#include <Arduino.h>

/**
 * Player 1: x = 0
 * Player 2: x = X_MAX-1
 */

#define PIN_LED_MATRIX        2
#define PIN_JOYSTICK_1_BUTTON 6
#define PIN_JOYSTICK_2_BUTTON 7
#define PIN_PIEZO             11
#define PIN_JOYSTICK_1_Y      A0
#define PIN_JOYSTICK_2_Y      A1

#define JOYSTICK_OFFSET_MIN 200
#define JOYSTICK_OFFSET_MAX 700

#define DEBOUNCE_TIME 300  // in ms

#define X_MAX 10
#define Y_MAX 20

#define GAME_DELAY 80         // in ms
#define BALL_DELAY_MAX   350  // in ms
#define BALL_DELAY_MIN    50  // in ms
#define BALL_DELAY_STEP    5  // in ms

#define PLAYER_AMOUNT 2
#define PLAYER_1 0
#define PLAYER_2 1

#define PADDLE_WIDTH 3

#define PADDLE_MOVE_NONE  0
#define PADDLE_MOVE_UP    1
#define PADDLE_MOVE_DOWN  2

#define LED_TYPE_OFF      1
#define LED_TYPE_PADDLE   2
#define LED_TYPE_BALL     3
#define LED_TYPE_BALL_RED 4

#define TONE_PLAYER 1
#define TONE_WALL   2
#define TONE_BUZZ   3

#define GAME_STATE_RUNNING 1
#define GAME_STATE_END     2
#define GAME_STATE_INIT    3

#include <Adafruit_NeoPixel.h>

struct Coords {
  byte x;
  byte y;
};

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(X_MAX * Y_MAX, PIN_LED_MATRIX, NEO_GRB + NEO_KHZ800);
bool buttonPressed = false;
byte gameState;
byte joystickPins[PLAYER_AMOUNT] = {PIN_JOYSTICK_1_Y, PIN_JOYSTICK_2_Y};
Coords paddles[PLAYER_AMOUNT][PADDLE_WIDTH];
Coords ball;
int ballMovement[2];
unsigned int ballDelay;
unsigned long lastDrawUpdate = 0;
unsigned long lastBallUpdate = 0;
unsigned long lastButtonClick = 0;

void setup()
{
  pinMode(PIN_JOYSTICK_1_Y, INPUT);
  pinMode(PIN_JOYSTICK_1_BUTTON, INPUT_PULLUP);
  pinMode(PIN_JOYSTICK_2_Y, INPUT);
  pinMode(PIN_JOYSTICK_2_BUTTON, INPUT_PULLUP);
  pixels.begin();
  resetLEDs();
  gameState = GAME_STATE_END;
}

void loop()
{
  switch(gameState) {
    case GAME_STATE_INIT:
      initGame();
      break;
    case GAME_STATE_RUNNING:
      updateBall();
      updateGame();
      break;
    case GAME_STATE_END:
      if (isButtonPressed()) {
        gameState = GAME_STATE_INIT;
      }
      break;
  }
}

void initGame()
{
  resetLEDs();
  lastButtonClick = millis();

  ball.x = 1;
  ball.y = (Y_MAX/2) - (PADDLE_WIDTH/2) + 1;
  ballMovement[0] =  1;
  ballMovement[1] = -1;
  ballDelay = BALL_DELAY_MAX;

  for(byte i=0; i<PADDLE_WIDTH; i++) {
    paddles[PLAYER_1][i].x = 0;
    paddles[PLAYER_1][i].y = (Y_MAX/2) - (PADDLE_WIDTH/2) + i;
    paddles[PLAYER_2][i].x = X_MAX - 1;
    paddles[PLAYER_2][i].y = paddles[PLAYER_1][i].y;
  }

  gameState = GAME_STATE_RUNNING;
}

void updateBall()
{
  bool hitBall = false;
  if ((millis() - lastBallUpdate) < ballDelay) {
    return;
  }
  lastBallUpdate = millis();
  toggleLed(ball.x, ball.y, LED_TYPE_OFF);

  // collision detection for player 1
  if (ballMovement[0] == -1 && ball.x == 1) {
    for(byte i=0; i<PADDLE_WIDTH; i++) {
      if (paddles[PLAYER_1][i].y == ball.y) {
        hitBall = true;
        break;
      }
    }
  }

