// Copyright 2018 Google LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package nftables

import (
	"github.com/google/nftables/binaryutil"
	"github.com/mdlayher/netlink"
	"golang.org/x/sys/unix"
)

// CounterObj implements Obj.
type CounterObj struct {
	Table *Table
	Name  string // e.g. “fwded”

	Bytes   uint64
	Packets uint64
}

func (c *CounterObj) unmarshal(ad *netlink.AttributeDecoder) error {
	for ad.Next() {
		switch ad.Type() {
		case unix.NFTA_COUNTER_BYTES:
			c.Bytes = ad.Uint64()
		case unix.NFTA_COUNTER_PACKETS:
			c.Packets = ad.Uint64()
		}
	}
	return ad.Err()
}

func (c *CounterObj) family() TableFamily {
	return c.Table.Family
}

func (c *CounterObj) marshal(data bool) ([]byte, error) {
	obj, err := netlink.MarshalAttributes([]netlink.Attribute{
		{Type: unix.NFTA_COUNTER_BYTES, Data: binaryutil.BigEndian.PutUint64(c.Bytes)},
		{Type: unix.NFTA_COUNTER_PACKETS, Data: binaryutil.BigEndian.PutUint64(c.Packets)},
	})
	if err != nil {
		return nil, err
	}
	const NFT_OBJECT_COUNTER = 1 // TODO: get into x/sys/unix
	attrs := []netlink.Attribute{
		{Type: unix.NFTA_OBJ_TABLE, Data: []byte(c.Table.Name + "\x00")},
		{Type: unix.NFTA_OBJ_NAME, Data: []byte(c.Name + "\x00")},
		{Type: unix.NFTA_OBJ_TYPE, Data: binaryutil.BigEndian.PutUint32(NFT_OBJECT_COUNTER)},
	}
	if data {
		attrs = append(attrs, netlink.Attribute{Type: unix.NLA_F_NESTED | unix.NFTA_OBJ_DATA, Data: obj})
	}
	return netlink.MarshalAttributes(attrs)
}