// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

// The wire codecs of the NFSv4.2 operations, RFC 7862, with the shapes
// taken from the XDR of RFC 7863.

package nfs4

import (
	"sourcedock.dev/petrbalvin/nfs/internal/xdr"
)

// Content types of the data_content4 enum, RFC 7862 section 8.2.
const (
	ContentData = 0
	ContentHole = 1
)

// Error codes the copy family answers with, RFC 7862 section 15.1.
const (
	ErrOffloadDenied  = 10091
	ErrOffloadNoReqs  = 10094
	NfsSyncNothing    = 0
	NfsSyncDataSync   = 1
	NfsSyncFileSync   = 2
	OffloadNotReq     = 0
	OffloadSuccess    = 1
	OffloadDenied     = 2
	OffloadFatal      = 3
	OffloadNoFallback = 4
)

// AppendSeekArgs encodes the SEEK argop: the stateid, the offset and the
// content kind the client searches for.
func AppendSeekArgs(b []byte, st Stateid, offset uint64, what uint32) []byte {
	b = xdr.AppendUint32(b, OpSeek)
	b = st.Append(b)
	b = xdr.AppendUint64(b, offset)
	return xdr.AppendUint32(b, what)
}

// AppendSeekRes encodes a successful SEEK result: the end of file flag
// and the offset of the next content of the requested kind.
func AppendSeekRes(b []byte, eof bool, offset uint64) []byte {
	b = xdr.AppendBool(b, eof)
	return xdr.AppendUint64(b, offset)
}

// AppendAllocateArgs encodes the ALLOCATE argop: the reserved range.
func AppendAllocateArgs(b []byte, st Stateid, offset, length uint64) []byte {
	b = xdr.AppendUint32(b, OpAllocate)
	b = st.Append(b)
	b = xdr.AppendUint64(b, offset)
	return xdr.AppendUint64(b, length)
}

// AppendDeallocateArgs encodes the DEALLOCATE argop: the released range.
func AppendDeallocateArgs(b []byte, st Stateid, offset, length uint64) []byte {
	b = xdr.AppendUint32(b, OpDeallocate)
	b = st.Append(b)
	b = xdr.AppendUint64(b, offset)
	return xdr.AppendUint64(b, length)
}

// AppendIoAdviseArgs encodes the IO_ADVISE argop: the range and the hint
// bitmap.
func AppendIoAdviseArgs(b []byte, st Stateid, offset, length uint64, hints Bitmap) []byte {
	b = xdr.AppendUint32(b, OpIoAdvise)
	b = st.Append(b)
	b = xdr.AppendUint64(b, offset)
	b = xdr.AppendUint64(b, length)
	return hints.AppendTo(b)
}

// AppendIoAdviseRes encodes a successful IO_ADVISE result: the hints the
// server accepted.
func AppendIoAdviseRes(b []byte, hints Bitmap) []byte {
	return hints.AppendTo(b)
}

// A CopySourceServer is one netloc4 of the COPY argument list: the
// servers the source lives on.
type CopySourceServer struct {
	Type uint32
	Name string
	Addr NetAddr
}

// AppendCopyArgs encodes the COPY argop: the source and destination
// stateids, the ranges and the source server list.
func AppendCopyArgs(b []byte, src, dst Stateid, srcOff, dstOff, count uint64, consecutive, synchronous bool, sources []CopySourceServer) []byte {
	b = xdr.AppendUint32(b, OpCopy)
	b = src.Append(b)
	b = dst.Append(b)
	b = xdr.AppendUint64(b, srcOff)
	b = xdr.AppendUint64(b, dstOff)
	b = xdr.AppendUint64(b, count)
	b = xdr.AppendBool(b, consecutive)
	b = xdr.AppendBool(b, synchronous)
	b = xdr.AppendUint32(b, uint32(len(sources)))
	for _, s := range sources {
		b = xdr.AppendUint32(b, s.Type)
		switch s.Type {
		case 1, 2:
			b = xdr.AppendString(b, s.Name)
		case 3:
			b = xdr.AppendString(b, s.Addr.Netid)
			b = xdr.AppendString(b, s.Addr.Uaddr)
		}
	}
	return b
}

