Tick method

model/SnakeLevel.cs

@@ -10,7 +10,8 @@ public class SnakeLevel{
         Obstacle,
         Egg,
         Snake,
-        SnakeHead
+        SnakeHead,
+        OutOfBounds
     }
 
     public enum SnakeDirection{
@@ -20,16 +21,23 @@ public class SnakeLevel{
         Right
     }
 
+    public enum GameState{
+        Running,
+        Dead
+    }
+
     private readonly List<Point> _obstacles;
     public ReadOnlyCollection<Point> Obstacles => _obstacles.AsReadOnly();
     public Point SnakeHead {get; private set;}
     private readonly List<Point> _snake;
     // Head is not in snake
+    // Last is closest to the head
     public ReadOnlyCollection<Point> Snake => _snake.AsReadOnly();
     public int SnakeLength => Snake.Count + 1;
     private readonly List<Point> _eggs;
     public ReadOnlyCollection<Point> Eggs => _eggs.AsReadOnly();
     public SnakeDirection SnakeHeadDirection {get; private set;}
+    public GameState State {get; private set;}
 
     public SnakeLevel(int size, IEnumerable<Point> obstacles, int snake_start_length){
         this.Size = size;
@@ -55,9 +63,48 @@ public class SnakeLevel{
                 return LevelBlock.Snake;
             }else if(_eggs.Contains(p)){
                 return LevelBlock.Egg;
+            }else if(p.X < 0 || p.Y < 0 || p.X>=Size || p.Y >= Size){
+                return LevelBlock.OutOfBounds;
             }
 
             return LevelBlock.Empty;
         }
     }
+
+    public void Tick(){
+        Point new_snake_head = (0,0);
+        switch(SnakeHeadDirection){
+            case SnakeDirection.Up:
+                new_snake_head = (SnakeHead.X, SnakeHead.Y - 1);
+                break;
+            case SnakeDirection.Down:
+                new_snake_head = (SnakeHead.X, SnakeHead.Y + 1);
+                break;
+            case SnakeDirection.Left:
+                new_snake_head = (SnakeHead.X - 1, SnakeHead.Y);
+                break;
+            case SnakeDirection.Right:
+                new_snake_head = (SnakeHead.X + 1, SnakeHead.Y);
+                break;
+        }
+
+        if(this[new_snake_head] is LevelBlock.Obstacle or LevelBlock.Snake or LevelBlock.OutOfBounds){
+            State = GameState.Dead;
+            return;
+        }
+
+        var first = Snake[0];
+
+        for(int i=_snake.Count-1; i>0; i--){
+            _snake[i-1] = _snake[i];
+        }
+        _snake[^1] = SnakeHead;
+
+        if(this[new_snake_head] is LevelBlock.Egg){
+            _snake.Insert(0, first);
+            _eggs.Remove(new_snake_head);
+        }
+
+        SnakeHead = new_snake_head;
+    }
 }