/*
 *
 * 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 e2e

import (
	"fmt"
	"net"
	"strconv"

	"github.com/envoyproxy/go-control-plane/pkg/wellknown"
	"github.com/golang/protobuf/proto"
	"google.golang.org/grpc/internal/testutils"

	v3clusterpb "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3"
	v3corepb "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
	v3endpointpb "github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3"
	v3listenerpb "github.com/envoyproxy/go-control-plane/envoy/config/listener/v3"
	v3routepb "github.com/envoyproxy/go-control-plane/envoy/config/route/v3"
	v3routerpb "github.com/envoyproxy/go-control-plane/envoy/extensions/filters/http/router/v3"
	v3httppb "github.com/envoyproxy/go-control-plane/envoy/extensions/filters/network/http_connection_manager/v3"
	v3tlspb "github.com/envoyproxy/go-control-plane/envoy/extensions/transport_sockets/tls/v3"
	wrapperspb "github.com/golang/protobuf/ptypes/wrappers"
)

const (
	// ServerListenerResourceNameTemplate is the Listener resource name template
	// used on the server side.
	ServerListenerResourceNameTemplate = "grpc/server?xds.resource.listening_address=%s"
	// ClientSideCertProviderInstance is the certificate provider instance name
	// used in the Cluster resource on the client side.
	ClientSideCertProviderInstance = "client-side-certificate-provider-instance"
	// ServerSideCertProviderInstance is the certificate provider instance name
	// used in the Listener resource on the server side.
	ServerSideCertProviderInstance = "server-side-certificate-provider-instance"
)

// SecurityLevel allows the test to control the security level to be used in the
// resource returned by this package.
type SecurityLevel int

const (
	// SecurityLevelNone is used when no security configuration is required.
	SecurityLevelNone SecurityLevel = iota
	// SecurityLevelTLS is used when security configuration corresponding to TLS
	// is required. Only the server presents an identity certificate in this
	// configuration.
	SecurityLevelTLS
	// SecurityLevelMTLS is used when security ocnfiguration corresponding to
	// mTLS is required. Both client and server present identity certificates in
	// this configuration.
	SecurityLevelMTLS
)

// ResourceParams wraps the arguments to be passed to DefaultClientResources.
type ResourceParams struct {
	// DialTarget is the client's dial target. This is used as the name of the
	// Listener resource.
	DialTarget string
	// NodeID is the id of the xdsClient to which this update is to be pushed.
	NodeID string
	// Host is the host of the default Endpoint resource.
	Host string
	// port is the port of the default Endpoint resource.
	Port uint32
	// SecLevel controls the security configuration in the Cluster resource.
	SecLevel SecurityLevel
}

// DefaultClientResources returns a set of resources (LDS, RDS, CDS, EDS) for a
// client to generically connect to one server.
func DefaultClientResources(params ResourceParams) UpdateOptions {
	routeConfigName := "route-" + params.DialTarget
	clusterName := "cluster-" + params.DialTarget
	endpointsName := "endpoints-" + params.DialTarget
	return UpdateOptions{
		NodeID:    params.NodeID,
		Listeners: []*v3listenerpb.Listener{DefaultClientListener(params.DialTarget, routeConfigName)},
		Routes:    []*v3routepb.RouteConfiguration{DefaultRouteConfig(routeConfigName, params.DialTarget, clusterName)},
		Clusters:  []*v3clusterpb.Cluster{DefaultCluster(clusterName, endpointsName, params.SecLevel)},
		Endpoints: []*v3endpointpb.ClusterLoadAssignment{DefaultEndpoint(endpointsName, params.Host, []uint32{params.Port})},
	}
}

// RouterHTTPFilter is the HTTP Filter configuration for the Router filter.
var RouterHTTPFilter = HTTPFilter("router", &v3routerpb.Router{})

// DefaultClientListener returns a basic xds Listener resource to be used on
// the client side.
func DefaultClientListener(target, routeName string) *v3listenerpb.Listener {
	hcm := testutils.MarshalAny(&v3httppb.HttpConnectionManager{
		RouteSpecifier: &v3httppb.HttpConnectionManager_Rds{Rds: &v3httppb.Rds{
			ConfigSource: &v3corepb.ConfigSource{
				ConfigSourceSpecifier: &v3corepb.ConfigSource_Ads{Ads: &v3corepb.AggregatedConfigSource{}},
			},
			RouteConfigName: routeName,
		}},
		HttpFilters: []*v3httppb.HttpFilter{HTTPFilter("router", &v3routerpb.Router{})}, // router fields are unused by grpc
	})
	return &v3listenerpb.Listener{
		Name:        target,
		ApiListener: &v3listenerpb.ApiListener{ApiListener: hcm},
		FilterChains: []*v3listenerpb.FilterChain{{
			Name: "filter-chain-name",
			Filters: []*v3listenerpb.Filter{{
				Name:       wellknown.HTTPConnectionManager,
				ConfigType: &v3listenerpb.Filter_TypedConfig{TypedConfig: hcm},
			}},
		}},
	}
}

