#8 Added a function to validate if something is a valid move.

game.go

@@ -65,8 +65,10 @@ func gameDirector(screen tcell.Screen, style tcell.Style, keypresses chan int, g
 		// Take input or sleep
 		select {
 		case press := <-keypresses:
-			snakeDirection(press, &snake)
-			lastpress = press
+			if validateDirection(&snake, press) {
+				snakeDirection(press, &snake)
+				lastpress = press
+			}
 		case <-time.After(500 * time.Millisecond):
 			snakeDirection(lastpress, &snake)
 		}

snake.go

@@ -55,29 +55,21 @@ func drawSnake(screen tcell.Screen, style tcell.Style, snake *Snake) {
 
 func snakeDirection(press int, snake *Snake) {
 	if press == Left {
-		if snake.direction != Right {
-			snake.head.x--
-			snake.tail = append(snake.tail, Position{x: snake.head.x + 1, y: snake.head.y})
-			snake.direction = press
-		}
+		snake.head.x--
+		snake.tail = append(snake.tail, Position{x: snake.head.x + 1, y: snake.head.y})
+		snake.direction = press
 	} else if press == Right {
-		if snake.direction != Left {
-			snake.head.x++
-			snake.tail = append(snake.tail, Position{x: snake.head.x - 1, y: snake.head.y})
-			snake.direction = press
-		}
+		snake.head.x++
+		snake.tail = append(snake.tail, Position{x: snake.head.x - 1, y: snake.head.y})
+		snake.direction = press
 	} else if press == Up {
-		if snake.direction != Down {
-			snake.head.y--
-			snake.tail = append(snake.tail, Position{x: snake.head.x, y: snake.head.y + 1})
-			snake.direction = press
-		}
+		snake.head.y--
+		snake.tail = append(snake.tail, Position{x: snake.head.x, y: snake.head.y + 1})
+		snake.direction = press
 	} else if press == Down {
-		if snake.direction != Up {
-			snake.head.y++
-			snake.tail = append(snake.tail, Position{x: snake.head.x, y: snake.head.y - 1})
-			snake.direction = press
-		}
+		snake.head.y++
+		snake.tail = append(snake.tail, Position{x: snake.head.x, y: snake.head.y - 1})
+		snake.direction = press
 	}
 }
 
@@ -101,3 +93,19 @@ func ReverseSlice[T comparable](s []T) []T {
 	}
 	return r
 }
+
+func validateDirection(snake *Snake, direction int) bool {
+	if snake.direction == direction {
+		return true
+	} else if snake.direction == Left && direction == Right {
+		return false
+	} else if snake.direction == Right && direction == Left {
+		return false
+	} else if snake.direction == Up && direction == Down {
+		return false
+	} else if snake.direction == Down && direction == Up {
+		return false
+	} else {
+		return true
+	}
+}