// Snake.java
// Written in class on Tue 13-Oct-09
// As with any code that is written in real time in class,
// this may contain a bug here or there and in any case
// cuts some corners on style (to wit: no comments!).

import java.awt.*;
import javax.swing.*;
import java.util.*;

public class Snake extends JComponentWithEvents {
  
  private boolean debug = true;
  private int rows = 10;
  private int cols = 10;
  private int[][] snake = new int[rows][cols];
  private int dir = UP;
  private int headRow, headCol;
  private int foodRow, foodCol;
  
  public void moveSnake() {
    int snakeLength = snake[headRow][headCol];
    int newHeadRow = headRow, newHeadCol = headCol;
    if (dir == UP) newHeadRow--;
    else if (dir == DOWN) newHeadRow++;
    else if (dir == RIGHT) newHeadCol++;
    else newHeadCol--;
    if ((newHeadRow < 0) || (newHeadRow >= rows) ||
        (newHeadCol < 0) || (newHeadCol >= cols)) {
      die();
    }
    else if (snake[newHeadRow][newHeadCol] > 0) {
      die();
    }
    else if ((newHeadRow == foodRow) && (newHeadCol == foodCol)) {
      headRow = newHeadRow;
      headCol = newHeadCol;
      snake[newHeadRow][newHeadCol] = snakeLength+1;
      placeFood();
    }
    else {
      for (int row=0; row<rows; row++)
        for (int col=0; col<cols; col++)
          if (snake[row][col] > 0)
            --snake[row][col];
      snake[newHeadRow][newHeadCol] = snakeLength;
      headRow = newHeadRow;
      headCol = newHeadCol;
    }
  }
  
  public void die() {
    reset();
  }
  
  public void keyPressed(char key) {
    if (key == 'm') moveSnake();
    else if (key == UP) dir = UP;
    else if (key == DOWN) dir = DOWN;
    else if (key == RIGHT) dir = RIGHT;
    else if (key == LEFT) dir = LEFT;
  }
  
  public void timerFired() {
    moveSnake();
  }

  public void start() {
    reset();
  }

  public void reset() {
    for (int row=0; row<rows; row++)
      for (int col=0; col<cols; col++)
        snake[row][col] = 0;
    headRow = 0;
    headCol = 1;
    snake[0][1] = 5;
    snake[1][1] = 4;
    snake[2][1] = 3;
    snake[2][2] = 2;
    snake[3][2] = 1;
    dir = RIGHT;
    placeFood();
  }
  
  private Random random = new Random();
  
  public void placeFood() {
    while (true) {
      foodRow = random.nextInt(rows);
      foodCol = random.nextInt(cols);
      System.out.println("placeFood: trying " + foodRow + "," + foodCol);
      if (snake[foodRow][foodCol] == 0)
        break;
    }
    System.out.println("placeFood: worked");
  }

  public void paintCell(Graphics2D page, int row, int col) {
    int width = getWidth(), height = getHeight();
    int left = col * width / cols;
    int right = (col + 1) * width / cols; 
    int top  = row * height / rows;
    int bottom = (row + 1) * height / rows;
    page.setColor(Color.black);
    page.drawRect(left, top, right-left, bottom-top);
    if ((row == foodRow) && (col == foodCol)) {
      page.setColor(Color.green);
      page.fillOval(left, top, right-left, bottom-top);
    }
    else if (snake[row][col] > 0) {
      page.setColor(Color.blue);
      page.fillOval(left, top, right-left, bottom-top);
      if (debug) {
        page.setColor(Color.white);
        page.setFont(new Font("Arial", Font.BOLD, 16));
        drawCenteredString(page, ""+snake[row][col],
                           left, top, right-left, bottom-top);
      }
    }
  }

  public void paint(Graphics2D page) {
    for (int row=0; row<rows; row++)
      for (int col=0; col<cols; col++)
        paintCell(page, row, col);
  }
  
  public static void main(String[] args) { launch(300, 300); }
}