// Copyright 2020 Google LLC
//
// 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
//
//     https://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.

// Code generated by protoc-gen-go_gapic. DO NOT EDIT.

package database

import (
	"context"
	"fmt"
	"math"
	"net/url"
	"time"

	"cloud.google.com/go/longrunning"
	lroauto "cloud.google.com/go/longrunning/autogen"
	"github.com/golang/protobuf/proto"
	gax "github.com/googleapis/gax-go/v2"
	"google.golang.org/api/iterator"
	"google.golang.org/api/option"
	gtransport "google.golang.org/api/transport/grpc"
	iampb "google.golang.org/genproto/googleapis/iam/v1"
	longrunningpb "google.golang.org/genproto/googleapis/longrunning"
	databasepb "google.golang.org/genproto/googleapis/spanner/admin/database/v1"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
)

// DatabaseAdminCallOptions contains the retry settings for each method of DatabaseAdminClient.
type DatabaseAdminCallOptions struct {
	ListDatabases          []gax.CallOption
	CreateDatabase         []gax.CallOption
	GetDatabase            []gax.CallOption
	UpdateDatabaseDdl      []gax.CallOption
	DropDatabase           []gax.CallOption
	GetDatabaseDdl         []gax.CallOption
	SetIamPolicy           []gax.CallOption
	GetIamPolicy           []gax.CallOption
	TestIamPermissions     []gax.CallOption
	CreateBackup           []gax.CallOption
	GetBackup              []gax.CallOption
	UpdateBackup           []gax.CallOption
	DeleteBackup           []gax.CallOption
	ListBackups            []gax.CallOption
	RestoreDatabase        []gax.CallOption
	ListDatabaseOperations []gax.CallOption
	ListBackupOperations   []gax.CallOption
}

func defaultDatabaseAdminClientOptions() []option.ClientOption {
	return []option.ClientOption{
		option.WithEndpoint("spanner.googleapis.com:443"),
		option.WithGRPCDialOption(grpc.WithDisableServiceConfig()),
		option.WithScopes(DefaultAuthScopes()...),
		option.WithGRPCDialOption(grpc.WithDefaultCallOptions(
			grpc.MaxCallRecvMsgSize(math.MaxInt32))),
	}
}

func defaultDatabaseAdminCallOptions() *DatabaseAdminCallOptions {
	return &DatabaseAdminCallOptions{
		ListDatabases: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		CreateDatabase: []gax.CallOption{},
		GetDatabase: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		UpdateDatabaseDdl: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DropDatabase: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetDatabaseDdl: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		SetIamPolicy: []gax.CallOption{},
		GetIamPolicy: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		TestIamPermissions: []gax.CallOption{},
		CreateBackup:       []gax.CallOption{},
		GetBackup: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		UpdateBackup: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DeleteBackup: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListBackups: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		RestoreDatabase: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListDatabaseOperations: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListBackupOperations: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        32000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
	}
}

// DatabaseAdminClient is a client for interacting with Cloud Spanner Database Admin API.
//
// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
type DatabaseAdminClient struct {
	// Connection pool of gRPC connections to the service.
	connPool gtransport.ConnPool

	// The gRPC API client.
	databaseAdminClient databasepb.DatabaseAdminClient

	// LROClient is used internally to handle longrunning operations.
	// It is exposed so that its CallOptions can be modified if required.
	// Users should not Close this client.
	LROClient *lroauto.OperationsClient

	// The call options for this service.
	CallOptions *DatabaseAdminCallOptions

	// The x-goog-* metadata to be sent with each request.
	xGoogMetadata metadata.MD
}

// NewDatabaseAdminClient creates a new database admin client.
//
// Cloud Spanner Database Admin API
//
// The Cloud Spanner Database Admin API can be used to create, drop, and
// list databases. It also enables updating the schema of pre-existing
// databases. It can be also used to create, delete and list backups for a
// database and to restore from an existing backup.
func NewDatabaseAdminClient(ctx context.Context, opts ...option.ClientOption) (*DatabaseAdminClient, error) {
	connPool, err := gtransport.DialPool(ctx, append(defaultDatabaseAdminClientOptions(), opts...)...)
	if err != nil {
		return nil, err
	}
	c := &DatabaseAdminClient{
		connPool:    connPool,
		CallOptions: defaultDatabaseAdminCallOptions(),

		databaseAdminClient: databasepb.NewDatabaseAdminClient(connPool),
	}
	c.setGoogleClientInfo()

	c.LROClient, err = lroauto.NewOperationsClient(ctx, gtransport.WithConnPool(connPool))
	if err != nil {
		// This error "should not happen", since we are just reusing old connection pool
		// and never actually need to dial.
		// If this does happen, we could leak connp. However, we cannot close conn:
		// If the user invoked the constructor with option.WithGRPCConn,
		// we would close a connection that's still in use.
		// TODO: investigate error conditions.
		return nil, err
	}
	return c, nil
}

