// Copyright 2022 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 compute

import (
	"bytes"
	"context"
	"fmt"
	"io/ioutil"
	"math"
	"net/http"
	"net/url"

	gax "github.com/googleapis/gax-go/v2"
	"google.golang.org/api/googleapi"
	"google.golang.org/api/iterator"
	"google.golang.org/api/option"
	"google.golang.org/api/option/internaloption"
	httptransport "google.golang.org/api/transport/http"
	computepb "google.golang.org/genproto/googleapis/cloud/compute/v1"
	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
	"google.golang.org/protobuf/encoding/protojson"
	"google.golang.org/protobuf/proto"
)

var newSnapshotsClientHook clientHook

// SnapshotsCallOptions contains the retry settings for each method of SnapshotsClient.
type SnapshotsCallOptions struct {
	Delete             []gax.CallOption
	Get                []gax.CallOption
	GetIamPolicy       []gax.CallOption
	List               []gax.CallOption
	SetIamPolicy       []gax.CallOption
	SetLabels          []gax.CallOption
	TestIamPermissions []gax.CallOption
}

// internalSnapshotsClient is an interface that defines the methods availaible from Google Compute Engine API.
type internalSnapshotsClient interface {
	Close() error
	setGoogleClientInfo(...string)
	Connection() *grpc.ClientConn
	Delete(context.Context, *computepb.DeleteSnapshotRequest, ...gax.CallOption) (*Operation, error)
	Get(context.Context, *computepb.GetSnapshotRequest, ...gax.CallOption) (*computepb.Snapshot, error)
	GetIamPolicy(context.Context, *computepb.GetIamPolicySnapshotRequest, ...gax.CallOption) (*computepb.Policy, error)
	List(context.Context, *computepb.ListSnapshotsRequest, ...gax.CallOption) *SnapshotIterator
	SetIamPolicy(context.Context, *computepb.SetIamPolicySnapshotRequest, ...gax.CallOption) (*computepb.Policy, error)
	SetLabels(context.Context, *computepb.SetLabelsSnapshotRequest, ...gax.CallOption) (*Operation, error)
	TestIamPermissions(context.Context, *computepb.TestIamPermissionsSnapshotRequest, ...gax.CallOption) (*computepb.TestPermissionsResponse, error)
}

// SnapshotsClient is a client for interacting with Google Compute Engine API.
// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
//
// The Snapshots API.
type SnapshotsClient struct {
	// The internal transport-dependent client.
	internalClient internalSnapshotsClient

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

// Wrapper methods routed to the internal client.

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

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

// Delete deletes the specified Snapshot resource. Keep in mind that deleting a single snapshot might not necessarily delete all the data on that snapshot. If any data on the snapshot that is marked for deletion is needed for subsequent snapshots, the data will be moved to the next corresponding snapshot. For more information, see Deleting snapshots.
func (c *SnapshotsClient) Delete(ctx context.Context, req *computepb.DeleteSnapshotRequest, opts ...gax.CallOption) (*Operation, error) {
	return c.internalClient.Delete(ctx, req, opts...)
}

// Get returns the specified Snapshot resource. Gets a list of available snapshots by making a list() request.
func (c *SnapshotsClient) Get(ctx context.Context, req *computepb.GetSnapshotRequest, opts ...gax.CallOption) (*computepb.Snapshot, error) {
	return c.internalClient.Get(ctx, req, opts...)
}

// GetIamPolicy gets the access control policy for a resource. May be empty if no such policy or resource exists.
func (c *SnapshotsClient) GetIamPolicy(ctx context.Context, req *computepb.GetIamPolicySnapshotRequest, opts ...gax.CallOption) (*computepb.Policy, error) {
	return c.internalClient.GetIamPolicy(ctx, req, opts...)
}

// List retrieves the list of Snapshot resources contained within the specified project.
func (c *SnapshotsClient) List(ctx context.Context, req *computepb.ListSnapshotsRequest, opts ...gax.CallOption) *SnapshotIterator {
	return c.internalClient.List(ctx, req, opts...)
}

// SetIamPolicy sets the access control policy on the specified resource. Replaces any existing policy.
func (c *SnapshotsClient) SetIamPolicy(ctx context.Context, req *computepb.SetIamPolicySnapshotRequest, opts ...gax.CallOption) (*computepb.Policy, error) {
	return c.internalClient.SetIamPolicy(ctx, req, opts...)
}

