wrapped ruleset (#30)

* wrapped ruleset

* resurrect like brad suggested

* introduce mode to binary

* go fmt

* address edge crossing collision and eating bugs

* Update board_state.go

* removed binary

* rename variable

wrapped.go

@@ -0,0 +1,66 @@
+package rules
+
+type WrappedRuleset struct {
+	StandardRuleset
+}
+
+func replace(value, min, max int32) int32 {
+	if value < min {
+		return max
+	}
+	if value > max {
+		return min
+	}
+	return value
+}
+
+func (r *WrappedRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
+	nextState := prevState.Clone()
+
+	err := r.moveSnakes(nextState, moves)
+	if err != nil {
+		return nil, err
+	}
+
+	err = r.reduceSnakeHealth(nextState)
+	if err != nil {
+		return nil, err
+	}
+
+	err = r.maybeDamageHazards(nextState)
+	if err != nil {
+		return nil, err
+	}
+
+	err = r.maybeFeedSnakes(nextState)
+	if err != nil {
+		return nil, err
+	}
+
+	err = r.maybeSpawnFood(nextState)
+	if err != nil {
+		return nil, err
+	}
+
+	err = r.maybeEliminateSnakes(nextState)
+	if err != nil {
+		return nil, err
+	}
+
+	return nextState, nil
+}
+
+func (r *WrappedRuleset) moveSnakes(b *BoardState, moves []SnakeMove) error {
+	err := r.StandardRuleset.moveSnakes(b, moves)
+	if err != nil {
+		return err
+	}
+
+	for i := 0; i < len(b.Snakes); i++ {
+		snake := &b.Snakes[i]
+		snake.Body[0].X = replace(snake.Body[0].X, 0, b.Width-1)
+		snake.Body[0].Y = replace(snake.Body[0].Y, 0, b.Height-1)
+	}
+
+	return nil
+}