Rework client, connect, to simplify and prepare for simpler healing.

Previously we had a single 'client' per grpc.ClientConnInterface.
This created a lot of complexity, particularly in connect.

This rework of client moves to a single 'client' that can handle
multiple grpc.ClientConnInterfaces.

This vastly simplified both the client chain and connect chain.

Finally, heal has been temporarily removed in preparation for a rework
of heal focused on back propogating Connection 'DOWN' events via
monitor.  The net net at the end of the process should be:

1)  Refresh is only originated by actual clients, not the 'client' part
of passthrough NSEs
2)  Heal will only be originated by actual clients, not the 'client' part
pf passthrough NSEs.

Signed-off-by: Ed Warnicke <hagbard@gmail.com>

pkg/networkservice/chains/client/client.go

@@ -1,6 +1,4 @@
-// Copyright (c) 2020-2021 Cisco Systems, Inc.
-//
-// Copyright (c) 2021 Doc.ai and/or its affiliates.
+// Copyright (c) 2021 Cisco and/or its affiliates.
 //
 // SPDX-License-Identifier: Apache-2.0
 //
@@ -21,146 +19,53 @@ package client
 
 import (
 	"context"
-	"net/url"
-	"time"
 
 	"github.com/google/uuid"
-	"google.golang.org/grpc"
-
-	"github.com/networkservicemesh/sdk/pkg/networkservice/common/begin"
-
 	"github.com/networkservicemesh/api/pkg/api/networkservice"
 
+	"github.com/networkservicemesh/sdk/pkg/networkservice/common/begin"
+	"github.com/networkservicemesh/sdk/pkg/networkservice/common/clientconn"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/common/clienturl"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/common/connect"
-	"github.com/networkservicemesh/sdk/pkg/networkservice/common/heal"
+	"github.com/networkservicemesh/sdk/pkg/networkservice/common/dial"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/common/null"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/common/refresh"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/common/updatepath"
-	"github.com/networkservicemesh/sdk/pkg/networkservice/core/adapters"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/core/chain"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/utils/metadata"
 )
 
-type clientOptions struct {
-	name                    string
-	additionalFunctionality []networkservice.NetworkServiceClient
-	authorizeClient         networkservice.NetworkServiceClient
-	dialOptions             []grpc.DialOption
-	dialTimeout             time.Duration
-}
-
-// Option modifies default client chain values.
-type Option func(c *clientOptions)
-
-// WithName sets name for the client.
-func WithName(name string) Option {
-	return Option(func(c *clientOptions) {
-		c.name = name
-	})
-}
-
-// WithAdditionalFunctionality sets additionalFunctionality for the client. Note: this adds into tail of the client chain.
-func WithAdditionalFunctionality(additionalFunctionality ...networkservice.NetworkServiceClient) Option {
-	return Option(func(c *clientOptions) {
-		c.additionalFunctionality = additionalFunctionality
-	})
-}
-
-// WithAuthorizeClient sets authorizeClient for the client chain.
-func WithAuthorizeClient(authorizeClient networkservice.NetworkServiceClient) Option {
-	if authorizeClient == nil {
-		panic("authorizeClient cannot be nil")
-	}
-	return Option(func(c *clientOptions) {
-		c.authorizeClient = authorizeClient
-	})
-}
-
-// WithDialOptions sets dial options
-func WithDialOptions(dialOptions ...grpc.DialOption) Option {
-	return Option(func(c *clientOptions) {
-		c.dialOptions = dialOptions
-	})
-}
-
-// WithDialTimeout sets dial timeout
-func WithDialTimeout(dialTimeout time.Duration) Option {
-	return func(c *clientOptions) {
-		c.dialTimeout = dialTimeout
-	}
-}
-
-// NewClient - returns a (1.) case NSM client.
+// NewClient - returns case NSM client.
 //             - ctx    - context for the lifecycle of the *Client* itself.  Cancel when discarding the client.
-//             - cc - grpc.ClientConnInterface for the endpoint to which this client should connect
-func NewClient(ctx context.Context, connectTo *url.URL, clientOpts ...Option) networkservice.NetworkServiceClient {
-	rv := new(networkservice.NetworkServiceClient)
+func NewClient(ctx context.Context, clientOpts ...Option) networkservice.NetworkServiceClient {
 	var opts = &clientOptions{
 		name:            "client-" + uuid.New().String(),
 		authorizeClient: null.NewClient(),
-		dialTimeout:     100 * time.Millisecond,
+		refreshClient:   refresh.NewClient(ctx),
 	}
 	for _, opt := range clientOpts {
 		opt(opts)
 	}
 
-	*rv = chain.NewNetworkServiceClient(
-		updatepath.NewClient(opts.name),
-		begin.NewClient(),
-		metadata.NewClient(),
-		refresh.NewClient(ctx),
-		adapters.NewServerToClient(
-			chain.NewNetworkServiceServer(
-				heal.NewServer(ctx,
-					heal.WithOnHeal(rv),
-					heal.WithOnRestore(heal.OnRestoreRestore),
-					heal.WithRestoreTimeout(time.Minute)),
-				clienturl.NewServer(connectTo),
-				connect.NewServer(ctx, func(ctx context.Context, cc grpc.ClientConnInterface) networkservice.NetworkServiceClient {
-					return chain.NewNetworkServiceClient(
-						append(
-							opts.additionalFunctionality,
-							// TODO: move back to the end of the chain when `begin` chain element will be ready
-							heal.NewClient(ctx, networkservice.NewMonitorConnectionClient(cc),
-								heal.WithEndpointChange()),
-							opts.authorizeClient,
-							networkservice.NewNetworkServiceClient(cc),
-						)...,
-					)
-				},
-					connect.WithDialOptions(opts.dialOptions...),
-					connect.WithDialTimeout(opts.dialTimeout)),
-			),
-		),
-	)
-	return *rv
-}
-
-// NewClientFactory - returns a (3.) case func(cc grpc.ClientConnInterface) NSM client factory.
-func NewClientFactory(clientOpts ...Option) connect.ClientFactory {
-	return func(ctx context.Context, cc grpc.ClientConnInterface) networkservice.NetworkServiceClient {
-		var rv networkservice.NetworkServiceClient
-		var opts = &clientOptions{
-			name:            "client-" + uuid.New().String(),
-			authorizeClient: null.NewClient(),
-		}
-		for _, opt := range clientOpts {
-			opt(opts)
-		}
-		rv = chain.NewNetworkServiceClient(
+	return chain.NewNetworkServiceClient(
+		append(
+			[]networkservice.NetworkServiceClient{
+				updatepath.NewClient(opts.name),
+				begin.NewClient(),
+				metadata.NewClient(),
+				opts.refreshClient,
+				clienturl.NewClient(opts.clientURL),
+				clientconn.NewClient(opts.cc),
+			},
 			append(
-				append([]networkservice.NetworkServiceClient{
-					updatepath.NewClient(opts.name),
-					begin.NewClient(),
-					metadata.NewClient(),
-					refresh.NewClient(ctx),
-					// TODO: move back to the end of the chain when `begin` chain element will be ready
-					heal.NewClient(ctx, networkservice.NewMonitorConnectionClient(cc)),
-				}, opts.additionalFunctionality...),
+				opts.additionalFunctionality,
+				dial.NewClient(ctx,
+					dial.WithDialOptions(opts.dialOptions...),
+					dial.WithDialTimeOut(opts.dialTimeout),
+				),
 				opts.authorizeClient,
-				networkservice.NewNetworkServiceClient(cc),
-			)...)
-		return rv
-	}
+				connect.NewClient(),
+			)...,
+		)...,
+	)
 }