package pubsublite

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"
	"google.golang.org/api/option/internaloption"
	gtransport "google.golang.org/api/transport/grpc"
	pubsublitepb "google.golang.org/genproto/googleapis/cloud/pubsublite/v1"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
)

var newAdminClientHook clientHook

type AdminCallOptions struct {
	CreateTopic            []gax.CallOption
	GetTopic               []gax.CallOption
	GetTopicPartitions     []gax.CallOption
	ListTopics             []gax.CallOption
	UpdateTopic            []gax.CallOption
	DeleteTopic            []gax.CallOption
	ListTopicSubscriptions []gax.CallOption
	CreateSubscription     []gax.CallOption
	GetSubscription        []gax.CallOption
	ListSubscriptions      []gax.CallOption
	UpdateSubscription     []gax.CallOption
	DeleteSubscription     []gax.CallOption
}

func defaultAdminClientOptions() []option.ClientOption {
	return []option.ClientOption{
		internaloption.WithDefaultEndpoint("pubsublite.googleapis.com:443"),
		internaloption.WithDefaultMTLSEndpoint("pubsublite.mtls.googleapis.com:443"),
		internaloption.WithDefaultAudience("https:
		internaloption.WithDefaultScopes(DefaultAuthScopes()...),
		option.WithGRPCDialOption(grpc.WithDisableServiceConfig()),
		option.WithGRPCDialOption(grpc.WithDefaultCallOptions(
			grpc.MaxCallRecvMsgSize(math.MaxInt32))),
	}
}

func defaultAdminCallOptions() *AdminCallOptions {
	return &AdminCallOptions{
		CreateTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetTopicPartitions: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListTopics: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		UpdateTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DeleteTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListTopicSubscriptions: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		CreateSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListSubscriptions: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		UpdateSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DeleteSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
	}
}

type AdminClient struct {

	connPool gtransport.ConnPool

	disableDeadlines bool

	adminClient pubsublitepb.AdminServiceClient

	CallOptions *AdminCallOptions

	xGoogMetadata metadata.MD
}

func NewAdminClient(ctx context.Context, opts ...option.ClientOption) (*AdminClient, error) {
	clientOpts := defaultAdminClientOptions()

	if newAdminClientHook != nil {
		hookOpts, err := newAdminClientHook(ctx, clientHookParams{})
		if err != nil {
			return nil, err
		}
		clientOpts = append(clientOpts, hookOpts...)
	}

	disableDeadlines, err := checkDisableDeadlines()
	if err != nil {
		return nil, err
	}

	connPool, err := gtransport.DialPool(ctx, append(clientOpts, opts...)...)
	if err != nil {
		return nil, err
	}
	c := &AdminClient{
		connPool:         connPool,
		disableDeadlines: disableDeadlines,
		CallOptions:      defaultAdminCallOptions(),

		adminClient: pubsublitepb.NewAdminServiceClient(connPool),
	}
	c.setGoogleClientInfo()

	return c, nil
}

func (c *AdminClient) Connection() *grpc.ClientConn {
	return c.connPool.Conn()
}

func (c *AdminClient) Close() error {
	return c.connPool.Close()
}

func (c *AdminClient) 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...))
}

