/**
*
* SMTPMail.cc *
*
* This plugin is for SMTP mail delivery for the Drogon web-framework.
Implementation
* reference from the project "SMTPClient" with Qt5 by kelvins. Please check out
* https://github.com/kelvins/SMTPClient.

Feel free to use the code. For the sake of any concern, the following licence is
attached.

 Copyright 2020 ihmc3jn09hk

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 */

#include "SMTPMail.h"
#include <drogon/HttpAppFramework.h>
#include <drogon/utils/Utilities.h>
#include <trantor/net/EventLoopThread.h>
#include <trantor/net/TcpClient.h>

using namespace drogon;
using namespace trantor;

struct EMail {
  enum states {
    Init,
    HandShake,
    Tls,
    Auth,
    User,
    Pass,
    Mail,
    Rcpt,
    Data,
    Body,
    Quit,
    Close
  };
  std::string m_from;
  std::string m_to;
  std::string m_subject;
  std::string m_content;
  std::string m_user;
  std::string m_passwd;
  states m_status;
  std::string m_uuid;
  bool m_isHTML{false};
  std::shared_ptr<trantor::TcpClient> m_socket;

  EMail(std::string from, std::string to, std::string subject,
        std::string content, std::string user, std::string passwd, bool isHTML,
        std::shared_ptr<trantor::TcpClient> socket)
      : m_from(std::move(from)), m_to(std::move(to)),
        m_subject(std::move(subject)), m_content(std::move(content)),
        m_user(std::move(user)), m_passwd(std::move(passwd)),
        m_socket(std::move(socket)), m_isHTML(isHTML),
        m_uuid(drogon::utils::getUuid()) {
    m_status = Init;
  }

  ~EMail() = default;

  static std::unordered_map<std::string, std::shared_ptr<EMail>>
      m_emails; // Container for processing emails
};

std::unordered_map<std::string, std::shared_ptr<EMail>> EMail::m_emails;

void SMTPMail::initAndStart(const Json::Value &config) {
  /// Initialize and start the plugin
  LOG_INFO << "SMTPMail initialized and started";
}

void SMTPMail::shutdown() {
  /// Shutdown the plugin
  LOG_INFO << "STMPMail shutdown";
}

void messagesHandle(const trantor::TcpConnectionPtr &connPtr,
                    trantor::MsgBuffer *msg,
                    const std::shared_ptr<EMail> &email,
                    const std::function<void(const std::string &msg)> &cb) {
  std::string receivedMsg;
  while (msg->readableBytes() > 0) {
    std::string buf(msg->peek(), msg->readableBytes());
    receivedMsg.append(buf);
    //        LOG_INFO << buf;
    msg->retrieveAll();
  }
  LOG_TRACE << "receive: " << receivedMsg;
  std::string responseCode(receivedMsg.begin(), receivedMsg.begin() + 3);
  //    std::string responseMsg(receivedMsg.begin() + 4, receivedMsg.end());

  if (email->m_status == EMail::Init && responseCode == "220") {
    std::string outMsg;
    trantor::MsgBuffer out;

    outMsg.append("EHLO smtpclient.qw");
    outMsg.append("\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::HandShake;
  } else if (email->m_status == EMail::HandShake && responseCode == "220") {
    std::string outMsg;
    trantor::MsgBuffer out;

    outMsg.append("EHLO smtpclient.qw");
    outMsg.append("\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->startClientEncryption(
        [connPtr, out]() {
          // LOG_TRACE << "SSL established";
          connPtr->send(out);
        },
        false, false);

    email->m_status = EMail::Auth;
  } else if (email->m_status == EMail::HandShake && responseCode == "250") {
    std::string outMsg;
    trantor::MsgBuffer out;

    outMsg.append("STARTTLS");
    outMsg.append("\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::HandShake;
  } else if (email->m_status == EMail::Auth && responseCode == "250") {
    trantor::MsgBuffer out;
    std::string outMsg;

    outMsg.append("AUTH LOGIN");
    outMsg.append("\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::User;
  } else if (email->m_status == EMail::User && responseCode == "334") {
    trantor::MsgBuffer out;
    std::string outMsg;

    std::string secret(email->m_user);

    // outMsg.append(base64_encode(reinterpret_cast<const unsigned
    // char*>(secret.c_str()), secret.length()));
    outMsg.append(drogon::utils::base64Encode(
        reinterpret_cast<const unsigned char *>(secret.c_str()),
        secret.length()));

    outMsg.append("\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::Pass;
  } else if (email->m_status == EMail::Pass && responseCode == "334") {
    trantor::MsgBuffer out;
    std::string outMsg;

    std::string secret(email->m_passwd);

    outMsg.append(drogon::utils::base64Encode(
        reinterpret_cast<const unsigned char *>(secret.c_str()),
        secret.length()));
    outMsg.append("\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::Mail;
  } else if (email->m_status == EMail::Mail && responseCode == "235") {
    trantor::MsgBuffer out;
    std::string outMsg;

    outMsg.append("MAIL FROM:<");
    outMsg.append(email->m_from);
    outMsg.append(">\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::Rcpt;
  } else if (email->m_status == EMail::Rcpt && responseCode == "250") {
    trantor::MsgBuffer out;
    std::string outMsg;

    outMsg.append("RCPT TO:<");
    outMsg.append(email->m_to);
    outMsg.append(">\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::Data;
  } else if (email->m_status == EMail::Data && responseCode == "250") {
    trantor::MsgBuffer out;
    std::string outMsg;