// Connection returns a connection to the API service.
//
// Deprecated.
func (c *DatabaseAdminClient) Connection() *grpc.ClientConn {
	return c.connPool.Conn()
}

// Close closes the connection to the API service. The user should invoke this when
// the client is no longer required.
func (c *DatabaseAdminClient) Close() error {
	return c.connPool.Close()
}

// setGoogleClientInfo sets the name and version of the application in
// the `x-goog-api-client` header passed on each request. Intended for
// use by Google-written clients.
func (c *DatabaseAdminClient) setGoogleClientInfo(keyval ...string) {
	kv := append([]string{"gl-go", versionGo()}, keyval...)
	kv = append(kv, "gapic", versionClient, "gax", gax.Version, "grpc", grpc.Version)
	c.xGoogMetadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
}

// ListDatabases lists Cloud Spanner databases.
func (c *DatabaseAdminClient) ListDatabases(ctx context.Context, req *databasepb.ListDatabasesRequest, opts ...gax.CallOption) *DatabaseIterator {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.ListDatabases[0:len(c.CallOptions.ListDatabases):len(c.CallOptions.ListDatabases)], opts...)
	it := &DatabaseIterator{}
	req = proto.Clone(req).(*databasepb.ListDatabasesRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*databasepb.Database, string, error) {
		var resp *databasepb.ListDatabasesResponse
		req.PageToken = pageToken
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.databaseAdminClient.ListDatabases(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.Databases, resp.NextPageToken, nil
	}
	fetch := func(pageSize int, pageToken string) (string, error) {
		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
		if err != nil {
			return "", err
		}
		it.items = append(it.items, items...)
		return nextPageToken, nil
	}
	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
	it.pageInfo.MaxSize = int(req.PageSize)
	it.pageInfo.Token = req.PageToken
	return it
}

// CreateDatabase creates a new Cloud Spanner database and starts to prepare it for serving.
// The returned [long-running operation][google.longrunning.Operation] will
// have a name of the format <database_name>/operations/<operation_id> and
// can be used to track preparation of the database. The
// [metadata][google.longrunning.Operation.metadata] field type is
// [CreateDatabaseMetadata][google.spanner.admin.database.v1.CreateDatabaseMetadata]. The
// [response][google.longrunning.Operation.response] field type is
// [Database][google.spanner.admin.database.v1.Database], if successful.
func (c *DatabaseAdminClient) CreateDatabase(ctx context.Context, req *databasepb.CreateDatabaseRequest, opts ...gax.CallOption) (*CreateDatabaseOperation, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.CreateDatabase[0:len(c.CallOptions.CreateDatabase):len(c.CallOptions.CreateDatabase)], opts...)
	var resp *longrunningpb.Operation
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.CreateDatabase(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return &CreateDatabaseOperation{
		lro: longrunning.InternalNewOperation(c.LROClient, resp),
	}, nil
}

// GetDatabase gets the state of a Cloud Spanner database.
func (c *DatabaseAdminClient) GetDatabase(ctx context.Context, req *databasepb.GetDatabaseRequest, opts ...gax.CallOption) (*databasepb.Database, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.GetDatabase[0:len(c.CallOptions.GetDatabase):len(c.CallOptions.GetDatabase)], opts...)
	var resp *databasepb.Database
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.GetDatabase(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// UpdateDatabaseDdl updates the schema of a Cloud Spanner database by
// creating/altering/dropping tables, columns, indexes, etc. The returned
// [long-running operation][google.longrunning.Operation] will have a name of
// the format <database_name>/operations/<operation_id> and can be used to
// track execution of the schema change(s). The
// [metadata][google.longrunning.Operation.metadata] field type is
// [UpdateDatabaseDdlMetadata][google.spanner.admin.database.v1.UpdateDatabaseDdlMetadata].  The operation has no response.
func (c *DatabaseAdminClient) UpdateDatabaseDdl(ctx context.Context, req *databasepb.UpdateDatabaseDdlRequest, opts ...gax.CallOption) (*UpdateDatabaseDdlOperation, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "database", url.QueryEscape(req.GetDatabase())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.UpdateDatabaseDdl[0:len(c.CallOptions.UpdateDatabaseDdl):len(c.CallOptions.UpdateDatabaseDdl)], opts...)
	var resp *longrunningpb.Operation
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.UpdateDatabaseDdl(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return &UpdateDatabaseDdlOperation{
		lro: longrunning.InternalNewOperation(c.LROClient, resp),
	}, nil
}

