// Copyright (C) MongoDB, Inc. 2017-present.
//
// 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 http://www.apache.org/licenses/LICENSE-2.0

package mongo

import (
	"context"
	"errors"
	"fmt"
	"reflect"
	"strings"
	"time"

	"go.mongodb.org/mongo-driver/v2/bson"
	"go.mongodb.org/mongo-driver/v2/internal/csfle"
	"go.mongodb.org/mongo-driver/v2/internal/mongoutil"
	"go.mongodb.org/mongo-driver/v2/internal/optionsutil"
	"go.mongodb.org/mongo-driver/v2/internal/ptrutil"
	"go.mongodb.org/mongo-driver/v2/internal/serverselector"
	"go.mongodb.org/mongo-driver/v2/mongo/options"
	"go.mongodb.org/mongo-driver/v2/mongo/readconcern"
	"go.mongodb.org/mongo-driver/v2/mongo/readpref"
	"go.mongodb.org/mongo-driver/v2/mongo/writeconcern"
	"go.mongodb.org/mongo-driver/v2/x/bsonx/bsoncore"
	"go.mongodb.org/mongo-driver/v2/x/mongo/driver"
	"go.mongodb.org/mongo-driver/v2/x/mongo/driver/description"
	"go.mongodb.org/mongo-driver/v2/x/mongo/driver/operation"
	"go.mongodb.org/mongo-driver/v2/x/mongo/driver/session"
)

// Collection is a handle to a MongoDB collection. It is safe for concurrent use by multiple goroutines.
type Collection struct {
	client         *Client
	db             *Database
	name           string
	readConcern    *readconcern.ReadConcern
	writeConcern   *writeconcern.WriteConcern
	readPreference *readpref.ReadPref
	readSelector   description.ServerSelector
	writeSelector  description.ServerSelector
	bsonOpts       *options.BSONOptions
	registry       *bson.Registry
}

// aggregateParams is used to store information to configure an Aggregate operation.
type aggregateParams struct {
	ctx            context.Context
	pipeline       any
	client         *Client
	bsonOpts       *options.BSONOptions
	registry       *bson.Registry
	readConcern    *readconcern.ReadConcern
	writeConcern   *writeconcern.WriteConcern
	retryRead      bool
	db             string
	col            string
	readSelector   description.ServerSelector
	writeSelector  description.ServerSelector
	readPreference *readpref.ReadPref
}

func closeImplicitSession(sess *session.Client) {
	if sess != nil && sess.IsImplicit {
		sess.EndSession()
	}
}

func newCollection(db *Database, name string, opts ...options.Lister[options.CollectionOptions]) *Collection {
	args, _ := mongoutil.NewOptions[options.CollectionOptions](opts...)

	rc := db.readConcern
	if args.ReadConcern != nil {
		rc = args.ReadConcern
	}

	wc := db.writeConcern
	if args.WriteConcern != nil {
		wc = args.WriteConcern
	}

	rp := db.readPreference
	if args.ReadPreference != nil {
		rp = args.ReadPreference
	}

	bsonOpts := db.bsonOpts
	if args.BSONOptions != nil {
		bsonOpts = args.BSONOptions
	}

	reg := db.registry
	if args.Registry != nil {
		reg = args.Registry
	}

	readSelector := &serverselector.Composite{
		Selectors: []description.ServerSelector{
			&serverselector.ReadPref{ReadPref: rp},
			&serverselector.Latency{Latency: db.client.localThreshold},
		},
	}

	writeSelector := &serverselector.Composite{
		Selectors: []description.ServerSelector{
			&serverselector.Write{},
			&serverselector.Latency{Latency: db.client.localThreshold},
		},
	}

	coll := &Collection{
		client:         db.client,
		db:             db,
		name:           name,
		readPreference: rp,
		readConcern:    rc,
		writeConcern:   wc,
		readSelector:   readSelector,
		writeSelector:  writeSelector,
		bsonOpts:       bsonOpts,
		registry:       reg,
	}

	return coll
}

func (coll *Collection) copy() *Collection {
	return &Collection{
		client:         coll.client,
		db:             coll.db,
		name:           coll.name,
		readConcern:    coll.readConcern,
		writeConcern:   coll.writeConcern,
		readPreference: coll.readPreference,
		readSelector:   coll.readSelector,
		writeSelector:  coll.writeSelector,
		registry:       coll.registry,
	}
}

// Clone creates a copy of the Collection configured with the given CollectionOptions.
// The specified options are merged with the existing options on the collection, with the specified options taking
// precedence.
func (coll *Collection) Clone(opts ...options.Lister[options.CollectionOptions]) *Collection {
	copyColl := coll.copy()

	args, _ := mongoutil.NewOptions[options.CollectionOptions](opts...)

	if args.ReadConcern != nil {
		copyColl.readConcern = args.ReadConcern
	}

	if args.WriteConcern != nil {
		copyColl.writeConcern = args.WriteConcern
	}

	if args.ReadPreference != nil {
		copyColl.readPreference = args.ReadPreference
	}

	if args.Registry != nil {
		copyColl.registry = args.Registry
	}

	copyColl.readSelector = &serverselector.Composite{
		Selectors: []description.ServerSelector{
			&serverselector.ReadPref{ReadPref: copyColl.readPreference},
			&serverselector.Latency{Latency: copyColl.client.localThreshold},
		},
	}

	return copyColl
}

// Name returns the name of the collection.
func (coll *Collection) Name() string {
	return coll.name
}

// Database returns the Database that was used to create the Collection.
func (coll *Collection) Database() *Database {
	return coll.db
}

// BulkWrite performs a bulk write operation (https://www.mongodb.com/docs/manual/core/bulk-write-operations/).
//
// The models parameter must be a slice of operations to be executed in this bulk write. It cannot be nil or empty.
// All of the models must be non-nil. See the mongo.WriteModel documentation for a list of valid model types and
// examples of how they should be used.
//
// The opts parameter can be used to specify options for the operation (see the options.BulkWriteOptions documentation.)
func (coll *Collection) BulkWrite(ctx context.Context, models []WriteModel,
	opts ...options.Lister[options.BulkWriteOptions],
) (*BulkWriteResult, error) {
	if len(models) == 0 {
		return nil, fmt.Errorf("invalid models: %w", ErrEmptySlice)
	}

	if ctx == nil {
		ctx = context.Background()
	}

	sess := sessionFromContext(ctx)
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}

	err := coll.client.validSession(sess)
	if err != nil {
		return nil, err
	}

	wc := coll.writeConcern
	if sess.TransactionRunning() {
		wc = nil
	}
	if !wc.Acknowledged() {
		sess = nil
	}

	selector := makePinnedSelector(sess, coll.writeSelector)

	for i, model := range models {
		if model == nil {
			return nil, fmt.Errorf("invalid model at index %d: %w", i, ErrNilDocument)
		}
	}

	// Ensure opts have the default case at the front.
	opts = append([]options.Lister[options.BulkWriteOptions]{options.BulkWrite()}, opts...)
	args, err := mongoutil.NewOptions(opts...)
	if err != nil {
		return nil, err
	}

	op := bulkWrite{
		comment:                  args.Comment,
		ordered:                  args.Ordered,
		bypassDocumentValidation: args.BypassDocumentValidation,
		models:                   models,
		session:                  sess,
		collection:               coll,
		selector:                 selector,
		writeConcern:             wc,
		let:                      args.Let,
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op.rawData = &rawData
	}
	if additionalCmd, ok := optionsutil.Value(args.Internal, "addCommandFields").(bson.D); ok {
		op.additionalCmd = additionalCmd
	}

	err = op.execute(ctx)

	return &op.result, wrapErrors(err)
}

func (coll *Collection) insert(
	ctx context.Context,
	documents []any,
	opts ...options.Lister[options.InsertManyOptions],
) ([]any, error) {
	if ctx == nil {
		ctx = context.Background()
	}

	result := make([]any, len(documents))
	docs := make([]bsoncore.Document, len(documents))

	for i, doc := range documents {
		bsoncoreDoc, err := marshal(doc, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		bsoncoreDoc, id, err := ensureID(bsoncoreDoc, bson.NilObjectID, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}

		docs[i] = bsoncoreDoc
		result[i] = id
	}

	sess := sessionFromContext(ctx)
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}

	err := coll.client.validSession(sess)
	if err != nil {
		return nil, err
	}

	wc := coll.writeConcern
	if sess.TransactionRunning() {
		wc = nil
	}
	if !wc.Acknowledged() {
		sess = nil
	}

