Add TeamRuleset (#13)

This builds on work done by @dlsteuer in #10

ruleset.go

@@ -34,5 +34,5 @@ type SnakeMove struct {
 
 type Ruleset interface {
 	CreateInitialBoardState(width int32, height int32, snakeIDs []string) (*BoardState, error)
-	ResolveMoves(prevState *BoardState, moves []SnakeMove) (*BoardState, error)
+	CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error)
 }

standard.go

@@ -131,7 +131,7 @@ func (r *StandardRuleset) isKnownBoardSize(b *BoardState) bool {
 	return false
 }
 
-func (r *StandardRuleset) ResolveMoves(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
+func (r *StandardRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
 	// We specifically want to copy prevState, so as not to alter it directly.
 	nextState := &BoardState{
 		Height: prevState.Height,
@@ -160,7 +160,7 @@ func (r *StandardRuleset) ResolveMoves(prevState *BoardState, moves []SnakeMove)
 	}
 
 	// TODO: LOG?
-	err = r.eliminateSnakes(nextState)
+	err = r.maybeEliminateSnakes(nextState)
 	if err != nil {
 		return nil, err
 	}
@@ -172,7 +172,7 @@ func (r *StandardRuleset) ResolveMoves(prevState *BoardState, moves []SnakeMove)
 	// of equal length actually show length + 1
 
 	// TODO: LOG?
-	err = r.feedSnakes(nextState)
+	err = r.maybeFeedSnakes(nextState)
 	if err != nil {
 		return nil, err
 	}
@@ -256,7 +256,7 @@ func (r *StandardRuleset) reduceSnakeHealth(b *BoardState) error {
 	return nil
 }
 
-func (r *StandardRuleset) eliminateSnakes(b *BoardState) error {
+func (r *StandardRuleset) maybeEliminateSnakes(b *BoardState) error {
 	// First order snake indices by length.
 	// In multi-collision scenarios we want to always attribute elimination to the longest snake.
 	snakeIndicesByLength := make([]int, len(b.Snakes))
@@ -351,7 +351,7 @@ func (r *StandardRuleset) snakeHasLostHeadToHead(s *Snake, other *Snake) bool {
 	return false
 }
 
-func (r *StandardRuleset) feedSnakes(b *BoardState) error {
+func (r *StandardRuleset) maybeFeedSnakes(b *BoardState) error {
 	newFood := []Point{}
 	for _, food := range b.Food {
 		foodHasBeenEaten := false
@@ -364,10 +364,8 @@ func (r *StandardRuleset) feedSnakes(b *BoardState) error {
 			}
 
 			if snake.Body[0].X == food.X && snake.Body[0].Y == food.Y {
+				r.feedSnake(snake)
 				foodHasBeenEaten = true
-				// Update snake
-				snake.Body = append(snake.Body, snake.Body[len(snake.Body)-1])
-				snake.Health = SnakeMaxHealth
 			}
 		}
 		// Persist food to next BoardState if not eaten
@@ -380,6 +378,17 @@ func (r *StandardRuleset) feedSnakes(b *BoardState) error {
 	return nil
 }
 
+func (r *StandardRuleset) feedSnake(snake *Snake) {
+	r.growSnake(snake)
+	snake.Health = SnakeMaxHealth
+}
+
+func (r *StandardRuleset) growSnake(snake *Snake) {
+	if len(snake.Body) > 0 {
+		snake.Body = append(snake.Body, snake.Body[len(snake.Body)-1])
+	}
+}
+
 func (r *StandardRuleset) maybeSpawnFood(b *BoardState) error {
 	if len(b.Food) == 0 || rand.Float32() <= FoodSpawnChance {
 		return r.spawnFood(b, 1)

standard_test.go

@@ -20,7 +20,7 @@ func TestSanity(t *testing.T) {
 	require.Len(t, state.Food, 0)
 	require.Len(t, state.Snakes, 0)
 
-	next, err := r.ResolveMoves(
+	next, err := r.CreateNextBoardState(
 		&BoardState{},
 		[]SnakeMove{},
 	)
@@ -244,7 +244,7 @@ func TestPlaceFood(t *testing.T) {
 	}
 }
 
