/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include <log4cxx/net/smtpappender.h>
#include <log4cxx/level.h>
#include <log4cxx/helpers/loglog.h>
#include <log4cxx/helpers/optionconverter.h>
#include <log4cxx/spi/loggingevent.h>
#include <log4cxx/helpers/stringhelper.h>
#include <log4cxx/helpers/stringtokenizer.h>
#include <log4cxx/helpers/transcoder.h>
#include <log4cxx/helpers/synchronized.h>
#if !defined(LOG4CXX)
#define LOG4CXX 1
#endif
#include <log4cxx/private/log4cxx_private.h>


#include <apr_strings.h>
#include <vector>

using namespace log4cxx;
using namespace log4cxx::helpers;
using namespace log4cxx::net;
using namespace log4cxx::spi;

#if LOG4CXX_HAVE_LIBESMTP
#include <auth-client.h>
#include <libesmtp.h>
#endif

namespace log4cxx {
    namespace net {
        //
        //   The following two classes implement an C++ SMTP wrapper over libesmtp.
        //   The same signatures could be implemented over different SMTP implementations
        //   or libesmtp could be combined with libgmime to enable support for non-ASCII
        //   content.  

#if LOG4CXX_HAVE_LIBESMTP        
        /**
         *   SMTP Session.
         */
        class SMTPSession {
        public:
           /**
           *   Create new instance.
           */
            SMTPSession(const LogString& smtpHost,
                        int smtpPort,
                        const LogString& smtpUsername,
                        const LogString& smtpPassword,
                        Pool& p) : session(0), authctx(0), 
                        user(toAscii(smtpUsername, p)), 
                        pwd(toAscii(smtpPassword, p)) {
                auth_client_init();
                session = smtp_create_session();
                if (session == 0) {
                    throw Exception("Could not initialize session.");
                }
                std::string host(toAscii(smtpHost, p));
                host.append(1, ':');
                host.append(p.itoa(smtpPort));
                smtp_set_server(session, host.c_str());
   
                authctx = auth_create_context();
                auth_set_mechanism_flags(authctx, AUTH_PLUGIN_PLAIN, 0);
                auth_set_interact_cb(authctx, authinteract, (void*) this);
   
                if (*user || *pwd) {
                    smtp_auth_set_context(session, authctx);
                }
            }
            
            ~SMTPSession() {
                 smtp_destroy_session(session);
                 auth_destroy_context(authctx);
            }
            
            void send(Pool& p) {
                 int status = smtp_start_session(session);
                 if (!status) {
                     size_t bufSize = 128;
                     char* buf = p.pstralloc(bufSize);
                     smtp_strerror(smtp_errno(), buf, bufSize);
                     throw Exception(buf);
                 }
            }
            
            operator smtp_session_t() {
                return session;
            }

            static char* toAscii(const LogString& str, Pool& p) {
                char* buf = p.pstralloc(str.length() + 1);
                char* current = buf;
                for(LogString::const_iterator iter = str.begin();
                    iter != str.end();
                    iter++) {
                    unsigned int c = *iter;
                    if (c > 0x7F) {
                       c = '?';
                    }
                    *current++ = c;
                }
                *current = 0;
                return buf;
            }
                        
            private:
            SMTPSession(SMTPSession&);
            SMTPSession& operator=(SMTPSession&);
            smtp_session_t session;
            auth_context_t authctx;
            char* user;
            char* pwd;

            /**
             *   This method is called if the SMTP server requests authentication.
             */
            static int authinteract(auth_client_request_t request, char **result, int fields,
              void *arg) {
              SMTPSession* pThis = (SMTPSession*) arg;
              for (int i = 0; i < fields; i++) {
                int flag = request[i].flags & 0x07;
                if (flag == AUTH_USER) {
                   result[i] = pThis->user;
                } else if(flag == AUTH_PASS) {
                   result[i] = pThis->pwd;
                }
              }
              return 1;
            }
            

        };
        
        /**
         *  A message in an SMTP session.
         */
        class SMTPMessage {
        public:
            SMTPMessage(SMTPSession& session, 
                        const LogString& from, 
                        const LogString& to,
                        const LogString& cc,
                        const LogString& bcc,
                        const LogString& subject,
                        const LogString msg, Pool& p) {
                 message = smtp_add_message(session);
                 body = current = toMessage(msg, p);
                 smtp_set_reverse_path(message, toAscii(from, p));
                 addRecipients(to, "To", p);
                 addRecipients(cc, "Cc", p);
                 addRecipients(bcc, "Bcc", p);
                 if (!subject.empty()) {
                    smtp_set_header(message, "Subject", toAscii(subject, p));
                 }
                 smtp_set_messagecb(message, messagecb, this); 
            }
            ~SMTPMessage() {
            }
            