// SetLabels sets the labels on a snapshot. To learn more about labels, read the Labeling Resources documentation.
func (c *SnapshotsClient) SetLabels(ctx context.Context, req *computepb.SetLabelsSnapshotRequest, opts ...gax.CallOption) (*Operation, error) {
	return c.internalClient.SetLabels(ctx, req, opts...)
}

// TestIamPermissions returns permissions that a caller has on the specified resource.
func (c *SnapshotsClient) TestIamPermissions(ctx context.Context, req *computepb.TestIamPermissionsSnapshotRequest, opts ...gax.CallOption) (*computepb.TestPermissionsResponse, error) {
	return c.internalClient.TestIamPermissions(ctx, req, opts...)
}

// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
type snapshotsRESTClient struct {
	// The http endpoint to connect to.
	endpoint string

	// The http client.
	httpClient *http.Client

	// operationClient is used to call the operation-specific management service.
	operationClient *GlobalOperationsClient

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

// NewSnapshotsRESTClient creates a new snapshots rest client.
//
// The Snapshots API.
func NewSnapshotsRESTClient(ctx context.Context, opts ...option.ClientOption) (*SnapshotsClient, error) {
	clientOpts := append(defaultSnapshotsRESTClientOptions(), opts...)
	httpClient, endpoint, err := httptransport.NewClient(ctx, clientOpts...)
	if err != nil {
		return nil, err
	}

	c := &snapshotsRESTClient{
		endpoint:   endpoint,
		httpClient: httpClient,
	}
	c.setGoogleClientInfo()

	o := []option.ClientOption{
		option.WithHTTPClient(httpClient),
		option.WithEndpoint(endpoint),
	}
	opC, err := NewGlobalOperationsRESTClient(ctx, o...)
	if err != nil {
		return nil, err
	}
	c.operationClient = opC

	return &SnapshotsClient{internalClient: c, CallOptions: &SnapshotsCallOptions{}}, nil
}

func defaultSnapshotsRESTClientOptions() []option.ClientOption {
	return []option.ClientOption{
		internaloption.WithDefaultEndpoint("https://compute.googleapis.com"),
		internaloption.WithDefaultMTLSEndpoint("https://compute.mtls.googleapis.com"),
		internaloption.WithDefaultAudience("https://compute.googleapis.com/"),
		internaloption.WithDefaultScopes(DefaultAuthScopes()...),
	}
}

// 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 *snapshotsRESTClient) setGoogleClientInfo(keyval ...string) {
	kv := append([]string{"gl-go", versionGo()}, keyval...)
	kv = append(kv, "gapic", versionClient, "gax", gax.Version, "rest", "UNKNOWN")
	c.xGoogMetadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
}

// Close closes the connection to the API service. The user should invoke this when
// the client is no longer required.
func (c *snapshotsRESTClient) Close() error {
	// Replace httpClient with nil to force cleanup.
	c.httpClient = nil
	if err := c.operationClient.Close(); err != nil {
		return err
	}
	return nil
}

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

// Delete deletes the specified Snapshot resource. Keep in mind that deleting a single snapshot might not necessarily delete all the data on that snapshot. If any data on the snapshot that is marked for deletion is needed for subsequent snapshots, the data will be moved to the next corresponding snapshot. For more information, see Deleting snapshots.
func (c *snapshotsRESTClient) Delete(ctx context.Context, req *computepb.DeleteSnapshotRequest, opts ...gax.CallOption) (*Operation, error) {
	baseUrl, _ := url.Parse(c.endpoint)
	baseUrl.Path += fmt.Sprintf("/compute/v1/projects/%v/global/snapshots/%v", req.GetProject(), req.GetSnapshot())

	params := url.Values{}
	if req != nil && req.RequestId != nil {
		params.Add("requestId", fmt.Sprintf("%v", req.GetRequestId()))
	}

	baseUrl.RawQuery = params.Encode()

