/*
 *
 * Copyright 2022 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 xdsclient_test

import (
	"context"
	"encoding/json"
	"fmt"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"github.com/google/uuid"
	"google.golang.org/grpc/internal/testutils"
	"google.golang.org/grpc/internal/testutils/xds/e2e"
	"google.golang.org/grpc/internal/xds/bootstrap"
	xdstestutils "google.golang.org/grpc/internal/xds/testutils"
	"google.golang.org/grpc/internal/xds/xdsclient"
	"google.golang.org/grpc/internal/xds/xdsclient/xdsresource"

	v3clusterpb "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3"
)

const (
	testAuthority1 = "test-authority1"
	testAuthority2 = "test-authority2"
	testAuthority3 = "test-authority3"
)

var (
	// These two resources use `testAuthority1`, which contains an empty server
	// config in the bootstrap file, and therefore will use the default
	// management server.
	authorityTestResourceName11 = xdstestutils.BuildResourceName(xdsresource.ClusterResourceTypeName, testAuthority1, cdsName+"1", nil)
	authorityTestResourceName12 = xdstestutils.BuildResourceName(xdsresource.ClusterResourceTypeName, testAuthority1, cdsName+"2", nil)
	// This resource uses `testAuthority2`, which contains an empty server
	// config in the bootstrap file, and therefore will use the default
	// management server.
	authorityTestResourceName2 = xdstestutils.BuildResourceName(xdsresource.ClusterResourceTypeName, testAuthority2, cdsName+"3", nil)
	// This resource uses `testAuthority3`, which contains a non-empty server
	// config in the bootstrap file, and therefore will use the non-default
	// management server.
	authorityTestResourceName3 = xdstestutils.BuildResourceName(xdsresource.ClusterResourceTypeName, testAuthority3, cdsName+"3", nil)
)

// setupForAuthorityTests spins up two management servers, one to act as the
// default and the other to act as the non-default. It also generates a
// bootstrap configuration with three authorities (the first two pointing to the
// default and the third one pointing to the non-default).
//
// Returns two listeners used by the default and non-default management servers
// respectively, and the xDS client and its close function.
func setupForAuthorityTests(ctx context.Context, t *testing.T) (*testutils.ListenerWrapper, *testutils.ListenerWrapper, xdsclient.XDSClient, func()) {
	// Create listener wrappers which notify on to a channel whenever a new
	// connection is accepted. We use this to track the number of transports
	// used by the xDS client.
	lisDefault := testutils.NewListenerWrapper(t, nil)
	lisNonDefault := testutils.NewListenerWrapper(t, nil)

	// Start a management server to act as the default authority.
	defaultAuthorityServer := e2e.StartManagementServer(t, e2e.ManagementServerOptions{Listener: lisDefault})

	// Start a management server to act as the non-default authority.
	nonDefaultAuthorityServer := e2e.StartManagementServer(t, e2e.ManagementServerOptions{Listener: lisNonDefault})

	// Create a bootstrap configuration with two non-default authorities which
	// have empty server configs, and therefore end up using the default server
	// config, which points to the above management server.
	nodeID := uuid.New().String()
	bootstrapContents, err := bootstrap.NewContentsForTesting(bootstrap.ConfigOptionsForTesting{
		Servers: []byte(fmt.Sprintf(`[{
			"server_uri": %q,
			"channel_creds": [{"type": "insecure"}]
		}]`, defaultAuthorityServer.Address)),
		Node: []byte(fmt.Sprintf(`{"id": "%s"}`, nodeID)),
		Authorities: map[string]json.RawMessage{
			testAuthority1: []byte(`{}`),
			testAuthority2: []byte(`{}`),
			testAuthority3: []byte(fmt.Sprintf(`{
				"xds_servers": [{
					"server_uri": %q,
					"channel_creds": [{"type": "insecure"}]
				}]}`, nonDefaultAuthorityServer.Address)),
		},
	})
	if err != nil {
		t.Fatalf("Failed to create bootstrap configuration: %v", err)
	}
	config, err := bootstrap.NewConfigFromContents(bootstrapContents)
	if err != nil {
		t.Fatalf("Failed to parse bootstrap contents: %s, %v", string(bootstrapContents), err)
	}
	pool := xdsclient.NewPool(config)
	client, close, err := pool.NewClientForTesting(xdsclient.OptionsForTesting{
		Name:               t.Name(),
		WatchExpiryTimeout: defaultTestWatchExpiryTimeout,
	})
	if err != nil {
		t.Fatalf("Failed to create an xDS client: %v", err)
	}

