#pragma once

#include <iostream>
#include <ctime>
#include <WinSock2.h>
#include <Windows.h>
#pragma comment(lib, "ws2_32.lib")

// 中国大陆优化的NTP服务器列表
const char* CN_NTP_SERVERS[] = {
	"ntp.aliyun.com",
	"time1.aliyun.com",
	"ntp1.tencent.com",
	"time.edu.cn",
	"ntp.tuna.tsinghua.edu.cn",
	"cn.ntp.org.cn",
};
const int CN_NTP_COUNT = sizeof(CN_NTP_SERVERS) / sizeof(CN_NTP_SERVERS[0]);
const int NTP_PORT = 123;
const uint64_t NTP_EPOCH_OFFSET = 2208988800ULL;

// 检测程序是否处于试用期
class DateVerify
{
private:
	// 初始化Winsock
	bool initWinsock() {
		WSADATA wsaData;
		return WSAStartup(MAKEWORD(2, 2), &wsaData) == 0;
	}

	// 从指定NTP服务器获取时间
	time_t getTimeFromServer(const char* server) {
		SOCKET sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
		if (sock == INVALID_SOCKET) return 0;

		sockaddr_in serverAddr{};
		serverAddr.sin_family = AF_INET;
		serverAddr.sin_port = htons(NTP_PORT);

		// 解析主机名
		hostent* host = gethostbyname(server);
		if (!host) {
			closesocket(sock);
			return 0;
		}
		serverAddr.sin_addr.s_addr = *((unsigned long*)host->h_addr_list[0]);

		// 设置超时
		DWORD timeout = 2000; // 2秒超时
		setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char*)&timeout, sizeof(timeout));

		// 准备NTP请求包
		char ntpPacket[48] = { 0 };
		ntpPacket[0] = 0x1B; // LI=0, VN=3, Mode=3

		// 发送请求
		if (sendto(sock, ntpPacket, sizeof(ntpPacket), 0,
			(sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR) {
			closesocket(sock);
			return 0;
		}

		// 接收响应
		if (recv(sock, ntpPacket, sizeof(ntpPacket), 0) <= 0) {
			closesocket(sock);
			return 0;
		}

		closesocket(sock);

		// 解析NTP时间
		uint32_t ntpTime = ntohl(*((uint32_t*)(ntpPacket + 40)));
		return ntpTime - NTP_EPOCH_OFFSET;
	}

	// 获取网络时间（尝试多个服务器）
	time_t getNetworkTimeInChina() {
		if (!initWinsock()) return 0;

		time_t result = 0;
		for (int i = 0; i < CN_NTP_COUNT && result == 0; i++) {
			result = getTimeFromServer(CN_NTP_SERVERS[i]);
			if (result != 0) {
				break;
			}
		}

		WSACleanup();
		return result;
	}

	// 将月份缩写转换为数字(1-12)
	int monthAbbrevToNumber(const std::string& month) {
		static const std::map<std::string, int> months = {
			{"Jan", 1}, {"Feb", 2}, {"Mar", 3}, {"Apr", 4},
			{"May", 5}, {"Jun", 6}, {"Jul", 7}, {"Aug", 8},
			{"Sep", 9}, {"Oct", 10}, {"Nov", 11}, {"Dec", 12}
		};
		auto it = months.find(month);
		return (it != months.end()) ? it->second : 0;
	}

	// 解析__DATE__字符串为tm结构
	tm parseCompileDate(const char* compileDate) {
		tm tmCompile = { 0 };
		std::string monthStr(compileDate, 3);
		std::string dayStr(compileDate + 4, 2);
		std::string yearStr(compileDate + 7, 4);

		tmCompile.tm_year = std::stoi(yearStr) - 1900;
		tmCompile.tm_mon = monthAbbrevToNumber(monthStr) - 1;
		tmCompile.tm_mday = std::stoi(dayStr);

		return tmCompile;
	}

	// 计算两个日期之间的天数差
	int daysBetweenDates(const tm& date1, const tm& date2) {
		auto timeToTimePoint = [](const tm& tmTime) {
			std::time_t tt = mktime(const_cast<tm*>(&tmTime));
			return std::chrono::system_clock::from_time_t(tt);
		};

		auto tp1 = timeToTimePoint(date1);
		auto tp2 = timeToTimePoint(date2);

		auto duration = tp1 > tp2 ? tp1 - tp2 : tp2 - tp1;
		return std::chrono::duration_cast<std::chrono::hours>(duration).count() / 24;
	}

	// 获取当前日期
	tm getCurrentDate() {
		std::time_t now = std::time(nullptr);
		tm tmNow = *std::localtime(&now);
		tmNow.tm_hour = 0;
		tmNow.tm_min = 0;
		tmNow.tm_sec = 0;
		return tmNow;
	}

	// 验证本地日期是否被修改
	bool isLocalDateModified() {
		time_t networkTime = getNetworkTimeInChina();
		if (networkTime == 0) {
			return true; // 无法验证
		}

		time_t localTime = time(nullptr);
		double diffDays = difftime(networkTime, localTime) / 86400.0;

		// 允许±1天的误差（考虑网络延迟和时区等因素）
		if (fabs(diffDays) > 1.0) {
			return true;
		}

		return false;
	}

public:

	bool isTrail(int trailDays=7) {
		if (isLocalDateModified())
			return false;

		tm tmCompile = parseCompileDate(__DATE__), tmCurrent = getCurrentDate();

		// 计算天数差
		int daysDiff = daysBetweenDates(tmCompile, tmCurrent);

		return daysDiff <= trailDays;
	}
};