/*
Copyright 2016 The GoStor Authors 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.
*/

// iSCSI Target Driver
package iscsit

import (
	"fmt"
	"strings"
	"sync"

	"github.com/gostor/gotgt/pkg/api"
)

const iSCSIDriverName = "iscsi"

const (
	IOSTATE_FREE = iota

	IOSTATE_RX_BHS
	IOSTATE_RX_INIT_AHS
	IOSTATE_RX_AHS
	IOSTATE_RX_INIT_HDIGEST
	IOSTATE_RX_HDIGEST
	IOSTATE_RX_CHECK_HDIGEST
	IOSTATE_RX_INIT_DATA
	IOSTATE_RX_DATA
	IOSTATE_RX_INIT_DDIGEST
	IOSTATE_RX_DDIGEST
	IOSTATE_RX_CHECK_DDIGEST
	IOSTATE_RX_END

	IOSTATE_TX_BHS
	IOSTATE_TX_INIT_AHS
	IOSTATE_TX_AHS
	IOSTATE_TX_INIT_HDIGEST
	IOSTATE_TX_HDIGEST
	IOSTATE_TX_INIT_DATA
	IOSTATE_TX_DATA
	IOSTATE_TX_INIT_DDIGEST
	IOSTATE_TX_DDIGEST
	IOSTATE_TX_END
)

var ISCSI_OPCODE_MASK byte = 0x3F

type ISCSIDiscoveryMethod string

var (
	ISCSIDiscoverySendTargets  ISCSIDiscoveryMethod = "sendtargets"
	ISCSIDiscoveryStaticConfig ISCSIDiscoveryMethod = "static"
	ISCSIDiscoveryISNS         ISCSIDiscoveryMethod = "isns"
)

type ISCSIRedirectInfo struct {
	Address  string
	Port     int
	Reason   uint8
	Callback string
}

type iSCSITPGT struct {
	// Mapping to SCSI Reltive Target Port ID
	TPGT    uint16
	Portals map[string]struct{}
}

type ISCSITarget struct {
	*api.SCSITarget
	api.SCSITargetDriverCommon
	// TPGT number is the key
	TPGTs map[uint16]*iSCSITPGT
	// TSIH is the key
	Sessions        map[uint16]*ISCSISession
	SessionsRWMutex sync.RWMutex
	Alias           string
	MaxSessions     int
	RedirectInfo    ISCSIRedirectInfo
	Rdma            int
	NopInterval     int
	NopCount        int
}

/*
 * RFC 3720 iSCSI SSID = ISID , TPGT
 * ISID is an 6 bytes number, TPGT is an 2 bytes number
 * We combine ISID and TPGT together to be SSID
 */
func MakeSSID(ISID uint64, TPGT uint16) uint64 {
	SSID := ISID<<16 | uint64(TPGT)
	return SSID
}

func ParseSSID(SSID uint64) (uint64, uint16) {
	TPGT := uint16(uint64(0xFFFF) & SSID)
	ISID := SSID >> 16
	return ISID, TPGT
}

func (tgt *ISCSITarget) FindTPG(portal string) (uint16, error) {
	for tpgt, TPG := range tgt.TPGTs {
		for tgtPortal := range TPG.Portals {
			if strings.EqualFold(portal, tgtPortal) {
				return tpgt, nil
			}
		}
	}
	return 0, fmt.Errorf("No TPGT found with IP(%s)", portal)
}

func newISCSITarget(target *api.SCSITarget) *ISCSITarget {
	return &ISCSITarget{
		SCSITarget: target,
		TPGTs:      make(map[uint16]*iSCSITPGT),
		Sessions:   make(map[uint16]*ISCSISession),
	}
}

func (tgt *ISCSITarget) Init() error {
	return nil
}

func (tgt *ISCSITarget) Exit() error {
	return nil
}

func (tgt *ISCSITarget) CreateTarget(target *api.SCSITarget) error {
	return nil
}

func (tgt *ISCSITarget) DestroyTarget(target *api.SCSITarget) error {
	return nil
}

func (tgt *ISCSITarget) CreatePortal(name string) error {
	return nil
}

func (tgt *ISCSITarget) DestroyPortal(name string) error {
	return nil
}

func (tgt *ISCSITarget) CreateLu(lu *api.SCSILu) error {
	return nil
}

func (tgt *ISCSITarget) GetLu(lun uint8) (uint64, error) {
	return 0, nil
}
func (tgt *ISCSITarget) CommandNotify(nid uint64, result int, cmd *api.SCSICommand) error {
	return nil
}