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

package nfsclient_test

import (
	"net"
	"os"
	"path/filepath"
	"testing"
	"time"

	"sourcedock.dev/petrbalvin/nfs/internal/nfs4"
	"sourcedock.dev/petrbalvin/nfs/internal/nfs4server"
	"sourcedock.dev/petrbalvin/nfs/internal/nfsclient"
	"sourcedock.dev/petrbalvin/nfs/internal/nfsfs"
	"sourcedock.dev/petrbalvin/nfs/internal/rpc"
	"sourcedock.dev/petrbalvin/nfs/internal/server"
	"sourcedock.dev/petrbalvin/nfs/internal/xdr"
)

// startServer runs the full stack, the TCP listener, the connection
// skeleton, the dispatcher and the local backend, on an ephemeral port.
func startServer(t *testing.T) *nfsclient.Client {
	t.Helper()
	root := t.TempDir()
	if err := os.WriteFile(filepath.Join(root, "hello.txt"), []byte("hello over the wire"), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.Mkdir(filepath.Join(root, "dir"), 0o755); err != nil {
		t.Fatal(err)
	}
	backend, err := nfsfs.NewLocal(root)
	if err != nil {
		t.Fatalf("backend: %v", err)
	}
	handler := &nfs4server.Handler{FS: backend}
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("listen: %v", err)
	}
	srv := &server.Server{Handle: handler.HandleConn}
	go srv.Serve(t.Context(), listener)

	c, err := nfsclient.Dial(listener.Addr().String())
	if err != nil {
		t.Fatalf("dial: %v", err)
	}
	if err := c.Establish("probe-client"); err != nil {
		t.Fatalf("establish: %v", err)
	}
	t.Cleanup(func() { c.Close(); listener.Close() })
	return c
}

func TestNullPingOverTCP(t *testing.T) {
	c := startServer(t)
	if err := c.Null(); err != nil {
		t.Fatalf("null: %v", err)
	}
}

func TestCompoundRoundTripOverTCP(t *testing.T) {
	c := startServer(t)
	ops := [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "hello.txt"),
		nfs4.AppendGetfh(nil),
		nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrType, nfs4.AttrSize, nfs4.AttrMode)),
		nfs4.AppendRead(nil, nfs4.AllZero, 0, 1024),
	}
	res, bodies, err := c.Compound("wire", ops)
	if err != nil {
		t.Fatalf("compound: %v", err)
	}
	if res.Status != nfs4.ErrOK || len(res.Ops) != 5 {
		t.Fatalf("status %d ops %d", res.Status, len(res.Ops))
	}
	_, attrs, err := nfs4.DecodeGetattrBody(bodies[3])
	if err != nil {
		t.Fatalf("getattr: %v", err)
	}
	if attrs.Type != nfs4.NF4Reg || attrs.Size != 19 {
		t.Fatalf("attrs: type %d size %d", attrs.Type, attrs.Size)
	}
	eof, data, err := nfs4.DecodeReadBody(bodies[4])
	if err != nil || !eof || string(data) != "hello over the wire" {
		t.Fatalf("read: %q eof %v, %v", data, eof, err)
	}
}

func TestUnknownProgramAndProcedure(t *testing.T) {
	c := startServer(t)
	// An unknown procedure is answered at the RPC layer with PROC_UNAVAIL.
	status, err := c.Procedure(999)
	if err != nil {
		t.Fatalf("procedure 999: %v", err)
	}
	if status != rpc.AcceptProcUnavail {
		t.Fatalf("procedure 999 answered with status %d", status)
	}
}

func TestRejectedOperationOverTCP(t *testing.T) {
	c := startServer(t)
	ops := [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "nope"),
	}
	res, _, err := c.Compound("miss", ops)
	if err != nil {
		t.Fatalf("compound: %v", err)
	}
	if res.Status != nfs4.ErrNoEnt {
		t.Fatalf("status %d, want NFS4ERR_NOENT", res.Status)
	}
}

func TestCreateAndWriteOverTCP(t *testing.T) {
	c := startServer(t)

	// Make a directory over the wire, then a file inside it would come
	// from OPEN, so the test writes into the file the fixture seeded by
	// creating one directly in the tree the backend serves.
	res, _, err := c.Compound("made-over-the-wire", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendCreateArgs(nil, nfs4.NF4Dir, "made-over-the-wire", "", 0, 0,
			0o755),
		nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrType, nfs4.AttrMode)),
	})
	if err != nil {
		t.Fatalf("create compound: %v", err)
	}
	if res.Status != nfs4.ErrOK {
		t.Fatalf("create status %d", res.Status)
	}
	_, attrs, err := nfs4.DecodeGetattrBody(res.Ops[2].Body)
	if err != nil || attrs.Type != nfs4.NF4Dir || attrs.Mode != 0o755 {
		t.Fatalf("created dir: %+v, %v", attrs, err)
	}

