#define BOARD_LENGTH 8

struct pair {
  int x;
  int y;
};

class Snake {
private:
  char state;
  int snake_size;
  pair pos[64];
  pair get_next_move(pair p);

public:
  Snake() {
    this->state = 'U';
    this->snake_size = 4;
    for (int i = snake_size - 1; i >= 0; i--) {
      pair p;
      p.x = 5;
      p.y = i;
      this->pos[i] = p;
    }
  }
  void change_state(char m);
  void eat(pair p);
  void snake_to_matrix(int (*pixels)[BOARD_LENGTH]){
    for(int i = 0; i < BOARD_LENGTH; i++){
      for(int j = 0; j < BOARD_LENGTH; j++){
        pixels[i][j] = HIGH; // CLEAR ALL PIXELS;
      }
    }
    for(int i = 0; i < snake_size; i++) {
      pair p = pos[i];
      pixels[p.x][p.y] = LOW; // TURN ON PIXELS OF SNAKE
    }
  }
  void next_move();
  pair snake_head() {
    return pos[0];
  }
};

pair Snake::get_next_move(pair p) {
  pair r;
  switch (state) {
  case 'U':
    r.x = (p.x + BOARD_LENGTH - 1) % BOARD_LENGTH;
    r.y = p.y;
    break;
  case 'D':
    r.x = (p.x + 1) % BOARD_LENGTH;
    r.y = p.y;
    break;
  case 'L':
    r.x = p.x;
    r.y = (p.y + 1) % BOARD_LENGTH;
    break;
  case 'R':
    r.x = p.x;
    r.y = (p.y + BOARD_LENGTH - 1) % BOARD_LENGTH;
    break;
  }
  return r;
}

void Snake::next_move() {
  for (int i = snake_size; i > 0; i--) {
    pos[i] = pos[i - 1];
  }
  pos[0] = get_next_move(pos[0]);
}

void Snake::eat(pair p) { pos[snake_size++] = p; }

const int row[8] = {2, 7, 19, 5, 13, 18, 12, 16};

// 2-dimensional array of column pin numbers:
const int col[8] = {6, 11, 10, 3, 17, 4, 8, 9};

// 2-dimensional array of pixels:
int pixels[8][8];

// cursor position:
int x = 5;
int y = 5;
Snake snake;

void setup() {
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }

  // initialize the pixel matrix:
  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      pixels[x][y] = HIGH;
    }
  }
}

void loop() {
  // read input:
  // readSensors();
  snake.snake_to_matrix(pixels);
  snake.next_move();
  // draw the screen:
  for(int i = 0; i < 100; i++)
    Display();
}

void readSensors() {
  // turn off the last position:
  pixels[x][y] = HIGH;
  // read the sensors for X and Y values:
  x = 7 - map(analogRead(A0), 0, 1022, 0, 7);
  y = map(analogRead(A1), 0, 1022, 0, 7);
  // set the new pixel position low so that the LED will turn on
  // in the next screen refresh:
  pixels[x][y] = LOW;
}

void Display()    
{  
  for(int c = 0; c<8;c++)  
  {  
    digitalWrite(col[c],LOW);//use thr column 
    //loop
    for(int r = 0;r<8;r++)  
    {  
      digitalWrite(row[r],(pixels[r][c]+1)%2);  
    }  
    delay(1);  
    Clear();  //Remove empty display light
  }  
}  
  
void Clear()                          //清空显示  
{  
  for(int i = 0;i<8;i++)  
  {  
    digitalWrite(row[i],LOW);  
    digitalWrite(col[i],HIGH);  
  }  
}