        private:
           SMTPMessage(const SMTPMessage&);
           SMTPMessage& operator=(const SMTPMessage&);
           smtp_message_t message;
           const char* body;
           const char* current;
           void addRecipients(const LogString& addresses, const char* field, Pool& p) {
              if (!addresses.empty()) {
                char* str = p.pstrdup(toAscii(addresses, p));;
                smtp_set_header(message, field, NULL, str);
                char* last;
                for(char* next = apr_strtok(str, ",", &last);
                    next;
                    next = apr_strtok(NULL, ",", &last)) {
                    smtp_add_recipient(message, next);
                }
              }
          }
           static const char* toAscii(const LogString& str, Pool& p) {
               return SMTPSession::toAscii(str, p);
           }
           
           /**
            *   Message bodies can only contain US-ASCII characters and 
            *   CR and LFs can only occur together.
            */
           static const char* toMessage(const LogString& str, Pool& p) {
               //
               //    count the number of carriage returns and line feeds
               //
               int feedCount = 0;
               for(size_t pos = str.find_first_of(LOG4CXX_STR("\n\r"));
                   pos != LogString::npos;
                   pos = str.find_first_of(LOG4CXX_STR("\n\r"), ++pos)) {
                   feedCount++;
               }
               //
               //   allocate sufficient space for the modified message
               char* retval = p.pstralloc(str.length() + feedCount + 1);
               char* current = retval;
               char* startOfLine = current;
               //
               //    iterator through message
               //
               for(LogString::const_iterator iter = str.begin();
                   iter != str.end();
                   iter++) {
                   unsigned int c = *iter;
                   //
                   //   replace non-ASCII characters with '?'
                   //
                   if (c > 0x7F) {
                      *current++ = 0x3F; // '?'
                   } else if (c == 0x0A || c == 0x0D) {
                      //
                      //   replace any stray CR or LF with CRLF
                      //      reset start of line
                      *current++ = 0x0D;
                      *current++ = 0x0A;
                      startOfLine = current;
                      LogString::const_iterator next = iter + 1;
                      if (next != str.end() && (*next == 0x0A || *next == 0x0D)) {
                         iter++;
                      }
                   } else {
                      //
                      //    truncate any lines to 1000 characters (including CRLF)
                      //       as required by RFC.
                      if (current < startOfLine + 998) {
                        *current++ = (char) c;
                      }
                   }
               }
               *current = 0;
               return retval;
           }
           
           /**
            *  Callback for message.
            */
           static const char* messagecb(void** ctx, int* len, void* arg) {
               *ctx = 0;
               const char* retval = 0;
               SMTPMessage* pThis = (SMTPMessage*) arg;
               //   rewind message
               if (len == NULL) {
                   pThis->current = pThis->body;
               } else {
                  if (pThis->current) {
                    *len = strlen(pThis->current);
                  }
                  retval = pThis->current;
                  pThis->current = 0;
               }
               return retval;
           }
           
        };
#endif        
        
                class LOG4CXX_EXPORT DefaultEvaluator :
                        public virtual spi::TriggeringEventEvaluator,
                        public virtual helpers::ObjectImpl
                {
                public:
                        DECLARE_LOG4CXX_OBJECT(DefaultEvaluator)
                        BEGIN_LOG4CXX_CAST_MAP()
                                LOG4CXX_CAST_ENTRY(DefaultEvaluator)
                                LOG4CXX_CAST_ENTRY(spi::TriggeringEventEvaluator)
                        END_LOG4CXX_CAST_MAP()

                        DefaultEvaluator();

                        /**
                        Is this <code>event</code> the e-mail triggering event?
                        <p>This method returns <code>true</code>, if the event level
                        has ERROR level or higher. Otherwise it returns
                        <code>false</code>.
                        */
                        virtual bool isTriggeringEvent(const spi::LoggingEventPtr& event);
                private:
                         DefaultEvaluator(const DefaultEvaluator&);
                         DefaultEvaluator& operator=(const DefaultEvaluator&);
                }; // class DefaultEvaluator
        
    }
}

IMPLEMENT_LOG4CXX_OBJECT(DefaultEvaluator)
IMPLEMENT_LOG4CXX_OBJECT(SMTPAppender)

DefaultEvaluator::DefaultEvaluator() {
}

bool DefaultEvaluator::isTriggeringEvent(const spi::LoggingEventPtr& event)
{
   return event->getLevel()->isGreaterOrEqual(Level::getError());
}

SMTPAppender::SMTPAppender()
: smtpPort(25), bufferSize(512), locationInfo(false), cb(bufferSize),
evaluator(new DefaultEvaluator())
{
}

