# backup.func – Snapshot/Backup-Logik mit Rollback via trap + Rotation + flexible Pfaderkennung

# Globale Variable (automatisch gesetzt)
SNAPSHOT_DIR=""

create_snapshot() {
  local app_name=$1
  local base_dir

  # Autodetect base_dir, bevorzugt /opt/<app>, sonst Arbeitsverzeichnis oder APP_DIR gesetzt vom Script
  base_dir="${APP_DIR:-/opt/$app_name}"
  if [[ ! -d "$base_dir" ]]; then
    msg_error "Cannot determine base directory for $app_name"
    return 1
  fi

  local snapshot_base="${base_dir}-snapshot"
  SNAPSHOT_DIR="${snapshot_base}-$(date +%F_%T | tr ':' '-')"

  msg_info "Creating snapshot for $app_name"

  mkdir -p "$SNAPSHOT_DIR"
  cp -a "$base_dir" "$SNAPSHOT_DIR/base" || {
    msg_error "Failed to backup base directory"
    return 1
  }

  mkdir -p "$SNAPSHOT_DIR/systemd"
  cp -a /etc/systemd/system/${app_name}-*.service "$SNAPSHOT_DIR/systemd/" 2>/dev/null || true

  [[ -f "/etc/default/$app_name" ]] && cp "/etc/default/$app_name" "$SNAPSHOT_DIR/"
  [[ -f "$base_dir/${app_name}_version.txt" ]] && cp "$base_dir/${app_name}_version.txt" "$SNAPSHOT_DIR/"

  rotate_snapshots "$snapshot_base"

  msg_ok "Snapshot created at $SNAPSHOT_DIR"
  return 0
}

rotate_snapshots() {
  local snapshot_base=$1
  local snapshots

  # Sortiert nach Datum absteigend, behalte nur die 3 neuesten
  mapfile -t snapshots < <(ls -dt ${snapshot_base}-* 2>/dev/null)
  if ((${#snapshots[@]} > 3)); then
    for ((i = 3; i < ${#snapshots[@]}; i++)); do
      rm -rf "${snapshots[$i]}"
      msg_info "Old snapshot removed: ${snapshots[$i]}"
    done
  fi
}

rollback_snapshot() {
  local app_name=$1
  local base_dir

  base_dir="${APP_DIR:-/opt/$app_name}"
  if [[ -z "$SNAPSHOT_DIR" || ! -d "$SNAPSHOT_DIR" ]]; then
    msg_error "No snapshot found. Cannot rollback."
    return 1
  fi

  msg_info "Rolling back $app_name from snapshot"

  systemctl stop ${app_name}-* 2>/dev/null || true

  rm -rf "$base_dir"
  cp -a "$SNAPSHOT_DIR/base" "$base_dir" || {
    msg_error "Failed to restore base directory"
    return 1
  }

  if [[ -d "$SNAPSHOT_DIR/systemd" ]]; then
    cp "$SNAPSHOT_DIR/systemd/"*.service /etc/systemd/system/ 2>/dev/null || true
    systemctl daemon-reload
  fi

  [[ -f "$SNAPSHOT_DIR/$app_name" ]] && cp "$SNAPSHOT_DIR/$app_name" "/etc/default/$app_name"
  [[ -f "$SNAPSHOT_DIR/${app_name}_version.txt" ]] && cp "$SNAPSHOT_DIR/${app_name}_version.txt" "$base_dir/"

  systemctl start ${app_name}-* 2>/dev/null || true

  msg_ok "Rollback for $app_name completed"
  return 0
}

cleanup_snapshot() {
  if [[ -n "$SNAPSHOT_DIR" && -d "$SNAPSHOT_DIR" ]]; then
    rm -rf "$SNAPSHOT_DIR"
    msg_ok "Cleaned up snapshot at $SNAPSHOT_DIR"
  fi
}

handle_failure() {
  local app_name=$1
  local line=$2
  msg_error "Update failed at line $line. Rolling back..."
  rollback_snapshot "$app_name"
  exit 1
}

safe_run_update_script() {
  local app_name="${APP:-paperless}"

  if ! create_snapshot "$app_name"; then
    msg_error "Snapshot creation failed. Aborting update."
    exit 1
  fi

  trap 'handle_failure "$app_name" $LINENO' ERR
  set -eE

  update_script

  cleanup_snapshot
}

wrap_update_script_with_snapshot() {
  local original_func
  original_func=$(declare -f update_script) || return 1

  eval "
  original_update_script() {
    ${original_func#*\{}
  }
  update_script() {
    local app_name=\"\${APP:-paperless}\"
    if ! create_snapshot \"\$app_name\"; then
      msg_error \"Snapshot creation failed. Aborting update.\"
      exit 1
    fi
    trap 'handle_failure \"\$app_name\" \$LINENO' ERR
    set -eE
    original_update_script
    cleanup_snapshot
  }
  "
}