#include <Adafruit_GFX.h>
#include <Adafruit_PCD8544.h>

#define PIN_SCLK 10
#define PIN_DIN  11
#define PIN_DC   14
#define PIN_CS   13
#define PIN_RST  12

Adafruit_PCD8544 display = Adafruit_PCD8544(PIN_SCLK, PIN_DIN, PIN_DC, PIN_CS, PIN_RST);

#define JOY_HORZ 1
#define JOY_VERT 2
#define JOY_SEL 4

// Snake grid size (each cell = 2x2 pixels)
#define GRID_W 42
#define GRID_H 24

// Snake storage
int snakeX[200];
int snakeY[200];
int snakeLength = 5;

int foodX, foodY;

int dirX = 1;  // start moving right
int dirY = 0;

unsigned long lastMove = 0;
int speedDelay = 120;

void spawnFood() {
  foodX = random(0, GRID_W);
  foodY = random(0, GRID_H);
}

void resetGame() {
  snakeLength = 5;
  for (int i = 0; i < snakeLength; i++) {
    snakeX[i] = GRID_W / 2 - i;
    snakeY[i] = GRID_H / 2;
  }
  dirX = 1;
  dirY = 0;
  spawnFood();
}

void drawCell(int gx, int gy) {
  display.fillRect(gx * 2, gy * 2, 2, 2, BLACK);
}

void setup() {
  Serial.begin(115200);
  pinMode(JOY_SEL, INPUT_PULLUP);

  display.begin();
  display.setContrast(60);
  display.clearDisplay();
  display.display();

  randomSeed(analogRead(1));
  resetGame();
}

void loop() {
  // Read joystick
  int h = analogRead(JOY_HORZ);
  int v = analogRead(JOY_VERT);
  int sel = digitalRead(JOY_SEL);

// Inverted direction control
  if (h < 1500 && dirX != -1) { dirX = 1; dirY = 0; }      // LEFT → RIGHT
  else if (h > 3000 && dirX != 1) { dirX = -1; dirY = 0; } // RIGHT → LEFT
  else if (v < 1500 && dirY != -1) { dirX = 0; dirY = 1; } // UP → DOWN
  else if (v > 3000 && dirY != 1) { dirX = 0; dirY = -1; } // DOWN → UP


  // Move snake
  if (millis() - lastMove > speedDelay) {
    lastMove = millis();

    // Shift body
    for (int i = snakeLength - 1; i > 0; i--) {
      snakeX[i] = snakeX[i - 1];
      snakeY[i] = snakeY[i - 1];
    }

    // Move head
    snakeX[0] += dirX;
    snakeY[0] += dirY;

    // Wall collision
    if (snakeX[0] < 0 || snakeX[0] >= GRID_W || snakeY[0] < 0 || snakeY[0] >= GRID_H) {
      resetGame();
    }

    // Self collision
    for (int i = 1; i < snakeLength; i++) {
      if (snakeX[0] == snakeX[i] && snakeY[0] == snakeY[i]) {
        resetGame();
      }
    }

    // Food collision
    if (snakeX[0] == foodX && snakeY[0] == foodY) {
      snakeLength++;
      spawnFood();
    }
  }

  // Draw everything
  display.clearDisplay();

  // Draw food
  drawCell(foodX, foodY);

  // Draw snake
  for (int i = 0; i < snakeLength; i++) {
    drawCell(snakeX[i], snakeY[i]);
  }

  display.display();

  // Restart on SEL
  if (sel == LOW) {
    resetGame();
    delay(300);
  }
}