	selector := makePinnedSelector(sess, coll.writeSelector)

	op := insert{
		documents:     docs,
		session:       sess,
		writeConcern:  wc,
		monitor:       coll.client.monitor,
		selector:      selector,
		clock:         coll.client.clock,
		database:      coll.db.name,
		collection:    coll.name,
		deployment:    coll.client.deployment,
		crypt:         coll.client.cryptFLE,
		ordered:       ptrutil.Ptr(true),
		serverAPI:     coll.client.serverAPI,
		timeout:       coll.client.timeout,
		logger:        coll.client.logger,
		authenticator: coll.client.authenticator,
	}

	args, err := mongoutil.NewOptions[options.InsertManyOptions](opts...)
	if err != nil {
		return nil, fmt.Errorf("failed to construct options from builder: %w", err)
	}

	if args.BypassDocumentValidation != nil && *args.BypassDocumentValidation {
		op.bypassDocumentValidation = args.BypassDocumentValidation
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op.comment = comment
	}
	if args.Ordered != nil {
		op.ordered = args.Ordered
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op.rawData = &rawData
	}
	if additionalCmd, ok := optionsutil.Value(args.Internal, "addCommandFields").(bson.D); ok {
		op.additionalCmd = additionalCmd
	}
	retry := driver.RetryNone
	if coll.client.retryWrites {
		retry = driver.RetryOncePerCommand
	}
	op.retry = &retry

	err = op.Execute(ctx)
	var wce driver.WriteCommandError
	if !errors.As(err, &wce) {
		return result, err
	}

	// remove the ids that had writeErrors from result
	for i, we := range wce.WriteErrors {
		// i indexes have been removed before the current error, so the index is we.Index-i
		idIndex := int(we.Index) - i
		// if the insert is ordered, nothing after the error was inserted
		if args.Ordered == nil || *args.Ordered {
			result = result[:idIndex]
			break
		}
		result = append(result[:idIndex], result[idIndex+1:]...)
	}

	return result, err
}

// InsertOne executes an insert command to insert a single document into the collection.
//
// The document parameter must be the document to be inserted. It cannot be nil. If the document does not have an _id
// field when transformed into BSON, one will be added automatically to the marshalled document. The original document
// will not be modified. The _id can be retrieved from the InsertedID field of the returned InsertOneResult.
//
// The opts parameter can be used to specify options for the operation (see the options.InsertOneOptions documentation.)
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/insert/.
func (coll *Collection) InsertOne(ctx context.Context, document any,
	opts ...options.Lister[options.InsertOneOptions],
) (*InsertOneResult, error) {
	args, err := mongoutil.NewOptions(opts...)
	if err != nil {
		return nil, err
	}
	imOpts := options.InsertMany()

	if args.BypassDocumentValidation != nil && *args.BypassDocumentValidation {
		imOpts.SetBypassDocumentValidation(*args.BypassDocumentValidation)
	}
	if args.Comment != nil {
		imOpts.SetComment(args.Comment)
	}
	if rawDataOpt := optionsutil.Value(args.Internal, "rawData"); rawDataOpt != nil {
		imOpts.Opts = append(imOpts.Opts, func(opts *options.InsertManyOptions) error {
			opts.Internal = optionsutil.WithValue(opts.Internal, "rawData", rawDataOpt)

			return nil
		})
	}
	if additionalCmd := optionsutil.Value(args.Internal, "addCommandFields"); additionalCmd != nil {
		imOpts.Opts = append(imOpts.Opts, func(opts *options.InsertManyOptions) error {
			opts.Internal = optionsutil.WithValue(opts.Internal, "addCommandFields", additionalCmd)

			return nil
		})
	}
	res, err := coll.insert(ctx, []any{document}, imOpts)

	rr, err := processWriteError(err)
	if rr&rrOne == 0 && rr.isAcknowledged() {
		return nil, err
	}

	return &InsertOneResult{
		InsertedID:   res[0],
		Acknowledged: rr.isAcknowledged(),
	}, err
}

// InsertMany executes an insert command to insert multiple documents into the collection. If write errors occur
// during the operation (e.g. duplicate key error), this method returns a BulkWriteException error.
//
// The documents parameter must be a slice of documents to insert. The slice cannot be nil or empty. The elements must
// all be non-nil. For any document that does not have an _id field when transformed into BSON, one will be added
// automatically to the marshalled document. The original document will not be modified. The _id values for the inserted
// documents can be retrieved from the InsertedIDs field of the returned InsertManyResult.
//
// The opts parameter can be used to specify options for the operation (see the options.InsertManyOptions documentation.)
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/insert/.
func (coll *Collection) InsertMany(
	ctx context.Context,
	documents any,
	opts ...options.Lister[options.InsertManyOptions],
) (*InsertManyResult, error) {
	dv := reflect.ValueOf(documents)
	if dv.Kind() != reflect.Slice {
		return nil, fmt.Errorf("invalid documents: %w", ErrNotSlice)
	}
	if dv.Len() == 0 {
		return nil, fmt.Errorf("invalid documents: %w", ErrEmptySlice)
	}

	docSlice := make([]any, 0, dv.Len())
	for i := 0; i < dv.Len(); i++ {
		docSlice = append(docSlice, dv.Index(i).Interface())
	}

	result, err := coll.insert(ctx, docSlice, opts...)
	rr, err := processWriteError(err)
	if rr&rrMany == 0 {
		return nil, err
	}

	imResult := &InsertManyResult{
		InsertedIDs:  result,
		Acknowledged: rr.isAcknowledged(),
	}
	var writeException WriteException
	if !errors.As(err, &writeException) {
		return imResult, err
	}

	// create and return a BulkWriteException
	bwErrors := make([]BulkWriteError, 0, len(writeException.WriteErrors))
	for _, we := range writeException.WriteErrors {
		bwErrors = append(bwErrors, BulkWriteError{
			WriteError: we,
			Request:    nil,
		})
	}

	return imResult, BulkWriteException{
		WriteErrors:       bwErrors,
		WriteConcernError: writeException.WriteConcernError,
		Labels:            writeException.Labels,
	}
}

func (coll *Collection) delete(
	ctx context.Context,
	filter any,
	deleteOne bool,
	expectedRr returnResult,
	args *options.DeleteManyOptions,
) (*DeleteResult, error) {
	if ctx == nil {
		ctx = context.Background()
	}

	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return nil, err
	}

	sess := sessionFromContext(ctx)
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}

	err = coll.client.validSession(sess)
	if err != nil {
		return nil, err
	}

	wc := coll.writeConcern
	if sess.TransactionRunning() {
		wc = nil
	}
	if !wc.Acknowledged() {
		sess = nil
	}

	selector := makePinnedSelector(sess, coll.writeSelector)

	var limit int32
	if deleteOne {
		limit = 1
	}

	didx, doc := bsoncore.AppendDocumentStart(nil)
	doc = bsoncore.AppendDocumentElement(doc, "q", f)
	doc = bsoncore.AppendInt32Element(doc, "limit", limit)
	if args.Collation != nil {
		doc = bsoncore.AppendDocumentElement(doc, "collation", toDocument(args.Collation))
	}
	if args.Hint != nil {
		if isUnorderedMap(args.Hint) {
			return nil, ErrMapForOrderedArgument{"hint"}
		}
		hint, err := marshalValue(args.Hint, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}

		doc = bsoncore.AppendValueElement(doc, "hint", hint)
	}
	doc, _ = bsoncore.AppendDocumentEnd(doc, didx)

	op := operation.NewDelete(doc).
		Session(sess).WriteConcern(wc).CommandMonitor(coll.client.monitor).
		ServerSelector(selector).ClusterClock(coll.client.clock).
		Database(coll.db.name).Collection(coll.name).
		Deployment(coll.client.deployment).Crypt(coll.client.cryptFLE).Ordered(true).
		ServerAPI(coll.client.serverAPI).Timeout(coll.client.timeout).Logger(coll.client.logger).Authenticator(coll.client.authenticator)
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op = op.Comment(comment)
	}
	if args.Hint != nil {
		op = op.Hint(true)
	}
	if args.Let != nil {
		let, err := marshal(args.Let, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op = op.Let(let)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}

	// deleteMany cannot be retried
	retryMode := driver.RetryNone
	if deleteOne && coll.client.retryWrites {
		retryMode = driver.RetryOncePerCommand
	}
	op = op.Retry(retryMode)
	rr, err := processWriteError(op.Execute(ctx))
	if rr&expectedRr == 0 {
		return nil, err
	}
	return &DeleteResult{
		DeletedCount: op.Result().N,
		Acknowledged: rr.isAcknowledged(),
	}, err
}

