/**
 * @file llpluginmessagepipe.cpp
 * @brief Classes that implement connections from the plugin system to pipes/pumps.
 *
 * @cond
 * $LicenseInfo:firstyear=2008&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 * @endcond
 */

#include "linden_common.h"

#include "llpluginmessagepipe.h"
#include "llbufferstream.h"

#include "llapr.h"

static const char MESSAGE_DELIMITER = '\0';

LLPluginMessagePipeOwner::LLPluginMessagePipeOwner() :
    mMessagePipe(NULL),
    mSocketError(APR_SUCCESS)
{
}

// virtual
LLPluginMessagePipeOwner::~LLPluginMessagePipeOwner()
{
    killMessagePipe();
}

// virtual
apr_status_t LLPluginMessagePipeOwner::socketError(apr_status_t error)
{
    mSocketError = error;
    return error;
};

//virtual
void LLPluginMessagePipeOwner::setMessagePipe(LLPluginMessagePipe *read_pipe)
{
    // Save a reference to this pipe
    mMessagePipe = read_pipe;
}

bool LLPluginMessagePipeOwner::canSendMessage(void)
{
    return (mMessagePipe != NULL);
}

bool LLPluginMessagePipeOwner::writeMessageRaw(const std::string &message)
{
    bool result = true;
    if(mMessagePipe != NULL)
    {
        result = mMessagePipe->addMessage(message);
    }
    else
    {
        LL_WARNS("Plugin") << "dropping message: " << message << LL_ENDL;
        result = false;
    }

    return result;
}

void LLPluginMessagePipeOwner::killMessagePipe(void)
{
    if(mMessagePipe != NULL)
    {
        delete mMessagePipe;
        mMessagePipe = NULL;
    }
}

LLPluginMessagePipe::LLPluginMessagePipe(LLPluginMessagePipeOwner *owner, LLSocket::ptr_t socket):
    mInputMutex(),
    mOutputMutex(),
    mOutputStartIndex(0),
    mOwner(owner),
    mSocket(socket)
{
    mOwner->setMessagePipe(this);
}

LLPluginMessagePipe::~LLPluginMessagePipe()
{
    if(mOwner != NULL)
    {
        mOwner->setMessagePipe(NULL);
    }
}

bool LLPluginMessagePipe::addMessage(const std::string &message)
{
    // queue the message for later output
    LLMutexLock lock(&mOutputMutex);

    // If we're starting to use up too much memory, clear
    if (mOutputStartIndex > 1024 * 1024)
    {
        mOutput = mOutput.substr(mOutputStartIndex);
        mOutputStartIndex = 0;
    }

    mOutput += message;
    mOutput += MESSAGE_DELIMITER;   // message separator

    return true;
}

void LLPluginMessagePipe::clearOwner(void)
{
    // The owner is done with this pipe.  The next call to process_impl should send any remaining data and exit.
    mOwner = NULL;
}

void LLPluginMessagePipe::setSocketTimeout(apr_interval_time_t timeout_usec)
{
    // We never want to sleep forever, so force negative timeouts to become non-blocking.

    // according to this page: http://dev.ariel-networks.com/apr/apr-tutorial/html/apr-tutorial-13.html
    // blocking/non-blocking with apr sockets is somewhat non-portable.

    if(timeout_usec <= 0)
    {
        // Make the socket non-blocking
        apr_socket_opt_set(mSocket->getSocket(), APR_SO_NONBLOCK, 1);
        apr_socket_timeout_set(mSocket->getSocket(), 0);
    }
    else
    {
        // Make the socket blocking-with-timeout
        apr_socket_opt_set(mSocket->getSocket(), APR_SO_NONBLOCK, 1);
        apr_socket_timeout_set(mSocket->getSocket(), timeout_usec);
    }
}

bool LLPluginMessagePipe::pump(F64 timeout)
{
    bool result = pumpOutput();

    if(result)
    {
        result = pumpInput(timeout);
    }

    return result;
}

bool LLPluginMessagePipe::pumpOutput()
{
    bool result = true;

    if(mSocket)
    {
        apr_status_t status;
        apr_size_t in_size, out_size;

        LLMutexLock lock(&mOutputMutex);

        const char * output_data = &(mOutput.data()[mOutputStartIndex]);
        if(*output_data != '\0')
        {
            // write any outgoing messages
            in_size = (apr_size_t) (mOutput.size() - mOutputStartIndex);
            out_size = in_size;

            setSocketTimeout(0);

//          LL_INFOS("Plugin") << "before apr_socket_send, size = " << size << LL_ENDL;

            status = apr_socket_send(mSocket->getSocket(),
                                     output_data,
                                     &out_size);

//          LL_INFOS("Plugin") << "after apr_socket_send, size = " << size << LL_ENDL;

            if((status == APR_SUCCESS) || APR_STATUS_IS_EAGAIN(status))
            {
                // Success or Socket buffer is full...