// DropDatabase drops (aka deletes) a Cloud Spanner database.
// Completed backups for the database will be retained according to their
// expire_time.
func (c *DatabaseAdminClient) DropDatabase(ctx context.Context, req *databasepb.DropDatabaseRequest, opts ...gax.CallOption) error {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "database", url.QueryEscape(req.GetDatabase())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.DropDatabase[0:len(c.CallOptions.DropDatabase):len(c.CallOptions.DropDatabase)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.databaseAdminClient.DropDatabase(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

// GetDatabaseDdl returns the schema of a Cloud Spanner database as a list of formatted
// DDL statements. This method does not show pending schema updates, those may
// be queried using the [Operations][google.longrunning.Operations] API.
func (c *DatabaseAdminClient) GetDatabaseDdl(ctx context.Context, req *databasepb.GetDatabaseDdlRequest, opts ...gax.CallOption) (*databasepb.GetDatabaseDdlResponse, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "database", url.QueryEscape(req.GetDatabase())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.GetDatabaseDdl[0:len(c.CallOptions.GetDatabaseDdl):len(c.CallOptions.GetDatabaseDdl)], opts...)
	var resp *databasepb.GetDatabaseDdlResponse
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.GetDatabaseDdl(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// SetIamPolicy sets the access control policy on a database or backup resource.
// Replaces any existing policy.
//
// Authorization requires spanner.databases.setIamPolicy
// permission on [resource][google.iam.v1.SetIamPolicyRequest.resource].
// For backups, authorization requires spanner.backups.setIamPolicy
// permission on [resource][google.iam.v1.SetIamPolicyRequest.resource].
func (c *DatabaseAdminClient) SetIamPolicy(ctx context.Context, req *iampb.SetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "resource", url.QueryEscape(req.GetResource())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.SetIamPolicy[0:len(c.CallOptions.SetIamPolicy):len(c.CallOptions.SetIamPolicy)], opts...)
	var resp *iampb.Policy
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.SetIamPolicy(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// GetIamPolicy gets the access control policy for a database or backup resource.
// Returns an empty policy if a database or backup exists but does not have a
// policy set.
//
// Authorization requires spanner.databases.getIamPolicy permission on
// [resource][google.iam.v1.GetIamPolicyRequest.resource].
// For backups, authorization requires spanner.backups.getIamPolicy
// permission on [resource][google.iam.v1.GetIamPolicyRequest.resource].
func (c *DatabaseAdminClient) GetIamPolicy(ctx context.Context, req *iampb.GetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "resource", url.QueryEscape(req.GetResource())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.GetIamPolicy[0:len(c.CallOptions.GetIamPolicy):len(c.CallOptions.GetIamPolicy)], opts...)
	var resp *iampb.Policy
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.GetIamPolicy(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// TestIamPermissions returns permissions that the caller has on the specified database or backup
// resource.
//
// Attempting this RPC on a non-existent Cloud Spanner database will
// result in a NOT_FOUND error if the user has
// spanner.databases.list permission on the containing Cloud
// Spanner instance. Otherwise returns an empty set of permissions.
// Calling this method on a backup that does not exist will
// result in a NOT_FOUND error if the user has
// spanner.backups.list permission on the containing instance.
func (c *DatabaseAdminClient) TestIamPermissions(ctx context.Context, req *iampb.TestIamPermissionsRequest, opts ...gax.CallOption) (*iampb.TestIamPermissionsResponse, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "resource", url.QueryEscape(req.GetResource())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.TestIamPermissions[0:len(c.CallOptions.TestIamPermissions):len(c.CallOptions.TestIamPermissions)], opts...)
	var resp *iampb.TestIamPermissionsResponse
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.TestIamPermissions(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// CreateBackup starts creating a new Cloud Spanner Backup.
// The returned backup [long-running operation][google.longrunning.Operation]
// will have a name of the format
// projects/<project>/instances/<instance>/backups/<backup>/operations/<operation_id>
// and can be used to track creation of the backup. The
// [metadata][google.longrunning.Operation.metadata] field type is
// [CreateBackupMetadata][google.spanner.admin.database.v1.CreateBackupMetadata]. The
// [response][google.longrunning.Operation.response] field type is
// [Backup][google.spanner.admin.database.v1.Backup], if successful. Cancelling the returned operation will stop the
// creation and delete the backup.
// There can be only one pending backup creation per database. Backup creation
// of different databases can run concurrently.
func (c *DatabaseAdminClient) CreateBackup(ctx context.Context, req *databasepb.CreateBackupRequest, opts ...gax.CallOption) (*CreateBackupOperation, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.CreateBackup[0:len(c.CallOptions.CreateBackup):len(c.CallOptions.CreateBackup)], opts...)
	var resp *longrunningpb.Operation
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.CreateBackup(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return &CreateBackupOperation{
		lro: longrunning.InternalNewOperation(c.LROClient, resp),
	}, nil
}

