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vendor/go.mongodb.org/mongo-driver/x/mongo/driverlegacy/count.go

@@ -0,0 +1,97 @@
+// 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 driverlegacy
+
+import (
+	"context"
+	"time"
+
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/x/bsonx"
+
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/description"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/session"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+	"go.mongodb.org/mongo-driver/x/network/command"
+)
+
+// Count handles the full cycle dispatch and execution of a count command against the provided
+// topology.
+func Count(
+	ctx context.Context,
+	cmd command.Count,
+	topo *topology.Topology,
+	selector description.ServerSelector,
+	clientID uuid.UUID,
+	pool *session.Pool,
+	registry *bsoncodec.Registry,
+	opts ...*options.CountOptions,
+) (int64, error) {
+
+	ss, err := topo.SelectServerLegacy(ctx, selector)
+	if err != nil {
+		return 0, err
+	}
+
+	desc := ss.Description()
+	conn, err := ss.ConnectionLegacy(ctx)
+	if err != nil {
+		return 0, err
+	}
+	defer conn.Close()
+
+	rp, err := getReadPrefBasedOnTransaction(cmd.ReadPref, cmd.Session)
+	if err != nil {
+		return 0, err
+	}
+	cmd.ReadPref = rp
+
+	// If no explicit session and deployment supports sessions, start implicit session.
+	if cmd.Session == nil && topo.SupportsSessions() {
+		cmd.Session, err = session.NewClientSession(pool, clientID, session.Implicit)
+		if err != nil {
+			return 0, err
+		}
+		defer cmd.Session.EndSession()
+	}
+
+	countOpts := options.MergeCountOptions(opts...)
+
+	if countOpts.Limit != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"limit", bsonx.Int64(*countOpts.Limit)})
+	}
+	if countOpts.MaxTime != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{
+			"maxTimeMS", bsonx.Int64(int64(*countOpts.MaxTime / time.Millisecond)),
+		})
+	}
+	if countOpts.Skip != nil {
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"skip", bsonx.Int64(*countOpts.Skip)})
+	}
+	if countOpts.Collation != nil {
+		if desc.WireVersion.Max < 5 {
+			return 0, ErrCollation
+		}
+		collDoc, err := bsonx.ReadDoc(countOpts.Collation.ToDocument())
+		if err != nil {
+			return 0, err
+		}
+		cmd.Opts = append(cmd.Opts, bsonx.Elem{"collation", bsonx.Document(collDoc)})
+	}
+	if countOpts.Hint != nil {
+		hintElem, err := interfaceToElement("hint", countOpts.Hint, registry)
+		if err != nil {
+			return 0, err
+		}
+
+		cmd.Opts = append(cmd.Opts, hintElem)
+	}
+
+	return cmd.RoundTrip(ctx, desc, conn)
+}