float ballX = 320;
float ballY = 240;
float ballVelocityX = 1;
float ballVelocityY = 0;
float ballSpeed = 2.5;
float leftPaddleY = 240;
float rightPaddleY = 240;
float paddleSize = 50;
float leftPaddleMovement = 0;
float rightPaddleMovement = 0;
float paddleSpeed = 2.5;
boolean gameOver = false;
int points = 0;
int highScore = 0;
int lastScore = 0;
boolean highScoreSaved = false;

void setup() {
  size(640, 480);

  loadLastAndHighScore();
}

void draw() {
  background(#000000);

  strokeWeight(1);
  stroke(#FFFFFF);
  fill(#FFFFFF);
  rect(5, leftPaddleY - paddleSize / 2, 5, paddleSize);
  rect(width - 10, rightPaddleY - paddleSize / 2, 5, paddleSize);

  strokeWeight(1);
  stroke(#FFFFFF);
  line(width / 2, 0, width / 2, height);

  strokeWeight(10);
  stroke(#FFFFFF);
  point(ballX, ballY);


  textAlign(LEFT, TOP);
  textSize(16);
  fill(#FFFFFF);
  text("Points: " + points + ", LastScore: " + lastScore + ", HighScore: " + highScore, 5, 0);

  if (gameOver) {
    textAlign(CENTER, TOP);
    textSize(96);
    fill(#FF0000);
    text("GAME OVER", 320, 0);

    saveScore();
    return;
  }

  leftPaddleY = constrain(leftPaddleY + leftPaddleMovement * paddleSpeed, 0, height);
  rightPaddleY = constrain(rightPaddleY + rightPaddleMovement * paddleSpeed, 0, height);

  ballX = constrain(ballX + ballVelocityX * ballSpeed, 0, width);
  ballY = constrain(ballY + ballVelocityY * ballSpeed, 0, height);

  if (ballX == 0 || ballX == width) {
    gameOver = true;
  }

  if (ballX <= 10 && ballY > leftPaddleY - paddleSize / 2 && ballY < leftPaddleY + paddleSize / 2) {
    ballVelocityX *= -1;
    points++;
    ballVelocityY = (leftPaddleY - ballY) / (paddleSize / 2f);
  }

  if (ballX >= width - 10 && ballY > rightPaddleY - paddleSize / 2 && ballY < rightPaddleY + paddleSize / 2) {
    ballVelocityX *= -1;
    points++;
    ballVelocityY = -1 * (rightPaddleY - ballY) / (paddleSize / 2f);
  }

  if (ballY == 0 || ballY == height) {
    ballVelocityY *= -1;
  }
}

void keyPressed() {
  if (keyCode == UP) {
    rightPaddleMovement = -1;
  } else if (keyCode == DOWN) {
    rightPaddleMovement = 1;
  }

  if (key == 'w') {
    leftPaddleMovement = -1;
  } else if (key == 's') {
    leftPaddleMovement = 1;
  }
}

void keyReleased() {
  if (keyCode == UP || keyCode == DOWN) {
    rightPaddleMovement = 0;
  }

  if (key == 'w' || key == 's') {
    leftPaddleMovement = 0;
  }
}

int[] loadInts(String fileName) {
  int[] ints = new int[0];
  
  try {
    String[] strings = loadStrings(fileName);
    ints = new int[strings.length];

    for (int i = 0; i < strings.length; i++) {
      ints[i] = int(strings[i]);
    }
  } catch (Exception e) { }
  
  return ints;
}

void saveInts(String fileName, int[] ints) {
  try {
    String[] strings = new String[ints.length];

    for (int i = 0; i < strings.length; i++) {
      strings[i] = "" + ints[i];
    }
  
    saveStrings(fileName, strings);
  } catch (Exception e) { }
}

void loadLastAndHighScore() {
  int[] scores = loadInts("points.txt");

  if (scores.length <= 0) return;
  
  lastScore = scores[scores.length - 1];
  highScore = lastScore;
}

void saveScore() {
  if (highScoreSaved) return;
  
  int[] oldScores = loadInts("points.txt");  
  int[] newScores = new int[oldScores.length + 1];

  for (int i = 0; i < oldScores.length; i++) {
    newScores[i] = oldScores[i];
  }

  newScores[oldScores.length] = points;

  saveInts("points.txt", newScores);
  
  highScoreSaved = true;
}