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

package nfs4

import (
	"bytes"
	"testing"

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

func TestSessionIDShape(t *testing.T) {
	// The session id is sixteen bytes on the wire, RFC 7863: an eight
	// byte server prefix and the eight byte client id.
	var prefix [8]byte
	copy(prefix[:], []byte("nfs-srv-"))
	id := MakeSessionID(prefix, 0xdeadbeefcafe)
	if len(id) != 16 {
		t.Fatalf("session id of %d bytes, want 16", len(id))
	}
	if id.ClientIDOf() != 0xdeadbeefcafe {
		t.Fatalf("client id half: %x", id.ClientIDOf())
	}
	if !bytes.Equal(id[:8], prefix[:]) {
		t.Fatalf("server prefix: %x", id[:8])
	}
}

func TestExchangeIDRoundTrip(t *testing.T) {
	var verifier [8]byte
	copy(verifier[:], []byte("verif-1-"))
	arg := AppendExchangeIDArgs(nil, verifier, []byte("owner-1"), ExchgIDUseNonPnfs)
	d := xdr.NewDecoder(arg)
	if op, err := d.Uint32(); err != nil || op != OpExchangeID {
		t.Fatalf("op: %d, %v", op, err)
	}
	a, err := DecodeExchangeIDArgs(d)
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if a.Verifier != verifier || string(a.OwnerID) != "owner-1" ||
		a.Flags != ExchgIDUseNonPnfs || a.Protect != StateProtectNone {
		t.Fatalf("args: %+v", a)
	}

	res := AppendExchangeIDRes(nil, 77, 0, ExchgIDUseNonPnfs|ExchgIDConfirmedR, []byte("major"))
	rd := xdr.NewDecoder(res)
	if clientid, err := rd.Uint64(); err != nil || clientid != 77 {
		t.Fatalf("clientid: %d, %v", clientid, err)
	}
	if seq, err := rd.Uint32(); err != nil || seq != 0 {
		t.Fatalf("sequence: %d, %v", seq, err)
	}
	if flags, err := rd.Uint32(); err != nil || flags&ExchgIDConfirmedR == 0 {
		t.Fatalf("flags: %x, %v", flags, err)
	}
	if n, err := resBodyLen(OpExchangeID, ErrOK, res); err != nil || n != len(res) {
		t.Fatalf("measure: %d of %d, %v", n, len(res), err)
	}
}

func TestCreateSessionRoundTrip(t *testing.T) {
	arg := AppendCreateSessionArgs(nil, 0x1234, 3, CreateSessionFlagPersist,
		DefaultForeChannel, DefaultBackChannel, 0xcafe)
	d := xdr.NewDecoder(arg)
	if op, err := d.Uint32(); err != nil || op != OpCreateSession {
		t.Fatalf("op: %d, %v", op, err)
	}
	a, err := DecodeCreateSessionArgs(d)
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if a.ClientID != 0x1234 || a.Sequence != 3 || a.Flags != CreateSessionFlagPersist ||
		a.Fore.MaxRequest != DefaultForeChannel.MaxRequest ||
		a.Fore.MaxRequests != DefaultForeChannel.MaxRequests ||
		a.Back.MaxRequest != DefaultBackChannel.MaxRequest ||
		a.CBProgram != 0xcafe {
		t.Fatalf("args: %+v", a)
	}

	id := MakeSessionID([8]byte{1, 2, 3, 4, 5, 6, 7, 8}, 0x1234)
	res := AppendCreateSessionRes(nil, id, 3, 0, DefaultForeChannel, DefaultBackChannel)
	if n, err := resBodyLen(OpCreateSession, ErrOK, res); err != nil || n != len(res) {
		t.Fatalf("measure: %d of %d, %v", n, len(res), err)
	}
}

func TestSequenceAndDestroyWire(t *testing.T) {
	id := MakeSessionID([8]byte{9, 9, 9, 9, 9, 9, 9, 9}, 42)
	arg := AppendSequenceArgs(nil, id, 5, 1, 7, true)
	a, err := DecodeSequenceArgs(xdr.NewDecoder(arg[4:]))
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if a.SessionID != id || a.Sequence != 5 || a.Slot != 1 ||
		a.HighestSlot != 7 || !a.CacheThis {
		t.Fatalf("args: %+v", a)
	}
	// The result carries exactly the five words after the session id
	// that RFC 7863 fixes: sequence, slot, highest, target, flags.
	res := AppendSequenceRes(nil, id, 5, 1, 7, 0)
	if len(res) != 36 {
		t.Fatalf("sequence result of %d bytes, want 36", len(res))
	}
	if n, err := resBodyLen(OpSequence, ErrOK, res); err != nil || n != 36 {
		t.Fatalf("sequence measure: %d, %v", n, err)
	}
	flags, err := xdr.NewDecoder(res[32:]).Uint32()
	if err != nil || flags != 0 {
		t.Fatalf("sr_status_flags: %d, %v", flags, err)
	}
	sid, seq, slot, high, target, statusFlags, err := DecodeSequenceRes(xdr.NewDecoder(res))
	if err != nil || sid != id || seq != 5 || slot != 1 || high != 7 ||
		target != 7 || statusFlags != 0 {
		t.Fatalf("decode res: %d %d %d %d %d %d, %v", seq, slot, high, target, statusFlags, 0, err)
	}

