#!/bin/bash
# docker-volume-backup.sh
# Backs up all named Docker volumes to compressed tar archives.
# Supports exclusions, rotation, and optional S3 upload via rclone.
#
# Usage: sudo bash docker-volume-backup.sh
# Restore: sudo bash docker-volume-backup.sh restore <volume-name> <backup-file>

set -euo pipefail

BACKUP_DIR="${BACKUP_DIR:-/var/backups/docker-volumes}"
RETENTION_DAYS="${RETENTION_DAYS:-7}"
RCLONE_DEST="${RCLONE_DEST:-}"           # e.g. "aws-s3:my-bucket/docker-volumes"
EXCLUDE_VOLUMES="${EXCLUDE_VOLUMES:-}"   # space-separated list of volumes to skip

DATE=$(date '+%Y-%m-%d_%H-%M-%S')
BACKUP_PATH="${BACKUP_DIR}/${DATE}"

# ── Restore mode ─────────────────────────────────────────────────
if [[ "${1:-}" == "restore" ]]; then
  volume="${2:-}"
  archive="${3:-}"
  if [[ -z "$volume" || -z "$archive" ]]; then
    echo "Usage: $0 restore <volume-name> <backup-file.tar.gz>"
    exit 1
  fi
  echo "Restoring $volume from $archive..."
  docker volume create "$volume" 2>/dev/null || true
  docker run --rm \
    -v "${volume}:/volume" \
    -v "$(dirname "$archive"):/backup" \
    alpine tar xzf "/backup/$(basename "$archive")" -C /volume --strip-components=1
  echo "✓ Restored $volume"
  exit 0
fi

# ── Backup mode ──────────────────────────────────────────────────
mkdir -p "$BACKUP_PATH"
echo "[$(date)] Starting Docker volume backup to $BACKUP_PATH"

# Get list of all named volumes
mapfile -t volumes < <(docker volume ls --format '{{.Name}}')
success=0
failed=0

for volume in "${volumes[@]}"; do
  # Skip excluded volumes
  if echo "$EXCLUDE_VOLUMES" | grep -qw "$volume"; then
    echo "  Skipping (excluded): $volume"
    continue
  fi

  archive="${BACKUP_PATH}/${volume}.tar.gz"
  echo -n "  Backing up: $volume ... "

  if docker run --rm \
      -v "${volume}:/volume:ro" \
      -v "${BACKUP_PATH}:/backup" \
      alpine tar czf "/backup/${volume}.tar.gz" -C /volume . 2>/dev/null; then
    size=$(du -sh "$archive" | cut -f1)
    echo "✓ (${size})"
    ((success++))
  else
    echo "FAILED"
    ((failed++))
  fi
done

echo ""
echo "[$(date)] Backup complete: ${success} succeeded, ${failed} failed"
echo "Location: $BACKUP_PATH"
echo "Total size: $(du -sh "$BACKUP_PATH" | cut -f1)"

# ── Upload to S3 via rclone ──────────────────────────────────────
if [[ -n "$RCLONE_DEST" ]]; then
  if command -v rclone &>/dev/null; then
    echo ""
    echo "Syncing to ${RCLONE_DEST}..."
    rclone sync "$BACKUP_DIR" "$RCLONE_DEST" --progress
    echo "✓ Sync complete"
  else
    echo "WARNING: RCLONE_DEST set but rclone not installed"
  fi
fi

# ── Rotate old backups ───────────────────────────────────────────
echo ""
echo "Rotating backups older than ${RETENTION_DAYS} days..."
find "$BACKUP_DIR" -maxdepth 1 -type d -mtime "+${RETENTION_DAYS}" -exec rm -rf {} + 2>/dev/null || true
echo "✓ Rotation complete"
echo ""
echo "Current backups:"
ls -lh "$BACKUP_DIR" | tail -10