// 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 secretmanager

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

	"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"
	secretmanagerpb "google.golang.org/genproto/googleapis/cloud/secretmanager/v1"
	iampb "google.golang.org/genproto/googleapis/iam/v1"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
)

// CallOptions contains the retry settings for each method of Client.
type CallOptions struct {
	ListSecrets          []gax.CallOption
	CreateSecret         []gax.CallOption
	AddSecretVersion     []gax.CallOption
	GetSecret            []gax.CallOption
	UpdateSecret         []gax.CallOption
	DeleteSecret         []gax.CallOption
	ListSecretVersions   []gax.CallOption
	GetSecretVersion     []gax.CallOption
	AccessSecretVersion  []gax.CallOption
	DisableSecretVersion []gax.CallOption
	EnableSecretVersion  []gax.CallOption
	DestroySecretVersion []gax.CallOption
	SetIamPolicy         []gax.CallOption
	GetIamPolicy         []gax.CallOption
	TestIamPermissions   []gax.CallOption
}

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

func defaultCallOptions() *CallOptions {
	return &CallOptions{
		ListSecrets:        []gax.CallOption{},
		CreateSecret:       []gax.CallOption{},
		AddSecretVersion:   []gax.CallOption{},
		GetSecret:          []gax.CallOption{},
		UpdateSecret:       []gax.CallOption{},
		DeleteSecret:       []gax.CallOption{},
		ListSecretVersions: []gax.CallOption{},
		GetSecretVersion:   []gax.CallOption{},
		AccessSecretVersion: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    1000 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DisableSecretVersion: []gax.CallOption{},
		EnableSecretVersion:  []gax.CallOption{},
		DestroySecretVersion: []gax.CallOption{},
		SetIamPolicy:         []gax.CallOption{},
		GetIamPolicy:         []gax.CallOption{},
		TestIamPermissions:   []gax.CallOption{},
	}
}

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

	// The gRPC API client.
	client secretmanagerpb.SecretManagerServiceClient

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

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

// NewClient creates a new secret manager service client.
//
// Secret Manager Service
//
// Manages secrets and operations using those secrets. Implements a REST
// model with the following objects:
//
//   Secret
//
//   SecretVersion
func NewClient(ctx context.Context, opts ...option.ClientOption) (*Client, error) {
	connPool, err := gtransport.DialPool(ctx, append(defaultClientOptions(), opts...)...)
	if err != nil {
		return nil, err
	}
	c := &Client{
		connPool:    connPool,
		CallOptions: defaultCallOptions(),

		client: secretmanagerpb.NewSecretManagerServiceClient(connPool),
	}
	c.setGoogleClientInfo()

	return c, nil
}

// Connection returns a connection to the API service.
//
// Deprecated.
func (c *Client) 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 *Client) 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 *Client) 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...))
}

// ListSecrets lists Secrets.
func (c *Client) ListSecrets(ctx context.Context, req *secretmanagerpb.ListSecretsRequest, opts ...gax.CallOption) *SecretIterator {
	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.ListSecrets[0:len(c.CallOptions.ListSecrets):len(c.CallOptions.ListSecrets)], opts...)
	it := &SecretIterator{}
	req = proto.Clone(req).(*secretmanagerpb.ListSecretsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*secretmanagerpb.Secret, string, error) {
		var resp *secretmanagerpb.ListSecretsResponse
		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.client.ListSecrets(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.Secrets, 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
}

// CreateSecret creates a new Secret containing no SecretVersions.
func (c *Client) CreateSecret(ctx context.Context, req *secretmanagerpb.CreateSecretRequest, opts ...gax.CallOption) (*secretmanagerpb.Secret, 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.CreateSecret[0:len(c.CallOptions.CreateSecret):len(c.CallOptions.CreateSecret)], opts...)
	var resp *secretmanagerpb.Secret
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.CreateSecret(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// AddSecretVersion creates a new SecretVersion containing secret data and attaches
// it to an existing Secret.
func (c *Client) AddSecretVersion(ctx context.Context, req *secretmanagerpb.AddSecretVersionRequest, opts ...gax.CallOption) (*secretmanagerpb.SecretVersion, 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.AddSecretVersion[0:len(c.CallOptions.AddSecretVersion):len(c.CallOptions.AddSecretVersion)], opts...)
	var resp *secretmanagerpb.SecretVersion
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.AddSecretVersion(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// GetSecret gets metadata for a given Secret.
func (c *Client) GetSecret(ctx context.Context, req *secretmanagerpb.GetSecretRequest, opts ...gax.CallOption) (*secretmanagerpb.Secret, 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.GetSecret[0:len(c.CallOptions.GetSecret):len(c.CallOptions.GetSecret)], opts...)
	var resp *secretmanagerpb.Secret
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.GetSecret(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// UpdateSecret updates metadata of an existing Secret.
func (c *Client) UpdateSecret(ctx context.Context, req *secretmanagerpb.UpdateSecretRequest, opts ...gax.CallOption) (*secretmanagerpb.Secret, error) {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "secret.name", url.QueryEscape(req.GetSecret().GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.UpdateSecret[0:len(c.CallOptions.UpdateSecret):len(c.CallOptions.UpdateSecret)], opts...)
	var resp *secretmanagerpb.Secret
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.UpdateSecret(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// DeleteSecret deletes a Secret.
func (c *Client) DeleteSecret(ctx context.Context, req *secretmanagerpb.DeleteSecretRequest, 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.DeleteSecret[0:len(c.CallOptions.DeleteSecret):len(c.CallOptions.DeleteSecret)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.client.DeleteSecret(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