	destroy := AppendDestroySessionArgs(nil, id)
	d := xdr.NewDecoder(destroy)
	if op, err := d.Uint32(); err != nil || op != OpDestroySession {
		t.Fatalf("destroy op: %d, %v", op, err)
	}
	if raw, err := d.Raw(16); err != nil || !bytes.Equal(raw, id[:]) {
		t.Fatalf("destroy id: %x, %v", raw, err)
	}
}

func TestExchangeIDImplArray(t *testing.T) {
	// One implementation entry walks exactly its three fields: domain,
	// name and the date, the shape RFC 7863 fixes. A trailing dummy
	// word stays in the stream and is the next operation's business.
	var blob []byte
	blob = append(blob, make([]byte, 8)...)        // verifier
	blob = xdr.AppendVarOpaque(blob, []byte("id")) // owner
	blob = xdr.AppendUint32(blob, 0)               // flags
	blob = xdr.AppendUint32(blob, StateProtectNone)
	blob = xdr.AppendUint32(blob, 1) // one impl entry
	blob = xdr.AppendString(blob, "example.org")
	blob = xdr.AppendString(blob, "probe")
	blob = xdr.AppendUint64(blob, 0) // date seconds
	blob = xdr.AppendUint32(blob, 0) // date nanoseconds

	d := xdr.NewDecoder(blob)
	a, err := DecodeExchangeIDArgs(d)
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if string(a.OwnerID) != "id" || d.Remaining() != 0 {
		t.Fatalf("owner %q, %d bytes left", a.OwnerID, d.Remaining())
	}

	// The word some clients append behind the entry is not consumed by
	// this decoder; the compound walk sees it as the next argop.
	withExtra := append(append([]byte{}, blob...), 0, 0, 0, 0)
	d = xdr.NewDecoder(withExtra)
	if _, err := DecodeExchangeIDArgs(d); err != nil || d.Remaining() != 4 {
		t.Fatalf("decode with extra: %v, %d bytes left", err, d.Remaining())
	}
}

func TestDecodeSessionChannelIrd(t *testing.T) {
	// A channel with the RDMA sizes present walks them all.
	var body []byte
	body = xdr.AppendUint32(body, 0)     // header pad
	body = xdr.AppendUint32(body, 1<<20) // max request
	body = xdr.AppendUint32(body, 1<<20) // max response
	body = xdr.AppendUint32(body, 1<<20) // resourced
	body = xdr.AppendUint32(body, 4)     // max operations
	body = xdr.AppendUint32(body, 2)     // max requests
	body = xdr.AppendUint32(body, 2)     // two rdma ird sizes
	body = xdr.AppendUint32(body, 1)
	body = xdr.AppendUint32(body, 4)

	c, err := DecodeSessionChannel(xdr.NewDecoder(body))
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if !c.RdmaIRDEnabled || len(c.RdmaIRSizes) != 2 || c.RdmaIRSizes[1] != 4 ||
		c.MaxRequests != 2 {
		t.Fatalf("channel: %+v", c)
	}
}

func TestExchangeIDStateProtectReject(t *testing.T) {
	// A state protection other than the plain none is refused with a
	// dedicated error, because this build does not speak RPCSEC_GSS
	// state protection yet.
	var blob []byte
	blob = append(blob, make([]byte, 8)...)
	blob = xdr.AppendVarOpaque(blob, []byte("id"))
	blob = xdr.AppendUint32(blob, 0)
	blob = xdr.AppendUint32(blob, StateProtectMachCred)
	if _, err := DecodeExchangeIDArgs(xdr.NewDecoder(blob)); err == nil {
		t.Fatal("an unsupported state protection decoded")
	}
}

func TestOpenCloseWire(t *testing.T) {
	arg := AppendOpenArgs(nil, 0xfeed, []byte("owner"), ShareAccessBoth, uint32(0),
		true, 0o640, "file.txt")
	d := xdr.NewDecoder(arg)
	if op, err := d.Uint32(); err != nil || op != OpOpen {
		t.Fatalf("op: %d, %v", op, err)
	}
	a, err := DecodeOpenArgs(d)
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if !a.Create || a.Access != ShareAccessBoth || a.Deny != uint32(0) ||
		a.ClientID != 0xfeed || string(a.Owner) != "owner" || a.Perm != 0o640 ||
		a.Name != "file.txt" {
		t.Fatalf("open args: %+v", a)
	}

