final int NONE = 0;
final int CROSS = 1;
final int CIRCLE = 2;
final int SPLASHSCREEN = 0;
final int PLAYING = 1;
final int GAMEOVER = 2;
final int[][] WINNING_COMBINATIONS = { 
  { 0, 1, 2 }, // first row
  { 3, 4, 5 }, // second row
  { 6, 7, 8 }, // third row
  { 0, 3, 6 }, // first column
  { 1, 4, 7 }, // second column
  { 2, 5, 8 }, // third column
  { 0, 4, 8 }, // first diagonal
  { 2, 4, 6 }  // second diagonal
};
int[] game = {
  NONE, NONE, NONE, 
  NONE, NONE, NONE, 
  NONE, NONE, NONE
};
int currentPlayer = NONE;
int[] winnerIndices = null;
boolean gameIsDraw = false;
String highScoreText = "";
int gameState = SPLASHSCREEN;
int size;
int xOffset;
int yOffset;
int cellSize;
PFont headingFont;
PFont textFont;

void setup() {
  size(500, 500);
  
  headingFont = createFont("Liberation Sans Bold", 32);
  textFont = createFont("Liberation Sans", 16);
  
  size = min(width, height);
  xOffset = (width - size) / 2;
  yOffset = (height - size) / 2;  
  cellSize = size / 3;
  
  rectMode(CENTER);
  ellipseMode(CENTER);
  textAlign(CENTER, CENTER);
}

void draw() {
  switch (gameState) {
    case SPLASHSCREEN:
      background(#000000);
      
      fill(#FFFFFF);
      
      textFont(headingFont);
      text("TikTakToe", width / 2, height / 4);
      
      textFont(textFont);
      text("A two-player game\n\nPress any key or click anywhere to start playing\n\n© 2022 Christian Weber", width / 2, height / 2);
      break;
    case PLAYING:
      background(#CCCCCC);
  
      checkWinner();
      
      drawWinnerIndices();
      drawBoard();
      drawPlayerMarkers();
      break;
    case GAMEOVER:
      background(#CCCCCC);
      
      drawWinnerIndices();
      drawBoard();
      drawPlayerMarkers();
      
      fill(#77000000);
      noStroke();
      rect(xOffset, yOffset, 6 * cellSize, 6 * cellSize);
      
      fill(#FFFFFF);
      textFont(headingFont);
      text("Game Over", width / 2, height / 4);
      
      textFont(textFont);
      String text = "The player using " + (currentPlayer == CROSS ? "crosses" : "circles") + " has won the game.";
      
      if (gameIsDraw) {
        text = "The game is a draw.";
      }
      
      text(text + "\n\nPress any key or click anywhere to play again." + highScoreText, width / 2, height / 2);
      break;
  }
}

void drawBoard() {
  stroke(#000000);
  strokeWeight(5);
  
  line(xOffset + cellSize, yOffset, xOffset + cellSize, height - yOffset);
  line(xOffset + 2*cellSize, yOffset, xOffset + 2*cellSize, height - yOffset);
  line(xOffset, yOffset + cellSize, width - xOffset, yOffset + cellSize);
  line(xOffset, yOffset + 2*cellSize, width - xOffset, yOffset + 2*cellSize);
}

void drawWinnerIndices() {
  if (winnerIndices == null || winnerIndices.length <= 0) return;
  
  for (int i = 0; i < winnerIndices.length; i++) {
    int x = winnerIndices[i] % 3;
    int y = winnerIndices[i] / 3;
    
    noStroke();
    fill(#AACCEE);
    rect(xOffset + x * cellSize + cellSize / 2, yOffset + y * cellSize + cellSize / 2, cellSize, cellSize);
  }
}

void drawPlayerMarkers() {
  for (int i = 0; i < game.length; i++) {
    int x = i % 3;
    int y = i / 3;
    
    int marker = game[i];
    
    noFill();
    strokeWeight(5);
    stroke(#000000);
    