  // collision detection for player 2
  if (ballMovement[0] == 1 && ball.x == X_MAX-2) {
    for(byte i=0; i<PADDLE_WIDTH; i++) {
      if (paddles[PLAYER_2][i].y == ball.y) {
        hitBall = true;
        break;
      }
    }
  }

  if (hitBall == true) {
    ballMovement[0] *= -1;
    playTone(TONE_PLAYER);
    if (ballDelay > BALL_DELAY_MIN) {
      ballDelay -= BALL_DELAY_STEP;
    }
  }

  ball.x += ballMovement[0];
  ball.y += ballMovement[1];

  if (ball.x <=0 || ball.x >= X_MAX-1) {
    endGame();
    return;
  }

  if (ball.y <= 0 || ball.y >= Y_MAX-1) {
    ballMovement[1] *= -1;
    playTone(TONE_WALL);
  }

  toggleLed(ball.x, ball.y, LED_TYPE_BALL);
  pixels.show();
}

void endGame()
{
  gameState = GAME_STATE_END;
  toggleLed(ball.x, ball.y, LED_TYPE_BALL_RED);
  pixels.show();
  playTone(TONE_BUZZ);
}

void updateGame()
{
  if ((millis() - lastDrawUpdate) < GAME_DELAY) {
    return;
  }
  lastDrawUpdate = millis();

  // turn off paddle LEDs
  for(byte p=0; p<PLAYER_AMOUNT; p++) {
    for(byte i=0; i<PADDLE_WIDTH; i++) {
      toggleLed(paddles[p][i].x, paddles[p][i].y, LED_TYPE_OFF);
    }
  }

  // move paddles
  for(byte p=0; p<PLAYER_AMOUNT; p++) {
    byte movement = getPlayerMovement(p);
    if (movement == PADDLE_MOVE_UP && paddles[p][PADDLE_WIDTH-1].y < (Y_MAX-1)) {
      for(byte i=0; i<PADDLE_WIDTH; i++) {
        paddles[p][i].y++;
      }
    }
    if (movement == PADDLE_MOVE_DOWN && paddles[p][0].y > 0) {
      for(byte i=0; i<PADDLE_WIDTH; i++) {
        paddles[p][i].y--;
      }
    }
  }

  // show paddle LEDs
  for(byte p=0; p<PLAYER_AMOUNT; p++) {
    for(byte i=0; i<PADDLE_WIDTH; i++) {
      toggleLed(paddles[p][i].x, paddles[p][i].y, LED_TYPE_PADDLE);
    }
  }
  pixels.show();
}

byte getPlayerMovement(byte playerId)
{
  int value = analogRead(joystickPins[playerId]);
  if (value < JOYSTICK_OFFSET_MIN) {
    if (playerId == PLAYER_2) {
      return PADDLE_MOVE_DOWN;
    } else {
      return PADDLE_MOVE_UP;
    }
  } else if (value > JOYSTICK_OFFSET_MAX) {
    if (playerId == PLAYER_2) {
      return PADDLE_MOVE_UP;
    } else {
      return PADDLE_MOVE_DOWN;
    }
  }
  return PADDLE_MOVE_NONE;
}

bool isButtonPressed()
{
  if ((millis() - lastButtonClick) < DEBOUNCE_TIME) {
    return false;
  }
  if (digitalRead(PIN_JOYSTICK_1_BUTTON) == LOW) {
    lastButtonClick = millis();
    return true;
  }
  if (digitalRead(PIN_JOYSTICK_2_BUTTON) == LOW) {
    lastButtonClick = millis();
    return true;
  }
  return false;
}

void resetLEDs()
{
  for(byte i=0; i<X_MAX*Y_MAX; i++) {
    pixels.setPixelColor(i, pixels.Color(0, 0, 0));
  }
  pixels.show();
}

void toggleLed(byte x, byte y, byte type)
{
  byte ledIndex = y * X_MAX + x;
  uint32_t color;

  switch(type) {
    case LED_TYPE_PADDLE:
      color = pixels.Color(0, 8, 8);
      break;
    case LED_TYPE_BALL_RED:
      color = pixels.Color(12, 0, 0);
      break;
    case LED_TYPE_BALL:
      color = pixels.Color(0, 10, 0);
      break;
    case LED_TYPE_OFF:
      color = pixels.Color(0, 0, 0);
      break;
  }

  pixels.setPixelColor(ledIndex, color);
}

void playTone(byte type)
{
  switch(type) {
    case TONE_PLAYER:
      tone(PIN_PIEZO, 440, 50);
      break;
    case TONE_WALL:
      tone(PIN_PIEZO, 550, 50);
      break;
    case TONE_BUZZ:
      for(byte i=0; i<20; i++) {
        tone(PIN_PIEZO, 220-i*10, 50);
        delay(50);
      }
      break;
  }
}