#!/usr/bin/env bash
# Consistent backup of the parts inventory.
#
# The database and the photos are two resources that reference each other, so
# capturing them at different moments is not a backup: a photo deleted between
# the two steps leaves the saved database pointing at a file that isn't in the
# archive, and one added leaves the reverse. Neither is repairable afterwards.
#
# So the app is stopped for the few seconds it takes to copy both. With no
# process attached, parts.db and its -wal/-shm sidecars are a consistent set and
# the images directory cannot move underneath us.
#
#   ./tools/backup.sh [output-directory]
set -euo pipefail

OUT_DIR="$(cd "${1:-$PWD}" && pwd)"
cd "$(dirname "$0")/.."
STAMP="$(date +%F-%H%M%S)"
NAME="parts-backup-$STAMP.tar.gz"
VOLUME="$(docker compose config --format json 2>/dev/null \
  | python3 -c 'import json,sys; print(list(json.load(sys.stdin)["volumes"])[0])' 2>/dev/null || echo parts_data)"
VOLUME="$(docker volume ls --format '{{.Name}}' | grep -E "parts.*data" | head -1)"

echo "Stopping the app so both halves are captured at one moment..."
docker compose stop parts >/dev/null

restart() { docker compose start parts >/dev/null && echo "App restarted."; }
trap restart EXIT

# What the database expects to exist, read while nothing can be writing.
EXPECTED="$(docker run --rm -v "$VOLUME":/data -e PARTS_DB=/data/parts.db \
  --entrypoint python parts -m app.admin list-image-files | sort)"

docker run --rm -v "$VOLUME":/data -v "$OUT_DIR":/out alpine \
  tar -czf "/out/$NAME" -C /data .

# Verify every referenced photo actually made it into the archive.
IN_TAR="$(tar -tzf "$OUT_DIR/$NAME" | sed -n 's#^\./images/##p' | sort)"
MISSING="$(comm -23 <(printf '%s\n' "$EXPECTED" | grep -v '^$' || true) \
                    <(printf '%s\n' "$IN_TAR" | grep -v '^$' || true) || true)"
if [ -n "$MISSING" ]; then
  echo "BACKUP INCOMPLETE — referenced photos missing from the archive:" >&2
  printf '  %s\n' $MISSING >&2
  exit 1
fi

COUNT="$(printf '%s\n' "$EXPECTED" | grep -c . || true)"
echo "Wrote $OUT_DIR/$NAME ($(du -h "$OUT_DIR/$NAME" | cut -f1)), $COUNT photo(s) verified present."