#include "__smtpsend.h"
#include "Exception.h"
#include "JFile.h"
#include "Base64.h"

#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <unistd.h>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iomanip>
#include <sstream>

namespace jet {

   void __smtpsend::sendLine(const std::string &line) {
      std::string data = line + "\r\n";
      size_t sent = 0;
      while (sent < data.size()) {
         int n = SSL_write(ssl, data.data() + sent, (int)(data.size() - sent));
         if (n <= 0)
            throw coreutils::Exception("smtpsend: write failed", __FILE__, __LINE__, 502);
         sent += (size_t)n;
      }
   }

   char __smtpsend::readByte() {
      if (recvPos >= recvBuffer.size()) {
         char buf[4096];
         int n = SSL_read(ssl, buf, sizeof(buf));
         if (n <= 0)
            throw coreutils::Exception("smtpsend: read failed", __FILE__, __LINE__, 502);
         recvBuffer.assign(buf, buf + n);
         recvPos = 0;
      }
      return recvBuffer[recvPos++];
   }

   std::string __smtpsend::readLine() {
      std::string line;
      char c;
      for (;;) {
         c = readByte();
         if (c == '\n')
            break;
         if (c != '\r')
            line += c;
      }
      return line;
   }

   int __smtpsend::readReply(int expectedCode) {
      int code = 0;
      std::string line;
      for (;;) {
         line = readLine();
         if (line.size() < 4)
            throw coreutils::Exception("smtpsend: malformed reply: " + line, __FILE__, __LINE__, 502);
         code = atoi(line.substr(0, 3).c_str());
         if (line[3] == ' ')
            break;
         // else line[3] == '-': a continuation line, same code - keep reading.
      }
      if (code / 100 != expectedCode / 100)
         throw coreutils::Exception("smtpsend: unexpected reply " + std::to_string(code) + ": " + line, __FILE__, __LINE__, 502);
      return code;
   }

   void __smtpsend::closeConnection() {
      if (ssl) { SSL_shutdown(ssl); SSL_free(ssl); ssl = nullptr; }
      if (fd >= 0) { ::close(fd); fd = -1; }
      if (ctx) { SSL_CTX_free(ctx); ctx = nullptr; }
   }

   std::string __smtpsend::base64Encode(const std::string &s) {
      coreutils::Base64 base64;
      std::string copy = s;
      coreutils::ZString z(copy);
      return base64.encode(z).str();
   }

   std::string __smtpsend::rfc2822Date() {
      time_t now = time(nullptr);
      struct tm tmResult{};
      gmtime_r(&now, &tmResult);
      char buf[64];
      strftime(buf, sizeof(buf), "%a, %d %b %Y %H:%M:%S +0000", &tmResult);
      return std::string(buf);
   }

   // RFC 5322 3.6.4: Message-ID "SHOULD be present" - in practice
   // several real receivers (confirmed live: Gmail) now hard-reject
   // anything missing one ("550 5.7.1 Messages missing a valid
   // Message-ID header are not accepted") rather than just marking it
   // down, so this isn't optional in practice. Domain part is the
   // sender's own domain (everything after '@' in `from`), matching
   // RFC 5322's own recommendation that it be a name under the
   // generating system's control - falls back to the literal `from`
   // string in the (should-never-happen) case it has no '@' at all.
   std::string __smtpsend::generateMessageId(const std::string &from) {
      size_t at = from.find('@');
      std::string domainPart = (at == std::string::npos) ? from : from.substr(at + 1);
      struct timespec ts;
      clock_gettime(CLOCK_REALTIME, &ts);
      std::ostringstream idStream;
      idStream << ts.tv_sec << "." << std::setfill('0') << std::setw(9) << ts.tv_nsec
                << "." << rand() << "@" << domainPart;
      return idStream.str();
   }