    if (marker == CROSS) {
      line(xOffset + x * cellSize + cellSize / 6, yOffset + y * cellSize + cellSize / 6, xOffset + (x + 1) * cellSize - cellSize / 6, yOffset + (y + 1) * cellSize - cellSize / 6);
      line(xOffset + (x + 1) * cellSize - cellSize / 6, yOffset + y * cellSize + cellSize / 6, xOffset + x * cellSize + cellSize / 6, yOffset + (y + 1) * cellSize - cellSize / 6);
    } else if (marker == CIRCLE) {
      ellipse(xOffset + x * cellSize + cellSize / 2, yOffset + y * cellSize + cellSize / 2, 2*cellSize / 3, 2*cellSize / 3); 
    }
  }
}

void checkWinner() {
  for (int[] indices : WINNING_COMBINATIONS) {
    int firstMarker = -1;
    boolean failed = false;
    
    for (int i = 0; i < indices.length; i++) {
      int marker = game[indices[i]];
      
      if (firstMarker == -1) {
        firstMarker = marker;
      } else if (firstMarker != marker) {
        failed = true;
      }
    }
    
    if ((firstMarker == CROSS || firstMarker == CIRCLE) && !failed) {
      endGame(indices, firstMarker, false);
      return;
    }
  }
  
  int usedCells = 0;
  
  for (int i = 0; i < game.length; i++) {
    if (game[i] > NONE) {
      usedCells++;
    }
  }
  
  if (usedCells == game.length) {
    endGame(null, NONE, true);
  }
}

void endGame(int[] indices, int marker, boolean isDraw) {
  winnerIndices = indices;
  gameState = GAMEOVER;
  gameIsDraw = isDraw;
  
  StringList highScores = new StringList();
  
  if (dataFile("highscores.txt").isFile()) {
    highScores.append(loadStrings("data/highscores.txt"));
  }
  
  String date = nf(year(), 4) + "-" + nf(month(), 2) + "-" + nf(day(), 2) + " " + nf(hour(), 2) + ":" + nf(minute(), 2) + ":" + nf(second(), 2);
  String text = isDraw
    ? "draw"
    : ((marker == CROSS ? "cross" : "circle") + "@" + join(nf(indices, 1), ","));
  
  highScores.append(date + " / " + text);

  saveStrings("data/highscores.txt", highScores.array());
      
  if (highScores.size() > 0) {
    int crossWins = 0;
    int circleWins = 0;
    int draw = 0;
    
    for (String s : highScores) {
      String winner = s.substring(22);
      
      if (winner.indexOf("@") > 0) {
        winner = winner.substring(0, winner.indexOf("@"));
      }
      
      if (winner.equals("cross")) crossWins++;
      else if (winner.equals("circle")) circleWins++;
      else if (winner.equals("draw")) draw++;
    }
    
    highScoreText = "\n\nHighScores:\nCross: " + crossWins + "\nCircle: " + circleWins + "\nDraw: " + draw;
  }
}

void startGame() {
  gameState = PLAYING;
  gameIsDraw = false;
  currentPlayer = NONE;
  game = new int[] {
    NONE, NONE, NONE, 
    NONE, NONE, NONE, 
    NONE, NONE, NONE
  };
  winnerIndices = null;
}

void keyPressed() {
  switch (gameState) {
    case PLAYING:
      break;
    case GAMEOVER:
    case SPLASHSCREEN:
      startGame();
      break;
  }
}

void mouseClicked() {
  switch (gameState) {
    case SPLASHSCREEN:
    case GAMEOVER:
      startGame();
      break;
    case PLAYING:
      int x = (mouseX - xOffset) / cellSize;
      int y = (mouseY - yOffset) / cellSize;
      int idx = y * 3 + x;
      
      if (game[idx] != NONE) break;
      
      if (currentPlayer == NONE || currentPlayer == CIRCLE) {
        currentPlayer = CROSS;
      } else {
        currentPlayer = CIRCLE;
      }
      
      game[idx] = currentPlayer;
      break;
  }  
}