#pragma once

#include <iostream>
#include <string>
#include <chrono>
#include <random>
#include <ctime>
#include <cstring>       // for memset
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/buffer.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>

class SendEmail
{
// 请确保在链接器设置中加入 libssl.lib 与 libcrypto.lib（或通过 vcpkg 自动集成）
public:
    using ptr = std::shared_ptr<SendEmail>;

    // 辅助函数：通过 SSL 发送数据，并检查返回值
    bool sendSSL(SSL* ssl, const std::string& msg, const char* label)
    {
    int bytesSent = SSL_write(ssl, msg.c_str(), static_cast<int>(msg.length()));
    if (bytesSent <= 0) {
        std::cerr << "Failed to send " << label << " message via SSL." << std::endl;
        ERR_print_errors_fp(stderr);
        return false;
    }
    return true;
    }

    std::string base64_encode(const std::string& input)
    {
    BIO* bmem = BIO_new(BIO_s_mem());
    BIO* b64 = BIO_new(BIO_f_base64());
    BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
    b64 = BIO_push(b64, bmem);
    BIO_write(b64, input.c_str(), static_cast<int>(input.length()));
    BIO_flush(b64);

    BUF_MEM* bptr;
    BIO_get_mem_ptr(b64, &bptr);

    std::string result(bptr->data, bptr->length);
    BIO_free_all(b64);
    return result;
    }

    // 辅助函数：通过 SSL 接收数据，并打印输出
    bool recvSSL(SSL* ssl, char* buff, int buffSize, const char* label)
    {
    int bytesReceived = SSL_read(ssl, buff, buffSize);
    if (bytesReceived <= 0) {
        std::cerr << "Failed to receive " << label << " message via SSL." << std::endl;
        ERR_print_errors_fp(stderr);
        return false;
    }
    buff[bytesReceived] = '\0';
    std::cout << label << " response: " << buff << std::endl;
    return true;
    }

    /// <summary>
    /// 发送邮件到指定邮箱
    /// </summary>
    /// <param name="收件人邮箱"></param>
    /// <returns>成功 = true，失败 = false</returns>
    bool SEND_email(const std::string& email)
    {
    // 1. DNS解析 smtp.qq.com（使用端口 465）
    struct addrinfo hints = {};
    hints.ai_family = AF_INET;       // IPv4
    hints.ai_socktype = SOCK_STREAM; // TCP

    struct addrinfo* addrResult = nullptr;
    int ret = getaddrinfo("smtp.qq.com", "465", &hints, &addrResult);
    if (ret != 0 || addrResult == nullptr) {
        std::cerr << "DNS resolution failed: " << gai_strerror(ret) << std::endl;
        return false;
    }

    // 2. 建立 TCP 连接
    int sock = socket(addrResult->ai_family, addrResult->ai_socktype, addrResult->ai_protocol);
    if (sock == -1) {
        std::cerr << "Socket creation failed!" << std::endl;
        freeaddrinfo(addrResult);
        return false;
    }

    if (connect(sock, addrResult->ai_addr, addrResult->ai_addrlen) != 0) {
        std::cerr << "Connection failed!" << std::endl;
        close(sock);
        freeaddrinfo(addrResult);
        return false;
    }
    freeaddrinfo(addrResult);

    // 3. 初始化 OpenSSL
    SSL_library_init();
    SSL_load_error_strings();
    OpenSSL_add_all_algorithms();

    const SSL_METHOD* method = TLS_client_method();
    SSL_CTX* sslCtx = SSL_CTX_new(method);
    if (!sslCtx) {
        std::cerr << "Unable to create SSL context." << std::endl;
        close(sock);
        return false;
    }