// DefaultServerListener returns a basic xds Listener resource to be used on
// the server side.
func DefaultServerListener(host string, port uint32, secLevel SecurityLevel) *v3listenerpb.Listener {
	var tlsContext *v3tlspb.DownstreamTlsContext
	switch secLevel {
	case SecurityLevelNone:
	case SecurityLevelTLS:
		tlsContext = &v3tlspb.DownstreamTlsContext{
			CommonTlsContext: &v3tlspb.CommonTlsContext{
				TlsCertificateCertificateProviderInstance: &v3tlspb.CommonTlsContext_CertificateProviderInstance{
					InstanceName: ServerSideCertProviderInstance,
				},
			},
		}
	case SecurityLevelMTLS:
		tlsContext = &v3tlspb.DownstreamTlsContext{
			RequireClientCertificate: &wrapperspb.BoolValue{Value: true},
			CommonTlsContext: &v3tlspb.CommonTlsContext{
				TlsCertificateCertificateProviderInstance: &v3tlspb.CommonTlsContext_CertificateProviderInstance{
					InstanceName: ServerSideCertProviderInstance,
				},
				ValidationContextType: &v3tlspb.CommonTlsContext_ValidationContextCertificateProviderInstance{
					ValidationContextCertificateProviderInstance: &v3tlspb.CommonTlsContext_CertificateProviderInstance{
						InstanceName: ServerSideCertProviderInstance,
					},
				},
			},
		}
	}

	var ts *v3corepb.TransportSocket
	if tlsContext != nil {
		ts = &v3corepb.TransportSocket{
			Name: "envoy.transport_sockets.tls",
			ConfigType: &v3corepb.TransportSocket_TypedConfig{
				TypedConfig: testutils.MarshalAny(tlsContext),
			},
		}
	}
	return &v3listenerpb.Listener{
		Name: fmt.Sprintf(ServerListenerResourceNameTemplate, net.JoinHostPort(host, strconv.Itoa(int(port)))),
		Address: &v3corepb.Address{
			Address: &v3corepb.Address_SocketAddress{
				SocketAddress: &v3corepb.SocketAddress{
					Address: host,
					PortSpecifier: &v3corepb.SocketAddress_PortValue{
						PortValue: port,
					},
				},
			},
		},
		FilterChains: []*v3listenerpb.FilterChain{
			{
				Name: "v4-wildcard",
				FilterChainMatch: &v3listenerpb.FilterChainMatch{
					PrefixRanges: []*v3corepb.CidrRange{
						{
							AddressPrefix: "0.0.0.0",
							PrefixLen: &wrapperspb.UInt32Value{
								Value: uint32(0),
							},
						},
					},
					SourceType: v3listenerpb.FilterChainMatch_SAME_IP_OR_LOOPBACK,
					SourcePrefixRanges: []*v3corepb.CidrRange{
						{
							AddressPrefix: "0.0.0.0",
							PrefixLen: &wrapperspb.UInt32Value{
								Value: uint32(0),
							},
						},
					},
				},
				Filters: []*v3listenerpb.Filter{
					{
						Name: "filter-1",
						ConfigType: &v3listenerpb.Filter_TypedConfig{
							TypedConfig: testutils.MarshalAny(&v3httppb.HttpConnectionManager{
								RouteSpecifier: &v3httppb.HttpConnectionManager_RouteConfig{
									RouteConfig: &v3routepb.RouteConfiguration{
										Name: "routeName",
										VirtualHosts: []*v3routepb.VirtualHost{{
											// This "*" string matches on any incoming authority. This is to ensure any
											// incoming RPC matches to Route_NonForwardingAction and will proceed as
											// normal.
											Domains: []string{"*"},
											Routes: []*v3routepb.Route{{
												Match: &v3routepb.RouteMatch{
													PathSpecifier: &v3routepb.RouteMatch_Prefix{Prefix: "/"},
												},
												Action: &v3routepb.Route_NonForwardingAction{},
											}}}}},
								},
								HttpFilters: []*v3httppb.HttpFilter{RouterHTTPFilter},
							}),
						},
					},
				},
				TransportSocket: ts,
			},
			{
				Name: "v6-wildcard",
				FilterChainMatch: &v3listenerpb.FilterChainMatch{
					PrefixRanges: []*v3corepb.CidrRange{
						{
							AddressPrefix: "::",
							PrefixLen: &wrapperspb.UInt32Value{
								Value: uint32(0),
							},
						},
					},
					SourceType: v3listenerpb.FilterChainMatch_SAME_IP_OR_LOOPBACK,
					SourcePrefixRanges: []*v3corepb.CidrRange{
						{
							AddressPrefix: "::",
							PrefixLen: &wrapperspb.UInt32Value{
								Value: uint32(0),
							},
						},
					},
				},
				Filters: []*v3listenerpb.Filter{
					{
						Name: "filter-1",
						ConfigType: &v3listenerpb.Filter_TypedConfig{
							TypedConfig: testutils.MarshalAny(&v3httppb.HttpConnectionManager{
								RouteSpecifier: &v3httppb.HttpConnectionManager_RouteConfig{
									RouteConfig: &v3routepb.RouteConfiguration{
										Name: "routeName",
										VirtualHosts: []*v3routepb.VirtualHost{{
											// This "*" string matches on any incoming authority. This is to ensure any
											// incoming RPC matches to Route_NonForwardingAction and will proceed as
											// normal.
											Domains: []string{"*"},
											Routes: []*v3routepb.Route{{
												Match: &v3routepb.RouteMatch{
													PathSpecifier: &v3routepb.RouteMatch_Prefix{Prefix: "/"},
												},
												Action: &v3routepb.Route_NonForwardingAction{},
											}}}}},
								},
								HttpFilters: []*v3httppb.HttpFilter{RouterHTTPFilter},
							}),
						},
					},
				},
				TransportSocket: ts,
			},
		},
	}
}