	resources := e2e.UpdateOptions{
		NodeID: nodeID,
		Clusters: []*v3clusterpb.Cluster{
			e2e.DefaultCluster(authorityTestResourceName11, edsName, e2e.SecurityLevelNone),
			e2e.DefaultCluster(authorityTestResourceName12, edsName, e2e.SecurityLevelNone),
			e2e.DefaultCluster(authorityTestResourceName2, edsName, e2e.SecurityLevelNone),
			e2e.DefaultCluster(authorityTestResourceName3, edsName, e2e.SecurityLevelNone),
		},
		SkipValidation: true,
	}
	if err := defaultAuthorityServer.Update(ctx, resources); err != nil {
		t.Fatalf("Failed to update management server with resources: %v, err: %v", resources, err)
	}
	return lisDefault, lisNonDefault, client, close
}

// Tests the xdsChannel sharing logic among authorities. The test verifies the
// following scenarios:
//   - A watch for a resource name with an authority matching an existing watch
//     should not result in a new transport being created.
//   - A watch for a resource name with different authority name but same
//     authority config as an existing watch should not result in a new transport
//     being created.
func (s) TestAuthority_XDSChannelSharing(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	lis, _, client, close := setupForAuthorityTests(ctx, t)
	defer close()

	// Verify that no connection is established to the management server at this
	// point. A transport is created only when a resource (which belongs to that
	// authority) is requested.
	sCtx, sCancel := context.WithTimeout(ctx, defaultTestShortTimeout)
	defer sCancel()
	if _, err := lis.NewConnCh.Receive(sCtx); err != context.DeadlineExceeded {
		t.Fatal("Unexpected new transport created to management server")
	}

	// Request the first resource. Verify that a new transport is created.
	watcher := noopClusterWatcher{}
	cdsCancel1 := xdsresource.WatchCluster(client, authorityTestResourceName11, watcher)
	defer cdsCancel1()
	if _, err := lis.NewConnCh.Receive(ctx); err != nil {
		t.Fatalf("Timed out when waiting for a new transport to be created to the management server: %v", err)
	}

	// Request the second resource. Verify that no new transport is created.
	cdsCancel2 := xdsresource.WatchCluster(client, authorityTestResourceName12, watcher)
	defer cdsCancel2()
	sCtx, sCancel = context.WithTimeout(ctx, defaultTestShortTimeout)
	defer sCancel()
	if _, err := lis.NewConnCh.Receive(sCtx); err != context.DeadlineExceeded {
		t.Fatal("Unexpected new transport created to management server")
	}

	// Request the third resource. Verify that no new transport is created.
	cdsCancel3 := xdsresource.WatchCluster(client, authorityTestResourceName2, watcher)
	defer cdsCancel3()
	sCtx, sCancel = context.WithTimeout(ctx, defaultTestShortTimeout)
	defer sCancel()
	if _, err := lis.NewConnCh.Receive(sCtx); err != context.DeadlineExceeded {
		t.Fatal("Unexpected new transport created to management server")
	}
}

// Test the xdsChannel close logic. The test verifies that the xDS client
// closes an xdsChannel immediately after the last watch is canceled.
func (s) TestAuthority_XDSChannelClose(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	lis, _, client, close := setupForAuthorityTests(ctx, t)
	defer close()

