package coordinator

import (
	"context"
	"errors"
	"io"
	"net"
	"sync"
	"testing"

	"github.com/edgelesssys/constellation/cli/file"
	"github.com/edgelesssys/constellation/coordinator/atls"
	"github.com/edgelesssys/constellation/coordinator/attestation/simulator"
	"github.com/edgelesssys/constellation/coordinator/core"
	"github.com/edgelesssys/constellation/coordinator/peer"
	"github.com/edgelesssys/constellation/coordinator/pubapi"
	"github.com/edgelesssys/constellation/coordinator/pubapi/pubproto"
	"github.com/edgelesssys/constellation/coordinator/state"
	"github.com/edgelesssys/constellation/coordinator/store"
	"github.com/edgelesssys/constellation/coordinator/util/grpcutil"
	"github.com/edgelesssys/constellation/coordinator/util/testdialer"
	"github.com/edgelesssys/constellation/coordinator/vpnapi"
	"github.com/edgelesssys/constellation/coordinator/vpnapi/vpnproto"
	kms "github.com/edgelesssys/constellation/kms/server/setup"
	"github.com/spf13/afero"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.uber.org/goleak"
	"go.uber.org/zap"
	"go.uber.org/zap/zaptest"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
)

func TestMain(m *testing.M) {
	goleak.VerifyTestMain(m,
		// https://github.com/census-instrumentation/opencensus-go/issues/1262
		goleak.IgnoreTopFunction("go.opencensus.io/stats/view.(*worker).start"),
	)
}

// TestCoordinator tests the integration of packages core, pubapi, and vpnapi. It activates
// a coordinator and some nodes and (virtually) sends a packet over the fake VPN.
func TestCoordinator(t *testing.T) {
	assert := assert.New(t)
	require := require.New(t)

	nodeIPs := []string{"192.0.2.11", "192.0.2.12", "192.0.2.13"}
	coordinatorIP := "192.0.2.1"
	bindPort := "9000"
	logger := zaptest.NewLogger(t)
	dialer := testdialer.NewBufconnDialer()
	netw := newNetwork()

	// spawn 4 peers: 1 designated coordinator and 3 nodes
	coordServer, coordPAPI, _ := spawnPeer(require, logger.Named("coord"), dialer, netw, net.JoinHostPort(coordinatorIP, bindPort))
	defer coordPAPI.Close()
	defer coordServer.GracefulStop()
	nodeServer1, nodePAPI1, nodeVPN1 := spawnPeer(require, logger.Named("node1"), dialer, netw, net.JoinHostPort(nodeIPs[0], bindPort))
	defer nodePAPI1.Close()
	defer nodeServer1.GracefulStop()
	nodeServer2, nodePAPI2, nodeVPN2 := spawnPeer(require, logger.Named("node2"), dialer, netw, net.JoinHostPort(nodeIPs[1], bindPort))
	defer nodePAPI2.Close()
	defer nodeServer2.GracefulStop()
	nodeServer3, nodePAPI3, nodeVPN3 := spawnPeer(require, logger.Named("node3"), dialer, netw, net.JoinHostPort(nodeIPs[2], bindPort))
	defer nodePAPI3.Close()
	defer nodeServer3.GracefulStop()

	require.NoError(activateCoordinator(require, dialer, coordinatorIP, bindPort, nodeIPs))

	// send something from node 1 to node 2

	nodeIP1, err := nodeVPN1.GetInterfaceIP()
	require.NoError(err)
	nodeIP2, err := nodeVPN2.GetInterfaceIP()
	require.NoError(err)
	assert.NotEqual(nodeIP1, nodeIP2)

	nodeVPN1.send(nodeIP2, "foo")
	assert.Nil(nodeVPN3.recv())
	pa := nodeVPN2.recv()
	require.NotNil(pa)
	assert.Equal(nodeIP1, pa.src)
	assert.Equal("foo", pa.data)
}

// TestConcurrent is supposed to detect data races when run with -race.
func TestConcurrent(t *testing.T) {
	assert := assert.New(t)
	require := require.New(t)

	nodeIPs := []string{"192.0.2.11", "192.0.2.12"}
	coordinatorIP := "192.0.2.1"
	bindPort := "9000"
	logger := zaptest.NewLogger(t)
	dialer := testdialer.NewBufconnDialer()
	netw := newNetwork()

	// spawn peers
	coordServer, coordPAPI, _ := spawnPeer(require, logger.Named("coord"), dialer, netw, net.JoinHostPort(coordinatorIP, bindPort))
	defer coordPAPI.Close()
	defer coordServer.GracefulStop()
	nodeServer1, nodePAPI1, _ := spawnPeer(require, logger.Named("node1"), dialer, netw, net.JoinHostPort(nodeIPs[0], bindPort))
	defer nodePAPI1.Close()
	defer nodeServer1.GracefulStop()
	nodeServer2, nodePAPI2, _ := spawnPeer(require, logger.Named("node2"), dialer, netw, net.JoinHostPort(nodeIPs[1], bindPort))
	defer nodePAPI2.Close()
	defer nodeServer2.GracefulStop()

	var wg sync.WaitGroup

	// This test is a rather rough check for concurrency errors in the pubapi. To this end, various funcs of the pubapi
	// are called concurrently. As a minimal verification, returned errors are checked.
	// The coverage of this test alone isn't sufficient. Not all funcs of the pubapi are tested, and arguments are constant.
	// In the future, we should have something more sophisticated.

