#!/usr/bin/env bash
#
# Nightly backup for the key register.
#
# SQLite's .backup makes a consistent copy while the app is running — do NOT
# just cp the .db file, because the WAL may hold recent writes that a plain
# copy would miss.
#
# Install:
#   chmod +x backup.sh
#   sudo crontab -e
#   20 3 * * *  /opt/keyreg/backup.sh >> /var/log/keyreg-backup.log 2>&1

set -Eeuo pipefail

APP_DIR="/opt/keyreg"
BACKUP_DIR="/mnt/backup/keyreg"     # MUST be a different physical disk
OFFSITE_DEST=""                     # e.g. "backup@nas2:/volume1/keyreg"
KEEP_DAYS=60

STAMP="$(date +%Y-%m-%d_%H%M)"
OUT="${BACKUP_DIR}/keyreg-${STAMP}.db"

log() { printf '[%s] %s\n' "$(date '+%F %T')" "$*"; }
trap 'log "FAILED at line $LINENO — backup NOT complete"; exit 1' ERR

mkdir -p "$BACKUP_DIR"
cd "$APP_DIR"

# 1. Consistent snapshot
log "Backing up database..."
docker compose exec -T keyreg \
  sqlite3 /data/keyreg.db ".backup '/data/_tmp_backup.db'"
docker compose cp keyreg:/data/_tmp_backup.db "$OUT"
docker compose exec -T keyreg rm -f /data/_tmp_backup.db

# 2. Verify — an unreadable backup is not a backup
sqlite3 "$OUT" "PRAGMA integrity_check;" | grep -q '^ok$' \
  || { log "Integrity check FAILED"; exit 1; }
ITEMS=$(sqlite3 "$OUT" "SELECT COUNT(*) FROM items;")
[ "$ITEMS" -gt 0 ] || { log "Backup has zero keys — refusing to call this good"; exit 1; }
gzip -9 "$OUT"
log "OK — ${ITEMS} keys, $(stat -c %s "${OUT}.gz") bytes"

# 3. A readable copy too. If the app is ever gone, a CSV still tells you
#    who holds which key — which is the whole point of the register.
curl -fsS "http://127.0.0.1:3000/api/admin/export.csv" \
  -o "${BACKUP_DIR}/keyreg-${STAMP}.csv" || log "WARNING: CSV export failed"

# 4. Off site — survives fire and theft, which is when you most need to know
#    who has keys to the building
if [ -n "$OFFSITE_DEST" ]; then
  rsync -az --delete "${BACKUP_DIR}/" "${OFFSITE_DEST}/"
  log "Off-site sync done"
else
  log "WARNING: OFFSITE_DEST empty — local copy only"
fi

# 5. Retention
find "$BACKUP_DIR" -maxdepth 1 -type f -mtime "+${KEEP_DAYS}" -delete
log "Complete"

# ===========================================================================
# RESTORE — test this once now, not on the day you need it
#
#   cd /opt/keyreg
#   docker compose down
#   gunzip -c /mnt/backup/keyreg/keyreg-DATE.db.gz > ./data/keyreg.db
#   rm -f ./data/keyreg.db-wal ./data/keyreg.db-shm
#   docker compose up -d
#
# That is the whole restore. One file.
# ===========================================================================