#include "stdafx.h"
#include <iostream>
#include <stdlib.h>
#include <time.h>
#include <conio.h>
#include <graphics.h>
 
#define N 100
 
using namespace std;
 
enum moved { UP, DOWN, LEFT, RIGHT };
class Snake {
private:
 struct {   //整條蛇的信息
 int x;
 int y;
 }snake[100];
 struct {
 int life;  //為1代表還活著，為0代表已經死了
 int length; //代表蛇的長度，初始值為3
 enum moved direction;  //前進方向
 }snake_head;
 struct {    //食物的信息
 int x;
 int y;
 }food;
public:
 void display();  //顯示界面
 void initSnake(); //隨機生成蛇
 void move();//蛇移動
 void boundary_check();//邊界判斷
 void _food();//生成食物
 int food_eatcheck();//檢查是否吃到食物,吃到則返回1，否則返回0
 int snake_eat();//判斷貪吃蛇是否咬到自己，咬到則返回1，否則返回0
 void run();   //主要運行函數
};
void Snake::display() {
 initgraph(800, 600);
 setbkcolor(WHITE);  //設置背景顏色為白色
 cleardevice();    //將背景顏色刷新到窗口上
 setfillcolor(BLACK); //設置填充的顏色為黑色，之后話填充的圖形都是這個顏色
 solidrectangle(20, 560, 560, 20);//這個區(qū)域每20*20為一個單位，一共有27*27個單位
}
//構造函數
void Snake::initSnake() {
 srand((unsigned)time(NULL));
 //因為一開始蛇是向右走的，所以不能讓蛇初始化在太靠右邊的地方
 int x = rand() % 22 + 3; //范圍是3-24
 int y = rand() % 22 + 3; //加三是因為初始的長度是3，必須讓整條蛇都在范圍內
 this->snake[0].x = x * 20 + 10;//加十是因為要確定圓心的位置
 this->snake[0].y = y * 20 + 10;
 //默認蛇一開始是橫著的所以三段的y坐標相同
 this->snake[1].y = this->snake[2].y = this->snake[0].y;
 this->snake[1].x = this->snake[0].x - 20;
 this->snake[2].x = this->snake[0].x - 40;
 setfillcolor(GREEN);  //設置填充色為綠色
 solidcircle(this->snake[0].x, this->snake[0].y, 10); //畫圓
 solidcircle(this->snake[1].x, this->snake[1].y, 10);
 solidcircle(this->snake[2].x, this->snake[2].y, 10);
 this->snake_head.length = 3;
 this->snake_head.life = 1;
 this->snake_head.direction = RIGHT;
}
void Snake::move() {
 char ch;
 if (_kbhit()) {  //如果有輸入的話就返回1，沒有輸入的話就返回0
 ch = _getch();//獲取輸入的字符
 switch (ch) {
  case 'w' :if (this->snake_head.direction != DOWN) this->snake_head.direction = UP; break;
  case 'W':if (this->snake_head.direction != DOWN) this->snake_head.direction = UP; break;
  case 's' :if (this->snake_head.direction != UP) this->snake_head.direction = DOWN; break;
  case 'S':if (this->snake_head.direction != UP) this->snake_head.direction = DOWN; break;
  case 'a':if (this->snake_head.direction != RIGHT) this->snake_head.direction = LEFT; break;
  case 'A':if (this->snake_head.direction != RIGHT) this->snake_head.direction = LEFT; break;
  case 'd':if (this->snake_head.direction != LEFT) this->snake_head.direction = RIGHT; break;
  case 'D':if (this->snake_head.direction != LEFT) this->snake_head.direction = RIGHT; break;
  default:break;
 }
 }
 //將蛇尾變成黑色
 int i = this->snake_head.length - 1;
 setfillcolor(BLACK);
 solidcircle(snake[i].x, snake[i].y, 10);
 //接下來遍歷每個身體，每個身體都更新為前一個身體，蛇頭除外
 for (; i > 0; i--) {
 this->snake[i].x = this->snake[i - 1].x;
 this->snake[i].y = this->snake[i - 1].y;
 }
 switch (this->snake_head.direction) {
 case RIGHT:this->snake[0].x += 20; break;
 case LEFT:this->snake[0].x -= 20; break;
 case UP:this->snake[0].y -= 20; break;
 case DOWN:this->snake[0].y += 20; break;
 default:break;
 }
 setfillcolor(GREEN);
 solidcircle(this->snake[0].x, this->snake[0].y, 10);//繪制蛇頭
 Sleep(1000);
}
void Snake::boundary_check() {
 if (this->snake[0].x <= 30 || this->snake[0].x >= 550 || this->snake[0].y <= 30 || this->snake[0].y >= 550) {
 this->snake_head.life = 0; 
 }
}
void Snake::_food() {
 srand((unsigned)time(NULL));
 int x = rand() % 21 + 3;  //范圍是3-23
 int y = rand() % 21 + 3;
 this->food.x = x * 20 + 10;
 this->food.y = y * 20 + 10;
 setfillcolor(YELLOW);
 solidcircle(this->food.x, this->food.y, 10);
}
int Snake::food_eatcheck() {
 if (this->snake[0].x == this->food.x && this->snake[0].y == this->food.y) {
 //如果滿足條件就是吃到食物了
 this->snake_head.length++;//長度加一
 setfillcolor(GREEN);
 solidcircle(food.x, food.y, 10);
 int k = this->snake_head.length;
 //吃到食物之后最后要在尾巴處加一個長度
 switch (this->snake_head.direction) {
  case RIGHT:this->snake[k - 1].x = this->snake[k - 2].x - 20; this->snake[k - 1].y = this->snake[k - 2].y; break;
  case LEFT:this->snake[k - 1].x = this->snake[k - 2].x += 20; this->snake[k - 1].y = this->snake[k - 2].y; break;
  case UP:this->snake[k - 1].x = this->snake[k - 2].x; this->snake[k - 1].y = this->snake[k - 2].y + 20; break;
  case DOWN:this->snake[k - 1].x = this->snake[k - 2].x; this->snake[k - 1].y = this->snake[k - 2].y - 20; break;
  default:break;
 }
 setfillcolor(GREEN);
 solidcircle(this->snake[k - 1].x, this->snake[k - 1].y, 10);
 return 1;
 }
 return 0;
}
int Snake::snake_eat() {
 int i;
 for (i = 1; i < this->snake_head.length; i++) {
 if (this->snake[i].x == this->snake[0].x && this->snake[i].y == this->snake[0].y) {
  return 1;
 }
 }
 return 0;
}
void Snake::run() {
 display(); //顯示游戲界面
 initSnake();
 _food();  //生成第一個食物
 while (true) {
 move();  //蛇移動
 if (snake_eat() == 1) {
  //自己吃到自己了，游戲失敗
  cout << "自己吃到自己了，游戲失敗" << endl;
  break;
 }
 boundary_check();//判斷是否撞墻
 if (this->snake_head.life == 0) {
  //撞墻了
  cout << "撞墻了，游戲結束" << endl;
  break;
 }
 if (food_eatcheck() == 1) {
  _food(); //吃到食物就重新生成一個食物
 }
 }
}
 
int main() {
 Snake s;
 s.run();
 return 0;
}