	actCoord := func(retErr chan error) {
		defer wg.Done()
		retErr <- activateCoordinator(require, dialer, coordinatorIP, bindPort, nodeIPs)
	}

	actNode := func(papi *pubapi.API) {
		defer wg.Done()
		// actNode is called on already activated nodes, so this will fail due to wrong state.
		assert.Error(papi.ActivateAsNode(nil))
	}

	updNode := func(papi *pubapi.API, noerr bool) {
		defer wg.Done()
		_, err := papi.TriggerNodeUpdate(context.Background(), &pubproto.TriggerNodeUpdateRequest{})
		if noerr {
			assert.NoError(err)
		}
	}

	getState := func(papi *pubapi.API) {
		defer wg.Done()
		// GetState should always succeed, regardless of what happened to the peer before.
		_, err := papi.GetState(context.Background(), &pubproto.GetStateRequest{})
		assert.NoError(err)
	}

	join := func(papi *pubapi.API) {
		defer wg.Done()
		// For now, we always pass an empty JoinClusterRequest, so JoinCluster
		// is expected to fail even if the peer is in the required state.
		_, err := papi.JoinCluster(context.Background(), &pubproto.JoinClusterRequest{})
		assert.Error(err)
	}

	// activate coordinator and make some other calls concurrently
	wg.Add(16)
	actCoordErrs := make(chan error, 2)
	go actCoord(actCoordErrs)
	go actCoord(actCoordErrs)
	// updNode on unactivated node should fail.
	// updNode on Coordinator should fail.
	// updNode on Node should succeed, but we don't know whether the node is already activated or not, so we can't expect no error.
	go updNode(coordPAPI, false)
	go updNode(coordPAPI, false)
	go updNode(nodePAPI1, false)
	go updNode(nodePAPI1, false)
	go updNode(nodePAPI2, false)
	go updNode(nodePAPI2, false)
	go getState(coordPAPI)
	go getState(coordPAPI)
	go getState(nodePAPI1)
	go getState(nodePAPI1)
	go getState(nodePAPI2)
	go getState(nodePAPI2)
	go join(coordPAPI)
	go join(coordPAPI)
	wg.Wait()
	actCoord1HasErr := <-actCoordErrs != nil
	actCoord2HasErr := <-actCoordErrs != nil
	require.NotEqual(actCoord1HasErr, actCoord2HasErr, "exactly one actCoord call should succeed")

	// make some concurrent calls on the activated peers
	wg.Add(26)
	go actCoord(actCoordErrs)
	go actCoord(actCoordErrs)
	go actNode(coordPAPI)
	go actNode(coordPAPI)
	go actNode(nodePAPI1)
	go actNode(nodePAPI1)
	go actNode(nodePAPI2)
	go actNode(nodePAPI2)
	go updNode(coordPAPI, false)
	go updNode(coordPAPI, false)
	go updNode(nodePAPI1, true)
	go updNode(nodePAPI1, true)
	go updNode(nodePAPI2, true)
	go updNode(nodePAPI2, true)
	go getState(coordPAPI)
	go getState(coordPAPI)
	go getState(nodePAPI1)
	go getState(nodePAPI1)
	go getState(nodePAPI2)
	go getState(nodePAPI2)
	go join(coordPAPI)
	go join(coordPAPI)
	go join(nodePAPI1)
	go join(nodePAPI1)
	go join(nodePAPI2)
	go join(nodePAPI2)
	wg.Wait()
	// One Coordinator is already activated, following both activation calls will fail now.
	assert.Error(<-actCoordErrs)
	assert.Error(<-actCoordErrs)
}

func spawnPeer(require *require.Assertions, logger *zap.Logger, netDialer *testdialer.BufconnDialer, netw *network, endpoint string) (*grpc.Server, *pubapi.API, *fakeVPN) {
	vpn := newVPN(netw, endpoint)
	cor, err := core.NewCore(vpn, &core.ClusterFake{}, &core.ProviderMetadataFake{}, &core.CloudControllerManagerFake{}, &core.CloudNodeManagerFake{}, &core.ClusterAutoscalerFake{}, &core.EncryptedDiskFake{}, logger, simulator.OpenSimulatedTPM, fakeStoreFactory{}, file.NewHandler(afero.NewMemMapFs()))
	require.NoError(err)
	require.NoError(cor.AdvanceState(state.AcceptingInit, nil, nil))

	getPublicAddr := func() (string, error) {
		return "192.0.2.1", nil
	}
	dialer := grpcutil.NewDialer(&core.MockValidator{}, netDialer)
	vapiServer := &fakeVPNAPIServer{logger: logger.Named("vpnapi"), core: cor, dialer: netDialer}

	papi := pubapi.New(logger, cor, dialer, vapiServer, getPublicAddr, nil)