func (c *AdminClient) CreateTopic(ctx context.Context, req *pubsublitepb.CreateTopicRequest, opts ...gax.CallOption) (*pubsublitepb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.CreateTopic[0:len(c.CallOptions.CreateTopic):len(c.CallOptions.CreateTopic)], opts...)
	var resp *pubsublitepb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.CreateTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *AdminClient) GetTopic(ctx context.Context, req *pubsublitepb.GetTopicRequest, opts ...gax.CallOption) (*pubsublitepb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.GetTopic[0:len(c.CallOptions.GetTopic):len(c.CallOptions.GetTopic)], opts...)
	var resp *pubsublitepb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.GetTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *AdminClient) GetTopicPartitions(ctx context.Context, req *pubsublitepb.GetTopicPartitionsRequest, opts ...gax.CallOption) (*pubsublitepb.TopicPartitions, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.GetTopicPartitions[0:len(c.CallOptions.GetTopicPartitions):len(c.CallOptions.GetTopicPartitions)], opts...)
	var resp *pubsublitepb.TopicPartitions
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.GetTopicPartitions(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *AdminClient) ListTopics(ctx context.Context, req *pubsublitepb.ListTopicsRequest, opts ...gax.CallOption) *TopicIterator {
	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.ListTopics[0:len(c.CallOptions.ListTopics):len(c.CallOptions.ListTopics)], opts...)
	it := &TopicIterator{}
	req = proto.Clone(req).(*pubsublitepb.ListTopicsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*pubsublitepb.Topic, string, error) {
		var resp *pubsublitepb.ListTopicsResponse
		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.adminClient.ListTopics(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetTopics(), 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.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()
	return it
}

func (c *AdminClient) UpdateTopic(ctx context.Context, req *pubsublitepb.UpdateTopicRequest, opts ...gax.CallOption) (*pubsublitepb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "topic.name", url.QueryEscape(req.GetTopic().GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.UpdateTopic[0:len(c.CallOptions.UpdateTopic):len(c.CallOptions.UpdateTopic)], opts...)
	var resp *pubsublitepb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.UpdateTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *AdminClient) DeleteTopic(ctx context.Context, req *pubsublitepb.DeleteTopicRequest, opts ...gax.CallOption) error {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.DeleteTopic[0:len(c.CallOptions.DeleteTopic):len(c.CallOptions.DeleteTopic)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.adminClient.DeleteTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

func (c *AdminClient) ListTopicSubscriptions(ctx context.Context, req *pubsublitepb.ListTopicSubscriptionsRequest, opts ...gax.CallOption) *StringIterator {
	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.ListTopicSubscriptions[0:len(c.CallOptions.ListTopicSubscriptions):len(c.CallOptions.ListTopicSubscriptions)], opts...)
	it := &StringIterator{}
	req = proto.Clone(req).(*pubsublitepb.ListTopicSubscriptionsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]string, string, error) {
		var resp *pubsublitepb.ListTopicSubscriptionsResponse
		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.adminClient.ListTopicSubscriptions(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetSubscriptions(), 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.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()
	return it
}

func (c *AdminClient) CreateSubscription(ctx context.Context, req *pubsublitepb.CreateSubscriptionRequest, opts ...gax.CallOption) (*pubsublitepb.Subscription, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.CreateSubscription[0:len(c.CallOptions.CreateSubscription):len(c.CallOptions.CreateSubscription)], opts...)
	var resp *pubsublitepb.Subscription
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.CreateSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *AdminClient) GetSubscription(ctx context.Context, req *pubsublitepb.GetSubscriptionRequest, opts ...gax.CallOption) (*pubsublitepb.Subscription, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.GetSubscription[0:len(c.CallOptions.GetSubscription):len(c.CallOptions.GetSubscription)], opts...)
	var resp *pubsublitepb.Subscription
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.GetSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *AdminClient) ListSubscriptions(ctx context.Context, req *pubsublitepb.ListSubscriptionsRequest, opts ...gax.CallOption) *SubscriptionIterator {
	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.ListSubscriptions[0:len(c.CallOptions.ListSubscriptions):len(c.CallOptions.ListSubscriptions)], opts...)
	it := &SubscriptionIterator{}
	req = proto.Clone(req).(*pubsublitepb.ListSubscriptionsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*pubsublitepb.Subscription, string, error) {
		var resp *pubsublitepb.ListSubscriptionsResponse
		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.adminClient.ListSubscriptions(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetSubscriptions(), 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.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()
	return it
}