// GetBackup gets metadata on a pending or completed [Backup][google.spanner.admin.database.v1.Backup].
func (c *DatabaseAdminClient) GetBackup(ctx context.Context, req *databasepb.GetBackupRequest, opts ...gax.CallOption) (*databasepb.Backup, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.GetBackup[0:len(c.CallOptions.GetBackup):len(c.CallOptions.GetBackup)], opts...)
	var resp *databasepb.Backup
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.GetBackup(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// UpdateBackup updates a pending or completed [Backup][google.spanner.admin.database.v1.Backup].
func (c *DatabaseAdminClient) UpdateBackup(ctx context.Context, req *databasepb.UpdateBackupRequest, opts ...gax.CallOption) (*databasepb.Backup, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "backup.name", url.QueryEscape(req.GetBackup().GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.UpdateBackup[0:len(c.CallOptions.UpdateBackup):len(c.CallOptions.UpdateBackup)], opts...)
	var resp *databasepb.Backup
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.UpdateBackup(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// DeleteBackup deletes a pending or completed [Backup][google.spanner.admin.database.v1.Backup].
func (c *DatabaseAdminClient) DeleteBackup(ctx context.Context, req *databasepb.DeleteBackupRequest, opts ...gax.CallOption) error {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.DeleteBackup[0:len(c.CallOptions.DeleteBackup):len(c.CallOptions.DeleteBackup)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.databaseAdminClient.DeleteBackup(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

// ListBackups lists completed and pending backups.
// Backups returned are ordered by create_time in descending order,
// starting from the most recent create_time.
func (c *DatabaseAdminClient) ListBackups(ctx context.Context, req *databasepb.ListBackupsRequest, opts ...gax.CallOption) *BackupIterator {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.ListBackups[0:len(c.CallOptions.ListBackups):len(c.CallOptions.ListBackups)], opts...)
	it := &BackupIterator{}
	req = proto.Clone(req).(*databasepb.ListBackupsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*databasepb.Backup, string, error) {
		var resp *databasepb.ListBackupsResponse
		req.PageToken = pageToken
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.databaseAdminClient.ListBackups(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.Backups, resp.NextPageToken, nil
	}
	fetch := func(pageSize int, pageToken string) (string, error) {
		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
		if err != nil {
			return "", err
		}
		it.items = append(it.items, items...)
		return nextPageToken, nil
	}
	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
	it.pageInfo.MaxSize = int(req.PageSize)
	it.pageInfo.Token = req.PageToken
	return it
}

// RestoreDatabase create a new database by restoring from a completed backup. The new
// database must be in the same project and in an instance with the same
// instance configuration as the instance containing
// the backup. The returned database [long-running
// operation][google.longrunning.Operation] has a name of the format
// projects/<project>/instances/<instance>/databases/<database>/operations/<operation_id>,
// and can be used to track the progress of the operation, and to cancel it.
// The [metadata][google.longrunning.Operation.metadata] field type is
// [RestoreDatabaseMetadata][google.spanner.admin.database.v1.RestoreDatabaseMetadata].
// The [response][google.longrunning.Operation.response] type
// is [Database][google.spanner.admin.database.v1.Database], if
// successful. Cancelling the returned operation will stop the restore and
// delete the database.
// There can be only one database being restored into an instance at a time.
// Once the restore operation completes, a new restore operation can be
// initiated, without waiting for the optimize operation associated with the
// first restore to complete.
func (c *DatabaseAdminClient) RestoreDatabase(ctx context.Context, req *databasepb.RestoreDatabaseRequest, opts ...gax.CallOption) (*RestoreDatabaseOperation, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.RestoreDatabase[0:len(c.CallOptions.RestoreDatabase):len(c.CallOptions.RestoreDatabase)], opts...)
	var resp *longrunningpb.Operation
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.databaseAdminClient.RestoreDatabase(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return &RestoreDatabaseOperation{
		lro: longrunning.InternalNewOperation(c.LROClient, resp),
	}, nil
}

