// 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/xdr"
)

// A configured referral answers LOOKUP with a stub, GETATTR with the
// location attributes, and everything that touches the backend with
// NFS4ERR_MOVED, RFC 5661 sections 8.4.2 and 11.9.
func TestReferralAndMoved(t *testing.T) {
	h := testTree(t)
	h.SetReferral("migrated", Referral{
		Servers:  []string{"10.0.0.9.8.1", "10.0.0.9.8.2"},
		RootPath: []string{"exports", "data"},
	})
	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, "ref", 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:]
	}

	// LOOKUP lands on the stub and GETATTR carries the locations.
	seq++
	res, bodies := run(seq, [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "migrated"),
		// The blob carries only the one attribute: attributes encode in
		// numeric order, so the test reads them one call at a time.
		nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrFsLocations)),
	})
	if res.Status != nfs4.ErrOK {
		t.Fatalf("lookup stub: status %d", res.Status)
	}
	ad := xdr.NewDecoder(bodies[2])
	words, aerr := ad.Uint32() // the response bitmap: count then words
	if aerr != nil {
		t.Fatal(aerr)
	}
	if _, rerr := ad.Raw(int(words) * 4); rerr != nil {
		t.Fatal(rerr)
	}
	blob, aerr := ad.VarOpaque()
	if aerr != nil {
		t.Fatal(aerr)
	}
	fsRoot, locations, err := nfs4.DecodeFsLocations(blob)
	if err != nil {
		t.Fatalf("decode fs_locations: %v", err)
	}
	if len(locations) != 1 || len(locations[0].Servers) != 2 ||
		locations[0].Servers[1] != "10.0.0.9.8.2" {
		t.Fatalf("locations %+v", locations)
	}
	if len(fsRoot) != 1 || fsRoot[0] != "" {
		t.Fatalf("fs root %v", fsRoot)
	}

	// A write against the stub is MOVED.
	seq++
	res, _ = run(seq, [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "migrated"),
		nfs4.AppendWriteArgs(nil, nfs4.Stateid{}, 0, nfs4.StableFileSync, []byte("x")),
	})
	if res.Status != nfs4.ErrMoved {
		t.Fatalf("write on stub: status %d, want MOVED", res.Status)
	}

	// The real tree still serves files under their own names.
	seq++
	res, _ = run(seq, [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "a.txt"),
		nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrSize)),
	})
	wantStatus(t, "real file", res.Status, nfs4.ErrOK)
}