// DeleteOne executes a delete command to delete at most one document from the collection.
//
// The filter parameter must be a document containing query operators and can be used to select the document to be
// deleted. It cannot be nil. If the filter does not match any documents, the operation will succeed and a DeleteResult
// with a DeletedCount of 0 will be returned. If the filter matches multiple documents, one will be selected from the
// matched set.
//
// The opts parameter can be used to specify options for the operation (see the options.DeleteOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/delete/.
func (coll *Collection) DeleteOne(
	ctx context.Context,
	filter any,
	opts ...options.Lister[options.DeleteOneOptions],
) (*DeleteResult, error) {
	args, err := mongoutil.NewOptions[options.DeleteOneOptions](opts...)
	if err != nil {
		return nil, fmt.Errorf("failed to construct options from builder: %w", err)
	}
	deleteOptions := &options.DeleteManyOptions{
		Collation: args.Collation,
		Comment:   args.Comment,
		Hint:      args.Hint,
		Let:       args.Let,
		Internal:  args.Internal,
	}

	return coll.delete(ctx, filter, true, rrOne, deleteOptions)
}

// DeleteMany executes a delete command to delete documents from the collection.
//
// The filter parameter must be a document containing query operators and can be used to select the documents to
// be deleted. It cannot be nil. An empty document (e.g. bson.D{}) should be used to delete all documents in the
// collection. If the filter does not match any documents, the operation will succeed and a DeleteResult with a
// DeletedCount of 0 will be returned.
//
// The opts parameter can be used to specify options for the operation (see the options.DeleteOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/delete/.
func (coll *Collection) DeleteMany(
	ctx context.Context,
	filter any,
	opts ...options.Lister[options.DeleteManyOptions],
) (*DeleteResult, error) {
	args, err := mongoutil.NewOptions[options.DeleteManyOptions](opts...)
	if err != nil {
		return nil, fmt.Errorf("failed to construct options from builder: %w", err)
	}

	return coll.delete(ctx, filter, false, rrMany, args)
}

func (coll *Collection) updateOrReplace(
	ctx context.Context,
	filter bsoncore.Document,
	update any,
	multi bool,
	expectedRr returnResult,
	checkDollarKey bool,
	sort any,
	args *options.UpdateManyOptions,
) (*UpdateResult, error) {
	if ctx == nil {
		ctx = context.Background()
	}

	// collation, arrayFilters, upsert, and hint are included on the individual update documents rather than as part of the
	// command
	updateDoc, err := updateDoc{
		filter:         filter,
		update:         update,
		hint:           args.Hint,
		sort:           sort,
		arrayFilters:   args.ArrayFilters,
		collation:      args.Collation,
		upsert:         args.Upsert,
		multi:          multi,
		checkDollarKey: checkDollarKey,
	}.marshal(coll.bsonOpts, coll.registry)
	if err != nil {
		return nil, err
	}

	sess := sessionFromContext(ctx)
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}

	err = coll.client.validSession(sess)
	if err != nil {
		return nil, err
	}

	wc := coll.writeConcern
	if sess.TransactionRunning() {
		wc = nil
	}
	if !wc.Acknowledged() {
		sess = nil
	}

	selector := makePinnedSelector(sess, coll.writeSelector)

	op := operation.NewUpdate(updateDoc).
		Session(sess).WriteConcern(wc).CommandMonitor(coll.client.monitor).
		ServerSelector(selector).ClusterClock(coll.client.clock).
		Database(coll.db.name).Collection(coll.name).
		Deployment(coll.client.deployment).Crypt(coll.client.cryptFLE).Hint(args.Hint != nil).
		ArrayFilters(args.ArrayFilters != nil).Ordered(true).ServerAPI(coll.client.serverAPI).
		Timeout(coll.client.timeout).Logger(coll.client.logger).Authenticator(coll.client.authenticator)
	if args.Let != nil {
		let, err := marshal(args.Let, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op = op.Let(let)
	}

	if args.BypassDocumentValidation != nil && *args.BypassDocumentValidation {
		op = op.BypassDocumentValidation(*args.BypassDocumentValidation)
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op = op.Comment(comment)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}
	if additionalCmd, ok := optionsutil.Value(args.Internal, "addCommandFields").(bson.D); ok {
		op = op.AdditionalCmd(additionalCmd)
	}
	retry := driver.RetryNone
	// retryable writes are only enabled updateOne/replaceOne operations
	if !multi && coll.client.retryWrites {
		retry = driver.RetryOncePerCommand
	}
	op = op.Retry(retry)
	err = op.Execute(ctx)

	rr, err := processWriteError(err)
	if rr&expectedRr == 0 {
		return nil, err
	}

	opRes := op.Result()
	res := &UpdateResult{
		MatchedCount:  opRes.N,
		ModifiedCount: opRes.NModified,
		UpsertedCount: int64(len(opRes.Upserted)),
		Acknowledged:  rr.isAcknowledged(),
	}
	if len(opRes.Upserted) > 0 {
		res.UpsertedID = opRes.Upserted[0].ID
		res.MatchedCount--
	}

	return res, err
}

// UpdateByID executes an update command to update the document whose _id value matches the provided ID in the collection.
// This is equivalent to running UpdateOne(ctx, bson.D{{"_id", id}}, update, opts...).
//
// The id parameter is the _id of the document to be updated. It cannot be nil. If the ID does not match any documents,
// the operation will succeed and an UpdateResult with a MatchedCount of 0 will be returned.
//
// The update parameter must be a document containing update operators
// (https://www.mongodb.com/docs/manual/reference/operator/update/) and can be used to specify the modifications to be
// made to the selected document. It cannot be nil or empty.
//
// The opts parameter can be used to specify options for the operation (see the options.UpdateOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/update/.
func (coll *Collection) UpdateByID(
	ctx context.Context,
	id any,
	update any,
	opts ...options.Lister[options.UpdateOneOptions],
) (*UpdateResult, error) {
	if id == nil {
		return nil, fmt.Errorf("invalid id: %w", ErrNilValue)
	}
	return coll.UpdateOne(ctx, bson.D{{"_id", id}}, update, opts...)
}

// UpdateOne executes an update command to update at most one document in the collection.
//
// The filter parameter must be a document containing query operators and can be used to select the document to be
// updated. It cannot be nil. If the filter does not match any documents, the operation will succeed and an UpdateResult
// with a MatchedCount of 0 will be returned. If the filter matches multiple documents, one will be selected from the
// matched set and MatchedCount will equal 1.
//
// The update parameter must be a document containing update operators
// (https://www.mongodb.com/docs/manual/reference/operator/update/) and can be used to specify the modifications to be
// made to the selected document. It cannot be nil or empty.
//
// The opts parameter can be used to specify options for the operation (see the options.UpdateOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/update/.
func (coll *Collection) UpdateOne(
	ctx context.Context,
	filter any,
	update any,
	opts ...options.Lister[options.UpdateOneOptions],
) (*UpdateResult, error) {
	if ctx == nil {
		ctx = context.Background()
	}

	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return nil, err
	}

	args, err := mongoutil.NewOptions[options.UpdateOneOptions](opts...)
	if err != nil {
		return nil, fmt.Errorf("failed to construct options from builder: %w", err)
	}
	updateOptions := &options.UpdateManyOptions{
		ArrayFilters:             args.ArrayFilters,
		BypassDocumentValidation: args.BypassDocumentValidation,
		Collation:                args.Collation,
		Comment:                  args.Comment,
		Hint:                     args.Hint,
		Upsert:                   args.Upsert,
		Let:                      args.Let,
		Internal:                 args.Internal,
	}

	return coll.updateOrReplace(ctx, f, update, false, rrOne, true, args.Sort, updateOptions)
}

// UpdateMany executes an update command to update documents in the collection.
//
// The filter parameter must be a document containing query operators and can be used to select the documents to be
// updated. It cannot be nil. If the filter does not match any documents, the operation will succeed and an UpdateResult
// with a MatchedCount of 0 will be returned.
//
// The update parameter must be a document containing update operators
// (https://www.mongodb.com/docs/manual/reference/operator/update/) and can be used to specify the modifications to be made
// to the selected documents. It cannot be nil or empty.
//
// The opts parameter can be used to specify options for the operation (see the options.UpdateOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/update/.
func (coll *Collection) UpdateMany(
	ctx context.Context,
	filter any,
	update any,
	opts ...options.Lister[options.UpdateManyOptions],
) (*UpdateResult, error) {
	if ctx == nil {
		ctx = context.Background()
	}