	// Request the first resource. Verify that a new transport is created.
	watcher := noopClusterWatcher{}
	cdsCancel1 := xdsresource.WatchCluster(client, authorityTestResourceName11, watcher)
	val, err := lis.NewConnCh.Receive(ctx)
	if err != nil {
		t.Fatalf("Timed out when waiting for a new transport to be created to the management server: %v", err)
	}
	conn := val.(*testutils.ConnWrapper)

	// Request the second resource. Verify that no new transport is created.
	cdsCancel2 := xdsresource.WatchCluster(client, authorityTestResourceName12, watcher)
	sCtx, sCancel := context.WithTimeout(ctx, defaultTestShortTimeout)
	defer sCancel()
	if _, err := lis.NewConnCh.Receive(sCtx); err != context.DeadlineExceeded {
		t.Fatal("Unexpected new transport created to management server")
	}

	// Cancel both watches, and verify that the connection to the management
	// server is closed.
	cdsCancel1()
	cdsCancel2()
	if _, err := conn.CloseCh.Receive(ctx); err != nil {
		t.Fatal("Timeout when waiting for connection to management server to be closed")
	}
}

// Tests the scenario where the primary management server is unavailable at
// startup and the xDS client falls back to the secondary.  The test verifies
// that the resource watcher is not notifified of the connectivity failure until
// all servers have failed.
func (s) TestAuthority_Fallback(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()

	// Create primary and secondary management servers with restartable
	// listeners.
	l, err := testutils.LocalTCPListener()
	if err != nil {
		t.Fatalf("testutils.LocalTCPListener() failed: %v", err)
	}
	primaryLis := testutils.NewRestartableListener(l)
	primaryMgmtServer := e2e.StartManagementServer(t, e2e.ManagementServerOptions{Listener: primaryLis})
	l, err = testutils.LocalTCPListener()
	if err != nil {
		t.Fatalf("testutils.LocalTCPListener() failed: %v", err)
	}
	secondaryLis := testutils.NewRestartableListener(l)
	secondaryMgmtServer := e2e.StartManagementServer(t, e2e.ManagementServerOptions{Listener: secondaryLis})

	// Create bootstrap configuration with the above primary and fallback
	// management servers, and an xDS client with that configuration.
	nodeID := uuid.New().String()
	bootstrapContents, err := bootstrap.NewContentsForTesting(bootstrap.ConfigOptionsForTesting{
		Servers: []byte(fmt.Sprintf(`
		[
			{
				"server_uri": %q,
				"channel_creds": [{"type": "insecure"}]
			},
			{
				"server_uri": %q,
				"channel_creds": [{"type": "insecure"}]
			}
		]`, primaryMgmtServer.Address, secondaryMgmtServer.Address)),
		Node: []byte(fmt.Sprintf(`{"id": "%s"}`, nodeID)),
	})
	if err != nil {
		t.Fatalf("Failed to create bootstrap configuration: %v", err)
	}
	config, err := bootstrap.NewConfigFromContents(bootstrapContents)
	if err != nil {
		t.Fatalf("Failed to parse bootstrap contents: %s, %v", string(bootstrapContents), err)
	}
	pool := xdsclient.NewPool(config)
	xdsC, close, err := pool.NewClientForTesting(xdsclient.OptionsForTesting{Name: t.Name()})
	if err != nil {
		t.Fatalf("Failed to create an xDS client: %v", err)
	}
	defer close()

	const clusterName = "cluster"
	const edsPrimaryName = "eds-primary"
	const edsSecondaryName = "eds-secondary"

	// Create a Cluster resource on the primary.
	resources := e2e.UpdateOptions{
		NodeID: nodeID,
		Clusters: []*v3clusterpb.Cluster{
			e2e.DefaultCluster(clusterName, edsPrimaryName, e2e.SecurityLevelNone),
		},
		SkipValidation: true,
	}
	if err := primaryMgmtServer.Update(ctx, resources); err != nil {
		t.Fatalf("Failed to update primary management server with resources: %v, err: %v", resources, err)
	}

