package upgrader_test

import (
	"context"
	"crypto/rand"
	"errors"
	"net"
	"testing"

	"github.com/libp2p/go-libp2p/core/connmgr"
	"github.com/libp2p/go-libp2p/core/crypto"
	"github.com/libp2p/go-libp2p/core/network"
	mocknetwork "github.com/libp2p/go-libp2p/core/network/mocks"
	"github.com/libp2p/go-libp2p/core/peer"
	"github.com/libp2p/go-libp2p/core/sec"
	"github.com/libp2p/go-libp2p/core/sec/insecure"
	"github.com/libp2p/go-libp2p/core/transport"
	"github.com/libp2p/go-libp2p/p2p/muxer/yamux"
	"github.com/libp2p/go-libp2p/p2p/net/upgrader"

	"github.com/golang/mock/gomock"
	ma "github.com/multiformats/go-multiaddr"
	manet "github.com/multiformats/go-multiaddr/net"
	"github.com/stretchr/testify/require"
)

func createUpgrader(t *testing.T) (peer.ID, transport.Upgrader) {
	return createUpgraderWithMuxers(t, []upgrader.StreamMuxer{{ID: "negotiate", Muxer: &negotiatingMuxer{}}}, nil, nil)
}

func createUpgraderWithConnGater(t *testing.T, connGater connmgr.ConnectionGater) (peer.ID, transport.Upgrader) {
	return createUpgraderWithMuxers(t, []upgrader.StreamMuxer{{ID: "negotiate", Muxer: &negotiatingMuxer{}}}, nil, connGater)
}

func createUpgraderWithResourceManager(t *testing.T, rcmgr network.ResourceManager) (peer.ID, transport.Upgrader) {
	return createUpgraderWithMuxers(t, []upgrader.StreamMuxer{{ID: "negotiate", Muxer: &negotiatingMuxer{}}}, rcmgr, nil)
}

func createUpgraderWithOpts(t *testing.T, opts ...upgrader.Option) (peer.ID, transport.Upgrader) {
	return createUpgraderWithMuxers(t, []upgrader.StreamMuxer{{ID: "negotiate", Muxer: &negotiatingMuxer{}}}, nil, nil, opts...)
}

func newPeer(t *testing.T) (peer.ID, crypto.PrivKey) {
	t.Helper()
	priv, _, err := crypto.GenerateEd25519Key(rand.Reader)
	require.NoError(t, err)
	id, err := peer.IDFromPrivateKey(priv)
	require.NoError(t, err)
	return id, priv
}

func createUpgraderWithMuxers(t *testing.T, muxers []upgrader.StreamMuxer, rcmgr network.ResourceManager, connGater connmgr.ConnectionGater, opts ...upgrader.Option) (peer.ID, transport.Upgrader) {
	id, priv := newPeer(t)
	u, err := upgrader.New([]sec.SecureTransport{insecure.NewWithIdentity(insecure.ID, id, priv)}, muxers, nil, rcmgr, connGater, opts...)
	require.NoError(t, err)
	return id, u
}

// negotiatingMuxer sets up a new yamux connection
// It makes sure that this happens at the same time for client and server.
type negotiatingMuxer struct{}

func (m *negotiatingMuxer) NewConn(c net.Conn, isServer bool, scope network.PeerScope) (network.MuxedConn, error) {
	var err error
	// run a fake muxer negotiation
	if isServer {
		_, err = c.Write([]byte("setup"))
	} else {
		_, err = c.Read(make([]byte, 5))
	}
	if err != nil {
		return nil, err
	}
	return yamux.DefaultTransport.NewConn(c, isServer, scope)
}

