_cmdline="${pc_cmdline} ${BACKUP_TARGET}"
    echo "${pc_cmdline}"
}

print_cron_schedule() {
    pcs_min="$(     echo "${1}" | awk '{print $1}' )"
    pcs_hour="$(    echo "${1}" | awk '{print $2}' )"
    pcs_day="$(     echo "${1}" | awk '{print $3}' )"
    pcs_month="$(   echo "${1}" | awk '{print $4}' )"
    pcs_weekday="$( echo "${1}" | awk '{print $5}' )"
    pcs_command="${2}"
    shift 2
    
    printf '%-8s%-8s%-8s%-8s%-8s%s\n' "${pcs_min}" "${pcs_hour}" "${pcs_day}" "${pcs_month}" "${pcs_weekday}" "${pcs_command}"
}

print_crontab() {
    echo   '# crontab generated for kiwi-backup'
    printf '# generation time: '; date
    echo   '#'

    # don't split the '#' from 'min'
    print_cron_schedule '#_min hour day month weekday' 'command' | tr '_' ' '

    print_cron_schedule "${SCHEDULE_BACKUP}"  "${this_exe} backup"
    print_cron_schedule "${SCHEDULE_CLEANUP}" "${this_exe} cleanup"
    print_cron_schedule "${SCHEDULE_RMFULL}"  "${this_exe} rmfull"
    print_cron_schedule "${SCHEDULE_RMINCR}"  "${this_exe} rmincr"
}

###############
# ENVIRONMENT #
###############

# load secrets file
if [ -f "${duplicity_secrets_file}" ]; then
    # shellcheck disable=SC1090
    . "${duplicity_secrets_file}"
fi

# check if uses encryption
if [ -n "${GPG_KEY_ID}" ]; then
    # gpg key given
    OPTIONS_ALL="$( append_options "${OPTIONS_ALL}" "--encrypt-key='${GPG_KEY_ID}'" )"

    # handle more verbose "GPG_PASSPHRASE" env_var
    PASSPHRASE="${GPG_PASSPHRASE:-${PASSPHRASE}}"
    export PASSPHRASE
    unset GPG_PASSPHRASE
else
    # no key given
    OPTIONS_ALL="$( append_options "${OPTIONS_ALL}" "--no-encryption" )"
fi

########
# MAIN #
########

if [ "${#}" -gt 0 ]; then

    # CLI
    task="${1}"
    shift 1

    # run task
    case "${task}" in
        print-*)
            task="${task##*-}"

            case "${task}" in
                # print out the crontab
                crontab)
                    print_crontab
                    ;;
                
                # print out a task
                backup|cleanup|rmfull|rmincr)
                    print_command "${task}"
                    ;;

                # unknown task
                *)
                    >&2 echo "Cannot print '${task}'."
                    >&2 echo "Choose from: crontab, backup, cleanup, rmfull, rmincr"
                    exit 1
                    ;;
            esac
            ;;

        # execute single task
        backup|cleanup|rmfull|rmincr)
            # shellcheck disable=SC2091
            $(print_command "${task}")
            ;;

        # unknown task
        *)
            >&2 echo "Unknown task '${task}'."
            >&2 echo "Choose from: backup, cleanup, rmfull, rmincr"
            exit 1
            ;;
    esac
else

    # default run: replace crontab, then start crond
    print_crontab | crontab -
    crond -fl 8
fi

exit 0