#include "snake_functions.h"

void gamePlay();

// ==================================================================
// ==================================================================
// MAIN -> including game mechanics
// ==================================================================

void setup() 
{
  Serial.begin(9600);
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) 
  {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
      delay(100);
  }

  display.setRotation(2);  // <- rotate screen 180 degrees here

  setupButtons();
  randomSeed(analogRead(0));
  resetGame(false);
}

void loop() 
{
  gamePlay();
}

// ==================================================================

// whole gameplay
void gamePlay()
{
  if (digitalRead(BTN_RESTART) == LOW) 
  {
    resetGame(true);
    delay(300);
    return;
  }

  if (digitalRead(BTN_PAUSE) == LOW && millis() - lastPauseTime > 500) // debounce the button press
  { 
    paused = !paused;  // Toggle the pause state
    lastPauseTime = millis();  // Record time of last button press
  }

  if (gameOver) 
  {
    drawGameOver();
    return;
  }

  if (paused) 
  {
    display.clearDisplay();
    display.setTextSize(2);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor((SCREEN_WIDTH / 2) - 30, (SCREEN_HEIGHT / 2) - 8);
    display.print("PAUSED");
    display.display();
    return;  // Skip the rest of the game logic if paused
  }

  // sterowanie
  if (digitalRead(BTN_UP) == LOW && dirY != 1) 
  {
    dirX = 0; dirY = -1;
  }
  if (digitalRead(BTN_DOWN) == LOW && dirY != -1) 
  {
    dirX = 0; dirY = 1;
  }
  if (digitalRead(BTN_LEFT) == LOW && dirX != 1) 
  {
    dirX = -1; dirY = 0;
  }
  if (digitalRead(BTN_RIGHT) == LOW && dirX != -1) 
  {
    dirX = 1; dirY = 0;
  }

  unsigned long now = millis();
  if (now - lastMoveTime >= moveInterval) 
  {
    lastMoveTime = now;
    Point newHead = {snake[0].x + dirX, snake[0].y + dirY}; // moving vector

    // ------------------------------------------
    // COLLISIONS

    // wall collision
    if (newHead.x <= 0 || newHead.y <= 0 || newHead.x >= GRID_WIDTH - 1 || newHead.y >= GRID_HEIGHT - 1) 
    {
      gameOver = true;
      return;
    }

    // snake self collision
    for (int i = 0; i < snakeLength; i++) {
      if (snake[i].x == newHead.x && snake[i].y == newHead.y)
       {
        gameOver = true;
        return;
      }
    }

    // ------------------------------------------
    // MOVEMENT

    // snake move
    for (int i = snakeLength; i > 0; i--) 
    {
      snake[i] = snake[i - 1];
    }
    snake[0] = newHead;

    // food eating
    if ((newHead.x == food1.x && newHead.y == food1.y) || (newHead.x == food2.x && newHead.y == food2.y)) 
    {
      score++; // Increment score when food is eaten
      if (snakeLength < SNAKE_MAX_LENGTH) 
      {
        snakeLength += 3;
        moveInterval = max(40, moveInterval - 20);  // Speed up
      }
      spawnFood(); // Spawn new food
    } else if (snakeLength > SNAKE_MAX_LENGTH) // dont go over array bounds
    {
      snakeLength = SNAKE_MAX_LENGTH;
    }

    // draw all
    drawGame();
  }
}