// ListDatabaseOperations lists database [longrunning-operations][google.longrunning.Operation].
// A database operation has a name of the form
// projects/<project>/instances/<instance>/databases/<database>/operations/<operation>.
// The long-running operation
// [metadata][google.longrunning.Operation.metadata] field type
// metadata.type_url describes the type of the metadata. Operations returned
// include those that have completed/failed/canceled within the last 7 days,
// and pending operations.
func (c *DatabaseAdminClient) ListDatabaseOperations(ctx context.Context, req *databasepb.ListDatabaseOperationsRequest, opts ...gax.CallOption) *OperationIterator {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.ListDatabaseOperations[0:len(c.CallOptions.ListDatabaseOperations):len(c.CallOptions.ListDatabaseOperations)], opts...)
	it := &OperationIterator{}
	req = proto.Clone(req).(*databasepb.ListDatabaseOperationsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*longrunningpb.Operation, string, error) {
		var resp *databasepb.ListDatabaseOperationsResponse
		req.PageToken = pageToken
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.databaseAdminClient.ListDatabaseOperations(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.Operations, resp.NextPageToken, nil
	}
	fetch := func(pageSize int, pageToken string) (string, error) {
		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
		if err != nil {
			return "", err
		}
		it.items = append(it.items, items...)
		return nextPageToken, nil
	}
	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
	it.pageInfo.MaxSize = int(req.PageSize)
	it.pageInfo.Token = req.PageToken
	return it
}

// ListBackupOperations lists the backup [long-running operations][google.longrunning.Operation] in
// the given instance. A backup operation has a name of the form
// projects/<project>/instances/<instance>/backups/<backup>/operations/<operation>.
// The long-running operation
// [metadata][google.longrunning.Operation.metadata] field type
// metadata.type_url describes the type of the metadata. Operations returned
// include those that have completed/failed/canceled within the last 7 days,
// and pending operations. Operations returned are ordered by
// operation.metadata.value.progress.start_time in descending order starting
// from the most recently started operation.
func (c *DatabaseAdminClient) ListBackupOperations(ctx context.Context, req *databasepb.ListBackupOperationsRequest, opts ...gax.CallOption) *OperationIterator {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.ListBackupOperations[0:len(c.CallOptions.ListBackupOperations):len(c.CallOptions.ListBackupOperations)], opts...)
	it := &OperationIterator{}
	req = proto.Clone(req).(*databasepb.ListBackupOperationsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*longrunningpb.Operation, string, error) {
		var resp *databasepb.ListBackupOperationsResponse
		req.PageToken = pageToken
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.databaseAdminClient.ListBackupOperations(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.Operations, resp.NextPageToken, nil
	}
	fetch := func(pageSize int, pageToken string) (string, error) {
		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
		if err != nil {
			return "", err
		}
		it.items = append(it.items, items...)
		return nextPageToken, nil
	}
	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
	it.pageInfo.MaxSize = int(req.PageSize)
	it.pageInfo.Token = req.PageToken
	return it
}

// CreateBackupOperation manages a long-running operation from CreateBackup.
type CreateBackupOperation struct {
	lro *longrunning.Operation
}

// CreateBackupOperation returns a new CreateBackupOperation from a given name.
// The name must be that of a previously created CreateBackupOperation, possibly from a different process.
func (c *DatabaseAdminClient) CreateBackupOperation(name string) *CreateBackupOperation {
	return &CreateBackupOperation{
		lro: longrunning.InternalNewOperation(c.LROClient, &longrunningpb.Operation{Name: name}),
	}
}

// Wait blocks until the long-running operation is completed, returning the response and any errors encountered.
//
// See documentation of Poll for error-handling information.
func (op *CreateBackupOperation) Wait(ctx context.Context, opts ...gax.CallOption) (*databasepb.Backup, error) {
	var resp databasepb.Backup
	if err := op.lro.WaitWithInterval(ctx, &resp, time.Minute, opts...); err != nil {
		return nil, err
	}
	return &resp, nil
}