-func TestResolveMoves(t *testing.T) {
+func TestCreateNextBoardState(t *testing.T) {
 	// TODO
 }
 
@@ -761,7 +761,7 @@ func TestSnakeHasLostHeadToHead(t *testing.T) {
 
 }
 
-func TestEliminateSnakes(t *testing.T) {
+func TestMaybeEliminateSnakes(t *testing.T) {
 	tests := []struct {
 		Name                     string
 		Snakes                   []Snake
@@ -938,7 +938,7 @@ func TestEliminateSnakes(t *testing.T) {
 				Height: 10,
 				Snakes: test.Snakes,
 			}
-			err := r.eliminateSnakes(b)
+			err := r.maybeEliminateSnakes(b)
 			require.Equal(t, test.Err, err)
 			for i, snake := range b.Snakes {
 				require.Equal(t, test.ExpectedEliminatedCauses[i], snake.EliminatedCause)
@@ -948,7 +948,7 @@ func TestEliminateSnakes(t *testing.T) {
 	}
 }
 
-func TestFeedSnakes(t *testing.T) {
+func TestMaybeFeedSnakes(t *testing.T) {
 	tests := []struct {
 		Name           string
 		Snakes         []Snake
@@ -1021,7 +1021,7 @@ func TestFeedSnakes(t *testing.T) {
 			Snakes: test.Snakes,
 			Food:   test.Food,
 		}
-		err := r.feedSnakes(b)
+		err := r.maybeFeedSnakes(b)
 		require.NoError(t, err, test.Name)
 		require.Equal(t, len(test.ExpectedSnakes), len(b.Snakes), test.Name)
 		for i := 0; i < len(b.Snakes); i++ {

team.go

@@ -0,0 +1,110 @@
+package rules
+
+import (
+	"errors"
+)
+
+type TeamRuleset struct {
+	StandardRuleset
+
+	TeamMap map[string]string
+
+	// These are intentionally designed so that they default to a standard game.
+	AllowBodyCollisions bool
+	SharedElimination   bool
+	SharedHealth        bool
+	SharedLength        bool
+}
+
+const EliminatedByTeam = "team-eliminated"
+
+func (r *TeamRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
+	nextBoardState, err := r.StandardRuleset.CreateNextBoardState(prevState, moves)
+	if err != nil {
+		return nil, err
+	}
+
+	// TODO: LOG?
+	err = r.resurrectTeamBodyCollisions(nextBoardState)
+	if err != nil {
+		return nil, err
+	}
+
+	// TODO: LOG?
+	err = r.shareTeamAttributes(nextBoardState)
+	if err != nil {
+		return nil, err
+	}
+
+	return nextBoardState, nil
+}
+
+func (r *TeamRuleset) areSnakesOnSameTeam(snake *Snake, other *Snake) bool {
+	return r.areSnakeIDsOnSameTeam(snake.ID, other.ID)
+}
+
+func (r *TeamRuleset) areSnakeIDsOnSameTeam(snakeID string, otherID string) bool {
+	return snakeID != otherID && r.TeamMap[snakeID] == r.TeamMap[otherID]
+}
+
+func (r *TeamRuleset) resurrectTeamBodyCollisions(b *BoardState) error {
+	if !r.AllowBodyCollisions {
+		return nil
+	}
+
+	for i := 0; i < len(b.Snakes); i++ {
+		snake := &b.Snakes[i]
+		if snake.EliminatedCause == EliminatedByCollision {
+			if snake.EliminatedBy == "" {
+				return errors.New("snake eliminated by collision and eliminatedby is not set")
+			}
+			if r.areSnakeIDsOnSameTeam(snake.ID, snake.EliminatedBy) {
+				snake.EliminatedCause = NotEliminated
+				snake.EliminatedBy = ""
+			}
+		}
+	}
+
+	return nil
+}
+
+func (r *TeamRuleset) shareTeamAttributes(b *BoardState) error {
+	if !(r.SharedElimination || r.SharedLength || r.SharedHealth) {
+		return nil
+	}
+
+	for i := 0; i < len(b.Snakes); i++ {
+		snake := &b.Snakes[i]
+		if snake.EliminatedCause != NotEliminated {
+			continue
+		}
+
+		for j := 0; j < len(b.Snakes); j++ {
+			other := &b.Snakes[j]
+			if r.areSnakesOnSameTeam(snake, other) {
+				if r.SharedHealth {
+					if snake.Health < other.Health {
+						snake.Health = other.Health
+					}
+				}
+				if r.SharedLength {
+					if len(snake.Body) == 0 || len(other.Body) == 0 {
+						return errors.New("found snake of zero length")
+					}
+					for len(snake.Body) < len(other.Body) {
+						r.growSnake(snake)
+					}
+				}
+				if r.SharedElimination {
+					if snake.EliminatedCause == NotEliminated && other.EliminatedCause != NotEliminated {
+						snake.EliminatedCause = EliminatedByTeam
+						// We intentionally do not set snake.EliminatedBy because there might be multiple culprits.
+						snake.EliminatedBy = ""
+					}
+				}
+			}
+		}
+	}
+
+	return nil
+}

