From d7ee7b97fb56c1389c3e7400ee4dd04d2b8a7d34 Mon Sep 17 00:00:00 2001
From: bvanvugt <1531419+bvanvugt@users.noreply.github.com>
Date: Mon, 7 Dec 2020 18:11:00 -0800
Subject: [PATCH] New "feast" game mode (alpha)

---
 feast.go      |  41 ++++++++++++++++++++
 feast_test.go | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 146 insertions(+)
 create mode 100644 feast.go
 create mode 100644 feast_test.go

diff --git a/feast.go b/feast.go
new file mode 100644
index 0000000..0f916f3
--- /dev/null
+++ b/feast.go
@@ -0,0 +1,41 @@
+package rules
+
+import ()
+
+type FeastRuleset struct {
+	StandardRuleset
+}
+
+func (r *FeastRuleset) CreateInitialBoardState(width int32, height int32, snakeIDs []string) (*BoardState, error) {
+	initialBoardState, err := r.StandardRuleset.CreateInitialBoardState(width, height, snakeIDs)
+	if err != nil {
+		return nil, err
+	}
+
+	err = r.fillBoardWithFood(initialBoardState)
+	if err != nil {
+		return nil, err
+	}
+
+	return initialBoardState, nil
+}
+
+func (r *FeastRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
+	nextState, err := r.StandardRuleset.CreateNextBoardState(prevState, moves)
+	if err != nil {
+		return nil, err
+	}
+
+	err = r.fillBoardWithFood(nextState)
+	if err != nil {
+		return nil, err
+	}
+
+	return nextState, nil
+}
+
+func (r *FeastRuleset) fillBoardWithFood(b *BoardState) error {
+	unoccupiedPoints := r.getUnoccupiedPoints(b, true)
+	b.Food = append(b.Food, unoccupiedPoints...)
+	return nil
+}
diff --git a/feast_test.go b/feast_test.go
new file mode 100644
index 0000000..c3eb74f
--- /dev/null
+++ b/feast_test.go
@@ -0,0 +1,105 @@
+package rules
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFeastRulesetInterface(t *testing.T) {
+	var _ Ruleset = (*FeastRuleset)(nil)
+}
+
+func TestFeastCreateInitialBoardState(t *testing.T) {
+	tests := []struct {
+		Height          int32
+		Width           int32
+		IDs             []string
+		ExpectedNumFood int
+		Err             error
+	}{
+		{1, 1, []string{}, 1, nil},
+		{1, 1, []string{"one"}, 0, nil},
+		{2, 2, []string{"one"}, 3, nil},
+		{2, 2, []string{"one", "two"}, 2, nil},
+		{11, 1, []string{"one", "two"}, 9, nil},
+		{11, 11, []string{}, 121, nil},
+		{11, 11, []string{"one", "two", "three", "four", "five"}, 116, nil},
+	}
+
+	r := FeastRuleset{}
+	for testNum, test := range tests {
+		state, err := r.CreateInitialBoardState(test.Width, test.Height, test.IDs)
+		require.Equal(t, test.Err, err)
+		if err != nil {
+			require.Nil(t, state)
+			continue
+		}
+		require.NotNil(t, state)
+		require.Equal(t, test.Width, state.Width)
+		require.Equal(t, test.Height, state.Height)
+		require.Equal(t, len(test.IDs), len(state.Snakes))
+		for i, id := range test.IDs {
+			require.Equal(t, id, state.Snakes[i].ID)
+		}
+		require.Len(t, state.Food, test.ExpectedNumFood, testNum)
+	}
+}
+
+func TestFeastCreateNextBoardState(t *testing.T) {
+	tests := []struct {
+		prevState     *BoardState
+		moves         []SnakeMove
+		expectedError error
+		expectedState *BoardState
+	}{
+		{
+			&BoardState{
+				Width:  3,
+				Height: 3,
+				Snakes: []Snake{
+					{
+						ID:     "one",
+						Body:   []Point{{0, 0}, {1, 0}, {2, 0}},
+						Health: 100,
+					},
+					{
+						ID:     "two",
+						Body:   []Point{{2, 2}, {1, 2}, {0, 2}},
+						Health: 100,
+					},
+				},
+				Food: []Point{},
+			},
+			[]SnakeMove{
+				{ID: "one", Move: MoveDown},
+				{ID: "two", Move: MoveUp},
+			},
+			nil,
+			&BoardState{
+				Width:  3,
+				Height: 3,
+				Snakes: []Snake{
+					{
+						ID:     "one",
+						Body:   []Point{{0, 1}, {0, 0}, {1, 0}},
+						Health: 99,
+					},
+					{
+						ID:     "two",
+						Body:   []Point{{2, 1}, {2, 2}, {1, 2}},
+						Health: 99,
+					},
+				},
+				Food: []Point{{0, 2}, {1, 1}, {2, 0}},
+			},
+		},
+	}
+
+	r := FeastRuleset{}
+	for _, test := range tests {
+		nextState, err := r.CreateNextBoardState(test.prevState, test.moves)
+		require.Equal(t, test.expectedError, err)
+		require.Equal(t, test.expectedState, nextState)
+	}
+}