#define BOARD_LENGTH 8
#define SNAKE_MAX_SIZE 32

struct pair {
  int x;
  int y;
};

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

public:
  Snake() {
    this->state = 'U';
    this->snake_size = 4;
    fruit = false;
    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 state) {
    if (state != '\0'){
      if((state == 'L' || state == 'R') && (this->state == 'U' || this->state=='D')) // if currently moving up or down and state change is left or right update
        this->state = state;
      else if((state == 'U' || state == 'D') && (this->state == 'L' || this->state=='R')) // the opposite
        this->state = state;
    }
    //else ignore    
  }
  void grow();
  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
    }
    if(fruit) 
      pixels[fruitPos.x][fruitPos.y] = LOW;
  }
  pair snake_head() {
    return pos[0];
  }
  void generate_fruit() {
    if(!fruit) {
      fruit = true;
      fruitPos.x = random(7);
      fruitPos.y = random(7);
    }
  }
  void next_move() {
    for (int i = snake_size; i > 0; i--) {
      pos[i] = pos[i - 1];
    }
    pos[0] = get_next_move(pos[0]);
    if (fruit) {
      if (pos[0].x == fruitPos.x && pos[0].y == fruitPos.y) {
        grow();
        fruit = false;
      }
    }
  }
  bool eats_itself() {
    for(int i = 1; i < snake_size; i++)
      if( pos[0].x == pos[i].x && pos[0].y == pos[i].y ) return true;
    return false;
  }
};

pair Snake::get_next_move(pair p) {
  pair r(p);
  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::grow() { 
  if (snake_size < SNAKE_MAX_SIZE) {
    pos[snake_size] = pos[snake_size - 1];
    ++snake_size;
  }
}

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() {
  Serial.begin(9600);          // 9600 bps
  // 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;
    }
  }
  randomSeed(analogRead(0));
}

void loop() {
  if(random(20) == 0) snake.generate_fruit();
  snake.snake_to_matrix(pixels);
  snake.next_move();
  // draw the screen:
  if(snake.eats_itself()){
    for(int i = 0; i < 3; i++){
      for(int j = 0; j < 100; j++)
        Display();
     delay(500);
    }
    int dead[8][8] = {
      {0,1,1,1,1,1,1,0},
      {1,0,1,1,1,1,0,1},
      {1,1,0,1,1,0,1,1},
      {1,1,1,0,0,1,1,1},
      {1,1,1,0,0,1,1,1},
      {1,1,0,1,1,0,1,1},
      {1,0,1,1,1,1,0,1},
      {0,1,1,1,1,1,1,0},
    };
    for(int i = 0; i < 8; i++)
      for(int j = 0; j < 8; j++)
        pixels[i][j] = dead[i][j];
    while(true) Display();
  }
  for(int i = 0; i < 30; i++) {
    Display();
    snake.change_state(read_sensors());
  }
  
}

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);  
  }  
} 

char read_sensors() {
  //int clicked = digitalRead(z); // if 0, then clicked
  //if(!clicked) return 'C';
  x = map(analogRead(A0),0,1023,0,10) - 5;
  y = map(analogRead(A1),0,1023,0,10) - 5;
  if(abs(x) <= 1 && abs(y) <= 1) { // test if joystick is the middle with some leeway
    return '\0';
  }else if(abs(x) > abs(y) ) { // test if move in x axis is > than in y axis
    if(x > 1) return 'L';
    else return 'R';
  } else {
    if(y > 1) return 'U';
    else return 'D';
  }
  return '\0';
}