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

package nfs4server

import (
	"testing"

	"sourcedock.dev/petrbalvin/nfs/internal/nfs4"
	"sourcedock.dev/petrbalvin/nfs/internal/nfsfs"
	"sourcedock.dev/petrbalvin/nfs/internal/xdr"
)

// OPENATTR opens the synthetic named attribute directory of a.txt, and
// CREATE, LOOKUP, READ and REMOVE over it map to the object's extended
// attributes, RFC 8881 section 5.3.
func TestNamedAttributes(t *testing.T) {
	h := testTree(t)
	sid, seq := newSession(t, h)
	run := func(s uint32, ops [][]byte) (nfs4.CompoundRes, [][]byte) {
		t.Helper()
		all := append([][]byte{nfs4.AppendSequenceArgs(nil, sid, s, 0, defaultSlots-1, true)}, ops...)
		payload := nfs4.AppendCompoundArgs(nil, "nattr", nfs4.MinorVersion, all)
		body, ok := h.compound(payload, cred{uid: 0, gid: 0})
		if !ok {
			t.Fatal("garbage")
		}
		r, bodies, derr := nfs4.DecodeCompoundResBodies(body)
		if derr != nil {
			t.Fatalf("decode: %v", derr)
		}
		return r, bodies[1:]
	}

	// OPENATTR on a.txt answers the synthetic directory.
	seq++
	res, bodies := run(seq, [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "a.txt"),
		nfs4.AppendOpenattrArgs(nil, false),
		nfs4.AppendGetfh(nil),
	})
	if res.Status != nfs4.ErrOK {
		t.Fatalf("openattr: status %d", res.Status)
	}
	dirHandle, derr := xdrDecoder(bodies[3])
	if derr != nil || len(dirHandle) == 0 {
		t.Fatalf("dir handle: %v", derr)
	}

	// CREATE makes the attribute with its initial size, WRITE fills it.
	seq++
	res, _ = run(seq, [][]byte{
		nfs4.AppendPutfh(nil, dirHandle),
		nfs4.AppendCreateArgs(nil, nfs4.NF4Reg, "user.comment", "", 0, 0,
			0o644),
	})
	wantStatus(t, "nattr create", res.Status, nfs4.ErrOK)
	seq++
	res, bodies = run(seq, [][]byte{
		nfs4.AppendPutfh(nil, dirHandle),
		nfs4.AppendLookup(nil, "user.comment"),
		nfs4.AppendGetfh(nil),
	})
	wantStatus(t, "nattr lookup", res.Status, nfs4.ErrOK)
	fileHandle, derr := xdrDecoder(bodies[2])
	if derr != nil {
		t.Fatal(derr)
	}
	seq++
	res, _ = run(seq, [][]byte{
		nfs4.AppendPutfh(nil, fileHandle),
		nfs4.AppendWriteArgs(nil, nfs4.Stateid{}, 0, nfs4.StableFileSync, []byte("hello")),
	})
	if res.Status != nfs4.ErrOK {
		t.Fatalf("nattr write: status %d", res.Status)
	}
	seq++
	res, bodies = run(seq, [][]byte{
		nfs4.AppendPutfh(nil, fileHandle),
		nfs4.AppendReadArgs(nil, nfs4.Stateid{}, 0, 64),
	})
	if res.Status != nfs4.ErrOK {
		t.Fatalf("nattr read: status %d", res.Status)
	}
	rd := xdr.NewDecoder(bodies[1])
	if eof, rerr := rd.Bool(); rerr != nil || !eof {
		t.Fatalf("eof %v: %v", eof, rerr)
	}
	value, rerr := rd.VarOpaque()
	if rerr != nil || string(value) != "hello" {
		t.Fatalf("value %q: %v", value, rerr)
	}

	// The value is visible through the xattr half of the same object.
	fh := mustLookup(t, h, "a.txt")
	got, gerr := h.FS.(nfsfs.XattrFS).GetXattr(fh, "user.comment", 0)
	if gerr != nil || string(got) != "hello" {
		t.Fatalf("xattr view %q: %v", got, gerr)
	}

	// REMOVE deletes the attribute.
	seq++
	res, _ = run(seq, [][]byte{
		nfs4.AppendPutfh(nil, dirHandle),
		nfs4.AppendRemoveArgs(nil, "user.comment"),
	})
	wantStatus(t, "nattr remove", res.Status, nfs4.ErrOK)
	seq++
	res, _ = run(seq, [][]byte{
		nfs4.AppendPutfh(nil, dirHandle),
		nfs4.AppendLookup(nil, "user.comment"),
	})
	wantStatus(t, "nattr lookup gone", res.Status, nfs4.ErrNoEnt)
}

// xdrDecoder decodes the file handle out of a GETFH result body.
func xdrDecoder(body []byte) ([]byte, error) {
	return xdr.NewDecoder(body).VarOpaque()
}