// AppendWriteResponse encodes the write_response4 the copy family
// answers with.
func AppendWriteResponse(b []byte, callbackSt Stateid, callbackSet bool, count uint64, committed uint32, verifier [8]byte) []byte {
	if callbackSet {
		b = xdr.AppendUint32(b, 1)
		b = callbackSt.Append(b)
	} else {
		b = xdr.AppendUint32(b, 0)
	}
	b = xdr.AppendUint64(b, count)
	b = xdr.AppendUint32(b, committed)
	return append(b, verifier[:]...)
}

// AppendCopyRes encodes a successful COPY result: the write response and
// the requirements the server met.
func AppendCopyRes(b []byte, callbackSt Stateid, callbackSet bool, count uint64, committed uint32, verifier [8]byte, consecutive, synchronous bool) []byte {
	b = AppendWriteResponse(b, callbackSt, callbackSet, count, committed, verifier)
	b = xdr.AppendBool(b, consecutive)
	return xdr.AppendBool(b, synchronous)
}

// AppendCopyNotifyArgs encodes the COPY_NOTIFY argop: the source stateid
// and the destination the client copies to.
func AppendCopyNotifyArgs(b []byte, st Stateid, dstType uint32, dstName string, dstAddr NetAddr) []byte {
	b = xdr.AppendUint32(b, OpCopyNotify)
	b = st.Append(b)
	b = xdr.AppendUint32(b, dstType)
	switch dstType {
	case 1, 2:
		b = xdr.AppendString(b, dstName)
	case 3:
		b = xdr.AppendString(b, dstAddr.Netid)
		b = xdr.AppendString(b, dstAddr.Uaddr)
	}
	return b
}

// AppendCopyNotifyRes encodes a successful COPY_NOTIFY result: the lease
// the authorization lives, the stateid naming it and the source servers.
func AppendCopyNotifyRes(b []byte, leaseSeconds int64, st Stateid, sources []CopySourceServer) []byte {
	b = xdr.AppendInt64(b, leaseSeconds)
	b = xdr.AppendUint32(b, 0)
	b = st.Append(b)
	b = xdr.AppendUint32(b, uint32(len(sources)))
	for _, s := range sources {
		b = xdr.AppendUint32(b, s.Type)
		switch s.Type {
		case 1, 2:
			b = xdr.AppendString(b, s.Name)
		case 3:
			b = xdr.AppendString(b, s.Addr.Netid)
			b = xdr.AppendString(b, s.Addr.Uaddr)
		}
	}
	return b
}

// AppendOffloadCancelArgs encodes the OFFLOAD_CANCEL argop: the stateid
// of the copy to abandon.
func AppendOffloadCancelArgs(b []byte, st Stateid) []byte {
	b = xdr.AppendUint32(b, OpOffloadCancel)
	return st.Append(b)
}

// AppendOffloadStatusArgs encodes the OFFLOAD_STATUS argop: the stateid
// of the copy in flight.
func AppendOffloadStatusArgs(b []byte, st Stateid) []byte {
	b = xdr.AppendUint32(b, OpOffloadStatus)
	return st.Append(b)
}

// AppendOffloadStatusRes encodes a successful OFFLOAD_STATUS result: the
// bytes copied so far and the completion code.
func AppendOffloadStatusRes(b []byte, count uint64, complete uint32) []byte {
	b = xdr.AppendUint64(b, count)
	return xdr.AppendUint32(b, complete)
}

// AppendCloneArgs encodes the CLONE argop: the ranges of the clone. The
// saved file handle is the source, the current one the destination.
func AppendCloneArgs(b []byte, src, dst Stateid, srcOff, dstOff, count uint64) []byte {
	b = xdr.AppendUint32(b, OpClone)
	b = src.Append(b)
	b = dst.Append(b)
	b = xdr.AppendUint64(b, srcOff)
	b = xdr.AppendUint64(b, dstOff)
	return xdr.AppendUint64(b, count)
}

