/*
Copyright 2017 The Kubernetes Authors.

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 ipvs

import (
	"net"
	"strconv"
)

// Interface is an injectable interface for running ipvs commands.  Implementations must be goroutine-safe.
type Interface interface {
	// Flush clears all virtual servers in system. return occurred error immediately.
	Flush() error
	// EnsureVirtualServerAddressBind checks if virtual server's address is bound to dummy interface and, if not, binds it. If the address is already bound, return true.
	EnsureVirtualServerAddressBind(serv *VirtualServer, dev string) (exist bool, err error)
	// UnbindVirtualServerAddress checks if virtual server's address is bound to dummy interface and, if so, unbinds it.
	UnbindVirtualServerAddress(serv *VirtualServer, dev string) error
	// AddVirtualServer creates the specified virtual server.
	AddVirtualServer(*VirtualServer) error
	// UpdateVirtualServer updates an already existing virtual server.  If the virtual server does not exist, return error.
	UpdateVirtualServer(*VirtualServer) error
	// DeleteVirtualServer deletes the specified virtual server.  If the virtual server does not exist, return error.
	DeleteVirtualServer(*VirtualServer) error
	// Given a partial virtual server, GetVirtualServer will return the specified virtual server information in the system.
	GetVirtualServer(*VirtualServer) (*VirtualServer, error)
	// GetVirtualServers lists all virtual servers in the system.
	GetVirtualServers() ([]*VirtualServer, error)
	// AddRealServer creates the specified real server for the specified virtual server.
	AddRealServer(*VirtualServer, *RealServer) error
	// GetRealServers returns all real servers for the specified virtual server.
	GetRealServers(*VirtualServer) ([]*RealServer, error)
	// DeleteRealServer deletes the specified real server from the specified virtual server.
	DeleteRealServer(*VirtualServer, *RealServer) error
}

// VirtualServer is an user-oriented definition of an IPVS virtual server in its entirety.
type VirtualServer struct {
	Address   net.IP
	Protocol  string
	Port      uint16
	Scheduler string
	Flags     ServiceFlags
	Timeout   uint32
}

// ServiceFlags is used to specify session affinity, ip hash etc.
type ServiceFlags uint32

const (
	// FlagPersistent specify IPVS service session affinity
	FlagPersistent = 0x1
)

// Equal check the equality of virtual server.
// We don't use struct == since it doesn't work because of slice.
func (svc *VirtualServer) Equal(other *VirtualServer) bool {
	return svc.Address.Equal(other.Address) &&
		svc.Protocol == other.Protocol &&
		svc.Port == other.Port &&
		svc.Scheduler == other.Scheduler &&
		svc.Flags == other.Flags &&
		svc.Timeout == other.Timeout
}

func (svc *VirtualServer) String() string {
	return net.JoinHostPort(svc.Address.String(), strconv.Itoa(int(svc.Port))) + "/" + svc.Protocol
}

// RealServer is an user-oriented definition of an IPVS real server in its entirety.
type RealServer struct {
	Address net.IP
	Port    uint16
	Weight  int
}

func (dest *RealServer) String() string {
	return net.JoinHostPort(dest.Address.String(), strconv.Itoa(int(dest.Port)))
}