// ListSecretVersions lists SecretVersions. This call does not return secret
// data.
func (c *Client) ListSecretVersions(ctx context.Context, req *secretmanagerpb.ListSecretVersionsRequest, opts ...gax.CallOption) *SecretVersionIterator {
	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.ListSecretVersions[0:len(c.CallOptions.ListSecretVersions):len(c.CallOptions.ListSecretVersions)], opts...)
	it := &SecretVersionIterator{}
	req = proto.Clone(req).(*secretmanagerpb.ListSecretVersionsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*secretmanagerpb.SecretVersion, string, error) {
		var resp *secretmanagerpb.ListSecretVersionsResponse
		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.client.ListSecretVersions(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.Versions, 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
}

// GetSecretVersion gets metadata for a SecretVersion.
//
// projects/*/secrets/*/versions/latest is an alias to the latest
// SecretVersion.
func (c *Client) GetSecretVersion(ctx context.Context, req *secretmanagerpb.GetSecretVersionRequest, opts ...gax.CallOption) (*secretmanagerpb.SecretVersion, 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.GetSecretVersion[0:len(c.CallOptions.GetSecretVersion):len(c.CallOptions.GetSecretVersion)], opts...)
	var resp *secretmanagerpb.SecretVersion
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.GetSecretVersion(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// AccessSecretVersion accesses a SecretVersion. This call returns the secret data.
//
// projects/*/secrets/*/versions/latest is an alias to the latest
// SecretVersion.
func (c *Client) AccessSecretVersion(ctx context.Context, req *secretmanagerpb.AccessSecretVersionRequest, opts ...gax.CallOption) (*secretmanagerpb.AccessSecretVersionResponse, 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.AccessSecretVersion[0:len(c.CallOptions.AccessSecretVersion):len(c.CallOptions.AccessSecretVersion)], opts...)
	var resp *secretmanagerpb.AccessSecretVersionResponse
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.AccessSecretVersion(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// DisableSecretVersion disables a SecretVersion.
//
// Sets the state of the SecretVersion to
// DISABLED.
func (c *Client) DisableSecretVersion(ctx context.Context, req *secretmanagerpb.DisableSecretVersionRequest, opts ...gax.CallOption) (*secretmanagerpb.SecretVersion, 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.DisableSecretVersion[0:len(c.CallOptions.DisableSecretVersion):len(c.CallOptions.DisableSecretVersion)], opts...)
	var resp *secretmanagerpb.SecretVersion
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.DisableSecretVersion(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// EnableSecretVersion enables a SecretVersion.
//
// Sets the state of the SecretVersion to
// ENABLED.
func (c *Client) EnableSecretVersion(ctx context.Context, req *secretmanagerpb.EnableSecretVersionRequest, opts ...gax.CallOption) (*secretmanagerpb.SecretVersion, 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.EnableSecretVersion[0:len(c.CallOptions.EnableSecretVersion):len(c.CallOptions.EnableSecretVersion)], opts...)
	var resp *secretmanagerpb.SecretVersion
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.EnableSecretVersion(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// DestroySecretVersion destroys a SecretVersion.
//
// Sets the state of the SecretVersion to
// DESTROYED and irrevocably destroys the
// secret data.
func (c *Client) DestroySecretVersion(ctx context.Context, req *secretmanagerpb.DestroySecretVersionRequest, opts ...gax.CallOption) (*secretmanagerpb.SecretVersion, 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.DestroySecretVersion[0:len(c.CallOptions.DestroySecretVersion):len(c.CallOptions.DestroySecretVersion)], opts...)
	var resp *secretmanagerpb.SecretVersion
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.DestroySecretVersion(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// SetIamPolicy sets the access control policy on the specified secret. Replaces any
// existing policy.
//
// Permissions on SecretVersions are enforced according
// to the policy set on the associated Secret.
func (c *Client) 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.client.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 secret.
// Returns empty policy if the secret exists and does not have a policy set.
func (c *Client) 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.client.GetIamPolicy(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// TestIamPermissions returns permissions that a caller has for the specified secret.
// If the secret does not exist, this call returns an empty set of
// permissions, not a NOT_FOUND error.
//
// Note: This operation is designed to be used for building permission-aware
// UIs and command-line tools, not for authorization checking. This operation
// may “fail open” without warning.
func (c *Client) 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.client.TestIamPermissions(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// SecretIterator manages a stream of *secretmanagerpb.Secret.
type SecretIterator struct {
	items    []*secretmanagerpb.Secret
	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 []*secretmanagerpb.Secret, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *SecretIterator) 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 *SecretIterator) Next() (*secretmanagerpb.Secret, error) {
	var item *secretmanagerpb.Secret
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

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

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

// SecretVersionIterator manages a stream of *secretmanagerpb.SecretVersion.
type SecretVersionIterator struct {
	items    []*secretmanagerpb.SecretVersion
	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 []*secretmanagerpb.SecretVersion, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *SecretVersionIterator) 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 *SecretVersionIterator) Next() (*secretmanagerpb.SecretVersion, error) {
	var item *secretmanagerpb.SecretVersion
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

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

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