team_test.go

@@ -0,0 +1,286 @@
+package rules
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCreateNextBoardStateSanity(t *testing.T) {
+	boardState := &BoardState{}
+	r := TeamRuleset{}
+	_, err := r.CreateNextBoardState(boardState, []SnakeMove{})
+	require.NoError(t, err)
+}
+
+func TestResurrectTeamBodyCollisionsSanity(t *testing.T) {
+	boardState := &BoardState{}
+	r := TeamRuleset{}
+	err := r.resurrectTeamBodyCollisions(boardState)
+	require.NoError(t, err)
+}
+
+func TestSharedAttributesSanity(t *testing.T) {
+	boardState := &BoardState{}
+	r := TeamRuleset{}
+	err := r.shareTeamAttributes(boardState)
+	require.NoError(t, err)
+}
+
+func TestAllowBodyCollisions(t *testing.T) {
+	testSnakes := []struct {
+		SnakeID         string
+		TeamID          string
+		EliminatedCause string
+		EliminatedBy    string
+		ExpectedCause   string
+		ExpectedBy      string
+	}{
+		// Team Red
+		{"R1", "red", NotEliminated, "", NotEliminated, ""},
+		{"R2", "red", EliminatedByCollision, "R1", NotEliminated, ""},
+		// Team Blue
+		{"B1", "blue", EliminatedByCollision, "R1", EliminatedByCollision, "R1"},
+		{"B2", "blue", EliminatedBySelfCollision, "B1", EliminatedBySelfCollision, "B1"},
+		{"B4", "blue", EliminatedByOutOfBounds, "", EliminatedByOutOfBounds, ""},
+		{"B3", "blue", NotEliminated, "", NotEliminated, ""},
+		// More Team Red
+		{"R3", "red", NotEliminated, "", NotEliminated, ""},
+		{"R4", "red", EliminatedByCollision, "R4", EliminatedByCollision, "R4"}, // this is an error case but worth testing
+		{"R5", "red", EliminatedByCollision, "R4", NotEliminated, ""},
+		// // Team Green
+		{"G1", "green", EliminatedByStarvation, "x", EliminatedByStarvation, "x"},
+		// // Team Yellow
+		{"Y1", "yellow", EliminatedByCollision, "B4", EliminatedByCollision, "B4"},
+	}
+
+	boardState := &BoardState{}
+	teamMap := make(map[string]string)
+	for _, testSnake := range testSnakes {
+		boardState.Snakes = append(boardState.Snakes, Snake{
+			ID:              testSnake.SnakeID,
+			EliminatedCause: testSnake.EliminatedCause,
+			EliminatedBy:    testSnake.EliminatedBy,
+		})
+		teamMap[testSnake.SnakeID] = testSnake.TeamID
+	}
+	require.Equal(t, len(teamMap), len(boardState.Snakes), "team map is wrong size, error in test setup")
+
+	r := TeamRuleset{TeamMap: teamMap, AllowBodyCollisions: true}
+	err := r.resurrectTeamBodyCollisions(boardState)
+
+	require.NoError(t, err)
+	require.Equal(t, len(boardState.Snakes), len(testSnakes))
+	for i := 0; i < len(boardState.Snakes); i++ {
+		require.Equal(
+			t,
+			testSnakes[i].ExpectedCause,
+			boardState.Snakes[i].EliminatedCause,
+			"snake %s failed shared eliminated cause",
+			testSnakes[i].SnakeID,
+		)
+		require.Equal(
+			t,
+			testSnakes[i].ExpectedBy,
+			boardState.Snakes[i].EliminatedBy,
+			"snake %s failed shared eliminated by",
+			testSnakes[i].SnakeID,
+		)
+	}
+}
+
+func TestAllowBodyCollisionsEliminatedByNotSet(t *testing.T) {
