LED Snake Game movement issue

Using Arduino Programming Questions
1

I am making a Snake game with the Arduino Uno using a MAX7219 8x8 LED module and two buttons, and the wiring is correct. The game is not complete and I have not added the ability to eat fruit. You can only move the snake and change the length in the code.
The issue I have is that when the snake is longer than 2 segments and I press a button to move, it forms a rectangle with the segments as it moves along until it is in a straight line configuration.

Here is my code:

#include <LedControl.h> // library for LED module control

LedControl lc = LedControl(11, 13, 12, 1); // object to control the MAX7219 8x8 LED module (pin 11 = DIN, 12 = CS, 13 = CLK, 1 means only one module is being used)

const int rightPin = 6; // Pin for right button
const int leftPin = 7; //  Pin for left button

const int MAX = 10; //  Maximum snake length

int dir = 1; // direction to move in (1 = left, 2 = up, 3 = right, 4 = down)

int snakeX[MAX] = {4, 5, 6}; // snake segment X-coordinate values
int snakeY[MAX] = {4, 4, 4}; // snake segment Y-coordinate values

int snakeLen = 3; // length of the snake

void setup() {
  lc.shutdown(0, false); // set up the LED module
  lc.setIntensity(0, 5);
  lc.clearDisplay(0);

  pinMode(rightPin, INPUT_PULLUP);
  pinMode(leftPin, INPUT_PULLUP);

  start();
}

void loop() {
  if (snakeX[0] > 7 || snakeX[0] < 0 || snakeY[0] > 7 || snakeY[0] < 0) start(); // checks if the snake's head is out of bounds
  buttonRead();
  snakeStep();
  drawSnake();
  delay(300);
  lc.clearDisplay(0); // reset the LEDs
}

void start() { // restart the game
  lc.clearDisplay(0);
  snakeX[0] = 4;
  snakeY[0] = 4;
  delay(1000);
}


void buttonRead() { // read button inputs
  if (digitalRead(rightPin) == LOW) {
    dir++; // right button moves direction clockwise
    if (dir == 5) dir = 1;
  }
  else if (digitalRead(leftPin) == LOW) {
    dir--; // left button moves direction counterclockwise
    if (dir == 0) dir = 4;
  }
}

void snakeStep() { // move the snake segments without drawing them
  for (int i = snakeLen - 1; i > 0; i--) { // shifts all the snake segments over 
    snakeX[i] = snakeX[i - 1];
    snakeY[i] = snakeY[i - 1];
  }
  switch (dir) { // change the X,Y values of the snake's head based on the direction
    case 1: // left
      snakeX[0]--;
      break;
    case 2: // up
      snakeY[0]++;
      break;
    case 3: // right
      snakeX[0]++;
      break;
    case 4: // down
      snakeY[0]--;
      break;
  }
}

void drawSnake() { // draws the snake
  for (int x = 0; x < snakeLen; x++) {
    for (int y = 0; y < snakeLen; y++) {
      lc.setLed(0, snakeX[x], snakeY[y], true); // turn on the LED at x, y
    }
  }
}

Please let me know how I can fix the issue described above.

2

I do not know about the question that was asked, but I am certain that this is wrong:

  else if (digitalRead(leftPin) == LOW) {
    dir--; // left button moves direction counterclockwise
    if (dir == -1) dir = 4;

dir may be 1, 2, 3, or 4, but this code causes dir to be 0 if dir is initially 1.

There is no default case in the switch statement that looks at dir.

I also do not understand why dir is described as clockwise or counterclockwise. I thought dir was up, down, left, or right.

3

I fixed the issue with -1, but I describe dir as clockwise because it never is supposed to go below 1 or above 4, and the buttons code I have moves it in a circular-numeric way.

4