#!/bin/sh
# fpenrol.sh -- enrol a finger with COVERAGE guidance.
#
#   fpenrol.sh [finger_name]        default right-middle-finger
#
# The first template on this device was enrolled from ten quick taps in
# roughly one position, and it matches roughly one frame in seven -- against
# 47-75% for the template the research harness enrolled. The algorithm was
# given ten near-duplicate images of one spot, so it recognises that spot and
# little else.
#
# This walks a different contact position per accepted sample. It reads
# fprintd-enroll's per-stage output and prompts the next position as each
# stage passes, so the guidance tracks what the trustlet ACCEPTED rather than
# how many times you pressed.
F=${1:-right-middle-finger}
i=1
set -- "centre of the pad" \
       "slightly LEFT of centre" \
       "slightly RIGHT of centre" \
       "higher up, toward the TIP" \
       "lower down, toward the JOINT" \
       "centre again, rolled LEFT" \
       "centre again, rolled RIGHT" \
       "tip, rolled slightly left" \
       "joint, rolled slightly right" \
       "centre, pressed a little firmer"
echo "enrolling $F with position guidance -- 10 samples"
echo "press FLAT and firm, hold about a second, then LIFT fully."
echo
# The reader runs in a subshell, so `shift` there cannot advance the caller's
# list. Index into it instead.
pos() { eval "printf '%s' \"\$$1\""; }
echo ">>> sample 1/10: $(pos 1)"
fprintd-enroll -f "$F" user 2>&1 | while IFS= read -r line; do
    case "$line" in
        *enroll-stage-passed*)
            i=$((i+1))
            if [ "$i" -le 10 ]; then
                echo "    accepted."
                echo ">>> sample $i/10: $(pos $i)"
            fi ;;
        *enroll-retry-scan*)  echo "    not accepted -- same position, press flatter and firmer" ;;
        *enroll-completed*)   echo; echo "COMPLETED." ;;
        *enroll-failed*)      echo; echo "FAILED." ;;
        *) printf '%s\n' "$line" ;;
    esac
done