	// Create a Cluster resource on the secondary .
	resources = e2e.UpdateOptions{
		NodeID: nodeID,
		Clusters: []*v3clusterpb.Cluster{
			e2e.DefaultCluster(clusterName, edsSecondaryName, e2e.SecurityLevelNone),
		},
		SkipValidation: true,
	}
	if err := secondaryMgmtServer.Update(ctx, resources); err != nil {
		t.Fatalf("Failed to update primary management server with resources: %v, err: %v", resources, err)
	}

	// Stop the primary.
	primaryLis.Close()

	// Register a watch.
	watcher := newClusterWatcherV2()
	cdsCancel := xdsresource.WatchCluster(xdsC, clusterName, watcher)
	defer cdsCancel()

	// Ensure that the connectivity error callback is not called.
	sCtx, sCancel := context.WithTimeout(ctx, defaultTestShortTimeout)
	defer sCancel()
	if v, err := watcher.ambientErrCh.Receive(sCtx); err != context.DeadlineExceeded {
		t.Fatalf("Error callback on the watcher with error:  %v", v.(error))
	}

	// Ensure that the resource update callback is invoked.
	v, err := watcher.updateCh.Receive(ctx)
	if err != nil {
		t.Fatalf("Error when waiting for a resource update callback:  %v", err)
	}
	gotUpdate := v.(*xdsresource.ClusterUpdate)
	wantUpdate := xdsresource.ClusterUpdate{
		ClusterName:    clusterName,
		EDSServiceName: edsSecondaryName,
	}
	cmpOpts := []cmp.Option{cmpopts.EquateEmpty(), cmpopts.IgnoreFields(xdsresource.ClusterUpdate{}, "Raw", "LBPolicy", "TelemetryLabels")}
	if diff := cmp.Diff(wantUpdate, *gotUpdate, cmpOpts...); diff != "" {
		t.Fatalf("Diff in the cluster resource update: (-want, got):\n%s", diff)
	}

	// Stop the secondary.
	secondaryLis.Close()

	// Ensure that the connectivity error callback is called.
	if _, err := watcher.ambientErrCh.Receive(ctx); err != nil {
		t.Fatal("Timeout when waiting for error callback on the watcher")
	}
}

// TODO: Get rid of the clusterWatcher type in cds_watchers_test.go and use this
// one instead. Also, rename this to clusterWatcher as part of that refactor.
type clusterWatcherV2 struct {
	updateCh      *testutils.Channel // Messages of type xdsresource.ClusterUpdate
	ambientErrCh  *testutils.Channel // Messages of type ambient error
	resourceErrCh *testutils.Channel // Messages of type resource error
}

func newClusterWatcherV2() *clusterWatcherV2 {
	return &clusterWatcherV2{
		updateCh:      testutils.NewChannel(),
		ambientErrCh:  testutils.NewChannel(),
		resourceErrCh: testutils.NewChannel(),
	}
}

func (cw *clusterWatcherV2) ResourceChanged(update *xdsresource.ClusterUpdate, onDone func()) {
	cw.updateCh.Send(update)
	onDone()
}

func (cw *clusterWatcherV2) AmbientError(err error, onDone func()) {
	// When used with a go-control-plane management server that continuously
	// resends resources which are NACKed by the xDS client, using a `Replace()`
	// here simplifies tests that want access to the most recently received
	// error.
	cw.ambientErrCh.Replace(err)
	onDone()
}

func (cw *clusterWatcherV2) ResourceError(err error, onDone func()) {
	// When used with a go-control-plane management server that continuously
	// resends resources which are NACKed by the xDS client, using a `Replace()`
	// here simplifies tests that want access to the most recently received
	// error.
	cw.resourceErrCh.Replace(err)
	onDone()
}