// Poll fetches the latest state of the long-running operation.
//
// Poll also fetches the latest metadata, which can be retrieved by Metadata.
//
// If Poll fails, the error is returned and op is unmodified. If Poll succeeds and
// the operation has completed with failure, the error is returned and op.Done will return true.
// If Poll succeeds and the operation has completed successfully,
// op.Done will return true, and the response of the operation is returned.
// If Poll succeeds and the operation has not completed, the returned response and error are both nil.
func (op *CreateBackupOperation) Poll(ctx context.Context, opts ...gax.CallOption) (*databasepb.Backup, error) {
	var resp databasepb.Backup
	if err := op.lro.Poll(ctx, &resp, opts...); err != nil {
		return nil, err
	}
	if !op.Done() {
		return nil, nil
	}
	return &resp, nil
}

// Metadata returns metadata associated with the long-running operation.
// Metadata itself does not contact the server, but Poll does.
// To get the latest metadata, call this method after a successful call to Poll.
// If the metadata is not available, the returned metadata and error are both nil.
func (op *CreateBackupOperation) Metadata() (*databasepb.CreateBackupMetadata, error) {
	var meta databasepb.CreateBackupMetadata
	if err := op.lro.Metadata(&meta); err == longrunning.ErrNoMetadata {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return &meta, nil
}

// Done reports whether the long-running operation has completed.
func (op *CreateBackupOperation) Done() bool {
	return op.lro.Done()
}

// Name returns the name of the long-running operation.
// The name is assigned by the server and is unique within the service from which the operation is created.
func (op *CreateBackupOperation) Name() string {
	return op.lro.Name()
}

// CreateDatabaseOperation manages a long-running operation from CreateDatabase.
type CreateDatabaseOperation struct {
	lro *longrunning.Operation
}

// CreateDatabaseOperation returns a new CreateDatabaseOperation from a given name.
// The name must be that of a previously created CreateDatabaseOperation, possibly from a different process.
func (c *DatabaseAdminClient) CreateDatabaseOperation(name string) *CreateDatabaseOperation {
	return &CreateDatabaseOperation{
		lro: longrunning.InternalNewOperation(c.LROClient, &longrunningpb.Operation{Name: name}),
	}
}

// Wait blocks until the long-running operation is completed, returning the response and any errors encountered.
//
// See documentation of Poll for error-handling information.
func (op *CreateDatabaseOperation) Wait(ctx context.Context, opts ...gax.CallOption) (*databasepb.Database, error) {
	var resp databasepb.Database
	if err := op.lro.WaitWithInterval(ctx, &resp, time.Minute, opts...); err != nil {
		return nil, err
	}
	return &resp, nil
}

// Poll fetches the latest state of the long-running operation.
//
// Poll also fetches the latest metadata, which can be retrieved by Metadata.
//
// If Poll fails, the error is returned and op is unmodified. If Poll succeeds and
// the operation has completed with failure, the error is returned and op.Done will return true.
// If Poll succeeds and the operation has completed successfully,
// op.Done will return true, and the response of the operation is returned.
// If Poll succeeds and the operation has not completed, the returned response and error are both nil.
func (op *CreateDatabaseOperation) Poll(ctx context.Context, opts ...gax.CallOption) (*databasepb.Database, error) {
	var resp databasepb.Database
	if err := op.lro.Poll(ctx, &resp, opts...); err != nil {
		return nil, err
	}
	if !op.Done() {
		return nil, nil
	}
	return &resp, nil
}

// Metadata returns metadata associated with the long-running operation.
// Metadata itself does not contact the server, but Poll does.
// To get the latest metadata, call this method after a successful call to Poll.
// If the metadata is not available, the returned metadata and error are both nil.
func (op *CreateDatabaseOperation) Metadata() (*databasepb.CreateDatabaseMetadata, error) {
	var meta databasepb.CreateDatabaseMetadata
	if err := op.lro.Metadata(&meta); err == longrunning.ErrNoMetadata {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return &meta, nil
}

// Done reports whether the long-running operation has completed.
func (op *CreateDatabaseOperation) Done() bool {
	return op.lro.Done()
}

// Name returns the name of the long-running operation.
// The name is assigned by the server and is unique within the service from which the operation is created.
func (op *CreateDatabaseOperation) Name() string {
	return op.lro.Name()
}