	tlsConfig, err := atls.CreateAttestationServerTLSConfig(&core.MockIssuer{})
	require.NoError(err)
	server := grpc.NewServer(grpc.Creds(credentials.NewTLS(tlsConfig)))
	pubproto.RegisterAPIServer(server, papi)

	listener := netDialer.GetListener(endpoint)
	go server.Serve(listener)

	return server, papi, vpn
}

func activateCoordinator(require *require.Assertions, dialer netDialer, coordinatorIP, bindPort string, nodeIPs []string) error {
	ctx := context.Background()
	conn, err := dialGRPC(ctx, dialer, net.JoinHostPort(coordinatorIP, bindPort))
	require.NoError(err)
	defer conn.Close()

	client := pubproto.NewAPIClient(conn)
	stream, err := client.ActivateAsCoordinator(ctx, &pubproto.ActivateAsCoordinatorRequest{
		NodePublicIps: nodeIPs,
		MasterSecret:  []byte("Constellation"),
		KmsUri:        kms.ClusterKMSURI,
		StorageUri:    kms.NoStoreURI,
	})
	require.NoError(err)

	for {
		_, err := stream.Recv()
		if errors.Is(err, io.EOF) {
			return nil
		}
		if err != nil {
			return err
		}
	}
}

func dialGRPC(ctx context.Context, dialer netDialer, target string) (*grpc.ClientConn, error) {
	tlsConfig, err := atls.CreateAttestationClientTLSConfig([]atls.Validator{&core.MockValidator{}})
	if err != nil {
		return nil, err
	}

	return grpc.DialContext(ctx, target,
		grpc.WithContextDialer(func(ctx context.Context, addr string) (net.Conn, error) {
			return dialer.DialContext(ctx, "tcp", addr)
		}),
		grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)),
	)
}

type fakeStoreFactory struct{}

func (fakeStoreFactory) New() (store.Store, error) {
	return store.NewStdStore(), nil
}

type fakeVPNAPIServer struct {
	logger   *zap.Logger
	core     vpnapi.Core
	dialer   *testdialer.BufconnDialer
	listener net.Listener
	server   *grpc.Server
}

func (v *fakeVPNAPIServer) Listen(endpoint string) error {
	api := vpnapi.New(v.logger, v.core)
	v.server = grpc.NewServer()
	vpnproto.RegisterAPIServer(v.server, api)
	v.listener = v.dialer.GetListener(endpoint)
	return nil
}

func (v *fakeVPNAPIServer) Serve() error {
	return v.server.Serve(v.listener)
}

func (v *fakeVPNAPIServer) Close() {
	if v.server != nil {
		v.server.GracefulStop()
	}
}

type network struct {
	packets map[string][]packet
}

func newNetwork() *network {
	return &network{packets: make(map[string][]packet)}
}

type packet struct {
	src  string
	data string
}

type fakeVPN struct {
	peers       map[string]string // vpnIP -> publicIP
	netw        *network
	publicIP    string
	interfaceIP string
}

func newVPN(netw *network, publicEndpoint string) *fakeVPN {
	publicIP, _, err := net.SplitHostPort(publicEndpoint)
	if err != nil {
		panic(err)
	}
	return &fakeVPN{
		peers:    make(map[string]string),
		netw:     netw,
		publicIP: publicIP,
	}
}

func (*fakeVPN) Setup(privKey []byte) error {
	return nil
}

func (*fakeVPN) GetPrivateKey() ([]byte, error) {
	return nil, nil
}

func (*fakeVPN) GetPublicKey() ([]byte, error) {
	return nil, nil
}

func (v *fakeVPN) GetInterfaceIP() (string, error) {
	return v.interfaceIP, nil
}

func (v *fakeVPN) SetInterfaceIP(ip string) error {
	v.interfaceIP = ip
	return nil
}

func (v *fakeVPN) AddPeer(pubKey []byte, publicIP string, vpnIP string) error {
	v.peers[vpnIP] = publicIP
	return nil
}

func (v *fakeVPN) RemovePeer(pubKey []byte) error {
	panic("dummy")
}

func (v *fakeVPN) UpdatePeers(peers []peer.Peer) error {
	for _, peer := range peers {
		if err := v.AddPeer(peer.VPNPubKey, peer.PublicIP, peer.VPNIP); err != nil {
			return err
		}
	}
	return nil
}

func (v *fakeVPN) send(dst string, data string) {
	pubdst := v.peers[dst]
	packets := v.netw.packets
	packets[pubdst] = append(packets[pubdst], packet{src: v.publicIP, data: data})
}

func (v *fakeVPN) recv() *packet {
	packets := v.netw.packets
	queue := packets[v.publicIP]
	if len(queue) == 0 {
		return nil
	}
	packet := queue[0]
	packets[v.publicIP] = queue[1:]
	for vpnIP, pubIP := range v.peers {
		if pubIP == packet.src {
			packet.src = vpnIP
		}
	}
	return &packet
}

type netDialer interface {
	DialContext(ctx context.Context, network, address string) (net.Conn, error)
}