// snake01.c  -- 精简了 snakeMove() 函数。

#include<stdio.h>
#include<time.h>
#include<windows.h>
#include<stdlib.h>

#define U 1
#define D 2
#define L 3
#define R 4       //蛇的状态，U：上 ；D：下；L:左 R：右

typedef struct SNAKE //蛇身的一个节点
{
    int x;
    int y;
    struct SNAKE *next;
}snake;

//全局变量//
int score = 0, add = 10;//总得分与每次吃食物得分。
int status, sleeptime = 200;//每次运行的时间间隔
snake *head, *food;//蛇头指针，食物指针
snake *q;//遍历蛇的时候用到的指针
int endGamestatus = 0; //游戏结束的情况，1：撞到墙；2：咬到自己；3：主动退出游戏。

//声明全部函数//
void Pos();
void creatMap();
void initSnake();
int biteSelf();
void createFood();
void cantCrossWall();
void snakeMove();
void pause();
void runGame();
void initGame();
void endGame();
void gameStart();

void Pos(int x, int y)//设置光标位置
{
    COORD pos;
    HANDLE hOutput;
    pos.X = x;
    pos.Y = y;
    hOutput = GetStdHandle(STD_OUTPUT_HANDLE);//返回标准的输入、输出或错误的设备的句柄，也就是获得输入、输出/错误的屏幕缓冲区的句柄
    SetConsoleCursorPosition(hOutput, pos);
}

void creatMap()//创建地图
{
    int i;
    for (i = 0; i<58; i += 2)//打印上下边框
    {
        Pos(i, 0);
        printf("■");//一个方块占两个位置
        Pos(i, 26);
        printf("■");
    }
    for (i = 1; i<26; i++)//打印左右边框
    {
        Pos(0, i);
        printf("■");
        Pos(56, i);
        printf("■");
    }
}

void initSnake()//初始化蛇身
{
    snake *tail;
    int i;
    tail = (snake*)malloc(sizeof(snake));//从蛇尾开始，头插法，以x,y设定开始的位置//
    tail->x = 24;
    tail->y = 5;
    tail->next = NULL;
    for (i = 1; i <= 4; i++)//初始长度为4
    {
        head = (snake*)malloc(sizeof(snake));
        head->next = tail;
        head->x = 24 + 2 * i;
        head->y = 5;
        tail = head;
    }
    while (tail != NULL)//从头到为，输出蛇身
    {
        Pos(tail->x, tail->y);
        printf("■");
        tail = tail->next;
    }
}
//??
int biteSelf()//判断是否咬到了自己
{
    snake *self;
    self = head->next;
    while (self != NULL)
    {
        if (self->x == head->x && self->y == head->y)
        {
            return 1;
        }
        self = self->next;
    }
    return 0;
}

void createFood()//随机出现食物
{
    snake *food_1;
    srand((unsigned)time(NULL));//为了防止每次产生的随机数相同，种子设置为time
    food_1 = (snake*)malloc(sizeof(snake));
    food_1->x = 1;
    while ((food_1->x % 2) != 0)    //保证其为偶数，使得食物能与蛇头对其
    {
        food_1->x = rand() % 52 + 2;
    }
    food_1->y = rand() % 24 + 1;
    q = head;
    while (q->next == NULL)
    {
        if (q->x == food_1->x && q->y == food_1->y) //判断蛇身是否与食物重合
        {
            free(food_1);
            createFood();
        }
        q = q->next;
    }
    Pos(food_1->x, food_1->y);
    food = food_1;
    printf("■");
}

void cantCrossWall()//不能穿墙
{
    if (head->x == 0 || head->x == 56 || head->y == 0 || head->y == 26)
    {
        endGamestatus = 1;
        endGame();
    }
}


void snakeMove()
{
    snake * nexthead;
    cantCrossWall();
    nexthead = (snake *)malloc(sizeof(snake));

    if (status == U){
        nexthead->x = head->x;
        nexthead->y = head->y - 1;
    }
    if (status == D){
        nexthead->x = head->x;
        nexthead->y = head->y + 1;
    }
    if (status == L){
        nexthead->x = head->x - 2;
        nexthead->y = head->y;
    }
    if (status == R){
        nexthead->x = head->x + 2;
        nexthead->y = head->y;
    }
    