	// Write into the seeded file and read back through a fresh session of
	// COMPOUNDs.
	res, _, err = c.Compound("write", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "hello.txt"),
		nfs4.AppendWriteArgs(nil, nfs4.AllZero, 0, nfs4.StableUnstable, []byte("WRITTEN OVER TCP")),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("write compound: status %d, %v", res.Status, err)
	}
	count, committed, verf, err := nfs4.DecodeWriteRes(res.Ops[2].Body)
	if err != nil || count != 16 || committed != nfs4.StableFileSync || verf == ([8]byte{}) {
		t.Fatalf("write res: %d %d %x, %v", count, committed, verf, err)
	}

	res, _, err = c.Compound("read", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "hello.txt"),
		nfs4.AppendRead(nil, nfs4.AllZero, 0, 1024),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("read compound: status %d, %v", res.Status, err)
	}
	eof, data, err := nfs4.DecodeReadBody(res.Ops[2].Body)
	// The write replaced the head of the seeded file; its tail survives.
	if err != nil || !eof || string(data) != "WRITTEN OVER TCPire" {
		t.Fatalf("read after write: %q eof %v, %v", data, eof, err)
	}
}

func TestRemoveAndRenameOverTCP(t *testing.T) {
	c := startServer(t)

	// Rename over the wire with the SAVEFH setup: the source directory in
	// the saved handle, the target directory as the current one.
	res, _, err := c.Compound("rename", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendSavefh(nil),
		nfs4.AppendLookup(nil, "dir"),
		nfs4.AppendRenameArgs(nil, "hello.txt", "moved.txt"),
	})
	if err != nil {
		t.Fatalf("rename compound: %v", err)
	}
	if res.Status != nfs4.ErrOK || len(res.Ops) != 4 {
		t.Fatalf("rename status %d ops %d", res.Status, len(res.Ops))
	}

	// The old name is gone and the new one answers.
	res, _, err = c.Compound("old-name", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "hello.txt"),
	})
	if err != nil {
		t.Fatalf("old name compound: %v", err)
	}
	if res.Status != nfs4.ErrNoEnt {
		t.Fatalf("the old name survived: status %d", res.Status)
	}
	res, _, err = c.Compound("present", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "dir"),
		nfs4.AppendLookup(nil, "moved.txt"),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("the moved file is not under dir: status %d, %v", res.Status, err)
	}

	// REMOVE clears the entry from its directory.
	res, _, err = c.Compound("remove", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "dir"),
		nfs4.AppendRemoveArgs(nil, "moved.txt"),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("remove: status %d, %v", res.Status, err)
	}
	res, _, err = c.Compound("gone", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "dir"),
		nfs4.AppendLookup(nil, "moved.txt"),
	})
	if err != nil {
		t.Fatalf("gone compound: %v", err)
	}
	if res.Status != nfs4.ErrNoEnt || len(res.Ops) != 3 {
		t.Fatalf("gone: status %d ops %d", res.Status, len(res.Ops))
	}
	if res.Ops[2].Status != nfs4.ErrNoEnt {
		t.Fatalf("lookup after remove status %d", res.Ops[2].Status)
	}
}

func TestSetattrAndLinkOverTCP(t *testing.T) {
	c := startServer(t)

	// SETATTR mode and size over the wire, then read back through the
	// same handle the server kept current.
	res, _, err := c.Compound("setattr", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "hello.txt"),
		nfs4.AppendGetfh(nil),
		nfs4.AppendSetattrArgs(nil, nfs4.AllZero,
			nfs4.OfBits(nfs4.AttrMode, nfs4.AttrSize),
			nfs4.Attrs{Mode: 0o600, Size: 5}),
		nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrMode, nfs4.AttrSize)),
	})
	if err != nil {
		t.Fatalf("setattr compound: %v", err)
	}
	if res.Status != nfs4.ErrOK || len(res.Ops) != 5 {
		t.Fatalf("setattr: status %d ops %d", res.Status, len(res.Ops))
	}
	_, attrs, err := nfs4.DecodeGetattrBody(res.Ops[4].Body)
	if err != nil || attrs.Mode != 0o600 || attrs.Size != 5 {
		t.Fatalf("after setattr: %+v, %v", attrs, err)
	}

	// LINK with the saved handle pointing at the file: the link lands in
	// the directory that is current.
	res, _, err = c.Compound("link", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "hello.txt"),
		nfs4.AppendSavefh(nil),
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLinkArgs(nil, "hard.txt"),
		nfs4.AppendRestorefh(nil),
		nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrNumlinks)),
	})
	if err != nil {
		t.Fatalf("link compound: %v", err)
	}
	if res.Status != nfs4.ErrOK || len(res.Ops) != 7 {
		t.Fatalf("link: status %d ops %d", res.Status, len(res.Ops))
	}
	_, attrs, err = nfs4.DecodeGetattrBody(res.Ops[6].Body)
	if err != nil || attrs.Numlinks != 2 {
		t.Fatalf("link count: %d, %v", attrs.Numlinks, err)
	}
}

func TestReadlinkAndCommitOverTCP(t *testing.T) {
	c := startServer(t)

