/*
 *
 * Copyright 2021 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package rls

import (
	"context"
	"crypto/tls"
	"crypto/x509"
	"errors"
	"fmt"
	"io/ioutil"
	"strings"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
	"google.golang.org/grpc"
	"google.golang.org/grpc/balancer"
	"google.golang.org/grpc/balancer/rls/internal/test/e2e"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/internal"
	rlspb "google.golang.org/grpc/internal/proto/grpc_lookup_v1"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/status"
	"google.golang.org/grpc/testdata"
	"google.golang.org/protobuf/proto"
)

// TestControlChannelThrottled tests the case where the adaptive throttler
// indicates that the control channel needs to be throttled.
func (s) TestControlChannelThrottled(t *testing.T) {
	// Start an RLS server and set the throttler to always throttle requests.
	rlsServer, rlsReqCh := setupFakeRLSServer(t, nil)
	overrideAdaptiveThrottler(t, alwaysThrottlingThrottler())

	// Create a control channel to the fake RLS server.
	ctrlCh, err := newControlChannel(rlsServer.Address, "", defaultTestTimeout, balancer.BuildOptions{}, nil)
	if err != nil {
		t.Fatalf("Failed to create control channel to RLS server: %v", err)
	}
	defer ctrlCh.close()

	// Perform the lookup and expect the attempt to be throttled.
	ctrlCh.lookup(nil, rlspb.RouteLookupRequest_REASON_MISS, staleHeaderData, nil)

	select {
	case <-rlsReqCh:
		t.Fatal("RouteLookup RPC invoked when control channel is throtlled")
	case <-time.After(defaultTestShortTimeout):
	}
}

// TestLookupFailure tests the case where the RLS server responds with an error.
func (s) TestLookupFailure(t *testing.T) {
	// Start an RLS server and set the throttler to never throttle requests.
	rlsServer, _ := setupFakeRLSServer(t, nil)
	overrideAdaptiveThrottler(t, neverThrottlingThrottler())

	// Setup the RLS server to respond with errors.
	rlsServer.SetResponseCallback(func(_ context.Context, req *rlspb.RouteLookupRequest) *e2e.RouteLookupResponse {
		return &e2e.RouteLookupResponse{Err: errors.New("rls failure")}
	})

	// Create a control channel to the fake RLS server.
	ctrlCh, err := newControlChannel(rlsServer.Address, "", defaultTestTimeout, balancer.BuildOptions{}, nil)
	if err != nil {
		t.Fatalf("Failed to create control channel to RLS server: %v", err)
	}
	defer ctrlCh.close()

	// Perform the lookup and expect the callback to be invoked with an error.
	errCh := make(chan error, 1)
	ctrlCh.lookup(nil, rlspb.RouteLookupRequest_REASON_MISS, staleHeaderData, func(_ []string, _ string, err error) {
		if err == nil {
			errCh <- errors.New("rlsClient.lookup() succeeded, should have failed")
			return
		}
		errCh <- nil
	})

	select {
	case <-time.After(defaultTestTimeout):
		t.Fatal("timeout when waiting for lookup callback to be invoked")
	case err := <-errCh:
		if err != nil {
			t.Fatal(err)
		}
	}
}

// TestLookupDeadlineExceeded tests the case where the RLS server does not
// respond within the configured rpc timeout.
func (s) TestLookupDeadlineExceeded(t *testing.T) {
	// A unary interceptor which returns a status error with DeadlineExceeded.
	interceptor := func(ctx context.Context, req interface{}, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
		return nil, status.Error(codes.DeadlineExceeded, "deadline exceeded")
	}

	// Start an RLS server and set the throttler to never throttle.
	rlsServer, _ := setupFakeRLSServer(t, nil, grpc.UnaryInterceptor(interceptor))
	overrideAdaptiveThrottler(t, neverThrottlingThrottler())

	// Create a control channel with a small deadline.
	ctrlCh, err := newControlChannel(rlsServer.Address, "", defaultTestShortTimeout, balancer.BuildOptions{}, nil)
	if err != nil {
		t.Fatalf("Failed to create control channel to RLS server: %v", err)
	}
	defer ctrlCh.close()

