fix for rivers and bridges snake start positions (#85)

* fix for rivers and bridges snake start positions

* update max player count, add unit test

* set player count to 12 (max for smallest size)

* fix: one of the 19x19 spawn points

* randomize snake placement at start positions

* randomly choose starts in quadrants

* fix: check that start positions are valid

* modify food placement to avoid hazards

maps/hazards.go

@@ -565,20 +565,68 @@ Each river has one or two 1-square "bridges" over them`,
 		Author:     "Battlesnake",
 		Version:    1,
 		MinPlayers: 1,
-		MaxPlayers: 8,
+		MaxPlayers: 12,
 		BoardSizes: FixedSizes(Dimensions{11, 11}, Dimensions{19, 19}, Dimensions{25, 25}),
 	}
 }
 
 func (m RiverAndBridgesHazardsMap) SetupBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	if err := (StandardMap{}).SetupBoard(lastBoardState, settings, editor); err != nil {
+	width := lastBoardState.Width
+	height := lastBoardState.Height
+	hazards, ok := riversAndBridgesHazards[rules.Point{X: width, Y: height}]
+	if !ok {
+		return rules.RulesetError("board size is not supported by this map")
+	}
+	startPositions, ok := riversAndBridgesStartPositions[rules.Point{X: width, Y: height}]
+	if !ok {
+		return rules.RulesetError("board size is not supported by this map")
+	}
+
+	numSnakes := len(lastBoardState.Snakes)
+	if numSnakes == 0 {
+		return rules.RulesetError("too few snakes - at least one snake must be present")
+	}
+
+	rand := settings.GetRand(0)
+
+	snakeIDs := make([]string, 0, len(lastBoardState.Snakes))
+	for _, snake := range lastBoardState.Snakes {
+		snakeIDs = append(snakeIDs, snake.ID)
+	}
+
+	tempBoardState := rules.NewBoardState(width, height)
+	tempBoardState.Snakes = make([]rules.Snake, len(snakeIDs))
+
+	for i := 0; i < len(snakeIDs); i++ {
+		tempBoardState.Snakes[i] = rules.Snake{
+			ID:     snakeIDs[i],
+			Health: rules.SnakeMaxHealth,
+		}
+	}
+	err := rules.PlaceSnakesInQuadrants(rand, tempBoardState, startPositions)
+	if err != nil {
 		return err
 	}
 
-	hazards, ok := riversAndBridgesMaps[rules.Point{X: lastBoardState.Width, Y: lastBoardState.Height}]
-	if !ok {
-		return rules.RulesetError("Board size is not supported by this map")
+	err = rules.PlaceFoodFixed(rand, tempBoardState)
+	if err != nil {
+		return err
 	}
+
+	// Copy food from temp board state
+	for _, f := range tempBoardState.Food {
+		// skip the center food
+		if f.X == lastBoardState.Width/2 && f.Y == lastBoardState.Height/2 {
+			continue
+		}
+		editor.AddFood(f)
+	}
+
+	// Copy snakes from temp board state
+	for _, snake := range tempBoardState.Snakes {
+		editor.PlaceSnake(snake.ID, snake.Body, snake.Health)
+	}
+
 	for _, p := range hazards {
 		editor.AddHazard(p)
 	}
@@ -587,10 +635,117 @@ func (m RiverAndBridgesHazardsMap) SetupBoard(lastBoardState *rules.BoardState,
 }
 
 func (m RiverAndBridgesHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	return StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	rand := settings.GetRand(lastBoardState.Turn)
+
+	foodNeeded := checkFoodNeedingPlacement(rand, settings, lastBoardState)
+	if foodNeeded > 0 {
+		pts := m.getUnoccupiedPoints(lastBoardState)
+		placeFoodRandomlyAtPositions(rand, lastBoardState, editor, foodNeeded, pts)
+	}
+
+	return nil
 }
 
-var riversAndBridgesMaps = map[rules.Point][]rules.Point{
+func (m RiverAndBridgesHazardsMap) getUnoccupiedPoints(lastBoardState *rules.BoardState) []rules.Point {
+	unoccupiedPoints := rules.GetUnoccupiedPoints(lastBoardState, false)
+
+	var totallyUnoccupiedPoints []rules.Point
+	// we want to avoid placing food on hazards in this map
+	for _, p := range unoccupiedPoints {
+		isHazard := false
+		for _, h := range lastBoardState.Hazards {
+			if p == h {
+				isHazard = true
+				break
+			}
+		}
+
+		if !isHazard {
+			totallyUnoccupiedPoints = append(totallyUnoccupiedPoints, p)
+		}
+	}
+
+	return totallyUnoccupiedPoints
+}
+
+var riversAndBridgesStartPositions = map[rules.Point][][]rules.Point{
+	{X: 11, Y: 11}: {
+		{
+			{X: 1, Y: 1},
+			{X: 3, Y: 3},
+			{X: 1, Y: 3},
+		},
+		{
+			{X: 9, Y: 9},
+			{X: 7, Y: 7},
+			{X: 9, Y: 7},
+		},
+		{
+			{X: 1, Y: 9},
+			{X: 3, Y: 7},
+			{X: 3, Y: 9},
+		},
+		{
+			{X: 9, Y: 3},
+			{X: 9, Y: 1},
+			{X: 7, Y: 3},
+		},
+	},
+	{X: 19, Y: 19}: {
+		{
+			{X: 1, Y: 1},
+			{X: 5, Y: 1},
+			{X: 1, Y: 5},
+			{X: 5, Y: 5},
+		},
+		{
+			{X: 17, Y: 1},
+			{X: 17, Y: 5},
+			{X: 13, Y: 5},
+			{X: 13, Y: 1},
+		},
+		{
+			{X: 1, Y: 17},
+			{X: 5, Y: 17},
+			{X: 1, Y: 13},
+			{X: 5, Y: 13},
+		},
+		{
+			{X: 17, Y: 17},
+			{X: 17, Y: 13},
+			{X: 13, Y: 17},
+			{X: 13, Y: 13},
+		},
+	},
+	{X: 25, Y: 25}: {
+		{
+			{X: 1, Y: 1},
+			{X: 9, Y: 9},
+			{X: 9, Y: 1},
+			{X: 1, Y: 9},
+		},
+		{
+			{X: 23, Y: 23},
+			{X: 15, Y: 15},
+			{X: 23, Y: 15},
+			{X: 15, Y: 23},
+		},
+		{
+			{X: 15, Y: 1},
+			{X: 15, Y: 9},
+			{X: 23, Y: 9},
+			{X: 23, Y: 1},
+		},
+		{
+			{X: 9, Y: 23},
+			{X: 1, Y: 23},
+			{X: 9, Y: 15},
+			{X: 1, Y: 15},
+		},
+	},
+}
+
+var riversAndBridgesHazards = map[rules.Point][]rules.Point{
 	{X: 11, Y: 11}: {
 		{X: 5, Y: 10},
 		{X: 5, Y: 9},