// blockingMuxer blocks the muxer negotiation until the contained chan is closed
type blockingMuxer struct {
	unblock chan struct{}
}

var _ network.Multiplexer = &blockingMuxer{}

func newBlockingMuxer() *blockingMuxer {
	return &blockingMuxer{unblock: make(chan struct{})}
}

func (m *blockingMuxer) NewConn(c net.Conn, isServer bool, scope network.PeerScope) (network.MuxedConn, error) {
	<-m.unblock
	return (&negotiatingMuxer{}).NewConn(c, isServer, scope)
}

func (m *blockingMuxer) Unblock() {
	close(m.unblock)
}

// errorMuxer is a muxer that errors while setting up
type errorMuxer struct{}

var _ network.Multiplexer = &errorMuxer{}

func (m *errorMuxer) NewConn(c net.Conn, isServer bool, scope network.PeerScope) (network.MuxedConn, error) {
	return nil, errors.New("mux error")
}

func testConn(t *testing.T, clientConn, serverConn transport.CapableConn) {
	t.Helper()
	require := require.New(t)

	cstr, err := clientConn.OpenStream(context.Background())
	require.NoError(err)

	_, err = cstr.Write([]byte("foobar"))
	require.NoError(err)

	sstr, err := serverConn.AcceptStream()
	require.NoError(err)

	b := make([]byte, 6)
	_, err = sstr.Read(b)
	require.NoError(err)
	require.Equal([]byte("foobar"), b)
}

func dial(t *testing.T, upgrader transport.Upgrader, raddr ma.Multiaddr, p peer.ID, scope network.ConnManagementScope) (transport.CapableConn, error) {
	t.Helper()

	macon, err := manet.Dial(raddr)
	if err != nil {
		return nil, err
	}
	return upgrader.Upgrade(context.Background(), nil, macon, network.DirOutbound, p, scope)
}

func TestOutboundConnectionGating(t *testing.T) {
	require := require.New(t)

	id, u := createUpgrader(t)
	ln := createListener(t, u)
	defer ln.Close()

	testGater := &testGater{}
	_, dialUpgrader := createUpgraderWithConnGater(t, testGater)
	conn, err := dial(t, dialUpgrader, ln.Multiaddr(), id, &network.NullScope{})
	require.NoError(err)
	require.NotNil(conn)
	_ = conn.Close()

	// blocking accepts doesn't affect the dialling side, only the listener.
	testGater.BlockAccept(true)
	conn, err = dial(t, dialUpgrader, ln.Multiaddr(), id, &network.NullScope{})
	require.NoError(err)
	require.NotNil(conn)
	_ = conn.Close()

	// now let's block all connections after being secured.
	testGater.BlockSecured(true)
	conn, err = dial(t, dialUpgrader, ln.Multiaddr(), id, &network.NullScope{})
	require.Error(err)
	require.Contains(err.Error(), "gater rejected connection")
	require.Nil(conn)
}

func TestOutboundResourceManagement(t *testing.T) {
	t.Run("successful handshake", func(t *testing.T) {
		id, upgrader := createUpgrader(t)
		ln := createListener(t, upgrader)
		defer ln.Close()

		ctrl := gomock.NewController(t)
		defer ctrl.Finish()
		connScope := mocknetwork.NewMockConnManagementScope(ctrl)
		gomock.InOrder(
			connScope.EXPECT().PeerScope(),
			connScope.EXPECT().SetPeer(id),
			connScope.EXPECT().PeerScope().Return(&network.NullScope{}),
		)
		_, dialUpgrader := createUpgrader(t)
		conn, err := dial(t, dialUpgrader, ln.Multiaddr(), id, connScope)
		require.NoError(t, err)
		require.NotNil(t, conn)
		connScope.EXPECT().Done()
		require.NoError(t, conn.Close())
	})

	t.Run("failed negotiation", func(t *testing.T) {
		id, upgrader := createUpgraderWithMuxers(t, []upgrader.StreamMuxer{{ID: "errorMuxer", Muxer: &errorMuxer{}}}, nil, nil)
		ln := createListener(t, upgrader)
		defer ln.Close()

		ctrl := gomock.NewController(t)
		defer ctrl.Finish()
		connScope := mocknetwork.NewMockConnManagementScope(ctrl)
		gomock.InOrder(
			connScope.EXPECT().PeerScope(),
			connScope.EXPECT().SetPeer(id),
			connScope.EXPECT().PeerScope().Return(&network.NullScope{}),
			connScope.EXPECT().Done(),
		)
		_, dialUpgrader := createUpgrader(t)
		_, err := dial(t, dialUpgrader, ln.Multiaddr(), id, connScope)
		require.Error(t, err)
	})
}