// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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 nfs

import "fmt"

const (
	opAccess             = 3
	opClose              = 4
	opCommit             = 5
	opCreate             = 6
	opDelegpurge         = 7
	opDelegreturn        = 8
	opGetattr            = 9
	opGetfh              = 10
	opLink               = 11
	opLock               = 12
	opLockt              = 13
	opLocku              = 14
	opLookup             = 15
	opLookupp            = 16
	opNverify            = 17
	opOpen               = 18
	opOpenattr           = 19
	opOpenConfirm        = 20
	opOpenDowngrade      = 21
	opPutfh              = 22
	opPutpubfh           = 23
	opPutrootfh          = 24
	opRead               = 25
	opReaddir            = 26
	opReadlink           = 27
	opRemove             = 28
	opRename             = 29
	opRenew              = 30
	opRestorefh          = 31
	opSavefh             = 32
	opSecinfo            = 33
	opSetattr            = 34
	opSetclientid        = 35
	opSetclientidConfirm = 36
	opVerify             = 37
	opWrite              = 38
	opReleaseLockowner   = 39
	opBackchannelCtl     = 40
	opBindConnToSession  = 41
	opExchangeID         = 42
	opCreateSession      = 43
	opDestroySession     = 44
	opFreeStateid        = 45
	opGetDirDelegation   = 46
	opGetdeviceinfo      = 47
	opGetdevicelist      = 48
	opLayoutcommit       = 49
	opLayoutget          = 50
	opLayoutreturn       = 51
	opSecinfoNoName      = 52
	opSequence           = 53
	opSetSsv             = 54
	opTestStateid        = 55
	opWantDelegation     = 56
	opDestroyClientid    = 57
	opReclaimComplete    = 58
	opAllocate           = 59
	opCopy               = 60
	opCopyNotify         = 61
	opDeallocate         = 62
	opIoAdvise           = 63
	opLayoutError        = 64
	opLayoutStats        = 65
	opOffloadCancel      = 66
	opOffloadStatus      = 67
	opReadPlus           = 68
	opSeek               = 69
	opWriteSame          = 70
	opClone              = 71
	opIllegal            = 10044
)

var nfsOpnum4 = map[int]string{
	3:     "ACCESS",
	4:     "CLOSE",
	5:     "COMMIT",
	6:     "CREATE",
	7:     "DELEGPURGE",
	8:     "DELEGRETURN",
	9:     "GETATTR",
	10:    "GETFH",
	11:    "LINK",
	12:    "LOCK",
	13:    "LOCKT",
	14:    "LOCKU",
	15:    "LOOKUP",
	16:    "LOOKUPP",
	17:    "NVERIFY",
	18:    "OPEN",
	19:    "OPENATTR",
	20:    "OPEN_CONFIRM",
	21:    "OPEN_DOWNGRADE",
	22:    "PUTFH",
	23:    "PUTPUBFH",
	24:    "PUTROOTFH",
	25:    "READ",
	26:    "READDIR",
	27:    "READLINK",
	28:    "REMOVE",
	29:    "RENAME",
	30:    "RENEW",
	31:    "RESTOREFH",
	32:    "SAVEFH",
	33:    "SECINFO",
	34:    "SETATTR",
	35:    "SETCLIENTID",
	36:    "SETCLIENTID_CONFIRM",
	37:    "VERIFY",
	38:    "WRITE",
	39:    "RELEASE_LOCKOWNER",
	40:    "BACKCHANNEL_CTL",
	41:    "BIND_CONN_TO_SESSION",
	42:    "EXCHANGE_ID",
	43:    "CREATE_SESSION",
	44:    "DESTROY_SESSION",
	45:    "FREE_STATEID",
	46:    "GET_DIR_DELEGATION",
	47:    "GETDEVICEINFO",
	48:    "GETDEVICELIST",
	49:    "LAYOUTCOMMIT",
	50:    "LAYOUTGET",
	51:    "LAYOUTRETURN",
	52:    "SECINFO_NO_NAME",
	53:    "SEQUENCE",
	54:    "SET_SSV",
	55:    "TEST_STATEID",
	56:    "WANT_DELEGATION",
	57:    "DESTROY_CLIENTID",
	58:    "RECLAIM_COMPLETE",
	59:    "ALLOCATE",
	60:    "COPY",
	61:    "COPY_NOTIFY",
	62:    "DEALLOCATE",
	63:    "IO_ADVISE",
	64:    "LAYOUTERROR",
	65:    "LAYOUTSTATS",
	66:    "OFFLOAD_CANCEL",
	67:    "OFFLOAD_STATUS",
	68:    "READ_PLUS",
	69:    "SEEK",
	70:    "WRITE_SAME",
	71:    "CLONE",
	10044: "ILLEGAL",
}