	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return nil, err
	}

	args, err := mongoutil.NewOptions[options.UpdateManyOptions](opts...)
	if err != nil {
		return nil, fmt.Errorf("failed to construct options from builder: %w", err)
	}

	return coll.updateOrReplace(ctx, f, update, true, rrMany, true, nil, args)
}

// ReplaceOne executes an update command to replace at most one document in the collection.
//
// The filter parameter must be a document containing query operators and can be used to select the document to be
// replaced. It cannot be nil. If the filter does not match any documents, the operation will succeed and an
// UpdateResult with a MatchedCount of 0 will be returned. If the filter matches multiple documents, one will be
// selected from the matched set and MatchedCount will equal 1.
//
// The replacement parameter must be a document that will be used to replace the selected document. It cannot be nil
// and cannot contain any update operators (https://www.mongodb.com/docs/manual/reference/operator/update/).
//
// The opts parameter can be used to specify options for the operation (see the options.ReplaceOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/update/.
func (coll *Collection) ReplaceOne(
	ctx context.Context,
	filter any,
	replacement any,
	opts ...options.Lister[options.ReplaceOptions],
) (*UpdateResult, error) {
	if ctx == nil {
		ctx = context.Background()
	}

	args, err := mongoutil.NewOptions[options.ReplaceOptions](opts...)
	if err != nil {
		return nil, fmt.Errorf("failed to construct options from builder: %w", err)
	}

	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return nil, err
	}

	r, err := marshal(replacement, coll.bsonOpts, coll.registry)
	if err != nil {
		return nil, err
	}

	if err := ensureNoDollarKey(r); err != nil {
		return nil, err
	}

	updateOptions := &options.UpdateManyOptions{
		BypassDocumentValidation: args.BypassDocumentValidation,
		Collation:                args.Collation,
		Upsert:                   args.Upsert,
		Hint:                     args.Hint,
		Let:                      args.Let,
		Comment:                  args.Comment,
		Internal:                 args.Internal,
	}

	return coll.updateOrReplace(ctx, f, r, false, rrOne, false, args.Sort, updateOptions)
}

// Aggregate executes an aggregate command against the collection and returns a cursor over the resulting documents.
//
// The pipeline parameter must be an array of documents, each representing an aggregation stage. The pipeline cannot
// be nil but can be empty. The stage documents must all be non-nil. For a pipeline of bson.D documents, the
// mongo.Pipeline type can be used. See
// https://www.mongodb.com/docs/manual/reference/operator/aggregation-pipeline/#db-collection-aggregate-stages for a list of
// valid stages in aggregations.
//
// The opts parameter can be used to specify options for the operation (see the options.AggregateOptions documentation.)
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/aggregate/.
func (coll *Collection) Aggregate(
	ctx context.Context,
	pipeline any,
	opts ...options.Lister[options.AggregateOptions],
) (*Cursor, error) {
	a := aggregateParams{
		ctx:            ctx,
		pipeline:       pipeline,
		client:         coll.client,
		registry:       coll.registry,
		readConcern:    coll.readConcern,
		writeConcern:   coll.writeConcern,
		bsonOpts:       coll.bsonOpts,
		retryRead:      coll.client.retryReads,
		db:             coll.db.name,
		col:            coll.name,
		readSelector:   coll.readSelector,
		writeSelector:  coll.writeSelector,
		readPreference: coll.readPreference,
	}

	return aggregate(a, opts...)
}

// aggregate is the helper method for Aggregate
func aggregate(a aggregateParams, opts ...options.Lister[options.AggregateOptions]) (cur *Cursor, err error) {
	if a.ctx == nil {
		a.ctx = context.Background()
	}

	pipelineArr, hasOutputStage, err := marshalAggregatePipeline(a.pipeline, a.bsonOpts, a.registry)
	if err != nil {
		return nil, err
	}

	sess := sessionFromContext(a.ctx)
	// Always close any created implicit sessions if aggregate returns an error.
	defer func() {
		if err != nil && sess != nil {
			closeImplicitSession(sess)
		}
	}()
	if sess == nil && a.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(a.client.sessionPool, a.client.id)
	}
	if err = a.client.validSession(sess); err != nil {
		return nil, err
	}

	var wc *writeconcern.WriteConcern
	if hasOutputStage {
		wc = a.writeConcern
	}
	rc := a.readConcern
	if sess.TransactionRunning() {
		wc = nil
		rc = nil
	}
	if !wc.Acknowledged() {
		closeImplicitSession(sess)
		sess = nil
	}

	selector := makeReadPrefSelector(sess, a.readSelector, a.client.localThreshold)
	if hasOutputStage {
		selector = makeOutputAggregateSelector(sess, a.readPreference, a.client.localThreshold)
	}

	args, err := mongoutil.NewOptions(opts...)
	if err != nil {
		return nil, err
	}

	cursorOpts := a.client.createBaseCursorOptions()

	cursorOpts.MarshalValueEncoderFn = newEncoderFn(a.bsonOpts, a.registry)

	op := operation.NewAggregate(pipelineArr).
		Session(sess).
		WriteConcern(wc).
		ReadConcern(rc).
		ReadPreference(a.readPreference).
		CommandMonitor(a.client.monitor).
		ServerSelector(selector).
		ClusterClock(a.client.clock).
		Database(a.db).
		Collection(a.col).
		Deployment(a.client.deployment).
		Crypt(a.client.cryptFLE).
		ServerAPI(a.client.serverAPI).
		HasOutputStage(hasOutputStage).
		Timeout(a.client.timeout).
		Authenticator(a.client.authenticator).
		// Omit "maxTimeMS" from operations that return a user-managed cursor to
		// prevent confusing "cursor not found" errors.
		//
		// See DRIVERS-2722 for more detail.
		OmitMaxTimeMS(true)

	if args.AllowDiskUse != nil {
		op.AllowDiskUse(*args.AllowDiskUse)
	}
	// ignore batchSize of 0 with $out
	if args.BatchSize != nil && (*args.BatchSize != 0 || !hasOutputStage) {
		op.BatchSize(*args.BatchSize)
		cursorOpts.BatchSize = *args.BatchSize
	}
	if args.BypassDocumentValidation != nil && *args.BypassDocumentValidation {
		op.BypassDocumentValidation(*args.BypassDocumentValidation)
	}
	if args.Collation != nil {
		op.Collation(bsoncore.Document(toDocument(args.Collation)))
	}
	if args.MaxAwaitTime != nil {
		cursorOpts.SetMaxAwaitTime(*args.MaxAwaitTime)
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, a.bsonOpts, a.registry)
		if err != nil {
			return nil, err
		}

		op.Comment(comment)
		cursorOpts.Comment = comment
	}
	if args.Hint != nil {
		if isUnorderedMap(args.Hint) {
			return nil, ErrMapForOrderedArgument{"hint"}
		}
		hintVal, err := marshalValue(args.Hint, a.bsonOpts, a.registry)
		if err != nil {
			return nil, err
		}
		op.Hint(hintVal)
	}
	if args.Let != nil {
		let, err := marshal(args.Let, a.bsonOpts, a.registry)
		if err != nil {
			return nil, err
		}
		op.Let(let)
	}
	if args.Custom != nil {
		// Marshal all custom options before passing to the aggregate operation. Return
		// any errors from Marshaling.
		customOptions := make(map[string]bsoncore.Value)
		for optionName, optionValue := range args.Custom {
			optionValueBSON, err := marshalValue(optionValue, nil, a.registry)
			if err != nil {
				return nil, err
			}
			customOptions[optionName] = optionValueBSON
		}
		op.CustomOptions(customOptions)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}

	retry := driver.RetryNone
	if a.retryRead && !hasOutputStage {
		retry = driver.RetryOncePerCommand
	}
	op = op.Retry(retry)

	err = op.Execute(a.ctx)
	if err != nil {
		var wce driver.WriteCommandError
		if errors.As(err, &wce) && wce.WriteConcernError != nil {
			return nil, *convertDriverWriteConcernError(wce.WriteConcernError)
		}
		return nil, wrapErrors(err)
	}

	bc, err := op.Result(cursorOpts)
	if err != nil {
		return nil, wrapErrors(err)
	}
	cursor, err := newCursorWithSession(bc, a.client.bsonOpts, a.registry, sess,

