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

package nfs4

import (
	"testing"

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

// The numbered session id: the prefix, the number and the client id
// halves, RFC 8881 section 18.36.
func TestMakeNumberedSessionID(t *testing.T) {
	id := MakeNumberedSessionID([4]byte{9, 9, 9, 9}, 0x11223344, 0x5566778899aabbcc)
	if id[0] != 9 || id[3] != 9 {
		t.Fatalf("prefix % x", id[:4])
	}
	if id[4] != 0x11 || id[7] != 0x44 {
		t.Fatalf("number % x", id[4:8])
	}
	if id.ClientIDOf() != 0x5566778899aabbcc {
		t.Fatalf("clientid %x", id.ClientIDOf())
	}
	// Every number mints a distinct id.
	if MakeNumberedSessionID([4]byte{}, 1, 5) == MakeNumberedSessionID([4]byte{}, 2, 5) {
		t.Fatal("two numbers minted the same session id")
	}
}

// NegotiateChannel clamps each value to the smaller of the request and
// the limit and leaves a zero request at zero.
func TestNegotiateChannel(t *testing.T) {
	got := NegotiateChannel(
		ChannelAttrs{MaxRequest: 1 << 30, MaxResponse: 1 << 10, MaxRespResourced: 1 << 10,
			MaxOperations: 64, MaxRequests: 0},
		ChannelAttrs{MaxRequest: 1 << 22, MaxResponse: 1 << 22, MaxRespResourced: 1 << 22,
			MaxOperations: 16, MaxRequests: 8},
	)
	want := ChannelAttrs{MaxRequest: 1 << 22, MaxResponse: 1 << 10, MaxRespResourced: 1 << 10,
		MaxOperations: 16, MaxRequests: 0}
	if got.MaxRequest != want.MaxRequest || got.MaxResponse != want.MaxResponse ||
		got.MaxRespResourced != want.MaxRespResourced || got.MaxOperations != want.MaxOperations ||
		got.MaxRequests != want.MaxRequests {
		t.Fatalf("negotiated %+v, want %+v", got, want)
	}
}

// The EXCLUSIVE4_1 open args round trip: guarded create, verifier
// consumed, mode carried.
func TestOpenArgsExclusive41RoundTrip(t *testing.T) {
	arg := AppendOpenArgsExclusive41(nil, 0x77, []byte("ex"),
		[8]byte{1, 2, 3, 4, 5, 6, 7, 8}, 0o640, "ex41.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.Fatal(err)
	}
	if !a.Create || !a.Guarded || a.Truncate || a.Perm != 0o640 || a.Name != "ex41.txt" ||
		a.ClientID != 0x77 || string(a.Owner) != "ex" {
		t.Fatalf("args %+v", a)
	}
	if d.Remaining() != 0 {
		t.Fatalf("%d bytes left", d.Remaining())
	}
	// The guarded form sets the flag the same way.
	arg = AppendOpenArgs(nil, 1, []byte("o"), ShareAccessRead, 0, true, 0o600, "g.txt")
	if _, err := DecodeOpenArgs(xdr.NewDecoder(arg[4:])); err != nil {
		t.Fatal(err)
	}
}

// The OPEN result measurement walks the write delegation with its space
// limit union and the permissions ace.
func TestResBodyLenOpenDelegations(t *testing.T) {
	var st Stateid
	st[0] = 1
	write := AppendOpenResDeleg(nil, st, OpenDelegWrite, st)
	if n, err := resBodyLen(OpOpen, ErrOK, write); err != nil || n != len(write) {
		t.Fatalf("write deleg measured %d of %d: %v", n, len(write), err)
	}
	read := AppendOpenResDeleg(nil, st, OpenDelegRead, st)
	if n, err := resBodyLen(OpOpen, ErrOK, read); err != nil || n != len(read) {
		t.Fatalf("read deleg measured %d of %d: %v", n, len(read), err)
	}
	none := AppendOpenRes(nil, st)
	if n, err := resBodyLen(OpOpen, ErrOK, none); err != nil || n != len(none) {
		t.Fatalf("no deleg measured %d of %d: %v", n, len(none), err)
	}
	// A truncated body of any of the three fails instead of measuring
	// past the payload.
	for n := 0; n < len(write); n += 4 {
		if _, err := resBodyLen(OpOpen, ErrOK, write[:n]); err == nil {
			t.Fatalf("a %d byte prefix measured cleanly", n)
		}
	}
}