	// Build HTTP headers from client and context metadata.
	headers := buildHeaders(ctx, c.xGoogMetadata, metadata.Pairs("Content-Type", "application/json"))
	unm := protojson.UnmarshalOptions{AllowPartial: true, DiscardUnknown: true}
	resp := &computepb.Operation{}
	e := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		httpReq, err := http.NewRequest("DELETE", baseUrl.String(), nil)
		if err != nil {
			return err
		}
		httpReq = httpReq.WithContext(ctx)
		httpReq.Header = headers

		httpRsp, err := c.httpClient.Do(httpReq)
		if err != nil {
			return err
		}
		defer httpRsp.Body.Close()

		if err = googleapi.CheckResponse(httpRsp); err != nil {
			return err
		}

		buf, err := ioutil.ReadAll(httpRsp.Body)
		if err != nil {
			return err
		}

		if err := unm.Unmarshal(buf, resp); err != nil {
			return maybeUnknownEnum(err)
		}

		return nil
	}, opts...)
	if e != nil {
		return nil, e
	}
	op := &Operation{
		&globalOperationsHandle{
			c:       c.operationClient,
			proto:   resp,
			project: req.GetProject(),
		},
	}
	return op, nil
}

// Get returns the specified Snapshot resource. Gets a list of available snapshots by making a list() request.
func (c *snapshotsRESTClient) Get(ctx context.Context, req *computepb.GetSnapshotRequest, opts ...gax.CallOption) (*computepb.Snapshot, error) {
	baseUrl, _ := url.Parse(c.endpoint)
	baseUrl.Path += fmt.Sprintf("/compute/v1/projects/%v/global/snapshots/%v", req.GetProject(), req.GetSnapshot())

	// Build HTTP headers from client and context metadata.
	headers := buildHeaders(ctx, c.xGoogMetadata, metadata.Pairs("Content-Type", "application/json"))
	unm := protojson.UnmarshalOptions{AllowPartial: true, DiscardUnknown: true}
	resp := &computepb.Snapshot{}
	e := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		httpReq, err := http.NewRequest("GET", baseUrl.String(), nil)
		if err != nil {
			return err
		}
		httpReq = httpReq.WithContext(ctx)
		httpReq.Header = headers

		httpRsp, err := c.httpClient.Do(httpReq)
		if err != nil {
			return err
		}
		defer httpRsp.Body.Close()

		if err = googleapi.CheckResponse(httpRsp); err != nil {
			return err
		}

		buf, err := ioutil.ReadAll(httpRsp.Body)
		if err != nil {
			return err
		}

		if err := unm.Unmarshal(buf, resp); err != nil {
			return maybeUnknownEnum(err)
		}

		return nil
	}, opts...)
	if e != nil {
		return nil, e
	}
	return resp, nil
}

// GetIamPolicy gets the access control policy for a resource. May be empty if no such policy or resource exists.
func (c *snapshotsRESTClient) GetIamPolicy(ctx context.Context, req *computepb.GetIamPolicySnapshotRequest, opts ...gax.CallOption) (*computepb.Policy, error) {
	baseUrl, _ := url.Parse(c.endpoint)
	baseUrl.Path += fmt.Sprintf("/compute/v1/projects/%v/global/snapshots/%v/getIamPolicy", req.GetProject(), req.GetResource())

	params := url.Values{}
	if req != nil && req.OptionsRequestedPolicyVersion != nil {
		params.Add("optionsRequestedPolicyVersion", fmt.Sprintf("%v", req.GetOptionsRequestedPolicyVersion()))
	}

	baseUrl.RawQuery = params.Encode()

	// Build HTTP headers from client and context metadata.
	headers := buildHeaders(ctx, c.xGoogMetadata, metadata.Pairs("Content-Type", "application/json"))
	unm := protojson.UnmarshalOptions{AllowPartial: true, DiscardUnknown: true}
	resp := &computepb.Policy{}
	e := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		httpReq, err := http.NewRequest("GET", baseUrl.String(), nil)
		if err != nil {
			return err
		}
		httpReq = httpReq.WithContext(ctx)
		httpReq.Header = headers

		httpRsp, err := c.httpClient.Do(httpReq)
		if err != nil {
			return err
		}
		defer httpRsp.Body.Close()

		if err = googleapi.CheckResponse(httpRsp); err != nil {
			return err
		}

		buf, err := ioutil.ReadAll(httpRsp.Body)
		if err != nil {
			return err
		}

		if err := unm.Unmarshal(buf, resp); err != nil {
			return maybeUnknownEnum(err)
		}