func (c *AdminClient) UpdateSubscription(ctx context.Context, req *pubsublitepb.UpdateSubscriptionRequest, opts ...gax.CallOption) (*pubsublitepb.Subscription, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "subscription.name", url.QueryEscape(req.GetSubscription().GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.UpdateSubscription[0:len(c.CallOptions.UpdateSubscription):len(c.CallOptions.UpdateSubscription)], opts...)
	var resp *pubsublitepb.Subscription
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.UpdateSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *AdminClient) DeleteSubscription(ctx context.Context, req *pubsublitepb.DeleteSubscriptionRequest, opts ...gax.CallOption) error {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.DeleteSubscription[0:len(c.CallOptions.DeleteSubscription):len(c.CallOptions.DeleteSubscription)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.adminClient.DeleteSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

type StringIterator struct {
	items    []string
	pageInfo *iterator.PageInfo
	nextFunc func() error

	Response interface{}

	InternalFetch func(pageSize int, pageToken string) (results []string, nextPageToken string, err error)
}

func (it *StringIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

func (it *StringIterator) Next() (string, error) {
	var item string
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

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

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

type SubscriptionIterator struct {
	items    []*pubsublitepb.Subscription
	pageInfo *iterator.PageInfo
	nextFunc func() error

	Response interface{}

	InternalFetch func(pageSize int, pageToken string) (results []*pubsublitepb.Subscription, nextPageToken string, err error)
}

func (it *SubscriptionIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

func (it *SubscriptionIterator) Next() (*pubsublitepb.Subscription, error) {
	var item *pubsublitepb.Subscription
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

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

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

type TopicIterator struct {
	items    []*pubsublitepb.Topic
	pageInfo *iterator.PageInfo
	nextFunc func() error

	Response interface{}

	InternalFetch func(pageSize int, pageToken string) (results []*pubsublitepb.Topic, nextPageToken string, err error)
}

func (it *TopicIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

func (it *TopicIterator) Next() (*pubsublitepb.Topic, error) {
	var item *pubsublitepb.Topic
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

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

func (it *TopicIterator) takeBuf() interface{} {
	b := it.items
	it.items = nil
	return b
}
// Copyright 2021 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 pubsublite

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"
	"google.golang.org/api/option/internaloption"
	gtransport "google.golang.org/api/transport/grpc"
	pubsublitepb "google.golang.org/genproto/googleapis/cloud/pubsublite/v1"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
)

var newAdminClientHook clientHook

// AdminCallOptions contains the retry settings for each method of AdminClient.
type AdminCallOptions struct {
	CreateTopic            []gax.CallOption
	GetTopic               []gax.CallOption
	GetTopicPartitions     []gax.CallOption
	ListTopics             []gax.CallOption
	UpdateTopic            []gax.CallOption
	DeleteTopic            []gax.CallOption
	ListTopicSubscriptions []gax.CallOption
	CreateSubscription     []gax.CallOption
	GetSubscription        []gax.CallOption
	ListSubscriptions      []gax.CallOption
	UpdateSubscription     []gax.CallOption
	DeleteSubscription     []gax.CallOption
}

func defaultAdminClientOptions() []option.ClientOption {
	return []option.ClientOption{
		internaloption.WithDefaultEndpoint("pubsublite.googleapis.com:443"),
		internaloption.WithDefaultMTLSEndpoint("pubsublite.mtls.googleapis.com:443"),
		internaloption.WithDefaultAudience("https://pubsublite.googleapis.com/"),
		internaloption.WithDefaultScopes(DefaultAuthScopes()...),
		option.WithGRPCDialOption(grpc.WithDisableServiceConfig()),
		option.WithGRPCDialOption(grpc.WithDefaultCallOptions(
			grpc.MaxCallRecvMsgSize(math.MaxInt32))),
	}
}

func defaultAdminCallOptions() *AdminCallOptions {
	return &AdminCallOptions{
		CreateTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetTopicPartitions: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListTopics: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		UpdateTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DeleteTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListTopicSubscriptions: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		CreateSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListSubscriptions: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		UpdateSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DeleteSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Unavailable,
					codes.Aborted,
					codes.Internal,
					codes.Unknown,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
	}
}