		// The only way the server will return a tailable/awaitData cursor for an
		// aggregate operation is for the first stage in the pipeline to
		// be $changeStream, this is the only time maxAwaitTimeMS should be applied.
		// For this reason, we pass the client timeout to the cursor.
		withCursorOptionClientTimeout(a.client.timeout))
	return cursor, wrapErrors(err)
}

// CountDocuments returns the number of documents in the collection. For a fast count of the documents in the
// collection, see the EstimatedDocumentCount method.
//
// The filter parameter must be a document and can be used to select which documents contribute to the count. It
// cannot be nil. An empty document (e.g. bson.D{}) should be used to count all documents in the collection. This will
// result in a full collection scan.
//
// The opts parameter can be used to specify options for the operation (see the options.CountOptions documentation).
func (coll *Collection) CountDocuments(ctx context.Context, filter any,
	opts ...options.Lister[options.CountOptions],
) (int64, error) {
	if ctx == nil {
		ctx = context.Background()
	}

	args, err := mongoutil.NewOptions[options.CountOptions](opts...)
	if err != nil {
		return 0, err
	}

	pipelineArr, err := countDocumentsAggregatePipeline(filter, coll.bsonOpts, coll.registry, args)
	if err != nil {
		return 0, err
	}

	sess := sessionFromContext(ctx)
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}
	if err = coll.client.validSession(sess); err != nil {
		return 0, err
	}

	rc := coll.readConcern
	if sess.TransactionRunning() {
		rc = nil
	}

	selector := makeReadPrefSelector(sess, coll.readSelector, coll.client.localThreshold)
	op := operation.NewAggregate(pipelineArr).Session(sess).ReadConcern(rc).ReadPreference(coll.readPreference).
		CommandMonitor(coll.client.monitor).ServerSelector(selector).ClusterClock(coll.client.clock).Database(coll.db.name).
		Collection(coll.name).Deployment(coll.client.deployment).Crypt(coll.client.cryptFLE).ServerAPI(coll.client.serverAPI).
		Timeout(coll.client.timeout).Authenticator(coll.client.authenticator)
	if args.Collation != nil {
		op.Collation(bsoncore.Document(toDocument(args.Collation)))
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return 0, err
		}

		op.Comment(comment)
	}
	if args.Hint != nil {
		if isUnorderedMap(args.Hint) {
			return 0, ErrMapForOrderedArgument{"hint"}
		}
		hintVal, err := marshalValue(args.Hint, coll.bsonOpts, coll.registry)
		if err != nil {
			return 0, err
		}
		op.Hint(hintVal)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}
	retry := driver.RetryNone
	if coll.client.retryReads {
		retry = driver.RetryOncePerCommand
	}
	op = op.Retry(retry)

	err = op.Execute(ctx)
	if err != nil {
		return 0, wrapErrors(err)
	}

	batch := op.ResultCursorResponse().FirstBatch
	if batch == nil {
		return 0, errors.New("invalid response from server, no 'firstBatch' field")
	}

	docs, err := batch.Documents()
	if err != nil || len(docs) == 0 {
		return 0, nil
	}

	val, ok := docs[0].Lookup("n").AsInt64OK()
	if !ok {
		return 0, errors.New("invalid response from server, no 'n' field")
	}

	return val, nil
}

// EstimatedDocumentCount executes a count command and returns an estimate of the number of documents in the collection
// using collection metadata.
//
// The opts parameter can be used to specify options for the operation (see the options.EstimatedDocumentCountOptions
// documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/count/.
func (coll *Collection) EstimatedDocumentCount(
	ctx context.Context,
	opts ...options.Lister[options.EstimatedDocumentCountOptions],
) (int64, error) {
	if ctx == nil {
		ctx = context.Background()
	}

	sess := sessionFromContext(ctx)

	var err error
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}

	err = coll.client.validSession(sess)
	if err != nil {
		return 0, err
	}

	rc := coll.readConcern
	if sess.TransactionRunning() {
		rc = nil
	}

	args, err := mongoutil.NewOptions[options.EstimatedDocumentCountOptions](opts...)
	if err != nil {
		return 0, fmt.Errorf("failed to construct options from builder: %w", err)
	}

	selector := makeReadPrefSelector(sess, coll.readSelector, coll.client.localThreshold)
	op := operation.NewCount().Session(sess).ClusterClock(coll.client.clock).
		Database(coll.db.name).Collection(coll.name).CommandMonitor(coll.client.monitor).
		Deployment(coll.client.deployment).ReadConcern(rc).ReadPreference(coll.readPreference).
		ServerSelector(selector).Crypt(coll.client.cryptFLE).ServerAPI(coll.client.serverAPI).
		Timeout(coll.client.timeout).Authenticator(coll.client.authenticator)

	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return 0, err
		}
		op = op.Comment(comment)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}

	retry := driver.RetryNone
	if coll.client.retryReads {
		retry = driver.RetryOncePerCommand
	}
	op.Retry(retry)

	err = op.Execute(ctx)
	return op.Result().N, wrapErrors(err)
}

// Distinct executes a distinct command to find the unique values for a specified field in the collection.
//
// The fieldName parameter specifies the field name for which distinct values should be returned.
//
// The filter parameter must be a document containing query operators and can be used to select which documents are
// considered. It cannot be nil. An empty document (e.g. bson.D{}) should be used to select all documents.
//
// The opts parameter can be used to specify options for the operation (see the options.DistinctOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/distinct/.
func (coll *Collection) Distinct(
	ctx context.Context,
	fieldName string,
	filter any,
	opts ...options.Lister[options.DistinctOptions],
) *DistinctResult {
	if ctx == nil {
		ctx = context.Background()
	}

	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return &DistinctResult{err: err}
	}

	sess := sessionFromContext(ctx)

	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}

	err = coll.client.validSession(sess)
	if err != nil {
		return &DistinctResult{err: err}
	}

	rc := coll.readConcern
	if sess.TransactionRunning() {
		rc = nil
	}

	selector := makeReadPrefSelector(sess, coll.readSelector, coll.client.localThreshold)

	args, err := mongoutil.NewOptions[options.DistinctOptions](opts...)
	if err != nil {
		err = fmt.Errorf("failed to construct options from builder: %w", err)

		return &DistinctResult{err: err}
	}

	op := operation.NewDistinct(fieldName, f).
		Session(sess).ClusterClock(coll.client.clock).
		Database(coll.db.name).Collection(coll.name).CommandMonitor(coll.client.monitor).
		Deployment(coll.client.deployment).ReadConcern(rc).ReadPreference(coll.readPreference).
		ServerSelector(selector).Crypt(coll.client.cryptFLE).ServerAPI(coll.client.serverAPI).
		Timeout(coll.client.timeout).Authenticator(coll.client.authenticator)

	if args.Collation != nil {
		op.Collation(bsoncore.Document(toDocument(args.Collation)))
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return &DistinctResult{err: err}
		}
		op.Comment(comment)
	}
	if args.Hint != nil {
		if isUnorderedMap(args.Hint) {
			return &DistinctResult{err: ErrMapForOrderedArgument{"hint"}}
		}
		hint, err := marshalValue(args.Hint, coll.bsonOpts, coll.registry)
		if err != nil {
			return &DistinctResult{err: err}
		}
		op.Hint(hint)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}
	retry := driver.RetryNone
	if coll.client.retryReads {
		retry = driver.RetryOncePerCommand
	}
	op = op.Retry(retry)

	err = op.Execute(ctx)
	if err != nil {
		return &DistinctResult{err: wrapErrors(err)}
	}

	arr, ok := op.Result().Values.ArrayOK()
	if !ok {
		err := fmt.Errorf("response field 'values' is type array, but received BSON type %s", op.Result().Values.Type)

		return &DistinctResult{err: err}
	}

	return &DistinctResult{
		reg:      coll.registry,
		arr:      bson.RawArray(arr),
		bsonOpts: coll.bsonOpts,
	}
}

// Find executes a find command and returns a Cursor over the matching documents in the collection.
//
// The filter parameter must be a document containing query operators and can be used to select which documents are
// included in the result. It cannot be nil. An empty document (e.g. bson.D{}) should be used to include all documents.
//
// The opts parameter can be used to specify options for the operation (see the options.FindOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/find/.
func (coll *Collection) Find(ctx context.Context, filter any,
	opts ...options.Lister[options.FindOptions],
) (*Cursor, error) {
	args, err := mongoutil.NewOptions(opts...)
	if err != nil {
		return nil, err
	}