                // If we've pumped the entire string, clear it
                if (out_size == in_size)
                {
                    mOutputStartIndex = 0;
                    mOutput.clear();
                }
                else
                {
                    llassert(in_size > out_size);

                    // Remove the written part from the buffer and try again later.
                    mOutputStartIndex += out_size;
                }
            }
            else if(APR_STATUS_IS_EOF(status))
            {
                // This is what we normally expect when a plugin exits.
                //LL_INFOS() << "Got EOF from plugin socket. " << LL_ENDL;

                if(mOwner)
                {
                    mOwner->socketError(status);
                }
                result = false;
            }
            else
            {
                // some other error
                // Treat this as fatal.
                ll_apr_warn_status(status);

                if(mOwner)
                {
                    mOwner->socketError(status);
                }
                result = false;
            }
        }
    }

    return result;
}

bool LLPluginMessagePipe::pumpInput(F64 timeout)
{
    bool result = true;

    if(mSocket)
    {
        apr_status_t status;
        apr_size_t size;

        // FIXME: For some reason, the apr timeout stuff isn't working properly on windows.
        // Until such time as we figure out why, don't try to use the socket timeout -- just sleep here instead.
#if LL_WINDOWS
        if(result)
        {
            if(timeout != 0.0f)
            {
                ms_sleep((int)(timeout * 1000.0f));
                timeout = 0.0f;
            }
        }
#endif

        // Check for incoming messages
        if(result)
        {
            char input_buf[1024];
            apr_size_t request_size;

            if(timeout == 0.0f)
            {
                // If we have no timeout, start out with a full read.
                request_size = sizeof(input_buf);
            }
            else
            {
                // Start out by reading one byte, so that any data received will wake us up.
                request_size = 1;
            }

            // and use the timeout so we'll sleep if no data is available.
            setSocketTimeout((apr_interval_time_t)(timeout * 1000000));

            while(1)
            {
                size = request_size;

//              LL_INFOS("Plugin") << "before apr_socket_recv, size = " << size << LL_ENDL;

                status = apr_socket_recv(
                        mSocket->getSocket(),
                        input_buf,
                        &size);

//              LL_INFOS("Plugin") << "after apr_socket_recv, size = " << size << LL_ENDL;

                if(size > 0)
                {
                    LLMutexLock lock(&mInputMutex);
                    mInput.append(input_buf, size);
                }

                if(status == APR_SUCCESS)
                {
                    LL_DEBUGS("PluginSocket") << "success, read " << size << LL_ENDL;

                    if(size != request_size)
                    {
                        // This was a short read, so we're done.
                        break;
                    }
                }
                else if(APR_STATUS_IS_TIMEUP(status))
                {
                    LL_DEBUGS("PluginSocket") << "TIMEUP, read " << size << LL_ENDL;

                    // Timeout was hit.  Since the initial read is 1 byte, this should never be a partial read.
                    break;
                }
                else if(APR_STATUS_IS_EAGAIN(status))
                {
                    LL_DEBUGS("PluginSocket") << "EAGAIN, read " << size << LL_ENDL;

                    // Non-blocking read returned immediately.
                    break;
                }
                else if(APR_STATUS_IS_EOF(status))
                {
                    // This is what we normally expect when a plugin exits.
                    //LL_INFOS("PluginSocket") << "Got EOF from plugin socket. " << LL_ENDL;

                    if(mOwner)
                    {
                        mOwner->socketError(status);
                    }
                    result = false;
                    break;
                }
                else
                {
                    // some other error
                    // Treat this as fatal.
                    ll_apr_warn_status(status);

                    if(mOwner)
                    {
                        mOwner->socketError(status);
                    }
                    result = false;
                    break;
                }

                if(timeout != 0.0f)
                {
                    // Second and subsequent reads should not use the timeout
                    setSocketTimeout(0);
                    // and should try to fill the input buffer
                    request_size = sizeof(input_buf);
                }
            }

            processInput();
        }
    }

    return result;
}

void LLPluginMessagePipe::processInput(void)
{
    // Look for input delimiter(s) in the input buffer.
    size_t delim;
    mInputMutex.lock();
    while((delim = mInput.find(MESSAGE_DELIMITER)) != std::string::npos)
    {
        // Let the owner process this message
        if (mOwner)
        {
            // Pull the message out of the input buffer before calling receiveMessageRaw.
            // It's now possible for this function to get called recursively (in the case where the plugin makes a blocking request)
            // and this guarantees that the messages will get dequeued correctly.
            std::string message(mInput, 0, delim);
            mInput.erase(0, delim + 1);
            mInputMutex.unlock();
            mOwner->receiveMessageRaw(message);
            mInputMutex.lock();
        }
        else
        {
            LL_WARNS("Plugin") << "!mOwner" << LL_ENDL;
        }
    }
    mInputMutex.unlock();
}