	// Create a symlink over the wire, then read it back.
	res, _, err := c.Compound("mklink", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendCreateArgs(nil, nfs4.NF4Lnk, "wire-link", "hello.txt", 0, 0,
			0o644),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("create symlink: status %d, %v", res.Status, err)
	}
	res, _, err = c.Compound("readlink", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "wire-link"),
		nfs4.AppendReadlinkArgs(nil),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("readlink: status %d, %v", res.Status, err)
	}
	target, err := xdr.NewDecoder(res.Ops[2].Body).String()
	if err != nil || target != "hello.txt" {
		t.Fatalf("readlink target: %q, %v", target, err)
	}

	// COMMIT of the written file answers with the server verifier.
	res, _, err = c.Compound("commit", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "hello.txt"),
		nfs4.AppendCommitArgs(nil, 0, 0, [8]byte{}),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("commit: status %d, %v", res.Status, err)
	}
	verf, err := xdr.NewDecoder(res.Ops[2].Body).Raw(8)
	if err != nil {
		t.Fatalf("commit body: %v", err)
	}
	if string(verf) == string(make([]byte, 8)) {
		t.Fatal("the commit verifier is zero")
	}
}

func TestSecinfoNoNameOverTCP(t *testing.T) {
	c := startServer(t)

	// The shape a Linux client uses: LOOKUP of the component it wants to
	// mount, then SECINFO_NO_NAME for the current component.
	res, _, err := c.Compound("secinfo", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "dir"),
		nfs4.AppendSecinfoNoNameArgs(nil, nfs4.StyleCurrentFH),
	})
	if err != nil {
		t.Fatalf("secinfo compound: %v", err)
	}
	if res.Status != nfs4.ErrOK || len(res.Ops) != 3 {
		t.Fatalf("secinfo: status %d ops %d", res.Status, len(res.Ops))
	}
	entries, err := nfs4.DecodeSecinfoRes(res.Ops[2].Body)
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if len(entries) != 1 || entries[0].Flavor != nfs4.SecFlavorSys {
		t.Fatalf("secinfo entries: %+v", entries)
	}
}

func TestOpenWriteCloseOverTCP(t *testing.T) {
	c := startServer(t)
	if err := c.Establish("integration-client"); err != nil {
		t.Fatalf("establish: %v", err)
	}

	// OPEN with create, WRITE under the open stateid, CLOSE.
	res, _, err := c.Compound("open", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendOpenArgs(nil, 0x7777, []byte("owner"), nfs4.ShareAccessBoth, 0,
			true, 0o644, "opened-over-tcp.txt"),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("open: status %d, %v", res.Status, err)
	}
	var stateid nfs4.Stateid
	copy(stateid[:], res.Ops[1].Body)

	res, _, err = c.Compound("write", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "opened-over-tcp.txt"),
		nfs4.AppendWriteArgs(nil, stateid, 0, nfs4.StableFileSync, []byte("stateful!")),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("write: status %d, %v", res.Status, err)
	}

	res, _, err = c.Compound("close", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "opened-over-tcp.txt"),
		nfs4.AppendCloseArgs(nil, stateid),
	})
	if err != nil || res.Status != nfs4.ErrOK {
		t.Fatalf("close: status %d, %v", res.Status, err)
	}

	// A write after the close is rejected as an old stateid.
	res, _, err = c.Compound("late-write", [][]byte{
		nfs4.AppendPutRootfh(nil),
		nfs4.AppendLookup(nil, "opened-over-tcp.txt"),
		nfs4.AppendWriteArgs(nil, stateid, 0, nfs4.StableFileSync, []byte("x")),
	})
	if err != nil || res.Status != nfs4.ErrOldStateid {
		t.Fatalf("write after close: status %d, %v", res.Status, err)
	}
}

// TestServesCallbackCalls drives a raw CB_COMPOUND from the server side
// of the connection to the client's callback dispatcher and checks the
// recall recording.
func TestServesCallbackCalls(t *testing.T) {
	root := t.TempDir()
	backend, err := nfsfs.NewLocal(root)
	if err != nil {
		t.Fatal(err)
	}
	handler := &nfs4server.Handler{FS: backend}
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	srv := &server.Server{Handle: handler.HandleConn}
	go srv.Serve(t.Context(), ln)

	c, err := nfsclient.Dial(ln.Addr().String())
	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()
	if err := c.Establish("cb-client"); err != nil {
		t.Fatalf("establish: %v", err)
	}
	sid, ok := c.SessionID()
	if !ok {
		t.Fatal("no session")
	}

	// The peer delivers a CB_COMPOUND: CB_SEQUENCE then CB_RECALL of a
	// fake delegation stateid, through the raw send the back channel uses.
	var fake nfs4.Stateid
	fake[0] = 0xde
	probe := [][]byte{
		nfs4.AppendCBRecallArgs(nil, fake, false, []byte{1, 2, 3}),
	}
	if _, _, err := handler.SendCB(sid, "recall", probe); err != nil {
		t.Fatalf("sendCB: %v", err)
	}

	deadline := time.Now().Add(2 * time.Second)
	for time.Now().Before(deadline) {
		if rec := c.Recalled(); len(rec) == 1 && rec[0] == fake {
			return
		}
		time.Sleep(time.Millisecond)
	}
	t.Fatal("the recall never reached the client")
}