	// Omit "maxTimeMS" from operations that return a user-managed cursor to
	// prevent confusing "cursor not found" errors.
	//
	// See DRIVERS-2722 for more detail.
	return coll.find(ctx, filter, true, args)
}

func (coll *Collection) find(
	ctx context.Context,
	filter any,
	omitMaxTimeMS bool,
	args *options.FindOptions,
) (cur *Cursor, err error) {
	if ctx == nil {
		ctx = context.Background()
	}

	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return nil, err
	}

	sess := sessionFromContext(ctx)
	// Always close any created implicit sessions if Find returns an error.
	defer func() {
		if err != nil && sess != nil {
			closeImplicitSession(sess)
		}
	}()
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
	}

	err = coll.client.validSession(sess)
	if err != nil {
		return nil, err
	}

	rc := coll.readConcern
	if sess.TransactionRunning() {
		rc = nil
	}

	selector := makeReadPrefSelector(sess, coll.readSelector, coll.client.localThreshold)
	op := operation.NewFind(f).
		Session(sess).ReadConcern(rc).ReadPreference(coll.readPreference).
		CommandMonitor(coll.client.monitor).ServerSelector(selector).
		ClusterClock(coll.client.clock).Database(coll.db.name).Collection(coll.name).
		Deployment(coll.client.deployment).Crypt(coll.client.cryptFLE).ServerAPI(coll.client.serverAPI).
		Timeout(coll.client.timeout).Logger(coll.client.logger).Authenticator(coll.client.authenticator).
		OmitMaxTimeMS(omitMaxTimeMS)

	cursorOpts := coll.client.createBaseCursorOptions()

	cursorOpts.MarshalValueEncoderFn = newEncoderFn(coll.bsonOpts, coll.registry)

	if args.AllowDiskUse != nil {
		op.AllowDiskUse(*args.AllowDiskUse)
	}
	if args.AllowPartialResults != nil {
		op.AllowPartialResults(*args.AllowPartialResults)
	}
	if args.BatchSize != nil {
		cursorOpts.BatchSize = *args.BatchSize
		op.BatchSize(*args.BatchSize)
	}
	if args.Collation != nil {
		op.Collation(bsoncore.Document(toDocument(args.Collation)))
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}

		op.Comment(comment)
		cursorOpts.Comment = comment
	}
	if args.CursorType != nil {
		switch *args.CursorType {
		case options.Tailable:
			op.Tailable(true)
		case options.TailableAwait:
			op.Tailable(true)
			op.AwaitData(true)
		}
	}
	if args.Hint != nil {
		if isUnorderedMap(args.Hint) {
			return nil, ErrMapForOrderedArgument{"hint"}
		}
		hint, err := marshalValue(args.Hint, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op.Hint(hint)
	}
	if args.Let != nil {
		let, err := marshal(args.Let, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op.Let(let)
	}
	if args.Limit != nil {
		limit := *args.Limit
		if limit < 0 {
			limit = -1 * limit
			op.SingleBatch(true)
		}
		cursorOpts.Limit = int32(limit)
		op.Limit(limit)
	}
	if args.Max != nil {
		max, err := marshal(args.Max, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op.Max(max)
	}
	if args.MaxAwaitTime != nil {
		cursorOpts.SetMaxAwaitTime(*args.MaxAwaitTime)
	}
	if args.Min != nil {
		min, err := marshal(args.Min, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op.Min(min)
	}
	if args.NoCursorTimeout != nil {
		op.NoCursorTimeout(*args.NoCursorTimeout)
	}
	if args.OplogReplay != nil {
		op.OplogReplay(*args.OplogReplay)
	}
	if args.Projection != nil {
		proj, err := marshal(args.Projection, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op.Projection(proj)
	}
	if args.ReturnKey != nil {
		op.ReturnKey(*args.ReturnKey)
	}
	if args.ShowRecordID != nil {
		op.ShowRecordID(*args.ShowRecordID)
	}
	if args.Skip != nil {
		op.Skip(*args.Skip)
	}
	if args.Sort != nil {
		if isUnorderedMap(args.Sort) {
			return nil, ErrMapForOrderedArgument{"sort"}
		}
		sort, err := marshal(args.Sort, coll.bsonOpts, coll.registry)
		if err != nil {
			return nil, err
		}
		op.Sort(sort)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}
	retry := driver.RetryNone
	if coll.client.retryReads {
		retry = driver.RetryOncePerCommand
	}
	op = op.Retry(retry)

	if err = op.Execute(ctx); err != nil {
		return nil, wrapErrors(err)
	}

	bc, err := op.Result(cursorOpts)
	if err != nil {
		return nil, wrapErrors(err)
	}

	return newCursorWithSession(bc, coll.bsonOpts, coll.registry, sess,
		withCursorOptionClientTimeout(coll.client.timeout))
}

func newFindArgsFromFindOneArgs(args *options.FindOneOptions) *options.FindOptions {
	var limit int64 = -1
	v := &options.FindOptions{Limit: &limit}
	if args != nil {
		v.AllowPartialResults = args.AllowPartialResults
		v.Collation = args.Collation
		v.Comment = args.Comment
		v.Hint = args.Hint
		v.Max = args.Max
		v.Min = args.Min
		v.OplogReplay = args.OplogReplay
		v.Projection = args.Projection
		v.ReturnKey = args.ReturnKey
		v.ShowRecordID = args.ShowRecordID
		v.Skip = args.Skip
		v.Sort = args.Sort
		v.Internal = args.Internal
	}
	return v
}

// FindOne executes a find command and returns a SingleResult for one document in the collection.
//
// The filter parameter must be a document containing query operators and can be used to select the document to be
// returned. It cannot be nil. If the filter does not match any documents, a SingleResult with an error set to
// ErrNoDocuments will be returned. If the filter matches multiple documents, one will be selected from the matched set.
//
// The opts parameter can be used to specify options for this operation (see the options.FindOneOptions documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/find/.
func (coll *Collection) FindOne(ctx context.Context, filter any,
	opts ...options.Lister[options.FindOneOptions],
) *SingleResult {
	if ctx == nil {
		ctx = context.Background()
	}

	args, err := mongoutil.NewOptions(opts...)
	if err != nil {
		return &SingleResult{err: err}
	}
	cursor, err := coll.find(ctx, filter, false, newFindArgsFromFindOneArgs(args))
	return &SingleResult{
		ctx:      ctx,
		cur:      cursor,
		bsonOpts: coll.bsonOpts,
		reg:      coll.registry,
		err:      wrapErrors(err),
	}
}

func (coll *Collection) findAndModify(ctx context.Context, op *operation.FindAndModify) *SingleResult {
	if ctx == nil {
		ctx = context.Background()
	}

	sess := sessionFromContext(ctx)
	var err error
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}

	err = coll.client.validSession(sess)
	if err != nil {
		return &SingleResult{err: err}
	}

	wc := coll.writeConcern
	if sess.TransactionRunning() {
		wc = nil
	}
	if !wc.Acknowledged() {
		sess = nil
	}

	selector := makePinnedSelector(sess, coll.writeSelector)

	retry := driver.RetryNone
	if coll.client.retryWrites {
		retry = driver.RetryOnce
	}

	op = op.Session(sess).
		WriteConcern(wc).
		CommandMonitor(coll.client.monitor).
		ServerSelector(selector).
		ClusterClock(coll.client.clock).
		Database(coll.db.name).
		Collection(coll.name).
		Deployment(coll.client.deployment).
		Retry(retry).
		Crypt(coll.client.cryptFLE)

	rr, err := processWriteError(op.Execute(ctx))
	if err != nil {
		return &SingleResult{err: err}
	}

	return &SingleResult{
		ctx:          ctx,
		rdr:          bson.Raw(op.Result().Value),
		bsonOpts:     coll.bsonOpts,
		reg:          coll.registry,
		Acknowledged: rr.isAcknowledged(),
	}
}

