#!/usr/bin/env bash
set -euo pipefail

mt -f "${DEVICE}" load
deadline=$(($(date +%s) + 60))
while true; do
    now=$(date +%s)
    if ((now >= deadline)); then
        break
    fi
    remaining=$((deadline - now))
    if info=$(timeout "${remaining}s" ./yatm-lto-info -f "${DEVICE}"); then
        # A present, empty field is readable MAM without an assigned barcode.
        # The prefix distinguishes it from a missing field or failed probe.
        barcode=$(awk '$1 == "Barcode" && $2 == ":" {
            value = $3
            if (length(value) == 8) {
                value = substr(value, 1, 6)
            }
            print ":" value
            exit
        }' <<< "${info}")
        if [[ -n ${barcode} ]]; then
            printf '{"barcode":"%s"}\n' "${barcode#:}" > "${OUT}"
            exit 0
        fi
    fi
    now=$(date +%s)
    if ((now >= deadline)); then
        break
    fi
    delay=$((deadline - now))
    if ((delay > 2)); then
        delay=2
    fi
    sleep "${delay}"
done
echo "Tape barcode is unavailable: ${DEVICE}" >&2
exit 1