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

	// flag to opt out of default deadlines via GOOGLE_API_GO_EXPERIMENTAL_DISABLE_DEFAULT_DEADLINE
	disableDeadlines bool

	// The gRPC API client.
	adminClient pubsublitepb.AdminServiceClient

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

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

// NewAdminClient creates a new admin service client.
//
// The service that a client application uses to manage topics and
// subscriptions, such creating, listing, and deleting topics and subscriptions.
func NewAdminClient(ctx context.Context, opts ...option.ClientOption) (*AdminClient, error) {
	clientOpts := defaultAdminClientOptions()

	if newAdminClientHook != nil {
		hookOpts, err := newAdminClientHook(ctx, clientHookParams{})
		if err != nil {
			return nil, err
		}
		clientOpts = append(clientOpts, hookOpts...)
	}

	disableDeadlines, err := checkDisableDeadlines()
	if err != nil {
		return nil, err
	}

	connPool, err := gtransport.DialPool(ctx, append(clientOpts, opts...)...)
	if err != nil {
		return nil, err
	}
	c := &AdminClient{
		connPool:         connPool,
		disableDeadlines: disableDeadlines,
		CallOptions:      defaultAdminCallOptions(),

		adminClient: pubsublitepb.NewAdminServiceClient(connPool),
	}
	c.setGoogleClientInfo()

	return c, nil
}

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

// CreateTopic creates a new topic.
func (c *AdminClient) CreateTopic(ctx context.Context, req *pubsublitepb.CreateTopicRequest, opts ...gax.CallOption) (*pubsublitepb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.CreateTopic[0:len(c.CallOptions.CreateTopic):len(c.CallOptions.CreateTopic)], opts...)
	var resp *pubsublitepb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.CreateTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// GetTopic returns the topic configuration.
func (c *AdminClient) GetTopic(ctx context.Context, req *pubsublitepb.GetTopicRequest, opts ...gax.CallOption) (*pubsublitepb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.GetTopic[0:len(c.CallOptions.GetTopic):len(c.CallOptions.GetTopic)], opts...)
	var resp *pubsublitepb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.GetTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// GetTopicPartitions returns the partition information for the requested topic.
func (c *AdminClient) GetTopicPartitions(ctx context.Context, req *pubsublitepb.GetTopicPartitionsRequest, opts ...gax.CallOption) (*pubsublitepb.TopicPartitions, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.GetTopicPartitions[0:len(c.CallOptions.GetTopicPartitions):len(c.CallOptions.GetTopicPartitions)], opts...)
	var resp *pubsublitepb.TopicPartitions
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.GetTopicPartitions(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// ListTopics returns the list of topics for the given project.
func (c *AdminClient) ListTopics(ctx context.Context, req *pubsublitepb.ListTopicsRequest, opts ...gax.CallOption) *TopicIterator {
	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.ListTopics[0:len(c.CallOptions.ListTopics):len(c.CallOptions.ListTopics)], opts...)
	it := &TopicIterator{}
	req = proto.Clone(req).(*pubsublitepb.ListTopicsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*pubsublitepb.Topic, string, error) {
		var resp *pubsublitepb.ListTopicsResponse
		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.adminClient.ListTopics(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetTopics(), 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.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()
	return it
}

// UpdateTopic updates properties of the specified topic.
func (c *AdminClient) UpdateTopic(ctx context.Context, req *pubsublitepb.UpdateTopicRequest, opts ...gax.CallOption) (*pubsublitepb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "topic.name", url.QueryEscape(req.GetTopic().GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.UpdateTopic[0:len(c.CallOptions.UpdateTopic):len(c.CallOptions.UpdateTopic)], opts...)
	var resp *pubsublitepb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.UpdateTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// DeleteTopic deletes the specified topic.
func (c *AdminClient) DeleteTopic(ctx context.Context, req *pubsublitepb.DeleteTopicRequest, opts ...gax.CallOption) error {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.DeleteTopic[0:len(c.CallOptions.DeleteTopic):len(c.CallOptions.DeleteTopic)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.adminClient.DeleteTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

