#include <LedControl.h>

LedControl lc = LedControl(11, 13, 10, 1);

#define UP 2
#define DOWN 3
#define LEFT 4
#define RIGHT 5

int snakeX[64];
int snakeY[64];
int length = 3;

int dx = 1;
int dy = 0;

int foodX = 5;
int foodY = 5;

void setup() {
  lc.shutdown(0, false);
  lc.setIntensity(0, 8);
  lc.clearDisplay(0);

  pinMode(UP, INPUT_PULLUP);
  pinMode(DOWN, INPUT_PULLUP);
  pinMode(LEFT, INPUT_PULLUP);
  pinMode(RIGHT, INPUT_PULLUP);

  for (int i = 0; i < length; i++) {
    snakeX[i] = i;
    snakeY[i] = 0;
  }
}

void loop() {
  if (!digitalRead(UP))    { dx = 0; dy = -1; }
  if (!digitalRead(DOWN))  { dx = 0; dy = 1; }
  if (!digitalRead(LEFT))  { dx = -1; dy = 0; }
  if (!digitalRead(RIGHT)) { dx = 1; dy = 0; }

  for (int i = length - 1; i > 0; i--) {
    snakeX[i] = snakeX[i - 1];
    snakeY[i] = snakeY[i - 1];
  }

  snakeX[0] += dx;
  snakeY[0] += dy;

  if (snakeX[0] < 0) snakeX[0] = 7;
  if (snakeX[0] > 7) snakeX[0] = 0;
  if (snakeY[0] < 0) snakeY[0] = 7;
  if (snakeY[0] > 7) snakeY[0] = 0;

  if (snakeX[0] == foodX && snakeY[0] == foodY) {
    length++;
    foodX = random(0, 8);
    foodY = random(0, 8);
  }

  for (int i = 1; i < length; i++) {
    if (snakeX[0] == snakeX[i] && snakeY[0] == snakeY[i]) {
      length = 3;
    }
  }

  lc.clearDisplay(0);

  lc.setLed(0, foodY, foodX, true);

  for (int i = 0; i < length; i++) {
    lc.setLed(0, snakeY[i], snakeX[i], true);
  }

  delay(300);
}