#!/usr/bin/env bash
# 🔄 Rotating Backup — keep N copies, replace oldest
#
# Usage:
#   ./rotate-backup.sh [--keep N] [--dir DIR] <path/to/database.db>
#
# Examples:
#   ./rotate-backup.sh /home/oplabs/projects/canteen-asset-tracker/assets.db
#   ./rotate-backup.sh --keep 5 --dir /backups/dbs /var/lib/app/data.db
#
# Default: keep 3 backups in /home/oplabs/backups/canteen-db/
set -euo pipefail

KEEP=3
BACKUP_DIR="/home/oplabs/backups/canteen-db"
PREFIX="assets.db"

# ── Parse args ────────────────────────────────────────────────────────────────
while [[ $# -gt 0 ]]; do
  case "$1" in
    --keep) shift; KEEP="$1"; shift ;;
    --dir)  shift; BACKUP_DIR="$1"; shift ;;
    --prefix) shift; PREFIX="$1"; shift ;;
    -h|--help)
      echo "Usage: $(basename "$0") [--keep N] [--dir DIR] [--prefix NAME] <database-path>"
      echo ""
      echo "Backs up a SQLite database with rotation (keep N, remove oldest)."
      echo ""
      echo "  --keep N     Number of backups to retain  (default: 3)"
      echo "  --dir DIR    Target backup directory      (default: /home/oplabs/backups/canteen-db)"
      echo "  --prefix NAME  Backup file name prefix    (default: assets.db)"
      exit 0
      ;;
    -*)
      echo "Unknown option: $1" >&2
      exit 1
      ;;
    *)
      DB_PATH="$1"
      shift
      ;;
  esac
done

if [[ -z "${DB_PATH:-}" ]]; then
  echo "❌ Usage: $(basename "$0") [--keep N] <database-path>" >&2
  exit 1
fi

if [[ ! -f "$DB_PATH" ]]; then
  echo "❌ Database not found: $DB_PATH" >&2
  exit 1
fi

# ── Create backup ─────────────────────────────────────────────────────────────
mkdir -p "$BACKUP_DIR"
TIMESTAMP=$(date +%Y%m%d-%H%M%S)
BACKUP_FILE="${BACKUP_DIR}/${PREFIX}-${TIMESTAMP}"

# Use sqlite3 .backup for safe online backup (consistent snapshot even if app is running)
if command -v sqlite3 &>/dev/null; then
  sqlite3 "$DB_PATH" ".backup '$BACKUP_FILE'"
  echo "✅  $(basename "$DB_PATH") → $BACKUP_FILE  (sqlite3 snapshot)"
else
  cp "$DB_PATH" "$BACKUP_FILE"
  echo "✅  $(basename "$DB_PATH") → $BACKUP_FILE  (file copy)"
fi

# ── Rotate: keep only N most recent ───────────────────────────────────────────
KEEP=$((KEEP + 0))  # ensure numeric
REMOVE_COUNT=$((KEEP))
REMOVE_FROM=$((REMOVE_COUNT + 1))

OLD_COUNT=$(ls -t "${BACKUP_DIR}/${PREFIX}-"* 2>/dev/null | wc -l)
ls -t "${BACKUP_DIR}/${PREFIX}-"* 2>/dev/null | tail -n +${REMOVE_FROM} | xargs rm -f 2>/dev/null || true
REMOVED=$((OLD_COUNT > KEEP ? OLD_COUNT - KEEP : 0))

echo "   📦 ${KEEP} kept · ${REMOVED} removed · ${BACKUP_DIR}"