// FindOneAndDelete executes a findAndModify command to delete at most one document in the collection. and returns the
// document as it appeared before deletion.
//
// The filter parameter must be a document containing query operators and can be used to select the document to be
// deleted. It cannot be nil. If the filter does not match any documents, a SingleResult with an error set to
// ErrNoDocuments wil be returned. If the filter matches multiple documents, one will be selected from the matched set.
//
// The opts parameter can be used to specify options for the operation (see the options.FindOneAndDeleteOptions
// documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/findAndModify/.
func (coll *Collection) FindOneAndDelete(
	ctx context.Context,
	filter any,
	opts ...options.Lister[options.FindOneAndDeleteOptions],
) *SingleResult {
	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return &SingleResult{err: err}
	}

	args, err := mongoutil.NewOptions[options.FindOneAndDeleteOptions](opts...)
	if err != nil {
		return &SingleResult{err: fmt.Errorf("failed to construct options from builder: %w", err)}
	}

	op := operation.NewFindAndModify(f).Remove(true).ServerAPI(coll.client.serverAPI).Timeout(coll.client.timeout).Authenticator(coll.client.authenticator)
	if args.Collation != nil {
		op = op.Collation(bsoncore.Document(toDocument(args.Collation)))
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Comment(comment)
	}
	if args.Projection != nil {
		proj, err := marshal(args.Projection, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Fields(proj)
	}
	if args.Sort != nil {
		if isUnorderedMap(args.Sort) {
			return &SingleResult{err: ErrMapForOrderedArgument{"sort"}}
		}
		sort, err := marshal(args.Sort, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Sort(sort)
	}
	if args.Hint != nil {
		if isUnorderedMap(args.Hint) {
			return &SingleResult{err: ErrMapForOrderedArgument{"hint"}}
		}
		hint, err := marshalValue(args.Hint, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Hint(hint)
	}
	if args.Let != nil {
		let, err := marshal(args.Let, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Let(let)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}

	return coll.findAndModify(ctx, op)
}

// FindOneAndReplace executes a findAndModify command to replace at most one document in the collection
// and returns the document as it appeared before replacement.
//
// The filter parameter must be a document containing query operators and can be used to select the document to be
// replaced. It cannot be nil. If the filter does not match any documents, a SingleResult with an error set to
// ErrNoDocuments wil be returned. If the filter matches multiple documents, one will be selected from the matched set.
//
// The replacement parameter must be a document that will be used to replace the selected document. It cannot be nil
// and cannot contain any update operators (https://www.mongodb.com/docs/manual/reference/operator/update/).
//
// The opts parameter can be used to specify options for the operation (see the options.FindOneAndReplaceOptions
// documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/findAndModify/.
func (coll *Collection) FindOneAndReplace(
	ctx context.Context,
	filter any,
	replacement any,
	opts ...options.Lister[options.FindOneAndReplaceOptions],
) *SingleResult {
	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return &SingleResult{err: err}
	}
	r, err := marshal(replacement, coll.bsonOpts, coll.registry)
	if err != nil {
		return &SingleResult{err: err}
	}
	if firstElem, err := r.IndexErr(0); err == nil && strings.HasPrefix(firstElem.Key(), "$") {
		return &SingleResult{err: errors.New("replacement document cannot contain keys beginning with '$'")}
	}

	args, err := mongoutil.NewOptions[options.FindOneAndReplaceOptions](opts...)
	if err != nil {
		return &SingleResult{err: fmt.Errorf("failed to construct options from builder: %w", err)}
	}

	op := operation.NewFindAndModify(f).Update(bsoncore.Value{Type: bsoncore.TypeEmbeddedDocument, Data: r}).
		ServerAPI(coll.client.serverAPI).Timeout(coll.client.timeout).Authenticator(coll.client.authenticator)
	if args.BypassDocumentValidation != nil && *args.BypassDocumentValidation {
		op = op.BypassDocumentValidation(*args.BypassDocumentValidation)
	}
	if args.Collation != nil {
		op = op.Collation(bsoncore.Document(toDocument(args.Collation)))
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Comment(comment)
	}
	if args.Projection != nil {
		proj, err := marshal(args.Projection, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Fields(proj)
	}
	if args.ReturnDocument != nil {
		op = op.NewDocument(*args.ReturnDocument == options.After)
	}
	if args.Sort != nil {
		if isUnorderedMap(args.Sort) {
			return &SingleResult{err: ErrMapForOrderedArgument{"sort"}}
		}
		sort, err := marshal(args.Sort, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Sort(sort)
	}
	if args.Upsert != nil {
		op = op.Upsert(*args.Upsert)
	}
	if args.Hint != nil {
		if isUnorderedMap(args.Hint) {
			return &SingleResult{err: ErrMapForOrderedArgument{"hint"}}
		}
		hint, err := marshalValue(args.Hint, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Hint(hint)
	}
	if args.Let != nil {
		let, err := marshal(args.Let, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Let(let)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}
	if additionalCmd, ok := optionsutil.Value(args.Internal, "addCommandFields").(bson.D); ok {
		op = op.AdditionalCmd(additionalCmd)
	}

	return coll.findAndModify(ctx, op)
}

// FindOneAndUpdate executes a findAndModify command to update at most one document in the collection and returns the
// document as it appeared before updating.
//
// The filter parameter must be a document containing query operators and can be used to select the document to be
// updated. It cannot be nil. If the filter does not match any documents, a SingleResult with an error set to
// ErrNoDocuments wil be returned. If the filter matches multiple documents, one will be selected from the matched set.
//
// The update parameter must be a document containing update operators
// (https://www.mongodb.com/docs/manual/reference/operator/update/) and can be used to specify the modifications to be made
// to the selected document. It cannot be nil or empty.
//
// The opts parameter can be used to specify options for the operation (see the options.FindOneAndUpdateOptions
// documentation).
//
// For more information about the command, see https://www.mongodb.com/docs/manual/reference/command/findAndModify/.
func (coll *Collection) FindOneAndUpdate(
	ctx context.Context,
	filter any,
	update any,
	opts ...options.Lister[options.FindOneAndUpdateOptions],
) *SingleResult {
	if ctx == nil {
		ctx = context.Background()
	}

	f, err := marshal(filter, coll.bsonOpts, coll.registry)
	if err != nil {
		return &SingleResult{err: err}
	}

	args, err := mongoutil.NewOptions[options.FindOneAndUpdateOptions](opts...)
	if err != nil {
		return &SingleResult{err: fmt.Errorf("failed to construct options from builder: %w", err)}
	}

	op := operation.NewFindAndModify(f).ServerAPI(coll.client.serverAPI).Timeout(coll.client.timeout).Authenticator(coll.client.authenticator)

	u, err := marshalUpdateValue(update, coll.bsonOpts, coll.registry, true)
	if err != nil {
		return &SingleResult{err: err}
	}
	op = op.Update(u)

	if args.ArrayFilters != nil {
		af := args.ArrayFilters
		reg := coll.registry
		filtersDoc, err := marshalValue(af, coll.bsonOpts, reg)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.ArrayFilters(filtersDoc.Data)
	}
	if args.BypassDocumentValidation != nil && *args.BypassDocumentValidation {
		op = op.BypassDocumentValidation(*args.BypassDocumentValidation)
	}
	if args.Collation != nil {
		op = op.Collation(bsoncore.Document(toDocument(args.Collation)))
	}
	if args.Comment != nil {
		comment, err := marshalValue(args.Comment, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Comment(comment)
	}
	if args.Projection != nil {
		proj, err := marshal(args.Projection, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Fields(proj)
	}
	if args.ReturnDocument != nil {
		op = op.NewDocument(*args.ReturnDocument == options.After)
	}
	if args.Sort != nil {
		if isUnorderedMap(args.Sort) {
			return &SingleResult{err: ErrMapForOrderedArgument{"sort"}}
		}
		sort, err := marshal(args.Sort, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Sort(sort)
	}
	if args.Upsert != nil {
		op = op.Upsert(*args.Upsert)
	}
	if args.Hint != nil {
		if isUnorderedMap(args.Hint) {
			return &SingleResult{err: ErrMapForOrderedArgument{"hint"}}
		}
		hint, err := marshalValue(args.Hint, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Hint(hint)
	}
	if args.Let != nil {
		let, err := marshal(args.Let, coll.bsonOpts, coll.registry)
		if err != nil {
			return &SingleResult{err: err}
		}
		op = op.Let(let)
	}
	if rawData, ok := optionsutil.Value(args.Internal, "rawData").(bool); ok {
		op = op.RawData(rawData)
	}
	if additionalCmd, ok := optionsutil.Value(args.Internal, "addCommandFields").(bson.D); ok {
		op = op.AdditionalCmd(additionalCmd)
	}

	return coll.findAndModify(ctx, op)
}

// Watch returns a change stream for all changes on the corresponding collection. See
// https://www.mongodb.com/docs/manual/changeStreams/ for more information about change streams.
//
// The Collection must be configured with read concern majority or no read concern for a change stream to be created
// successfully.
//
// The pipeline parameter must be an array of documents, each representing a pipeline stage. The pipeline cannot be
// nil but can be empty. The stage documents must all be non-nil. See https://www.mongodb.com/docs/manual/changeStreams/ for
// a list of pipeline stages that can be used with change streams. For a pipeline of bson.D documents, the
// mongo.Pipeline{} type can be used.
//
// The opts parameter can be used to specify options for change stream creation (see the options.ChangeStreamOptions
// documentation).
func (coll *Collection) Watch(ctx context.Context, pipeline any,
	opts ...options.Lister[options.ChangeStreamOptions],
) (*ChangeStream, error) {
	csConfig := changeStreamConfig{
		readConcern:    coll.readConcern,
		readPreference: coll.readPreference,
		client:         coll.client,
		bsonOpts:       coll.bsonOpts,
		registry:       coll.registry,
		streamType:     CollectionStream,
		collectionName: coll.Name(),
		databaseName:   coll.db.Name(),
		crypt:          coll.client.cryptFLE,
	}
	return newChangeStream(ctx, csConfig, pipeline, opts...)
}