/**
Use <code>evaluator</code> passed as parameter as the
TriggeringEventEvaluator for this SMTPAppender.  */
SMTPAppender::SMTPAppender(spi::TriggeringEventEvaluatorPtr evaluator)
: smtpPort(25), bufferSize(512), locationInfo(false), cb(bufferSize),
evaluator(evaluator)
{
}

SMTPAppender::~SMTPAppender()
{
   finalize();
}

bool SMTPAppender::requiresLayout() const { 
    return true; 
}


LogString SMTPAppender::getFrom() const {
    return from;
}

void SMTPAppender::setFrom(const LogString& newVal) {
    from = newVal;
}


LogString SMTPAppender::getSubject() const {
    return subject;
}

void SMTPAppender::setSubject(const LogString& newVal) {
    subject = newVal;
}

LogString SMTPAppender::getSMTPHost() const {
    return smtpHost;
}

void SMTPAppender::setSMTPHost(const LogString& newVal) {
    smtpHost = newVal;
}

int SMTPAppender::getSMTPPort() const {
    return smtpPort;
}

void SMTPAppender::setSMTPPort(int newVal) {
    smtpPort = newVal;
}

bool SMTPAppender::getLocationInfo() const {
   return locationInfo;
}

void SMTPAppender::setLocationInfo(bool newVal) { 
    locationInfo = newVal; 
}

LogString SMTPAppender::getSMTPUsername() const {
    return smtpUsername;
}

void SMTPAppender::setSMTPUsername(const LogString& newVal) {
    smtpUsername = newVal;
}

LogString SMTPAppender::getSMTPPassword() const {
    return smtpPassword;
}

void SMTPAppender::setSMTPPassword(const LogString& newVal) {
    smtpPassword = newVal;
}


void SMTPAppender::setOption(const LogString& option,
   const LogString& value)
{
   if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("BUFFERSIZE"), LOG4CXX_STR("buffersize")))
   {
      setBufferSize(OptionConverter::toInt(value, 512));
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("EVALUATORCLASS"), LOG4CXX_STR("evaluatorclass")))
   {
      setEvaluatorClass(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("FROM"), LOG4CXX_STR("from")))
   {
      setFrom(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SMTPHOST"), LOG4CXX_STR("smtphost")))
   {
      setSMTPHost(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SMTPUSERNAME"), LOG4CXX_STR("smtpusername")))
   {
      setSMTPUsername(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SMTPPASSWORD"), LOG4CXX_STR("smtppassword")))
   {
      setSMTPPassword(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SUBJECT"), LOG4CXX_STR("subject")))
   {
      setSubject(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("TO"), LOG4CXX_STR("to")))
   {
      setTo(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("CC"), LOG4CXX_STR("cc")))
   {
      setCc(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("BCC"), LOG4CXX_STR("bcc")))
   {
      setBcc(value);
   }
   else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SMTPPORT"), LOG4CXX_STR("smtpport")))
   {
      setSMTPPort(OptionConverter::toInt(value, 25));
   }
   else
   {
      AppenderSkeleton::setOption(option, value);
   }
}


bool SMTPAppender::asciiCheck(const LogString& value, const LogString& field) {
     for(LogString::const_iterator iter = value.begin();
         iter != value.end();
         iter++) {
         if (0x7F < (unsigned int) *iter) {
            LogLog::warn(field + LOG4CXX_STR(" contains non-ASCII character"));
            return false;
         } 
     }
     return true;
}

/**
Activate the specified options, such as the smtp host, the
recipient, from, etc. */
void SMTPAppender::activateOptions(Pool& p)
{
   bool activate = true;
   if (layout == 0) {
      LogLog::error(LOG4CXX_STR("No layout set for appender named [") +name+ LOG4CXX_STR("]."));
      activate = false;
   }
   if(evaluator == 0) {
      LogLog::error(LOG4CXX_STR("No TriggeringEventEvaluator is set for appender [")+
          name+LOG4CXX_STR("]."));
      activate = false;
   }
   if(smtpHost.empty()) {
      LogLog::error(LOG4CXX_STR("No smtpHost is set for appender [")+
          name+LOG4CXX_STR("]."));
      activate = false;
   }
   if(to.empty() && cc.empty() && bcc.empty()) {
      LogLog::error(LOG4CXX_STR("No recipient address is set for appender [")+
          name+LOG4CXX_STR("]."));
      activate = false;
   }
   activate &= asciiCheck(to, LOG4CXX_STR("to"));
   activate &= asciiCheck(cc, LOG4CXX_STR("cc"));
   activate &= asciiCheck(bcc, LOG4CXX_STR("bcc"));
   activate &= asciiCheck(from, LOG4CXX_STR("from"));
 