		return nil
	}, opts...)
	if e != nil {
		return nil, e
	}
	return resp, nil
}

// List retrieves the list of Snapshot resources contained within the specified project.
func (c *snapshotsRESTClient) List(ctx context.Context, req *computepb.ListSnapshotsRequest, opts ...gax.CallOption) *SnapshotIterator {
	it := &SnapshotIterator{}
	req = proto.Clone(req).(*computepb.ListSnapshotsRequest)
	unm := protojson.UnmarshalOptions{AllowPartial: true, DiscardUnknown: true}
	it.InternalFetch = func(pageSize int, pageToken string) ([]*computepb.Snapshot, string, error) {
		resp := &computepb.SnapshotList{}
		if pageToken != "" {
			req.PageToken = proto.String(pageToken)
		}
		if pageSize > math.MaxInt32 {
			req.MaxResults = proto.Uint32(math.MaxInt32)
		} else if pageSize != 0 {
			req.MaxResults = proto.Uint32(uint32(pageSize))
		}
		baseUrl, _ := url.Parse(c.endpoint)
		baseUrl.Path += fmt.Sprintf("/compute/v1/projects/%v/global/snapshots", req.GetProject())

		params := url.Values{}
		if req != nil && req.Filter != nil {
			params.Add("filter", fmt.Sprintf("%v", req.GetFilter()))
		}
		if req != nil && req.MaxResults != nil {
			params.Add("maxResults", fmt.Sprintf("%v", req.GetMaxResults()))
		}
		if req != nil && req.OrderBy != nil {
			params.Add("orderBy", fmt.Sprintf("%v", req.GetOrderBy()))
		}
		if req != nil && req.PageToken != nil {
			params.Add("pageToken", fmt.Sprintf("%v", req.GetPageToken()))
		}
		if req != nil && req.ReturnPartialSuccess != nil {
			params.Add("returnPartialSuccess", fmt.Sprintf("%v", req.GetReturnPartialSuccess()))
		}

		baseUrl.RawQuery = params.Encode()

		// Build HTTP headers from client and context metadata.
		headers := buildHeaders(ctx, c.xGoogMetadata, metadata.Pairs("Content-Type", "application/json"))
		e := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			httpReq, err := http.NewRequest("GET", baseUrl.String(), nil)
			if err != nil {
				return err
			}
			httpReq.Header = headers

			httpRsp, err := c.httpClient.Do(httpReq)
			if err != nil {
				return err
			}
			defer httpRsp.Body.Close()

			if err = googleapi.CheckResponse(httpRsp); err != nil {
				return err
			}

			buf, err := ioutil.ReadAll(httpRsp.Body)
			if err != nil {
				return err
			}

			if err := unm.Unmarshal(buf, resp); err != nil {
				return maybeUnknownEnum(err)
			}

			return nil
		}, opts...)
		if e != nil {
			return nil, "", e
		}
		it.Response = resp
		return resp.GetItems(), resp.GetNextPageToken(), 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.GetMaxResults())
	it.pageInfo.Token = req.GetPageToken()

	return it
}

// SetIamPolicy sets the access control policy on the specified resource. Replaces any existing policy.
func (c *snapshotsRESTClient) SetIamPolicy(ctx context.Context, req *computepb.SetIamPolicySnapshotRequest, opts ...gax.CallOption) (*computepb.Policy, error) {
	m := protojson.MarshalOptions{AllowPartial: true}
	body := req.GetGlobalSetPolicyRequestResource()
	jsonReq, err := m.Marshal(body)
	if err != nil {
		return nil, err
	}

	baseUrl, _ := url.Parse(c.endpoint)
	baseUrl.Path += fmt.Sprintf("/compute/v1/projects/%v/global/snapshots/%v/setIamPolicy", req.GetProject(), req.GetResource())

	// Build HTTP headers from client and context metadata.
	headers := buildHeaders(ctx, c.xGoogMetadata, metadata.Pairs("Content-Type", "application/json"))
	unm := protojson.UnmarshalOptions{AllowPartial: true, DiscardUnknown: true}
	resp := &computepb.Policy{}
	e := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		httpReq, err := http.NewRequest("POST", baseUrl.String(), bytes.NewReader(jsonReq))
		if err != nil {
			return err
		}
		httpReq = httpReq.WithContext(ctx)
		httpReq.Header = headers

		httpRsp, err := c.httpClient.Do(httpReq)
		if err != nil {
			return err
		}
		defer httpRsp.Body.Close()