	// Perform the lookup and expect the callback to be invoked with an error.
	errCh := make(chan error)
	ctrlCh.lookup(nil, rlspb.RouteLookupRequest_REASON_MISS, staleHeaderData, func(_ []string, _ string, err error) {
		if st, ok := status.FromError(err); !ok || st.Code() != codes.DeadlineExceeded {
			errCh <- fmt.Errorf("rlsClient.lookup() returned error: %v, want %v", err, codes.DeadlineExceeded)
			return
		}
		errCh <- nil
	})

	select {
	case <-time.After(defaultTestTimeout):
		t.Fatal("timeout when waiting for lookup callback to be invoked")
	case err := <-errCh:
		if err != nil {
			t.Fatal(err)
		}
	}
}

// testCredsBundle wraps a test call creds and real transport creds.
type testCredsBundle struct {
	transportCreds credentials.TransportCredentials
	callCreds      credentials.PerRPCCredentials
}

func (f *testCredsBundle) TransportCredentials() credentials.TransportCredentials {
	return f.transportCreds
}

func (f *testCredsBundle) PerRPCCredentials() credentials.PerRPCCredentials {
	return f.callCreds
}

func (f *testCredsBundle) NewWithMode(mode string) (credentials.Bundle, error) {
	if mode != internal.CredsBundleModeFallback {
		return nil, fmt.Errorf("unsupported mode: %v", mode)
	}
	return &testCredsBundle{
		transportCreds: f.transportCreds,
		callCreds:      f.callCreds,
	}, nil
}

var (
	// Call creds sent by the testPerRPCCredentials on the client, and verified
	// by an interceptor on the server.
	perRPCCredsData = map[string]string{
		"test-key":     "test-value",
		"test-key-bin": string([]byte{1, 2, 3}),
	}
)

type testPerRPCCredentials struct {
	callCreds map[string]string
}

func (f *testPerRPCCredentials) GetRequestMetadata(context.Context, ...string) (map[string]string, error) {
	return f.callCreds, nil
}

func (f *testPerRPCCredentials) RequireTransportSecurity() bool {
	return true
}

// Unary server interceptor which validates if the RPC contains call credentials
// which match `perRPCCredsData
func callCredsValidatingServerInterceptor(ctx context.Context, req interface{}, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return nil, status.Error(codes.PermissionDenied, "didn't find metadata in context")
	}
	for k, want := range perRPCCredsData {
		got, ok := md[k]
		if !ok {
			return ctx, status.Errorf(codes.PermissionDenied, "didn't find call creds key %v in context", k)
		}
		if got[0] != want {
			return ctx, status.Errorf(codes.PermissionDenied, "for key %v, got value %v, want %v", k, got, want)
		}
	}
	return handler(ctx, req)
}

// makeTLSCreds is a test helper which creates a TLS based transport credentials
// from files specified in the arguments.
func makeTLSCreds(t *testing.T, certPath, keyPath, rootsPath string) credentials.TransportCredentials {
	cert, err := tls.LoadX509KeyPair(testdata.Path(certPath), testdata.Path(keyPath))
	if err != nil {
		t.Fatalf("tls.LoadX509KeyPair(%q, %q) failed: %v", certPath, keyPath, err)
	}
	b, err := ioutil.ReadFile(testdata.Path(rootsPath))
	if err != nil {
		t.Fatalf("ioutil.ReadFile(%q) failed: %v", rootsPath, err)
	}
	roots := x509.NewCertPool()
	if !roots.AppendCertsFromPEM(b) {
		t.Fatal("failed to append certificates")
	}
	return credentials.NewTLS(&tls.Config{
		Certificates: []tls.Certificate{cert},
		RootCAs:      roots,
	})
}

const (
	wantHeaderData  = "headerData"
	staleHeaderData = "staleHeaderData"
)

var (
	keyMap = map[string]string{
		"k1": "v1",
		"k2": "v2",
	}
	wantTargets   = []string{"us_east_1.firestore.googleapis.com"}
	lookupRequest = &rlspb.RouteLookupRequest{
		TargetType:      "grpc",
		KeyMap:          keyMap,
		Reason:          rlspb.RouteLookupRequest_REASON_MISS,
		StaleHeaderData: staleHeaderData,
	}
	lookupResponse = &e2e.RouteLookupResponse{
		Resp: &rlspb.RouteLookupResponse{
			Targets:    wantTargets,
			HeaderData: wantHeaderData,
		},
	}
)

func testControlChannelCredsSuccess(t *testing.T, sopts []grpc.ServerOption, bopts balancer.BuildOptions) {
	// Start an RLS server and set the throttler to never throttle requests.
	rlsServer, _ := setupFakeRLSServer(t, nil, sopts...)
	overrideAdaptiveThrottler(t, neverThrottlingThrottler())