func (nfs *nfs) eatData(op int, xdr *xdr) {
	switch op {
	case opGetattr:
		xdr.getUIntVector()
	case opGetfh:
		// nothing to eat
	case opLookup:
		xdr.getDynamicOpaque()
	case opLookupp:
		// nothing to eat
	case opNverify:
		xdr.getUIntVector()
		xdr.getDynamicOpaque()
	case opPutfh:
		xdr.getDynamicOpaque()
	case opPutpubfh:
		// nothing to eat
	case opPutrootfh:
		// nothing to eat
	case opReadlink:
		// nothing to eat
	case opRenew:
		xdr.getUHyper()
	case opRestorefh:
		// nothing to eat
	case opSavefh:
		// nothing to eat
	case opSecinfo:
		xdr.getDynamicOpaque()
	case opVerify:
		xdr.getUIntVector()
		xdr.getDynamicOpaque()
	case opSequence:
		xdr.getOpaque(16)
		xdr.getUInt()
		xdr.getUInt()
		xdr.getUInt()
		xdr.getUInt()

	}
}

// findV4MainOpcode finds the main operation in a compound call. If no main operation can be found, the last operation
// in compound call is returned.
//
// Compound requests group multiple nfs operations into a single request. Nevertheless, all compound requests are
// triggered by end-user activity, like 'ls', 'open', 'stat' and IO calls. Depending on which operations are combined
// the main operation can be different. For example, in compound:
//
// PUTFH + READDIR + GETATTR
//
// READDIR is the main operation. while in
//
// PUTFH + GETATTR
//
// GETATTR is the main operation.
func (nfs *nfs) findV4MainOpcode(xdr *xdr) string {
	// did we find a main operation opcode?
	found := false

	// default op code
	currentOpname := "ILLEGAL"

	opcount := int(xdr.getUInt())
	for i := 0; !found && i < opcount; i++ {
		op := int(xdr.getUInt())
		opname, ok := nfsOpnum4[op]

		if !ok {
			return fmt.Sprintf("ILLEGAL (%d)", op)
		}
		currentOpname = opname

		switch op {
		// First class ops
		//
		// The first class ops usually the main operation in the compound.
		// NFS spec allows to build compound operation where multiple
		// first class ops are used, like OPEN->LOCK->WRITE->LOCKU->CLOSE,
		// but such construction are not used in the practice.
		case
			opAccess,
			opBackchannelCtl,
			opBindConnToSession,
			opClose,
			opCommit,
			opCreate,
			opCreateSession,
			opDelegpurge,
			opDelegreturn,
			opDestroyClientid,
			opDestroySession,
			opExchangeID,
			opFreeStateid,
			opGetdeviceinfo,
			opGetdevicelist,
			opGetDirDelegation,
			opLayoutcommit,
			opLayoutget,
			opLayoutreturn,
			opLink,
			opLock,
			opLockt,
			opLocku,
			opOpen,
			opOpenattr,
			opOpenConfirm,
			opOpenDowngrade,
			opRead,
			opReaddir,
			opReadlink,
			opReclaimComplete,
			opReleaseLockowner,
			opRemove,
			opRename,
			opSecinfoNoName,
			opSetattr,
			opSetclientid,
			opSetclientidConfirm,
			opSetSsv,
			opTestStateid,
			opWantDelegation,
			opWrite,
			opAllocate,
			opCopy,
			opCopyNotify,
			opDeallocate,
			opIoAdvise,
			opLayoutError,
			opLayoutStats,
			opOffloadCancel,
			opOffloadStatus,
			opReadPlus,
			opSeek,
			opWriteSame,
			opClone:

			found = true
		default:
			nfs.eatData(op, xdr)
		}
	}
	return currentOpname
}