    outMsg.append("DATA");
    outMsg.append("\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::Body;
  } else if (email->m_status == EMail::Body && responseCode == "354") {
    trantor::MsgBuffer out;
    std::string outMsg;
    std::time_t t = std::time(nullptr);
    char buf[100];
    std::strftime(buf, 100, "%a, %d %b %Y %T %z",  std::localtime(&t));

    outMsg.append("To: " + email->m_to + "\r\n");
    outMsg.append("From: " + email->m_from + "\r\n");
    outMsg.append("Date: " + std::string(buf) + "\r\n");
    if (email->m_isHTML) {
      outMsg.append("Content-Type: text/html;\r\n");
    }
    outMsg.append("Subject: " + email->m_subject + "\r\n\r\n");

    outMsg.append(email->m_content);
    outMsg.append("\r\n.\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::Quit;
  } else if (email->m_status == EMail::Quit && responseCode == "250") {
    trantor::MsgBuffer out;
    std::string outMsg;

    outMsg.append("QUIT");
    outMsg.append("\r\n");

    out.append(outMsg.data(), outMsg.size());

    connPtr->send(std::move(out));

    email->m_status = EMail::Close;
  } else if (email->m_status == EMail::Close) {
    /*Callback here for succeed delivery is probable*/
    cb("EMail sent. ID : " + email->m_uuid);
    return;
  } else {
    email->m_status = EMail::Close;
    /*Callback here for notification is probable*/
    cb(receivedMsg);
  }
}

std::string
SMTPMail::sendEmail(const std::string &mailServer, const uint16_t &port,
                    const std::string &from, const std::string &to,
                    const std::string &subject, const std::string &content,
                    const std::string &user, const std::string &passwd,
                    bool isHTML,
                    const std::function<void(const std::string &)> &cb) {
  if (mailServer.empty() || from.empty() || to.empty() || subject.empty() ||
      user.empty() || passwd.empty()) {
    LOG_WARN << "Invalid input(s) - "
             << "\nServer : " << mailServer << "\nPort : " << port
             << "\nfrom : " << from << "\nto : " << to
             << "\nsubject : " << subject << "\nuser : " << user
             << "\npasswd : " << passwd;
    return {};
  }

  static auto hasLineBreak = [](const std::string &msg) {
    if (std::string::npos != msg.find_first_of("\n") ||
        std::string::npos != msg.find_first_of("\r")) {
      return true;
    }
    return false;
  };

  if (hasLineBreak(from)) {
    LOG_WARN << "Invalid \"FROM\" data : " << from;
    return {};
  }
  if (hasLineBreak(to)) {
    LOG_WARN << "Invalid \"TO\" data : " << to;
    return {};
  }
  if (hasLineBreak(subject)) {
    LOG_WARN << "Invalid \"SUBJECT\" data : " << subject.data();
    return {};
  }

  LOG_TRACE << "New TcpClient : " << mailServer << ":" << port;

  // Create the email
  auto email = std::make_shared<EMail>(from, to, subject, content, user, passwd,
                                       isHTML, nullptr);

  auto resolver = app().getResolver();
  resolver->resolve(
      mailServer, [email, port, cb](const trantor::InetAddress &addr) {
        constexpr size_t defaultLoopIdA = 10;
        constexpr size_t defaultLoopIdB = 9;
        auto loopA = app().getIOLoop(defaultLoopIdA);
        auto loopB = app().getIOLoop(defaultLoopIdB);
        
        if ( loopA == loopB ) {
          LOG_WARN << "Please provide at least 2 threads for this plugin";
          return;
        }

        auto loop = loopA->isInLoopThread() ? loopB : loopA;
        
        assert(loop);                    // Should never be null
        trantor::InetAddress addr_(addr.toIp(), port, false);
        auto tcpSocket =
            std::make_shared<trantor::TcpClient>(loop, addr_, "SMTPMail");

        email->m_socket = tcpSocket;

        std::weak_ptr<EMail> email_wptr = email;

        EMail::m_emails.emplace(email->m_uuid,
                                email); // Assuming there is no uuid collision
        tcpSocket->setConnectionCallback(
            [email_wptr](const trantor::TcpConnectionPtr &connPtr) {
              auto email_ptr = email_wptr.lock();
              if (!email_ptr) {
                LOG_WARN << "EMail pointer gone";
                return;
              }
              if (connPtr->connected()) {
                // send request;
                LOG_TRACE << "Connection established!";
              } else {
                LOG_TRACE << "Connection disconnect";
                EMail::m_emails.erase(
                    email_ptr->m_uuid); // Remove the email in list
                // thisPtr->onError(std::string("ReqResult::NetworkFailure"));
              }
            });
        tcpSocket->setConnectionErrorCallback([email_wptr]() {
          auto email_ptr = email_wptr.lock();
          if (!email_ptr) {
            LOG_ERROR << "EMail pointer gone";
            return;
          }
          // can't connect to server
          LOG_ERROR << "Bad Server address";
          EMail::m_emails.erase(email_ptr->m_uuid); // Remove the email in list
          // thisPtr->onError(std::string("ReqResult::BadServerAddress"));
        });
        auto cb_(cb ? cb : [](const std::string &msg) {
          LOG_INFO << "Default email callback : " << msg;
        });
        tcpSocket->setMessageCallback(
            [email_wptr, cb_](const trantor::TcpConnectionPtr &connPtr,
                              trantor::MsgBuffer *msg) {
              auto email_ptr = email_wptr.lock();
              if (!email_ptr) {
                LOG_ERROR << "EMail pointer gone";
                return;
              }
              // email->m_socket->disconnect();
              messagesHandle(connPtr, msg, email_ptr, cb_);
            });
        tcpSocket->connect(); // Start trying to send the email
      });
  return email->m_uuid;
}