    if (nexthead->x == food->x && nexthead->y == food->y){
        nexthead->next = head;
        head = nexthead;
        q = head;

        while (q != NULL){
            Pos(q->x, q->y);
            printf("■");
            q = q->next;
        }
        
        score = score + add;
        createFood();   // 食物已被吃掉，需要生成新的食物
    } else {
        nexthead->next = head;
        head = nexthead;
        q = head;
        while (q->next->next != NULL){
            Pos(q->x, q->y);
            printf("■");
            q = q->next;
        }
        Pos(q->next->x, q->next->y);
        printf(" ");
        free(q->next);
        q->next = NULL;
    }
    
    if (biteSelf() == 1){  // 检查是否已经咬到了自己
        endGamestatus = 2;
        endGame();
    }
}


void pause()//暂停
{
    while (1)
    {
        Sleep(300);
        if (GetAsyncKeyState(VK_SPACE))
        {
            break;
        }

    }
}

void runGame()//控制游戏
{

    Pos(64, 15);
    printf("不能穿墙，不能咬到自己\n");
    Pos(64, 16);
    printf("用↑.↓.←.→分别控制蛇的移动.");
    Pos(64, 17);
    printf("F1 为加速，F2 为减速\n");
    Pos(64, 18);
    printf("ESC ：退出游戏.space：暂停游戏.");
    status = R;
    while (1)
    {
        Pos(64, 10);
        printf("得分：%d  ", score);
        Pos(64, 11);
        printf("每个食物得分：%d分", add);
        if (GetAsyncKeyState(VK_UP) && status != D)
        {
            status = U;
        }
        else if (GetAsyncKeyState(VK_DOWN) && status != U)
        {
            status = D;
        }
        else if (GetAsyncKeyState(VK_LEFT) && status != R)
        {
            status = L;
        }
        else if (GetAsyncKeyState(VK_RIGHT) && status != L)
        {
            status = R;
        }
        else if (GetAsyncKeyState(VK_SPACE))
        {
            pause();
        }
        else if (GetAsyncKeyState(VK_ESCAPE))
        {
            endGamestatus = 3;
            break;
        }
        else if (GetAsyncKeyState(VK_F1))
        {
            if (sleeptime >= 50)
            {
                sleeptime = sleeptime - 30;
                add = add + 2;
                if (sleeptime == 320)
                {
                    add = 2;//防止减到1之后再加回来有错
                }
            }
        }
        else if (GetAsyncKeyState(VK_F2))
        {
            if (sleeptime<350)
            {
                sleeptime = sleeptime + 30;
                add = add - 2;
                if (sleeptime == 350)
                {
                    add = 1;  //保证最低分为1
                }
            }
        }
        Sleep(sleeptime);
        snakeMove();
    }
}

void initGame()//开始界面
{
    Pos(40, 12);
    printf("欢迎来到贪食蛇游戏！");
    Pos(20, 25);
    printf("可以到我的简书获取源码：//www.greatytc.com/u/945f89e93afe\n");
    system("pause");
    system("cls");
    Pos(25, 12);
    printf("用↑.↓.←.→分别控制蛇的移动， F1 为加速，2 为减速\n");
    Pos(25, 13);
    printf("加速将能得到更高的分数。\n");
    system("pause");
    system("cls");
}

void endGame()//结束游戏
{

    system("cls");
    Pos(24, 12);
    if (endGamestatus == 1)
    {
        printf("对不起，您撞到墙了。游戏结束.");
    }
    else if (endGamestatus == 2)
    {
        printf("对不起，您咬到自己了。游戏结束.");
    }
    else if (endGamestatus == 3)
    {
        printf("您的已经结束了游戏。");
    }
    Pos(24, 13);
    printf("您的得分是%d\n", score);
    while (getchar() != 'y')
    {
        printf("close?[y]");
    }
    exit(0);
}

void gameStart()//游戏初始化
{
    system("mode con cols=100 lines=30");
    initGame();
    creatMap();
    initSnake();
    createFood();
}

int main()
{
    gameStart();
    runGame();
    endGame();
    return 0;
}