#include <LedControl.h>

// Pin definitions for MAX7219


#define DIN 11  // Data In pin
#define CS  10  // Chip Select pin
#define CLK 13  // Clock pin

// Initialize LedControl: 4 modules, using pins DIN, CLK, CS
LedControl lc = LedControl(DIN, CLK, CS, 4);

// Snake properties
int snakeLength = 72;  // Length of the snake
int snakeX[72];       // X coordinates of snake segments
int snakeY[72];       // Y coordinates of snake segments
int snakeDirection;   // 0: right, 1: down, 2: left, 3: up
int headPos;          // Index of snake head
unsigned long lastMove = 0;
int moveDelay = 300;  // Delay between movements in ms

void setup() {
  // Initialize all MAX7219 modules
  for (int i = 0; i < 4; i++) {
    lc.shutdown(i, false);      // Wake up display
    lc.setIntensity(i, 8);      // Set brightness (0-15)
    lc.clearDisplay(i);         // Clear display
  }

  // Initialize snake at top-left, moving right
  for (int i = 0; i < snakeLength; i++) {
    snakeX[i] = i;  // Start at x=0 to x=7
    snakeY[i] = 0;  // Top row
  }
  headPos = snakeLength - 1;
  snakeDirection = 0;  // Start moving right
}

void loop() {
  if (millis() - lastMove >= moveDelay) {
    moveSnake();
    updateDisplay();
    lastMove = millis();
  }
}

void moveSnake() {
  // Calculate new head position
  int newX = snakeX[headPos];
  int newY = snakeY[headPos];

  switch (snakeDirection) {
    case 0: // Right
      newX++;
      if (newX > 31) { // Hit right edge
        newX = 31;
        newY++;
        snakeDirection = 1; // Turn down
      }
      break;
    case 1: // Down
      newY++;
      if (newY > 7) { // Hit bottom edge
        newY = 7;
        newX--;
        snakeDirection = 2; // Turn left
      }
      break;
    case 2: // Left
      newX--;
      if (newX < 0) { // Hit left edge
        newX = 0;
        newY--;
        snakeDirection = 3; // Turn up
      }
      break;
    case 3: // Up
      newY--;
      if (newY < 0) { // Hit top edge
        newY = 0;
        newX++;
        snakeDirection = 0; // Turn right
      }
      break;
  }

  // Shift snake segments
  for (int i = 0; i < headPos; i++) {
    snakeX[i] = snakeX[i + 1];
    snakeY[i] = snakeY[i + 1];
  }

  // Update head position
  snakeX[headPos] = newX;
  snakeY[headPos] = newY;

  // Ensure continuous running effect by resetting position after one full cycle
  if (newX == 0 && newY == 0 && snakeDirection == 0) {
    for (int i = 0; i < snakeLength; i++) {
      snakeX[i] = i;
      snakeY[i] = 0;
    }
    headPos = snakeLength - 1;
  }
}

void updateDisplay() {
  // Clear all displays
  for (int i = 0; i < 4; i++) {
    lc.clearDisplay(i);
  }

  // Draw snake
  for (int i = 0; i < snakeLength; i++) {
    int module = snakeX[i] / 8;        // Determine which module (0-3)
    int moduleX = snakeX[i] % 8;       // X position within module
    lc.setLed(module, snakeY[i], moduleX, true); // Set LED on
  }
}