// RestoreDatabaseOperation manages a long-running operation from RestoreDatabase.
type RestoreDatabaseOperation struct {
	lro *longrunning.Operation
}

// RestoreDatabaseOperation returns a new RestoreDatabaseOperation from a given name.
// The name must be that of a previously created RestoreDatabaseOperation, possibly from a different process.
func (c *DatabaseAdminClient) RestoreDatabaseOperation(name string) *RestoreDatabaseOperation {
	return &RestoreDatabaseOperation{
		lro: longrunning.InternalNewOperation(c.LROClient, &longrunningpb.Operation{Name: name}),
	}
}

// Wait blocks until the long-running operation is completed, returning the response and any errors encountered.
//
// See documentation of Poll for error-handling information.
func (op *RestoreDatabaseOperation) Wait(ctx context.Context, opts ...gax.CallOption) (*databasepb.Database, error) {
	var resp databasepb.Database
	if err := op.lro.WaitWithInterval(ctx, &resp, time.Minute, opts...); err != nil {
		return nil, err
	}
	return &resp, nil
}

// Poll fetches the latest state of the long-running operation.
//
// Poll also fetches the latest metadata, which can be retrieved by Metadata.
//
// If Poll fails, the error is returned and op is unmodified. If Poll succeeds and
// the operation has completed with failure, the error is returned and op.Done will return true.
// If Poll succeeds and the operation has completed successfully,
// op.Done will return true, and the response of the operation is returned.
// If Poll succeeds and the operation has not completed, the returned response and error are both nil.
func (op *RestoreDatabaseOperation) Poll(ctx context.Context, opts ...gax.CallOption) (*databasepb.Database, error) {
	var resp databasepb.Database
	if err := op.lro.Poll(ctx, &resp, opts...); err != nil {
		return nil, err
	}
	if !op.Done() {
		return nil, nil
	}
	return &resp, nil
}

// Metadata returns metadata associated with the long-running operation.
// Metadata itself does not contact the server, but Poll does.
// To get the latest metadata, call this method after a successful call to Poll.
// If the metadata is not available, the returned metadata and error are both nil.
func (op *RestoreDatabaseOperation) Metadata() (*databasepb.RestoreDatabaseMetadata, error) {
	var meta databasepb.RestoreDatabaseMetadata
	if err := op.lro.Metadata(&meta); err == longrunning.ErrNoMetadata {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return &meta, nil
}

// Done reports whether the long-running operation has completed.
func (op *RestoreDatabaseOperation) Done() bool {
	return op.lro.Done()
}

// Name returns the name of the long-running operation.
// The name is assigned by the server and is unique within the service from which the operation is created.
func (op *RestoreDatabaseOperation) Name() string {
	return op.lro.Name()
}

// UpdateDatabaseDdlOperation manages a long-running operation from UpdateDatabaseDdl.
type UpdateDatabaseDdlOperation struct {
	lro *longrunning.Operation
}

// UpdateDatabaseDdlOperation returns a new UpdateDatabaseDdlOperation from a given name.
// The name must be that of a previously created UpdateDatabaseDdlOperation, possibly from a different process.
func (c *DatabaseAdminClient) UpdateDatabaseDdlOperation(name string) *UpdateDatabaseDdlOperation {
	return &UpdateDatabaseDdlOperation{
		lro: longrunning.InternalNewOperation(c.LROClient, &longrunningpb.Operation{Name: name}),
	}
}

// Wait blocks until the long-running operation is completed, returning the response and any errors encountered.
//
// See documentation of Poll for error-handling information.
func (op *UpdateDatabaseDdlOperation) Wait(ctx context.Context, opts ...gax.CallOption) error {
	return op.lro.WaitWithInterval(ctx, nil, time.Minute, opts...)
}

// Poll fetches the latest state of the long-running operation.
//
// Poll also fetches the latest metadata, which can be retrieved by Metadata.
//
// If Poll fails, the error is returned and op is unmodified. If Poll succeeds and
// the operation has completed with failure, the error is returned and op.Done will return true.
// If Poll succeeds and the operation has completed successfully,
// op.Done will return true, and the response of the operation is returned.
// If Poll succeeds and the operation has not completed, the returned response and error are both nil.
func (op *UpdateDatabaseDdlOperation) Poll(ctx context.Context, opts ...gax.CallOption) error {
	return op.lro.Poll(ctx, nil, opts...)
}

