#include "pch.h"
#include "Snake.h"
#include <list>
#include <random>

#define MAXx 34
#define MAXy 34
#define MINx 0
#define MINy 0

#define UP 1
#define DOWN 2
#define LEFT 3
#define RIGHT 4

#define EXIST_ITEM 1
#define NON_EXIST_ITEM 0

Snake::Snake()
{
	body.push_front({ 12,15 });
	body.push_front({ 12,14 });
	body.push_front({ 12,13 });
	body.push_front({ 12,12 });
	direction = RIGHT;
	speed = 1;
	length = 3;
	score = 0;
	lose = false;
	itemOldTime = clock();
	speedOldTime = clock();
	memset(map, 0, sizeof map);
}


void Snake::move()
{
	auto head = body.back();
	
	//判断蛇是否会死亡
	switch (direction)
	{
	case UP:
		if (head.first - 1 < MINy || !checkIsOnSnake({ head.first - 1, head.second })) {
			lose = true;
			return;
		}
		break;
	case DOWN:
		if (head.first + 1 > MAXy || !checkIsOnSnake({ head.first + 1, head.second })) {
			lose = true;
			return;
		}
		break;
	case LEFT:
		if (head.second - 1 < MINx || !checkIsOnSnake({ head.first, head.second - 1 })) {
			lose = true;
			return;
		}
		break;
	case RIGHT:
		if (head.second + 1 > MAXx || !checkIsOnSnake({ head.first, head.second + 1 })) {
			lose = true;
			return;
		}
		break;
	}


	auto Tempit = body.begin();				//保存前一格蛇身的指针
	auto tail = *Tempit;					//保存蛇尾

	for (auto it = ++body.begin(); it != body.end(); ++it) {
		*Tempit = *it;
		Tempit = it;

		//判断是否为蛇头
		if (next(it) == body.end()) {		

			switch (direction)				//进行移动
			{
			case UP:
				it->first--;
				break;
			case DOWN:
				it->first++;
				break;
			case LEFT:
				it->second--;
				break;
			case RIGHT:
				it->second++;
				break;
			}

			//判断是否吃到食物
			if (map[it->second][it->first] == EXIST_ITEM) {
				map[it->second][it->first] = NON_EXIST_ITEM;
				
				//查找并删除食物
				std::pair<int, int> point = { it->second, it->first };
				auto tempit = find(item.begin(), item.end(), point);
				item.erase(tempit);

				length++;
				body.push_front(tail);
				score += speed;
			}
		}
	}
}


bool Snake::gameOver()
{
	if (lose == true) {
		return true;
	}
	return false;
}


void Snake::addItem()
{
	//添加食物
	if (item.size() == 1) return;
	//获取随机数
	std::default_random_engine engine;
	std::uniform_int_distribution<int> random(0, 50);
	engine.seed(time(0));
	//定时产生食物
	if (clock() > itemOldTime + 1000) {
		itemOldTime = clock();
		int x, y;
		do{
			srand(time(NULL));
			x = random(engine) % MAXy;
			y = random(engine) % MAXx;
		} while (map[x][y] == EXIST_ITEM && checkIsOnSnake({x, y}));
		map[x][y] = EXIST_ITEM;
		item.push_back({ x, y });
	}
}


bool Snake::checkIsOnSnake(std::pair<int, int> temp)
{
	//检测坐标是否不在蛇身上
	for (auto it = body.begin(); it != body.end(); ++it) {
		if (*it == temp) return false;
	}
	return true;
}


bool Snake::speedUp()
{
	//定时加速
	switch (speed)
	{
	case 1:
		if (clock() > speedOldTime + 30000) speed += 2;
		return true;
	case 3:
		if (clock() > speedOldTime + 60000) speed += 2;
		return true;
	case 5:
		if (clock() > speedOldTime + 90000) speed += 2;
		return true;
	case 7:
		if (clock() > speedOldTime + 120000) speed += 2;
		return true;
	}
	return false;
}