+	boardState := &BoardState{
+		Snakes: []Snake{
+			Snake{ID: "1", EliminatedCause: EliminatedByCollision},
+			Snake{ID: "2"},
+		},
+	}
+	r := TeamRuleset{
+		AllowBodyCollisions: true,
+		TeamMap: map[string]string{
+			"1": "red",
+			"2": "red",
+		},
+	}
+	err := r.resurrectTeamBodyCollisions(boardState)
+	require.Error(t, err)
+}
+
+func TestShareTeamHealth(t *testing.T) {
+	testSnakes := []struct {
+		SnakeID        string
+		TeamID         string
+		Health         int32
+		ExpectedHealth int32
+	}{
+		// Team Red
+		{"R1", "red", 11, 88},
+		{"R2", "red", 22, 88},
+		// Team Blue
+		{"B1", "blue", 33, 333},
+		{"B2", "blue", 333, 333},
+		{"B3", "blue", 3, 333},
+		// More Team Red
+		{"R3", "red", 77, 88},
+		{"R4", "red", 88, 88},
+		// Team Green
+		{"G1", "green", 100, 100},
+		// Team Yellow
+		{"Y1", "yellow", 1, 1},
+	}
+
+	boardState := &BoardState{}
+	teamMap := make(map[string]string)
+	for _, testSnake := range testSnakes {
+		boardState.Snakes = append(boardState.Snakes, Snake{
+			ID:     testSnake.SnakeID,
+			Health: testSnake.Health,
+		})
+		teamMap[testSnake.SnakeID] = testSnake.TeamID
+	}
+	require.Equal(t, len(teamMap), len(boardState.Snakes), "team map is wrong size, error in test setup")
+
+	r := TeamRuleset{SharedHealth: true, TeamMap: teamMap}
+	err := r.shareTeamAttributes(boardState)
+
+	require.NoError(t, err)
+	require.Equal(t, len(boardState.Snakes), len(testSnakes))
+	for i := 0; i < len(boardState.Snakes); i++ {
+		require.Equal(
+			t,
+			testSnakes[i].ExpectedHealth,
+			boardState.Snakes[i].Health,
+			"snake %s failed shared health",
+			testSnakes[i].SnakeID,
+		)
+	}
+}
+
+func TestSharedLength(t *testing.T) {
+	testSnakes := []struct {
+		SnakeID      string
+		TeamID       string
+		Body         []Point
+		ExpectedBody []Point
+	}{
+		// Team Red
+		{"R1", "red", []Point{{1, 1}}, []Point{{1, 1}, {1, 1}, {1, 1}, {1, 1}, {1, 1}}},
+		{"R2", "red", []Point{{2, 2}, {2, 2}}, []Point{{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}}},
+		// Team Blue
+		{"B1", "blue", []Point{{1, 1}, {1, 2}}, []Point{{1, 1}, {1, 2}}},
+		{"B2", "blue", []Point{{2, 1}}, []Point{{2, 1}, {2, 1}}},
+		{"B3", "blue", []Point{{3, 3}}, []Point{{3, 3}, {3, 3}}},
+		// More Team Red
+		{"R3", "red", []Point{{1, 1}, {2, 2}, {3, 3}, {4, 4}, {5, 5}}, []Point{{1, 1}, {2, 2}, {3, 3}, {4, 4}, {5, 5}}},
+		{"R4", "red", []Point{{4, 4}}, []Point{{4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4}}},
+		// Team Green
+		{"G1", "green", []Point{{1, 1}}, []Point{{1, 1}}},
+		// Team Yellow
+		{"Y1", "yellow", []Point{{1, 3}, {1, 4}, {1, 5}, {1, 6}}, []Point{{1, 3}, {1, 4}, {1, 5}, {1, 6}}},
+	}
+
+	boardState := &BoardState{}
+	teamMap := make(map[string]string)
+	for _, testSnake := range testSnakes {
+		boardState.Snakes = append(boardState.Snakes, Snake{
+			ID:   testSnake.SnakeID,
+			Body: testSnake.Body,
+		})