	// Setup the RLS server to respond with a valid response.
	rlsServer.SetResponseCallback(func(_ context.Context, req *rlspb.RouteLookupRequest) *e2e.RouteLookupResponse {
		return lookupResponse
	})

	// Verify that the request received by the RLS matches the expected one.
	rlsServer.SetRequestCallback(func(got *rlspb.RouteLookupRequest) {
		if diff := cmp.Diff(lookupRequest, got, cmp.Comparer(proto.Equal)); diff != "" {
			t.Errorf("RouteLookupRequest diff (-want, +got):\n%s", diff)
		}
	})

	// Create a control channel to the fake server.
	ctrlCh, err := newControlChannel(rlsServer.Address, "", defaultTestTimeout, bopts, nil)
	if err != nil {
		t.Fatalf("Failed to create control channel to RLS server: %v", err)
	}
	defer ctrlCh.close()

	// Perform the lookup and expect a successful callback invocation.
	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	errCh := make(chan error, 1)
	ctrlCh.lookup(keyMap, rlspb.RouteLookupRequest_REASON_MISS, staleHeaderData, func(targets []string, headerData string, err error) {
		if err != nil {
			errCh <- fmt.Errorf("rlsClient.lookup() failed with err: %v", err)
			return
		}
		if !cmp.Equal(targets, wantTargets) || headerData != wantHeaderData {
			errCh <- fmt.Errorf("rlsClient.lookup() = (%v, %s), want (%v, %s)", targets, headerData, wantTargets, wantHeaderData)
			return
		}
		errCh <- nil
	})

	select {
	case <-ctx.Done():
		t.Fatal("timeout when waiting for lookup callback to be invoked")
	case err := <-errCh:
		if err != nil {
			t.Fatal(err)
		}
	}
}

// TestControlChannelCredsSuccess tests creation of the control channel with
// different credentials, which are expected to succeed.
func (s) TestControlChannelCredsSuccess(t *testing.T) {
	serverCreds := makeTLSCreds(t, "x509/server1_cert.pem", "x509/server1_key.pem", "x509/client_ca_cert.pem")
	clientCreds := makeTLSCreds(t, "x509/client1_cert.pem", "x509/client1_key.pem", "x509/server_ca_cert.pem")

	tests := []struct {
		name  string
		sopts []grpc.ServerOption
		bopts balancer.BuildOptions
	}{
		{
			name:  "insecure",
			sopts: nil,
			bopts: balancer.BuildOptions{},
		},
		{
			name:  "transport creds only",
			sopts: []grpc.ServerOption{grpc.Creds(serverCreds)},
			bopts: balancer.BuildOptions{
				DialCreds: clientCreds,
				Authority: "x.test.example.com",
			},
		},
		{
			name: "creds bundle",
			sopts: []grpc.ServerOption{
				grpc.Creds(serverCreds),
				grpc.UnaryInterceptor(callCredsValidatingServerInterceptor),
			},
			bopts: balancer.BuildOptions{
				CredsBundle: &testCredsBundle{
					transportCreds: clientCreds,
					callCreds:      &testPerRPCCredentials{callCreds: perRPCCredsData},
				},
				Authority: "x.test.example.com",
			},
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			testControlChannelCredsSuccess(t, test.sopts, test.bopts)
		})
	}
}

func testControlChannelCredsFailure(t *testing.T, sopts []grpc.ServerOption, bopts balancer.BuildOptions, wantCode codes.Code, wantErr string) {
	// StartFakeRouteLookupServer a fake server.
	//
	// Start an RLS server and set the throttler to never throttle requests. The
	// creds failures happen before the RPC handler on the server is invoked.
	// So, there is need to setup the request and responses on the fake server.
	rlsServer, _ := setupFakeRLSServer(t, nil, sopts...)
	overrideAdaptiveThrottler(t, neverThrottlingThrottler())

