From 61449fe2cf39b0c7cdeb3fafbbc96205154dffd3 Mon Sep 17 00:00:00 2001
From: Saurabh Wagh <sawagh@google.com>
Date: Tue, 17 Sep 2019 17:48:47 -0700
Subject: [PATCH] Implement Roster based MMF that populates roster pools with
 tickets from the pools supplied. (#806)

* update

* Implement the Roster based match function for scale tests
---
 .../golang/rosterbased/mmf/matchfunction.go   | 98 +++++++++++++++++--
 1 file changed, 89 insertions(+), 9 deletions(-)

diff --git a/examples/functions/golang/rosterbased/mmf/matchfunction.go b/examples/functions/golang/rosterbased/mmf/matchfunction.go
index 2ef1c8535..42d61c394 100644
--- a/examples/functions/golang/rosterbased/mmf/matchfunction.go
+++ b/examples/functions/golang/rosterbased/mmf/matchfunction.go
@@ -12,28 +12,108 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package mmf provides a sample match function that uses the GRPC harness to set up 1v1 matches.
-// This sample is a reference to demonstrate the usage of the GRPC harness and should only be used as
-// a starting point for your match function. You will need to modify the
-// matchmaking logic in this function based on your game's requirements.
 package mmf
 
 import (
+	"fmt"
+	"time"
+
 	"github.com/sirupsen/logrus"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 	mmfHarness "open-match.dev/open-match/pkg/harness/function/golang"
 	"open-match.dev/open-match/pkg/pb"
 )
 
 var (
-	matchName = "roster-based-matchfunction"
-	logger    = logrus.WithFields(logrus.Fields{
+	matchName       = "roster-based-matchfunction"
+	emptyRosterSpot = "EMPTY_ROSTER_SPOT"
+	logger          = logrus.WithFields(logrus.Fields{
 		"app":       "openmatch",
 		"component": "mmf.rosterbased",
 	})
 )
 
-// MakeMatches is where your custom matchmaking logic lives.
 func MakeMatches(p *mmfHarness.MatchFunctionParams) ([]*pb.Match, error) {
-	logger.Infof("MakeMatches called for Profile:%v", p.ProfileName)
-	return []*pb.Match{}, nil
+	// This roster based match function expects the match profile to have a
+	// populated roster specifying the empty slots for each pool name and also
+	// have the ticket pools referenced in the roster. It generates matches by
+	// populating players from the specified pools into rosters.
+	wantTickets, err := wantPoolTickets(p.Rosters)
+	if err != nil {
+		return nil, err
+	}
+
+	var matches []*pb.Match
+	for {
+		insufficientTickets := false
+		matchTickets := []*pb.Ticket{}
+		matchRosters := []*pb.Roster{}
+		// Loop through each pool wanted in the rosters and pick the number of
+		// wanted players from the respective Pool.
+		for poolName, want := range wantTickets {
+			have, ok := p.PoolNameToTickets[poolName]
+			if !ok {
+				// A wanted Pool was not found in the Pools specified in the profile.
+				insufficientTickets = true
+				break
+			}
+
+			if len(have) < want {
+				// The Pool in the profile has fewer tickets than what the roster needs.
+				insufficientTickets = true
+				break
+			}
+
+			// Populate the wanted tickets from the Tickets in the corresponding Pool.
+			matchTickets = append(matchTickets, have[0:want]...)
+			p.PoolNameToTickets[poolName] = have[want:]
+			var ids []string
+			for _, ticket := range matchTickets {
+				ids = append(ids, ticket.Id)
+			}
+
+			matchRosters = append(matchRosters, &pb.Roster{
+				Name:      poolName,
+				TicketIds: ids,
+			})
+		}
+
+		if insufficientTickets {
+			// Ran out of Tickets. Matches cannot be created from the remaining Tickets.
+			break
+		}
+
+		matches = append(matches, &pb.Match{
+			MatchId:       fmt.Sprintf("profile-%v-time-%v", p.ProfileName, time.Now().Format("2006-01-02T15:04:05.00")),
+			MatchProfile:  p.ProfileName,
+			MatchFunction: matchName,
+			Tickets:       matchTickets,
+			Rosters:       matchRosters,
+		})
+	}
+
+	return matches, nil
+}
+
+// wantPoolTickets parses the roster to return a map of the Pool name to the
+// number of empty roster slots for that Pool.
+func wantPoolTickets(rosters []*pb.Roster) (map[string]int, error) {
+	wantTickets := make(map[string]int)
+	for _, r := range rosters {
+		if _, ok := wantTickets[r.Name]; ok {
+			// We do not expect multiple Roster Pools to have the same name.
+			logger.Errorf("multiple rosters with same name not supported")
+			return nil, status.Error(codes.InvalidArgument, "multiple rosters with same name not supported")
+		}
+
+		wantTickets[r.Name] = 0
+		for _, slot := range r.TicketIds {
+			if slot == emptyRosterSpot {
+				wantTickets[r.Name] = wantTickets[r.Name] + 1
+			}
+		}
+	}
+
+	return wantTickets, nil
 }