   std::string __smtpsend::buildMessage(const std::string &from, const std::string &to,
                                         const std::string &subject, const std::string &html) {
      std::string msg;
      msg += "Date: " + rfc2822Date() + "\r\n";
      msg += "Message-ID: <" + generateMessageId(from) + ">\r\n";
      msg += "From: " + from + "\r\n";
      msg += "To: " + to + "\r\n";
      msg += "Subject: " + subject + "\r\n";
      msg += "MIME-Version: 1.0\r\n";
      msg += "Content-Type: text/html; charset=UTF-8\r\n";
      msg += "Content-Transfer-Encoding: 8bit\r\n";
      msg += "\r\n";
      // SMTP DATA's dot-stuffing rule: any body line starting with '.'
      // needs a second '.' prepended, or the server treats it as the
      // end-of-data marker prematurely and truncates the message.
      std::string stuffed;
      stuffed.reserve(html.size());
      bool atLineStart = true;
      for (size_t i = 0; i < html.size(); i++) {
         char c = html[i];
         if (atLineStart && c == '.')
            stuffed += '.';
         stuffed += c;
         atLineStart = (c == '\n');
      }
      msg += stuffed;
      return msg;
   }

   __smtpsend::__smtpsend(coreutils::ZString &in, coreutils::MString &parentOut, Global &global, Tag *parent, Tag *local) : Tag(in, parentOut, global, parent, local) {

      std::string user = resolveKeyword("user").str();
      std::string password = resolveKeyword("password").str();
      std::string to = resolveKeyword("to").str();
      std::string subject = resolveKeyword("subject").str();
      std::string html = resolveKeyword("html").str();
      coreutils::MString configPath = resolveKeyword("config");

      if (user.empty() || password.empty())
         throw coreutils::Exception("smtpsend: user/password must be specified.", __FILE__, __LINE__, 401);
      if (to.empty())
         throw coreutils::Exception("smtpsend: to address must be specified.", __FILE__, __LINE__, 400);

      coreutils::JFile config(configPath);
      std::string host = config.getString("host");
      long port = (long)config.getNumber("smtpPort");
      if (port <= 0)
         port = 465;

      struct addrinfo hints {};
      hints.ai_family = AF_UNSPEC;
      hints.ai_socktype = SOCK_STREAM;
      struct addrinfo *result = nullptr;
      std::string portStr = std::to_string(port);
      if (getaddrinfo(host.c_str(), portStr.c_str(), &hints, &result) != 0 || !result)
         throw coreutils::Exception("smtpsend: could not resolve " + host, __FILE__, __LINE__, 502);

      int newFd = -1;
      for (struct addrinfo *rp = result; rp != nullptr; rp = rp->ai_next) {
         newFd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
         if (newFd < 0)
            continue;
         if (::connect(newFd, rp->ai_addr, rp->ai_addrlen) == 0)
            break;
         ::close(newFd);
         newFd = -1;
      }
      freeaddrinfo(result);
      if (newFd < 0)
         throw coreutils::Exception("smtpsend: could not connect to " + host, __FILE__, __LINE__, 502);

      struct timeval timeout { 30, 0 };
      setsockopt(newFd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
      setsockopt(newFd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout));

      SSL_CTX *newCtx = SSL_CTX_new(SSLv23_client_method());
      if (!newCtx) {
         ::close(newFd);
         throw coreutils::Exception("smtpsend: SSL_CTX_new failed", __FILE__, __LINE__, 502);
      }
      SSL *newSsl = SSL_new(newCtx);
      SSL_set_fd(newSsl, newFd);
      if (SSL_connect(newSsl) != 1) {
         SSL_free(newSsl);
         SSL_CTX_free(newCtx);
         ::close(newFd);
         throw coreutils::Exception("smtpsend: TLS handshake failed", __FILE__, __LINE__, 502);
      }

      ctx = newCtx;
      ssl = newSsl;
      fd = newFd;

      try {
         readReply(220);

         sendLine("EHLO " + host);
         readReply(250);

         sendLine("AUTH LOGIN");
         readReply(334);
         sendLine(base64Encode(user));
         readReply(334);
         sendLine(base64Encode(password));
         readReply(235);

         sendLine("MAIL FROM:<" + user + ">");
         readReply(250);
         sendLine("RCPT TO:<" + to + ">");
         readReply(250);
         sendLine("DATA");
         readReply(354);

         std::string message = buildMessage(user, to, subject, html);
         sendLine(message);
         sendLine(".");
         readReply(250);

         sendLine("QUIT");
         readReply(221);
      } catch (...) {
         closeConnection();
         throw;
      }

      closeConnection();

      out = coreutils::MString(std::string("{\"ok\":true}"));
   }

}