	// Create the control channel to the fake server.
	ctrlCh, err := newControlChannel(rlsServer.Address, "", defaultTestTimeout, bopts, nil)
	if err != nil {
		t.Fatalf("Failed to create control channel to RLS server: %v", err)
	}
	defer ctrlCh.close()

	// Perform the lookup and expect the callback to be invoked with an error.
	errCh := make(chan error)
	ctrlCh.lookup(nil, rlspb.RouteLookupRequest_REASON_MISS, staleHeaderData, func(_ []string, _ string, err error) {
		if st, ok := status.FromError(err); !ok || st.Code() != wantCode || !strings.Contains(st.String(), wantErr) {
			errCh <- fmt.Errorf("rlsClient.lookup() returned error: %v, wantCode: %v, wantErr: %s", err, wantCode, wantErr)
			return
		}
		errCh <- nil
	})

	select {
	case <-time.After(defaultTestTimeout):
		t.Fatal("timeout when waiting for lookup callback to be invoked")
	case err := <-errCh:
		if err != nil {
			t.Fatal(err)
		}
	}
}

// TestControlChannelCredsFailure tests creation of the control channel with
// different credentials, which are expected to fail.
func (s) TestControlChannelCredsFailure(t *testing.T) {
	serverCreds := makeTLSCreds(t, "x509/server1_cert.pem", "x509/server1_key.pem", "x509/client_ca_cert.pem")
	clientCreds := makeTLSCreds(t, "x509/client1_cert.pem", "x509/client1_key.pem", "x509/server_ca_cert.pem")

	tests := []struct {
		name     string
		sopts    []grpc.ServerOption
		bopts    balancer.BuildOptions
		wantCode codes.Code
		wantErr  string
	}{
		{
			name:  "transport creds authority mismatch",
			sopts: []grpc.ServerOption{grpc.Creds(serverCreds)},
			bopts: balancer.BuildOptions{
				DialCreds: clientCreds,
				Authority: "authority-mismatch",
			},
			wantCode: codes.Unavailable,
			wantErr:  "transport: authentication handshake failed: x509: certificate is valid for *.test.example.com, not authority-mismatch",
		},
		{
			name:  "transport creds handshake failure",
			sopts: nil, // server expects insecure connection
			bopts: balancer.BuildOptions{
				DialCreds: clientCreds,
				Authority: "x.test.example.com",
			},
			wantCode: codes.Unavailable,
			wantErr:  "transport: authentication handshake failed: tls: first record does not look like a TLS handshake",
		},
		{
			name: "call creds mismatch",
			sopts: []grpc.ServerOption{
				grpc.Creds(serverCreds),
				grpc.UnaryInterceptor(callCredsValidatingServerInterceptor), // server expects call creds
			},
			bopts: balancer.BuildOptions{
				CredsBundle: &testCredsBundle{
					transportCreds: clientCreds,
					callCreds:      &testPerRPCCredentials{}, // sends no call creds
				},
				Authority: "x.test.example.com",
			},
			wantCode: codes.PermissionDenied,
			wantErr:  "didn't find call creds",
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			testControlChannelCredsFailure(t, test.sopts, test.bopts, test.wantCode, test.wantErr)
		})
	}
}

type unsupportedCredsBundle struct {
	credentials.Bundle
}

func (*unsupportedCredsBundle) NewWithMode(mode string) (credentials.Bundle, error) {
	return nil, fmt.Errorf("unsupported mode: %v", mode)
}

// TestNewControlChannelUnsupportedCredsBundle tests the case where the control
// channel is configured with a bundle which does not support the mode we use.
func (s) TestNewControlChannelUnsupportedCredsBundle(t *testing.T) {
	rlsServer, _ := setupFakeRLSServer(t, nil)

	// Create the control channel to the fake server.
	ctrlCh, err := newControlChannel(rlsServer.Address, "", defaultTestTimeout, balancer.BuildOptions{CredsBundle: &unsupportedCredsBundle{}}, nil)
	if err == nil {
		ctrlCh.close()
		t.Fatal("newControlChannel succeeded when expected to fail")
	}
}