#if !LOG4CXX_HAS_LIBESMTP
   LogLog::error(LOG4CXX_STR("log4cxx built without SMTP support."));
   activate = false;
#endif     
   if (activate) {
        AppenderSkeleton::activateOptions(p);
   }
}

/**
Perform SMTPAppender specific appending actions, mainly adding
the event to a cyclic buffer and checking if the event triggers
an e-mail to be sent. */
void SMTPAppender::append(const spi::LoggingEventPtr& event, Pool& p)
{
   if(!checkEntryConditions())
   {
      return;
   }

   LogString ndc;
   event->getNDC(ndc);
   event->getThreadName();
   // Get a copy of this thread's MDC.
   event->getMDCCopy();

   cb.add(event);

   if(evaluator->isTriggeringEvent(event))
   {
      sendBuffer(p);
   }
}

/**
This method determines if there is a sense in attempting to append.
<p>It checks whether there is a set output target and also if
there is a set layout. If these checks fail, then the boolean
value <code>false</code> is returned. */
bool SMTPAppender::checkEntryConditions()
{
#if LOG4CXX_HAVE_LIBESMTP
   if((to.empty() && cc.empty() && bcc.empty()) || from.empty() || smtpHost.empty())
   {
      errorHandler->error(LOG4CXX_STR("Message not configured."));
      return false;
   }

   if(evaluator == 0)
   {
      errorHandler->error(LOG4CXX_STR("No TriggeringEventEvaluator is set for appender [")+
         name+ LOG4CXX_STR("]."));
      return false;
   }


   if(layout == 0)
   {
      errorHandler->error(LOG4CXX_STR("No layout set for appender named [")+name+LOG4CXX_STR("]."));
      return false;
   }
   return true;
#else
   return false;
#endif   
}


void SMTPAppender::close() {
   this->closed = true;
}

LogString SMTPAppender::getTo() const{
   return to;
}

void SMTPAppender::setTo(const LogString& addressStr) {
     to = addressStr;
}

LogString SMTPAppender::getCc() const{
   return cc;
}

void SMTPAppender::setCc(const LogString& addressStr) {
     cc = addressStr;
}

LogString SMTPAppender::getBcc() const{
   return bcc;
}

void SMTPAppender::setBcc(const LogString& addressStr) {
     bcc = addressStr;
}

/**
Send the contents of the cyclic buffer as an e-mail message.
*/
void SMTPAppender::sendBuffer(Pool& p)
{
#if LOG4CXX_HAS_LIBESMTP
   // Note: this code already owns the monitor for this
   // appender. This frees us from needing to synchronize on 'cb'.
   try
   {
      LogString sbuf;
      layout->appendHeader(sbuf, p);

      int len = cb.length();
      for(int i = 0; i < len; i++)
      {
         LoggingEventPtr event = cb.get();
         layout->format(sbuf, event, p);
      }

      layout->appendFooter(sbuf, p);

      SMTPSession session(smtpHost, smtpPort, smtpUsername, smtpPassword, p);
      
      SMTPMessage message(session, from, to, cc, 
          bcc, subject, sbuf, p);
      
      session.send(p);

   }
   catch(std::exception& e)
   {
      LogLog::error(LOG4CXX_STR("Error occured while sending e-mail notification."), e);
   }
#endif   
}

/**
Returns value of the <b>EvaluatorClass</b> option.
*/
LogString SMTPAppender::getEvaluatorClass()
{
   return evaluator == 0 ? LogString() : evaluator->getClass().getName();
}

log4cxx::spi::TriggeringEventEvaluatorPtr SMTPAppender::getEvaluator() const {
   return evaluator;
}

void SMTPAppender::setEvaluator(log4cxx::spi::TriggeringEventEvaluatorPtr& trigger) {
    evaluator = trigger;
}

/**
The <b>BufferSize</b> option takes a positive integer
representing the maximum number of logging events to collect in a
cyclic buffer. When the <code>BufferSize</code> is reached,
oldest events are deleted as new events are added to the
buffer. By default the size of the cyclic buffer is 512 events.
*/
void SMTPAppender::setBufferSize(int bufferSize)
{
   this->bufferSize = bufferSize;
   cb.resize(bufferSize);
}

/**
The <b>EvaluatorClass</b> option takes a string value
representing the name of the class implementing the {@link
TriggeringEventEvaluator} interface. A corresponding object will
be instantiated and assigned as the triggering event evaluator
for the SMTPAppender.
*/
void SMTPAppender::setEvaluatorClass(const LogString& value)
{
   evaluator = OptionConverter::instantiateByClassName(value,
      TriggeringEventEvaluator::getStaticClass(), evaluator);
}