// ListTopicSubscriptions lists the subscriptions attached to the specified topic.
func (c *AdminClient) ListTopicSubscriptions(ctx context.Context, req *pubsublitepb.ListTopicSubscriptionsRequest, opts ...gax.CallOption) *StringIterator {
	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.ListTopicSubscriptions[0:len(c.CallOptions.ListTopicSubscriptions):len(c.CallOptions.ListTopicSubscriptions)], opts...)
	it := &StringIterator{}
	req = proto.Clone(req).(*pubsublitepb.ListTopicSubscriptionsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]string, string, error) {
		var resp *pubsublitepb.ListTopicSubscriptionsResponse
		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.adminClient.ListTopicSubscriptions(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetSubscriptions(), 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.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()
	return it
}

// CreateSubscription creates a new subscription.
func (c *AdminClient) CreateSubscription(ctx context.Context, req *pubsublitepb.CreateSubscriptionRequest, opts ...gax.CallOption) (*pubsublitepb.Subscription, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.CreateSubscription[0:len(c.CallOptions.CreateSubscription):len(c.CallOptions.CreateSubscription)], opts...)
	var resp *pubsublitepb.Subscription
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.CreateSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// GetSubscription returns the subscription configuration.
func (c *AdminClient) GetSubscription(ctx context.Context, req *pubsublitepb.GetSubscriptionRequest, opts ...gax.CallOption) (*pubsublitepb.Subscription, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.GetSubscription[0:len(c.CallOptions.GetSubscription):len(c.CallOptions.GetSubscription)], opts...)
	var resp *pubsublitepb.Subscription
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.GetSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// ListSubscriptions returns the list of subscriptions for the given project.
func (c *AdminClient) ListSubscriptions(ctx context.Context, req *pubsublitepb.ListSubscriptionsRequest, opts ...gax.CallOption) *SubscriptionIterator {
	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.ListSubscriptions[0:len(c.CallOptions.ListSubscriptions):len(c.CallOptions.ListSubscriptions)], opts...)
	it := &SubscriptionIterator{}
	req = proto.Clone(req).(*pubsublitepb.ListSubscriptionsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*pubsublitepb.Subscription, string, error) {
		var resp *pubsublitepb.ListSubscriptionsResponse
		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.adminClient.ListSubscriptions(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetSubscriptions(), 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.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()
	return it
}

// UpdateSubscription updates properties of the specified subscription.
func (c *AdminClient) UpdateSubscription(ctx context.Context, req *pubsublitepb.UpdateSubscriptionRequest, opts ...gax.CallOption) (*pubsublitepb.Subscription, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "subscription.name", url.QueryEscape(req.GetSubscription().GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append(c.CallOptions.UpdateSubscription[0:len(c.CallOptions.UpdateSubscription):len(c.CallOptions.UpdateSubscription)], opts...)
	var resp *pubsublitepb.Subscription
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.adminClient.UpdateSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// DeleteSubscription deletes the specified subscription.
func (c *AdminClient) DeleteSubscription(ctx context.Context, req *pubsublitepb.DeleteSubscriptionRequest, opts ...gax.CallOption) error {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 600000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	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.DeleteSubscription[0:len(c.CallOptions.DeleteSubscription):len(c.CallOptions.DeleteSubscription)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.adminClient.DeleteSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

// StringIterator manages a stream of string.
type StringIterator struct {
	items    []string
	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 []string, nextPageToken string, err error)
}

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

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

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

// SubscriptionIterator manages a stream of *pubsublitepb.Subscription.
type SubscriptionIterator struct {
	items    []*pubsublitepb.Subscription
	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 []*pubsublitepb.Subscription, nextPageToken string, err error)
}

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

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

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

// TopicIterator manages a stream of *pubsublitepb.Topic.
type TopicIterator struct {
	items    []*pubsublitepb.Topic
	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 []*pubsublitepb.Topic, nextPageToken string, err error)
}

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

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

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