    SSL* ssl = SSL_new(sslCtx);
    if (!ssl) {
        std::cerr << "Unable to create SSL structure." << std::endl;
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 绑定 socket 到 SSL
    SSL_set_fd(ssl, sock);
    if (SSL_connect(ssl) <= 0) {
        std::cerr << "SSL_connect failed." << std::endl;
        ERR_print_errors_fp(stderr);
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 4. 读取服务器欢迎信息
    char buff[2048] = { 0 };
    if (!recvSSL(ssl, buff, sizeof(buff) - 1, "Server")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 5. 发送 EHLO 命令
    std::string sendMsg = "EHLO localhost\r\n";
    if (!sendSSL(ssl, sendMsg, "EHLO") || !recvSSL(ssl, buff, sizeof(buff) - 1, "EHLO")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 6. 认证流程：AUTH LOGIN
    sendMsg = "AUTH LOGIN\r\n";
    if (!sendSSL(ssl, sendMsg, "AUTH") || !recvSSL(ssl, buff, sizeof(buff) - 1, "AUTH")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 7. 发送用户名（Base64编码后的）
    std::string username = base64_encode("zxiao_xin@qq.com") + "\r\n";
    if (!sendSSL(ssl, username, "Username") || !recvSSL(ssl, buff, sizeof(buff) - 1, "Username")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 8. 发送密码（Base64编码后的）
    std::string password = base64_encode("ydfslvabdryvejai") + "\r\n";
    if (!sendSSL(ssl, password, "Password") || !recvSSL(ssl, buff, sizeof(buff) - 1, "Password")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 9. 设置发件人
    sendMsg = "MAIL FROM:<zxiao_xin@qq.com>\r\n";
    if (!sendSSL(ssl, sendMsg, "MAIL FROM") || !recvSSL(ssl, buff, sizeof(buff) - 1, "MAIL FROM")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 10. 设置收件人
    sendMsg = "RCPT TO:<" + email + ">\r\n";
    if (!sendSSL(ssl, sendMsg, "RCPT TO") || !recvSSL(ssl, buff, sizeof(buff) - 1, "RCPT TO")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }
    
    // 检查回复是否为成功代码
    std::string s = buff;
    s = s.substr(0, 3);
    if (s != "250") {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 11. 命令 DATA
    sendMsg = "DATA\r\n";
    if (!sendSSL(ssl, sendMsg, "DATA") || !recvSSL(ssl, buff, sizeof(buff) - 1, "DATA")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 12. 生成验证码
    std::default_random_engine engine(static_cast<unsigned int>(std::time(nullptr)));
    std::uniform_int_distribution<int> distribution(10000, 99999);
    std::string verificationCode = std::to_string(distribution(engine));

    _verifyCode = verificationCode;

    // 13. 构造邮件头和正文
    sendMsg =
        "From: \"Mysterious系统\" <zxiao_xin@qq.com>\r\n"
        "Reply-To: \"请勿回复\" <no-reply@qq.com>\r\n"
        "To: <" + email + ">\r\n"
        "Subject: Mysterious验证码\r\n"
        "Content-Type: text/plain; charset=UTF-8\r\n"
        "\r\n"
        "这是您的验证码: " + verificationCode + "\r\n"
        "用于身份验证，请勿泄露。如非本人操作，请忽略此邮件。\r\n"
        "\r\n.\r\n";

    if (!sendSSL(ssl, sendMsg, "Email DATA") || !recvSSL(ssl, buff, sizeof(buff) - 1, "DATA send")) {
        SSL_free(ssl);
        SSL_CTX_free(sslCtx);
        close(sock);
        return false;
    }

    // 14. 命令 QUIT
    sendMsg = "QUIT\r\n";
    sendSSL(ssl, sendMsg, "QUIT");
    recvSSL(ssl, buff, sizeof(buff) - 1, "QUIT");

    // 15. 清理资源
    SSL_shutdown(ssl);
    SSL_free(ssl);
    SSL_CTX_free(sslCtx);
    close(sock);
    
    return true;
    }

    std::string getVerifyCode() {
        return _verifyCode;
    }

private:
    // std::string _email;
    std::string _verifyCode;
};