// HTTPFilter constructs an xds HttpFilter with the provided name and config.
func HTTPFilter(name string, config proto.Message) *v3httppb.HttpFilter {
	return &v3httppb.HttpFilter{
		Name: name,
		ConfigType: &v3httppb.HttpFilter_TypedConfig{
			TypedConfig: testutils.MarshalAny(config),
		},
	}
}

// DefaultRouteConfig returns a basic xds RouteConfig resource.
func DefaultRouteConfig(routeName, ldsTarget, clusterName string) *v3routepb.RouteConfiguration {
	return &v3routepb.RouteConfiguration{
		Name: routeName,
		VirtualHosts: []*v3routepb.VirtualHost{{
			Domains: []string{ldsTarget},
			Routes: []*v3routepb.Route{{
				Match: &v3routepb.RouteMatch{PathSpecifier: &v3routepb.RouteMatch_Prefix{Prefix: "/"}},
				Action: &v3routepb.Route_Route{Route: &v3routepb.RouteAction{
					ClusterSpecifier: &v3routepb.RouteAction_WeightedClusters{WeightedClusters: &v3routepb.WeightedCluster{
						Clusters: []*v3routepb.WeightedCluster_ClusterWeight{
							{
								Name:   clusterName,
								Weight: &wrapperspb.UInt32Value{Value: 100},
							},
						},
					}},
				}},
			}},
		}},
	}
}

// DefaultCluster returns a basic xds Cluster resource.
func DefaultCluster(clusterName, edsServiceName string, secLevel SecurityLevel) *v3clusterpb.Cluster {
	return ClusterResourceWithOptions(&ClusterOptions{
		ClusterName:   clusterName,
		ServiceName:   edsServiceName,
		Policy:        LoadBalancingPolicyRoundRobin,
		SecurityLevel: secLevel,
	})
}

// LoadBalancingPolicy determines the policy used for balancing load across
// endpoints in the Cluster.
type LoadBalancingPolicy int

const (
	// LoadBalancingPolicyRoundRobin results in the use of the weighted_target
	// LB policy to balance load across localities and endpoints in the cluster.
	LoadBalancingPolicyRoundRobin LoadBalancingPolicy = iota
	// LoadBalancingPolicyRingHash results in the use of the ring_hash LB policy
	// as the leaf policy.
	LoadBalancingPolicyRingHash
)