		if err = googleapi.CheckResponse(httpRsp); err != nil {
			return err
		}

		buf, err := ioutil.ReadAll(httpRsp.Body)
		if err != nil {
			return err
		}

		if err := unm.Unmarshal(buf, resp); err != nil {
			return maybeUnknownEnum(err)
		}

		return nil
	}, opts...)
	if e != nil {
		return nil, e
	}
	return resp, nil
}

// SetLabels sets the labels on a snapshot. To learn more about labels, read the Labeling Resources documentation.
func (c *snapshotsRESTClient) SetLabels(ctx context.Context, req *computepb.SetLabelsSnapshotRequest, opts ...gax.CallOption) (*Operation, error) {
	m := protojson.MarshalOptions{AllowPartial: true}
	body := req.GetGlobalSetLabelsRequestResource()
	jsonReq, err := m.Marshal(body)
	if err != nil {
		return nil, err
	}

	baseUrl, _ := url.Parse(c.endpoint)
	baseUrl.Path += fmt.Sprintf("/compute/v1/projects/%v/global/snapshots/%v/setLabels", req.GetProject(), req.GetResource())

	// Build HTTP headers from client and context metadata.
	headers := buildHeaders(ctx, c.xGoogMetadata, metadata.Pairs("Content-Type", "application/json"))
	unm := protojson.UnmarshalOptions{AllowPartial: true, DiscardUnknown: true}
	resp := &computepb.Operation{}
	e := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		httpReq, err := http.NewRequest("POST", baseUrl.String(), bytes.NewReader(jsonReq))
		if err != nil {
			return err
		}
		httpReq = httpReq.WithContext(ctx)
		httpReq.Header = headers

		httpRsp, err := c.httpClient.Do(httpReq)
		if err != nil {
			return err
		}
		defer httpRsp.Body.Close()

		if err = googleapi.CheckResponse(httpRsp); err != nil {
			return err
		}

		buf, err := ioutil.ReadAll(httpRsp.Body)
		if err != nil {
			return err
		}

		if err := unm.Unmarshal(buf, resp); err != nil {
			return maybeUnknownEnum(err)
		}

		return nil
	}, opts...)
	if e != nil {
		return nil, e
	}
	op := &Operation{
		&globalOperationsHandle{
			c:       c.operationClient,
			proto:   resp,
			project: req.GetProject(),
		},
	}
	return op, nil
}

// TestIamPermissions returns permissions that a caller has on the specified resource.
func (c *snapshotsRESTClient) TestIamPermissions(ctx context.Context, req *computepb.TestIamPermissionsSnapshotRequest, opts ...gax.CallOption) (*computepb.TestPermissionsResponse, error) {
	m := protojson.MarshalOptions{AllowPartial: true}
	body := req.GetTestPermissionsRequestResource()
	jsonReq, err := m.Marshal(body)
	if err != nil {
		return nil, err
	}

	baseUrl, _ := url.Parse(c.endpoint)
	baseUrl.Path += fmt.Sprintf("/compute/v1/projects/%v/global/snapshots/%v/testIamPermissions", req.GetProject(), req.GetResource())

	// Build HTTP headers from client and context metadata.
	headers := buildHeaders(ctx, c.xGoogMetadata, metadata.Pairs("Content-Type", "application/json"))
	unm := protojson.UnmarshalOptions{AllowPartial: true, DiscardUnknown: true}
	resp := &computepb.TestPermissionsResponse{}
	e := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		httpReq, err := http.NewRequest("POST", baseUrl.String(), bytes.NewReader(jsonReq))
		if err != nil {
			return err
		}
		httpReq = httpReq.WithContext(ctx)
		httpReq.Header = headers

		httpRsp, err := c.httpClient.Do(httpReq)
		if err != nil {
			return err
		}
		defer httpRsp.Body.Close()

		if err = googleapi.CheckResponse(httpRsp); err != nil {
			return err
		}

		buf, err := ioutil.ReadAll(httpRsp.Body)
		if err != nil {
			return err
		}

		if err := unm.Unmarshal(buf, resp); err != nil {
			return maybeUnknownEnum(err)
		}

		return nil
	}, opts...)
	if e != nil {
		return nil, e
	}
	return resp, nil
}

// SnapshotIterator manages a stream of *computepb.Snapshot.
type SnapshotIterator struct {
	items    []*computepb.Snapshot
	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 []*computepb.Snapshot, nextPageToken string, err error)
}

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

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

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