	// NOCREATE: the create switch is absent.
	arg = AppendOpenArgs(nil, 1, []byte("o"), ShareAccessRead, 0, false, 0, "there.txt")
	a, err = DecodeOpenArgs(xdr.NewDecoder(arg[4:]))
	if err != nil || a.Create || a.Name != "there.txt" {
		t.Fatalf("nocreate args: %+v, %v", a, err)
	}

	res := AppendOpenRes(nil, AllZero)
	if n, err := resBodyLen(OpOpen, ErrOK, res); err != nil || n != len(res) {
		t.Fatalf("open measure: %d of %d, %v", n, len(res), err)
	}

	closeArg := AppendCloseArgs(nil, AllZero)
	d = xdr.NewDecoder(closeArg)
	if op, err := d.Uint32(); err != nil || op != OpClose {
		t.Fatalf("close op: %d, %v", op, err)
	}
	if seqid, err := d.Uint32(); err != nil || seqid != 0 {
		t.Fatalf("close seqid: %d, %v", seqid, err)
	}
	if raw, err := d.Raw(16); err != nil || !bytes.Equal(raw, AllZero[:]) {
		t.Fatalf("close stateid: %x, %v", raw, err)
	}
	closeRes := AppendCloseRes(nil, AllZero)
	if n, err := resBodyLen(OpClose, ErrOK, closeRes); err != nil || n != 16 {
		t.Fatalf("close measure: %d, %v", n, err)
	}
}

func TestOpenDowngradeDestroyReclaimWire(t *testing.T) {
	// OPEN_DOWNGRADE args: seqid, stateid, access, deny.
	arg := AppendOpenDowngradeArgs(nil, AllZero, ShareAccessRead, 0)
	d := xdr.NewDecoder(arg)
	if op, err := d.Uint32(); err != nil || op != OpOpenDowngrade {
		t.Fatalf("op: %d, %v", op, err)
	}
	if seqid, err := d.Uint32(); err != nil || seqid != 0 {
		t.Fatalf("seqid: %d, %v", seqid, err)
	}
	if raw, err := d.Raw(16); err != nil || !bytes.Equal(raw, AllZero[:]) {
		t.Fatalf("stateid: %x, %v", raw, err)
	}
	if access, err := d.Uint32(); err != nil || access != ShareAccessRead {
		t.Fatalf("access: %v", err)
	}
	if deny, err := d.Uint32(); err != nil || deny != 0 {
		t.Fatalf("deny: %v", err)
	}
	dgRes := AppendOpenDowngradeRes(nil)
	if n, err := resBodyLen(OpOpenDowngrade, ErrOK, dgRes); err != nil || n != 20 {
		t.Fatalf("downgrade measure: %d, %v", n, err)
	}

	// DESTROY_CLIENTID args and its empty result body.
	dc := AppendDestroyClientIDArgs(nil, 0x1234)
	d = xdr.NewDecoder(dc)
	if op, err := d.Uint32(); err != nil || op != OpDestroyClientID {
		t.Fatalf("destroy op: %d, %v", op, err)
	}
	if cid, err := d.Uint64(); err != nil || cid != 0x1234 {
		t.Fatalf("clientid: %v", err)
	}
	if n, err := resBodyLen(OpDestroyClientID, ErrOK, nil); err != nil || n != 0 {
		t.Fatalf("destroy measure: %d, %v", n, err)
	}

	// RECLAIM_COMPLETE args: the one client flag alone, RFC 7863.
	rc := AppendReclaimCompleteArgs(nil, false)
	d = xdr.NewDecoder(rc)
	if op, err := d.Uint32(); err != nil || op != OpReclaimComplete {
		t.Fatalf("op: %d, %v", op, err)
	}
	if one, err := d.Bool(); err != nil || one {
		t.Fatalf("one_client: %v", err)
	}
	if d.Remaining() != 0 {
		t.Fatalf("%d bytes left in the reclaim args", d.Remaining())
	}
	if n, err := resBodyLen(OpReclaimComplete, ErrOK, nil); err != nil || n != 0 {
		t.Fatalf("reclaim measure: %d, %v", n, err)
	}
}

func TestAppendOpenResDelegLength(t *testing.T) {
	// The write delegation carries the space limit union and the
	// permissions ace on top of the read form, RFC 7863: the whole
	// successful OPEN result measures 96 bytes with one.
	var st Stateid
	st[0] = 1
	res := AppendOpenResDeleg(nil, st, OpenDelegWrite, st)
	if len(res) != 96 {
		t.Fatalf("res %d bytes, want 96", len(res))
	}
	// The read form ends after the ace: 84 bytes.
	res = AppendOpenResDeleg(nil, st, OpenDelegRead, st)
	if len(res) != 84 {
		t.Fatalf("read res %d bytes, want 84", len(res))
	}
	if _, _, _, err := DecodeOpenResDeleg(res); err != nil {
		t.Fatalf("read round trip: %v", err)
	}
}