// Indexes returns an IndexView instance that can be used to perform operations on the indexes for the collection.
func (coll *Collection) Indexes() IndexView {
	return IndexView{coll: coll}
}

// SearchIndexes returns a SearchIndexView instance that can be used to perform operations on the search indexes for the collection.
func (coll *Collection) SearchIndexes() SearchIndexView {
	c := coll.Clone()
	c.readConcern = nil
	c.writeConcern = nil
	return SearchIndexView{
		coll: c,
	}
}

// Drop drops the collection on the server. This method ignores "namespace not found" errors so it is safe to drop
// a collection that does not exist on the server.
func (coll *Collection) Drop(ctx context.Context, opts ...options.Lister[options.DropCollectionOptions]) error {
	args, err := mongoutil.NewOptions[options.DropCollectionOptions](opts...)
	if err != nil {
		return fmt.Errorf("failed to construct options from builder: %w", err)
	}

	ef := args.EncryptedFields

	if ef == nil {
		ef = coll.db.getEncryptedFieldsFromMap(coll.name)
	}

	if ef == nil && coll.db.client.encryptedFieldsMap != nil {
		var err error
		if ef, err = coll.db.getEncryptedFieldsFromServer(ctx, coll.name); err != nil {
			return err
		}
	}

	if ef != nil {
		return coll.dropEncryptedCollection(ctx, ef)
	}

	return coll.drop(ctx)
}

// dropEncryptedCollection drops a collection with EncryptedFields.
func (coll *Collection) dropEncryptedCollection(ctx context.Context, ef any) error {
	efBSON, err := marshal(ef, coll.bsonOpts, coll.registry)
	if err != nil {
		return fmt.Errorf("error transforming document: %w", err)
	}

	// Drop the two encryption-related, associated collections: `escCollection` and `ecocCollection`.
	// Drop ESCCollection.
	escCollection, err := csfle.GetEncryptedStateCollectionName(efBSON, coll.name, csfle.EncryptedStateCollection)
	if err != nil {
		return err
	}
	if err := coll.db.Collection(escCollection).drop(ctx); err != nil {
		return err
	}

	// Drop ECOCCollection.
	ecocCollection, err := csfle.GetEncryptedStateCollectionName(efBSON, coll.name, csfle.EncryptedCompactionCollection)
	if err != nil {
		return err
	}
	if err := coll.db.Collection(ecocCollection).drop(ctx); err != nil {
		return err
	}

	// Drop the data collection.
	return coll.drop(ctx)
}

// drop drops a collection without EncryptedFields.
func (coll *Collection) drop(ctx context.Context) error {
	if ctx == nil {
		ctx = context.Background()
	}

	sess := sessionFromContext(ctx)
	if sess == nil && coll.client.sessionPool != nil {
		sess = session.NewImplicitClientSession(coll.client.sessionPool, coll.client.id)
		defer sess.EndSession()
	}

	err := coll.client.validSession(sess)
	if err != nil {
		return err
	}

	wc := coll.writeConcern
	if sess.TransactionRunning() {
		wc = nil
	}
	if !wc.Acknowledged() {
		sess = nil
	}

	selector := makePinnedSelector(sess, coll.writeSelector)

	op := operation.NewDropCollection().
		Session(sess).WriteConcern(wc).CommandMonitor(coll.client.monitor).
		ServerSelector(selector).ClusterClock(coll.client.clock).
		Database(coll.db.name).Collection(coll.name).
		Deployment(coll.client.deployment).Crypt(coll.client.cryptFLE).
		ServerAPI(coll.client.serverAPI).Timeout(coll.client.timeout).
		Authenticator(coll.client.authenticator)
	err = op.Execute(ctx)

	// ignore namespace not found errors
	var driverErr driver.Error
	if !errors.As(err, &driverErr) || !driverErr.NamespaceNotFound() {
		return wrapErrors(err)
	}
	return nil
}

func toDocument(co *options.Collation) bson.Raw {
	idx, doc := bsoncore.AppendDocumentStart(nil)
	if co.Locale != "" {
		doc = bsoncore.AppendStringElement(doc, "locale", co.Locale)
	}
	if co.CaseLevel {
		doc = bsoncore.AppendBooleanElement(doc, "caseLevel", true)
	}
	if co.CaseFirst != "" {
		doc = bsoncore.AppendStringElement(doc, "caseFirst", co.CaseFirst)
	}
	if co.Strength != 0 {
		doc = bsoncore.AppendInt32Element(doc, "strength", int32(co.Strength))
	}
	if co.NumericOrdering {
		doc = bsoncore.AppendBooleanElement(doc, "numericOrdering", true)
	}
	if co.Alternate != "" {
		doc = bsoncore.AppendStringElement(doc, "alternate", co.Alternate)
	}
	if co.MaxVariable != "" {
		doc = bsoncore.AppendStringElement(doc, "maxVariable", co.MaxVariable)
	}
	if co.Normalization {
		doc = bsoncore.AppendBooleanElement(doc, "normalization", true)
	}
	if co.Backwards {
		doc = bsoncore.AppendBooleanElement(doc, "backwards", true)
	}
	doc, _ = bsoncore.AppendDocumentEnd(doc, idx)
	return doc
}

type pinnedServerSelector struct {
	stringer fmt.Stringer
	fallback description.ServerSelector
	session  *session.Client
}

var _ description.ServerSelector = pinnedServerSelector{}

func (pss pinnedServerSelector) String() string {
	if pss.stringer == nil {
		return ""
	}

	return pss.stringer.String()
}

func (pss pinnedServerSelector) SelectServer(
	t description.Topology,
	svrs []description.Server,
) ([]description.Server, error) {
	if pss.session != nil && pss.session.PinnedServerAddr != nil {
		// If there is a pinned server, try to find it in the list of candidates.
		for _, candidate := range svrs {
			if candidate.Addr == *pss.session.PinnedServerAddr {
				return []description.Server{candidate}, nil
			}
		}

		return nil, nil
	}

	return pss.fallback.SelectServer(t, svrs)
}

func makePinnedSelector(sess *session.Client, fallback description.ServerSelector) pinnedServerSelector {
	pss := pinnedServerSelector{
		session:  sess,
		fallback: fallback,
	}

	if srvSelectorStringer, ok := fallback.(fmt.Stringer); ok {
		pss.stringer = srvSelectorStringer
	}

	return pss
}

func makeReadPrefSelector(
	sess *session.Client,
	selector description.ServerSelector,
	localThreshold time.Duration,
) pinnedServerSelector {
	if sess != nil && sess.TransactionRunning() {
		selector = &serverselector.Composite{
			Selectors: []description.ServerSelector{
				&serverselector.ReadPref{ReadPref: sess.CurrentRp},
				&serverselector.Latency{Latency: localThreshold},
			},
		}
	}

	return makePinnedSelector(sess, selector)
}

func makeOutputAggregateSelector(
	sess *session.Client,
	rp *readpref.ReadPref,
	localThreshold time.Duration,
) pinnedServerSelector {
	if sess != nil && sess.TransactionRunning() {
		// Use current transaction's read preference if available
		rp = sess.CurrentRp
	}

	selector := &serverselector.Composite{
		Selectors: []description.ServerSelector{
			&serverselector.ReadPref{ReadPref: rp, IsOutputAggregate: true},
			&serverselector.Latency{Latency: localThreshold},
		},
	}

	return makePinnedSelector(sess, selector)
}

// isUnorderedMap returns true if val is a map with more than 1 element. It is typically used to
// check for unordered Go values that are used in nested command documents where different field
// orders mean different things. Examples are the "sort" and "hint" fields.
func isUnorderedMap(val any) bool {
	refValue := reflect.ValueOf(val)
	return refValue.Kind() == reflect.Map && refValue.Len() > 1
}