// Metadata returns metadata associated with the long-running operation.
// Metadata itself does not contact the server, but Poll does.
// To get the latest metadata, call this method after a successful call to Poll.
// If the metadata is not available, the returned metadata and error are both nil.
func (op *UpdateDatabaseDdlOperation) Metadata() (*databasepb.UpdateDatabaseDdlMetadata, error) {
	var meta databasepb.UpdateDatabaseDdlMetadata
	if err := op.lro.Metadata(&meta); err == longrunning.ErrNoMetadata {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return &meta, nil
}

// Done reports whether the long-running operation has completed.
func (op *UpdateDatabaseDdlOperation) Done() bool {
	return op.lro.Done()
}

// Name returns the name of the long-running operation.
// The name is assigned by the server and is unique within the service from which the operation is created.
func (op *UpdateDatabaseDdlOperation) Name() string {
	return op.lro.Name()
}

// BackupIterator manages a stream of *databasepb.Backup.
type BackupIterator struct {
	items    []*databasepb.Backup
	pageInfo *iterator.PageInfo
	nextFunc func() error

	// Response is the raw response for the current page.
	// It must be cast to the RPC response type.
	// Calling Next() or InternalFetch() updates this value.
	Response interface{}

	// InternalFetch is for use by the Google Cloud Libraries only.
	// It is not part of the stable interface of this package.
	//
	// InternalFetch returns results from a single call to the underlying RPC.
	// The number of results is no greater than pageSize.
	// If there are no more results, nextPageToken is empty and err is nil.
	InternalFetch func(pageSize int, pageToken string) (results []*databasepb.Backup, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *BackupIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

// Next returns the next result. Its second return value is iterator.Done if there are no more
// results. Once Next returns Done, all subsequent calls will return Done.
func (it *BackupIterator) Next() (*databasepb.Backup, error) {
	var item *databasepb.Backup
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

func (it *BackupIterator) bufLen() int {
	return len(it.items)
}

func (it *BackupIterator) takeBuf() interface{} {
	b := it.items
	it.items = nil
	return b
}

// DatabaseIterator manages a stream of *databasepb.Database.
type DatabaseIterator struct {
	items    []*databasepb.Database
	pageInfo *iterator.PageInfo
	nextFunc func() error

	// Response is the raw response for the current page.
	// It must be cast to the RPC response type.
	// Calling Next() or InternalFetch() updates this value.
	Response interface{}

	// InternalFetch is for use by the Google Cloud Libraries only.
	// It is not part of the stable interface of this package.
	//
	// InternalFetch returns results from a single call to the underlying RPC.
	// The number of results is no greater than pageSize.
	// If there are no more results, nextPageToken is empty and err is nil.
	InternalFetch func(pageSize int, pageToken string) (results []*databasepb.Database, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *DatabaseIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

// Next returns the next result. Its second return value is iterator.Done if there are no more
// results. Once Next returns Done, all subsequent calls will return Done.
func (it *DatabaseIterator) Next() (*databasepb.Database, error) {
	var item *databasepb.Database
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

func (it *DatabaseIterator) bufLen() int {
	return len(it.items)
}

func (it *DatabaseIterator) takeBuf() interface{} {
	b := it.items
	it.items = nil
	return b
}

// OperationIterator manages a stream of *longrunningpb.Operation.
type OperationIterator struct {
	items    []*longrunningpb.Operation
	pageInfo *iterator.PageInfo
	nextFunc func() error

	// Response is the raw response for the current page.
	// It must be cast to the RPC response type.
	// Calling Next() or InternalFetch() updates this value.
	Response interface{}

	// InternalFetch is for use by the Google Cloud Libraries only.
	// It is not part of the stable interface of this package.
	//
	// InternalFetch returns results from a single call to the underlying RPC.
	// The number of results is no greater than pageSize.
	// If there are no more results, nextPageToken is empty and err is nil.
	InternalFetch func(pageSize int, pageToken string) (results []*longrunningpb.Operation, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *OperationIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

// Next returns the next result. Its second return value is iterator.Done if there are no more
// results. Once Next returns Done, all subsequent calls will return Done.
func (it *OperationIterator) Next() (*longrunningpb.Operation, error) {
	var item *longrunningpb.Operation
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

func (it *OperationIterator) bufLen() int {
	return len(it.items)
}

func (it *OperationIterator) takeBuf() interface{} {
	b := it.items
	it.items = nil
	return b
}