// AppendLayoutErrorArgs encodes the LAYOUTERROR argop: the failing range
// and one error per device.
func AppendLayoutErrorArgs(b []byte, offset, length uint64, st Stateid, device [16]byte, status, opnum uint32) []byte {
	b = xdr.AppendUint32(b, OpLayoutError)
	b = xdr.AppendUint64(b, offset)
	b = xdr.AppendUint64(b, length)
	b = st.Append(b)
	b = xdr.AppendUint32(b, 1)
	b = append(b, device[:]...)
	b = xdr.AppendUint32(b, status)
	return xdr.AppendUint32(b, opnum)
}

// AppendLayoutStatsArgs encodes the LAYOUTSTATS argop: the reported range
// and the IO counters of the data server.
func AppendLayoutStatsArgs(b []byte, offset, length uint64, st Stateid, readCount, readBytes, writeCount, writeBytes uint64, device [16]byte, updateType uint32, updateBody []byte) []byte {
	b = xdr.AppendUint32(b, OpLayoutStats)
	b = xdr.AppendUint64(b, offset)
	b = xdr.AppendUint64(b, length)
	b = st.Append(b)
	b = xdr.AppendUint64(b, readCount)
	b = xdr.AppendUint64(b, readBytes)
	b = xdr.AppendUint64(b, writeCount)
	b = xdr.AppendUint64(b, writeBytes)
	b = append(b, device[:]...)
	b = xdr.AppendUint32(b, updateType)
	return xdr.AppendVarOpaque(b, updateBody)
}

// AppendReadPlusArgs encodes the READ_PLUS argop: the range to read.
func AppendReadPlusArgs(b []byte, st Stateid, offset uint64, count uint32) []byte {
	b = xdr.AppendUint32(b, OpReadPlus)
	b = st.Append(b)
	b = xdr.AppendUint64(b, offset)
	return xdr.AppendUint32(b, count)
}

// AppendReadPlusDataRes encodes a successful READ_PLUS result that
// carries one data segment.
func AppendReadPlusDataRes(b []byte, eof bool, offset uint64, data []byte) []byte {
	b = xdr.AppendBool(b, eof)
	b = xdr.AppendUint32(b, 1)
	b = xdr.AppendUint32(b, ContentData)
	b = xdr.AppendUint64(b, offset)
	return xdr.AppendVarOpaque(b, data)
}

// AppendReadPlusHoleRes encodes a successful READ_PLUS result that
// reports a hole.
func AppendReadPlusHoleRes(b []byte, eof bool, offset, length uint64) []byte {
	b = xdr.AppendBool(b, eof)
	b = xdr.AppendUint32(b, 1)
	b = xdr.AppendUint32(b, ContentHole)
	b = xdr.AppendUint64(b, offset)
	return xdr.AppendUint64(b, length)
}

// AppendWriteSameArgs encodes the WRITE_SAME argop: the stateid, the
// stability and the application data block to write. The block number
// is a count4 on the wire, RFC 7862 section 15.8.
func AppendWriteSameArgs(b []byte, st Stateid, stable uint32, offset, blockSize, blockCount, relOffBlocknum uint64, blockNum uint32, relOffPattern uint64, pattern []byte) []byte {
	b = xdr.AppendUint32(b, OpWriteSame)
	b = st.Append(b)
	b = xdr.AppendUint32(b, stable)
	b = xdr.AppendUint64(b, offset)
	b = xdr.AppendUint64(b, blockSize)
	b = xdr.AppendUint64(b, blockCount)
	b = xdr.AppendUint64(b, relOffBlocknum)
	b = xdr.AppendUint32(b, blockNum)
	b = xdr.AppendUint64(b, relOffPattern)
	return xdr.AppendVarOpaque(b, pattern)
}

// AppendWriteSameRes encodes a successful WRITE_SAME result: the write
// response alone.
func AppendWriteSameRes(b []byte, count uint64, committed uint32, verifier [8]byte) []byte {
	b = xdr.AppendUint32(b, 0)
	b = xdr.AppendUint64(b, count)
	b = xdr.AppendUint32(b, committed)
	return append(b, verifier[:]...)
}