#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

Adafruit_SSD1306 display(
  SCREEN_WIDTH,
  SCREEN_HEIGHT,
  &Wire,
  -1
);

//================ BUTTON =================
#define BTN_UP PB12
#define BTN_DOWN PB13
#define BTN_SELECT PB14

#define BTN_A PB15
#define BTN_B PA8

#define BTN_BACK PA9

#define BUZZER PA0

//================ STATE ==================
enum State {
  MENU,
  FLAPPY,
  PINGPONG
};

State currentState = MENU;

int menuIndex = 0;

//================ FLAPPY =================
int birdY = 30;
int velocity = 0;

int pipeX = 128;
int gapY = 25;

int flappyScore = 0;

//================ PINGPONG ===============
int paddleY = 25;

int ballX = 64;
int ballY = 32;

int ballVX = 2;
int ballVY = 2;

int pongScore = 0;

//=========================================
bool pressed(int pin)
{
  if (digitalRead(pin) == LOW)
  {
    delay(120);
    return true;
  }
  return false;
}

//=========================================
void beep()
{
  tone(BUZZER, 1200, 50);
}

//=========================================
void drawMenu()
{
  display.clearDisplay();

  display.setTextSize(1);
  display.setTextColor(WHITE);

  display.setCursor(20, 5);
  display.println("STM32 GAME");

  display.setCursor(0, 25);
  if(menuIndex==0) display.print(">");
  display.print(" Flappy Bird");

  display.setCursor(0, 40);
  if(menuIndex==1) display.print(">");
  display.print(" Ping Pong");

  display.display();
}

//=========================================
void resetFlappy()
{
  birdY = 30;
  velocity = 0;

  pipeX = 128;
  gapY = random(15,45);

  flappyScore = 0;
}

//=========================================
void runFlappy()
{
  if(pressed(BTN_A))
  {
    velocity = -5;
    beep();
  }

  velocity += 1;
  birdY += velocity;

  pipeX -= 3;

  if(pipeX < -10)
  {
    pipeX = 128;
    gapY = random(15,45);
    flappyScore++;
    beep();
  }

  if(birdY < 0 || birdY > 63)
  {
    resetFlappy();
  }

  if(pipeX < 20 && pipeX > 5)
  {
    if(birdY < gapY || birdY > gapY+20)
    {
      resetFlappy();
    }
  }

  display.clearDisplay();

  display.fillCircle(15,birdY,3,WHITE);

  display.fillRect(pipeX,0,10,gapY,WHITE);
  display.fillRect(pipeX,gapY+20,10,64-gapY,WHITE);

  display.setCursor(100,0);
  display.print(flappyScore);

  display.display();

  if(pressed(BTN_BACK))
  {
    currentState = MENU;
  }
}

//=========================================
void resetPong()
{
  paddleY = 25;

  ballX = 64;
  ballY = 32;

  ballVX = 2;
  ballVY = 2;

  pongScore = 0;
}

//=========================================
void runPong()
{
  if(digitalRead(BTN_A)==LOW)
    paddleY -= 3;

  if(digitalRead(BTN_B)==LOW)
    paddleY += 3;

  if(paddleY<0) paddleY=0;
  if(paddleY>44) paddleY=44;

  ballX += ballVX;
  ballY += ballVY;

  if(ballY<=0 || ballY>=63)
  {
    ballVY = -ballVY;
    beep();
  }

  if(ballX<=5)
  {
    if(ballY>=paddleY &&
       ballY<=paddleY+20)
    {
      ballVX = -ballVX;
      pongScore++;
      beep();
    }
    else
    {
      resetPong();
    }
  }

  if(ballX>=127)
  {
    ballVX = -ballVX;
  }

  display.clearDisplay();

  display.fillRect(0,paddleY,3,20,WHITE);

  display.fillCircle(ballX,ballY,2,WHITE);

  display.setCursor(100,0);
  display.print(pongScore);

  display.display();

  if(pressed(BTN_BACK))
  {
    currentState = MENU;
  }
}

//=========================================
void setup()
{
  pinMode(BTN_UP, INPUT_PULLUP);
  pinMode(BTN_DOWN, INPUT_PULLUP);
  pinMode(BTN_SELECT, INPUT_PULLUP);

  pinMode(BTN_A, INPUT_PULLUP);
  pinMode(BTN_B, INPUT_PULLUP);
  pinMode(BTN_BACK, INPUT_PULLUP);

  pinMode(BUZZER, OUTPUT);

  Wire.begin();

  display.begin(
    SSD1306_SWITCHCAPVCC,
    0x3C
  );

  randomSeed(millis());

  drawMenu();
}

//=========================================
void loop()
{
  switch(currentState)
  {
    case MENU:

      if(pressed(BTN_UP))
      {
        menuIndex--;
        if(menuIndex<0)
          menuIndex=1;

        beep();
      }

      if(pressed(BTN_DOWN))
      {
        menuIndex++;
        if(menuIndex>1)
          menuIndex=0;

        beep();
      }

      if(pressed(BTN_SELECT))
      {
        beep();

        if(menuIndex==0)
        {
          resetFlappy();
          currentState = FLAPPY;
        }
        else
        {
          resetPong();
          currentState = PINGPONG;
        }
      }

      drawMenu();
      break;

    case FLAPPY:
      runFlappy();
      delay(40);
      break;

    case PINGPONG:
      runPong();
      delay(25);
      break;
  }
}