+		teamMap[testSnake.SnakeID] = testSnake.TeamID
+	}
+	require.Equal(t, len(teamMap), len(boardState.Snakes), "team map is wrong size, error in test setup")
+
+	r := TeamRuleset{SharedLength: true, TeamMap: teamMap}
+	err := r.shareTeamAttributes(boardState)
+
+	require.NoError(t, err)
+	require.Equal(t, len(boardState.Snakes), len(testSnakes))
+	for i := 0; i < len(boardState.Snakes); i++ {
+		require.Equal(
+			t,
+			testSnakes[i].ExpectedBody,
+			boardState.Snakes[i].Body,
+			"snake %s failed shared length",
+			testSnakes[i].SnakeID,
+		)
+	}
+}
+
+func TestSharedElimination(t *testing.T) {
+	testSnakes := []struct {
+		SnakeID         string
+		TeamID          string
+		EliminatedCause string
+		EliminatedBy    string
+		ExpectedCause   string
+		ExpectedBy      string
+	}{
+		// Team Red
+		{"R1", "red", NotEliminated, "", EliminatedByTeam, ""},
+		{"R2", "red", EliminatedByHeadToHeadCollision, "y", EliminatedByHeadToHeadCollision, "y"},
+		// Team Blue
+		{"B1", "blue", EliminatedByOutOfBounds, "z", EliminatedByOutOfBounds, "z"},
+		{"B2", "blue", NotEliminated, "", EliminatedByTeam, ""},
+		{"B3", "blue", NotEliminated, "", EliminatedByTeam, ""},
+		// More Team Red
+		{"R3", "red", NotEliminated, "", EliminatedByTeam, ""},
+		{"R4", "red", EliminatedByCollision, "B1", EliminatedByCollision, "B1"},
+		// Team Green
+		{"G1", "green", EliminatedByStarvation, "x", EliminatedByStarvation, "x"},
+		// Team Yellow
+		{"Y1", "yellow", NotEliminated, "", NotEliminated, ""},
+	}
+
+	boardState := &BoardState{}
+	teamMap := make(map[string]string)
+	for _, testSnake := range testSnakes {
+		boardState.Snakes = append(boardState.Snakes, Snake{
+			ID:              testSnake.SnakeID,
+			EliminatedCause: testSnake.EliminatedCause,
+			EliminatedBy:    testSnake.EliminatedBy,
+		})
+		teamMap[testSnake.SnakeID] = testSnake.TeamID
+	}
+	require.Equal(t, len(teamMap), len(boardState.Snakes), "team map is wrong size, error in test setup")
+
+	r := TeamRuleset{SharedElimination: true, TeamMap: teamMap}
+	err := r.shareTeamAttributes(boardState)
+
+	require.NoError(t, err)
+	require.Equal(t, len(boardState.Snakes), len(testSnakes))
+	for i := 0; i < len(boardState.Snakes); i++ {
+		require.Equal(
+			t,
+			testSnakes[i].ExpectedCause,
+			boardState.Snakes[i].EliminatedCause,
+			"snake %s failed shared eliminated cause",
+			testSnakes[i].SnakeID,
+		)
+		require.Equal(
+			t,
+			testSnakes[i].ExpectedBy,
+			boardState.Snakes[i].EliminatedBy,
+			"snake %s failed shared eliminated by",
+			testSnakes[i].SnakeID,
+		)
+	}
+}
+
+func TestSharedAttributesErrorLengthZero(t *testing.T) {
+	boardState := &BoardState{
+		Snakes: []Snake{
+			Snake{ID: "1"},
+			Snake{ID: "2"},
+		},
+	}
+	r := TeamRuleset{
+		SharedLength: true,
+		TeamMap: map[string]string{
+			"1": "red",
+			"2": "red",
+		},
+	}
+	err := r.shareTeamAttributes(boardState)
+	require.Error(t, err)
+}