/*
 * 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/telnetappender.h>
#include <log4cxx/helpers/loglog.h>
#include <log4cxx/helpers/optionconverter.h>
#include <log4cxx/helpers/stringhelper.h>
#include <apr_thread_proc.h>
#include <apr_atomic.h>
#include <apr_strings.h>
#include <log4cxx/helpers/charsetencoder.h>
#include <log4cxx/helpers/bytebuffer.h>

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

IMPLEMENT_LOG4CXX_OBJECT(TelnetAppender)

/** The default telnet server port */
const int TelnetAppender::DEFAULT_PORT = 23;

/** The maximum number of concurrent connections */
const int TelnetAppender::MAX_CONNECTIONS = 20;

TelnetAppender::TelnetAppender()
	: port(DEFAULT_PORT), connections(MAX_CONNECTIONS),
	  encoding(LOG4CXX_STR("UTF-8")),
	  encoder(CharsetEncoder::getUTF8Encoder()),
	  serverSocket(NULL), sh()
{
	activeConnections = 0;
}

TelnetAppender::~TelnetAppender()
{
	finalize();
	delete serverSocket;
}

void TelnetAppender::activateOptions(Pool& /* p */)
{
	if (serverSocket == NULL)
	{
		serverSocket = new ServerSocket(port);
		serverSocket->setSoTimeout(1000);
	}

    sh = std::thread( &TelnetAppender::acceptConnections, this );
}

void TelnetAppender::setOption(const LogString& option,
	const LogString& value)
{
	if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("PORT"), LOG4CXX_STR("port")))
	{
		setPort(OptionConverter::toInt(value, DEFAULT_PORT));
	}
	else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("ENCODING"), LOG4CXX_STR("encoding")))
	{
		setEncoding(value);
	}
	else
	{
		AppenderSkeleton::setOption(option, value);
	}
}

LogString TelnetAppender::getEncoding() const
{
    std::shared_lock lock(mutex);
	return encoding;
}

void TelnetAppender::setEncoding(const LogString& value)
{
    std::unique_lock lock(mutex);
	encoder = CharsetEncoder::getEncoder(value);
	encoding = value;
}


void TelnetAppender::close()
{
    std::unique_lock lock(mutex);

	if (closed)
	{
		return;
	}

	closed = true;

	SocketPtr nullSocket;

	for (ConnectionList::iterator iter = connections.begin();
		iter != connections.end();
		iter++)
	{
		if (*iter != 0)
		{
			(*iter)->close();
			*iter = nullSocket;
		}
	}

	if (serverSocket != NULL)
	{
		try
		{
			serverSocket->close();
		}
		catch (Exception&)
		{
		}
	}

	if( sh.joinable() ){
		sh.join();
	}

	activeConnections = 0;
}


void TelnetAppender::write(ByteBuffer& buf)
{
	for (ConnectionList::iterator iter = connections.begin();
		iter != connections.end();
		iter++)
	{
		if (*iter != 0)
		{
			try
			{
				ByteBuffer b(buf.current(), buf.remaining());
				(*iter)->write(b);
			}
			catch (Exception&)
			{
				// The client has closed the connection, remove it from our list:
				*iter = 0;
				activeConnections--;
			}
		}
	}
}

void TelnetAppender::writeStatus(const SocketPtr& socket, const LogString& msg, Pool& p)
{
	size_t bytesSize = msg.size() * 2;
	char* bytes = p.pstralloc(bytesSize);

	LogString::const_iterator msgIter(msg.begin());
	ByteBuffer buf(bytes, bytesSize);

	while (msgIter != msg.end())
	{
		encoder->encode(msg, msgIter, buf);
		buf.flip();
		socket->write(buf);
		buf.clear();
	}
}

void TelnetAppender::append(const spi::LoggingEventPtr& event, Pool& p)
{
	size_t count = activeConnections;

	if (count > 0)
	{
		LogString msg;
		this->layout->format(msg, event, pool);
		msg.append(LOG4CXX_STR("\r\n"));
		size_t bytesSize = msg.size() * 2;
		char* bytes = p.pstralloc(bytesSize);

		LogString::const_iterator msgIter(msg.begin());
		ByteBuffer buf(bytes, bytesSize);

        std::shared_lock lock(mutex);

		while (msgIter != msg.end())
		{
			log4cxx_status_t stat = encoder->encode(msg, msgIter, buf);
			buf.flip();
			write(buf);
			buf.clear();

			if (CharsetEncoder::isError(stat))
			{
				LogString unrepresented(1, 0x3F /* '?' */);
				LogString::const_iterator unrepresentedIter(unrepresented.begin());
				stat = encoder->encode(unrepresented, unrepresentedIter, buf);
				buf.flip();
				write(buf);
				buf.clear();
				msgIter++;
			}
		}
	}
}

void TelnetAppender::acceptConnections()
{

	// main loop; is left when This->closed is != 0 after an accept()
	while (true)
	{
		try
		{
            SocketPtr newClient = serverSocket->accept();
            bool done = closed;

			if (done)
			{
				Pool p;
                writeStatus(newClient, LOG4CXX_STR("Log closed.\r\n"), p);
				newClient->close();

				break;
			}

            size_t count = activeConnections;

            if (count >= connections.size())
			{
				Pool p;
                writeStatus(newClient, LOG4CXX_STR("Too many connections.\r\n"), p);
				newClient->close();
			}
			else
			{
				//
				//   find unoccupied connection
				//
                std::unique_lock lock(mutex);

                for (ConnectionList::iterator iter = connections.begin();
                    iter != connections.end();
					iter++)
				{
					if (*iter == NULL)
					{
						*iter = newClient;
                        activeConnections++;

						break;
					}
				}

				Pool p;
				LogString oss(LOG4CXX_STR("TelnetAppender v1.0 ("));
				StringHelper::toString((int) count + 1, p, oss);
				oss += LOG4CXX_STR(" active connections)\r\n\r\n");
                writeStatus(newClient, oss, p);
			}
		}
		catch (InterruptedIOException&)
		{
            if (closed)
			{
				break;
			}
		}
		catch (Exception& e)
		{
            if (!closed)
			{
				LogLog::error(LOG4CXX_STR("Encountered error while in SocketHandler loop."), e);
			}
			else
			{
				break;
			}
		}
	}

}