// ClusterOptions contains options to configure a Cluster resource.
type ClusterOptions struct {
	// ClusterName is the name of the Cluster resource.
	ClusterName string
	// ServiceName is the EDS service name of the Cluster.
	ServiceName string
	// Policy is the LB policy to be used.
	Policy LoadBalancingPolicy
	// SecurityLevel determines the security configuration for the Cluster.
	SecurityLevel SecurityLevel
}

// ClusterResourceWithOptions returns an xDS Cluster resource configured with
// the provided options.
func ClusterResourceWithOptions(opts *ClusterOptions) *v3clusterpb.Cluster {
	var tlsContext *v3tlspb.UpstreamTlsContext
	switch opts.SecurityLevel {
	case SecurityLevelNone:
	case SecurityLevelTLS:
		tlsContext = &v3tlspb.UpstreamTlsContext{
			CommonTlsContext: &v3tlspb.CommonTlsContext{
				ValidationContextType: &v3tlspb.CommonTlsContext_ValidationContextCertificateProviderInstance{
					ValidationContextCertificateProviderInstance: &v3tlspb.CommonTlsContext_CertificateProviderInstance{
						InstanceName: ClientSideCertProviderInstance,
					},
				},
			},
		}
	case SecurityLevelMTLS:
		tlsContext = &v3tlspb.UpstreamTlsContext{
			CommonTlsContext: &v3tlspb.CommonTlsContext{
				ValidationContextType: &v3tlspb.CommonTlsContext_ValidationContextCertificateProviderInstance{
					ValidationContextCertificateProviderInstance: &v3tlspb.CommonTlsContext_CertificateProviderInstance{
						InstanceName: ClientSideCertProviderInstance,
					},
				},
				TlsCertificateCertificateProviderInstance: &v3tlspb.CommonTlsContext_CertificateProviderInstance{
					InstanceName: ClientSideCertProviderInstance,
				},
			},
		}
	}

	var lbPolicy v3clusterpb.Cluster_LbPolicy
	switch opts.Policy {
	case LoadBalancingPolicyRoundRobin:
		lbPolicy = v3clusterpb.Cluster_ROUND_ROBIN
	case LoadBalancingPolicyRingHash:
		lbPolicy = v3clusterpb.Cluster_RING_HASH
	}
	cluster := &v3clusterpb.Cluster{
		Name:                 opts.ClusterName,
		ClusterDiscoveryType: &v3clusterpb.Cluster_Type{Type: v3clusterpb.Cluster_EDS},
		EdsClusterConfig: &v3clusterpb.Cluster_EdsClusterConfig{
			EdsConfig: &v3corepb.ConfigSource{
				ConfigSourceSpecifier: &v3corepb.ConfigSource_Ads{
					Ads: &v3corepb.AggregatedConfigSource{},
				},
			},
			ServiceName: opts.ServiceName,
		},
		LbPolicy: lbPolicy,
	}
	if tlsContext != nil {
		cluster.TransportSocket = &v3corepb.TransportSocket{
			Name: "envoy.transport_sockets.tls",
			ConfigType: &v3corepb.TransportSocket_TypedConfig{
				TypedConfig: testutils.MarshalAny(tlsContext),
			},
		}
	}
	return cluster
}

// DefaultEndpoint returns a basic xds Endpoint resource.
func DefaultEndpoint(clusterName string, host string, ports []uint32) *v3endpointpb.ClusterLoadAssignment {
	var lbEndpoints []*v3endpointpb.LbEndpoint
	for _, port := range ports {
		lbEndpoints = append(lbEndpoints, &v3endpointpb.LbEndpoint{
			HostIdentifier: &v3endpointpb.LbEndpoint_Endpoint{Endpoint: &v3endpointpb.Endpoint{
				Address: &v3corepb.Address{Address: &v3corepb.Address_SocketAddress{
					SocketAddress: &v3corepb.SocketAddress{
						Protocol:      v3corepb.SocketAddress_TCP,
						Address:       host,
						PortSpecifier: &v3corepb.SocketAddress_PortValue{PortValue: port}},
				}},
			}},
		})
	}
	return &v3endpointpb.ClusterLoadAssignment{
		ClusterName: clusterName,
		Endpoints: []*v3endpointpb.LocalityLbEndpoints{{
			Locality:            &v3corepb.Locality{SubZone: "subzone"},
			LbEndpoints:         lbEndpoints,
			LoadBalancingWeight: &wrapperspb.UInt32Value{Value: 1},
			Priority:            0,
		}},
	}
}