/**
 * @file llxfer.cpp
 * @brief implementation of LLXfer class for a single xfer.
 *
 * $LicenseInfo:firstyear=2001&license=viewerlgpl$
 * 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
 * $/LicenseInfo$
 */

#include "linden_common.h"

#include "llxfer.h"
#include "lluuid.h"
#include "llerror.h"
#include "llmath.h"
#include "u64.h"

//number of bytes sent in each message
const U32 LL_XFER_CHUNK_SIZE = 1000;

const U32 LLXfer::XFER_FILE = 1;
const U32 LLXfer::XFER_VFILE = 2;
const U32 LLXfer::XFER_MEM = 3;

///////////////////////////////////////////////////////////

LLXfer::LLXfer (S32 chunk_size)
{
    init(chunk_size);
}

///////////////////////////////////////////////////////////

LLXfer::~LLXfer ()
{
    cleanup();
}

///////////////////////////////////////////////////////////

void LLXfer::init (S32 chunk_size)
{
    mID = 0;

    mPacketNum = -1; // there's a preincrement before sending the zeroth packet
    mXferSize = 0;

    mStatus = e_LL_XFER_UNINITIALIZED;
    mWaitingForACK = false;

    mCallback = NULL;
    mCallbackDataHandle = NULL;
    mCallbackResult = 0;

    mBufferContainsEOF = false;
    mBuffer = NULL;
    mBufferLength = 0;
    mBufferStartOffset = 0;

    mRetries = 0;

    if (chunk_size < 1)
    {
        chunk_size = LL_XFER_CHUNK_SIZE;
    }
    mChunkSize = chunk_size;
}

///////////////////////////////////////////////////////////

void LLXfer::cleanup ()
{
    if (mBuffer)
    {
        delete[] mBuffer;
        mBuffer = NULL;
    }
}

///////////////////////////////////////////////////////////

S32 LLXfer::startSend (U64 xfer_id, const LLHost &remote_host)
{
    LL_WARNS("Xfer") << "unexpected call to base class LLXfer::startSend for " << getFileName() << LL_ENDL;
    return (-1);
}

///////////////////////////////////////////////////////////

void LLXfer::closeFileHandle()
{
    LL_WARNS("Xfer") << "unexpected call to base class LLXfer::closeFileHandle for " << getFileName() << LL_ENDL;
}

///////////////////////////////////////////////////////////

S32 LLXfer::reopenFileHandle()
{
    LL_WARNS("Xfer") << "unexpected call to base class LLXfer::reopenFileHandle for " << getFileName() << LL_ENDL;
    return (-1);
}

///////////////////////////////////////////////////////////

void LLXfer::setXferSize (S32 xfer_size)
{
    mXferSize = xfer_size;
//  cout << "starting transfer of size: " << xfer_size << endl;
}

///////////////////////////////////////////////////////////

S32 LLXfer::startDownload()
{
    LL_WARNS("Xfer") << "undifferentiated LLXfer::startDownload for " << getFileName()
            << LL_ENDL;
    return (-1);
}

///////////////////////////////////////////////////////////

S32 LLXfer::receiveData (char *datap, S32 data_size)
{
    S32 retval = 0;

    if (((S32) mBufferLength + data_size) > getMaxBufferSize())
    {   // Write existing data to disk if it's larger than the buffer size
        retval = flush();
    }

    if (!retval)
    {
        if (datap != NULL)
        {   // Append new data to mBuffer
            memcpy(&mBuffer[mBufferLength],datap,data_size);    /*Flawfinder: ignore*/
            mBufferLength += data_size;
        }
        else
        {
            LL_ERRS("Xfer") << "NULL data passed in receiveData" << LL_ENDL;
        }
    }

    return (retval);
}

///////////////////////////////////////////////////////////

S32 LLXfer::flush()
{
    // only files have somewhere to flush to
    // if we get called with a flush it means we've blown past our
    // allocated buffer size

    return (-1);
}


///////////////////////////////////////////////////////////

S32 LLXfer::suck(S32 start_position)
{
    LL_WARNS("Xfer") << "Attempted to send a packet outside the buffer bounds in LLXfer::suck()" << LL_ENDL;
    return (-1);
}

///////////////////////////////////////////////////////////

void LLXfer::sendPacket(S32 packet_num)
{
    char fdata_buf[LL_XFER_LARGE_PAYLOAD+4];        /* Flawfinder: ignore */
    S32 fdata_size = mChunkSize;
    bool last_packet = false;
    S32 num_copy = 0;

    // if the desired packet is not in our current buffered excerpt from the file. . .
    if (((U32)packet_num*fdata_size < mBufferStartOffset)
        || ((U32)llmin((U32)mXferSize,(U32)((U32)(packet_num+1)*fdata_size)) > mBufferStartOffset + mBufferLength))

    {
        if (suck(packet_num*fdata_size))  // returns non-zero on failure
        {
            abort(LL_ERR_EOF);
            return;
        }
    }

    S32 desired_read_position = 0;

    desired_read_position = packet_num * fdata_size - mBufferStartOffset;

    fdata_size = llmin((S32)mBufferLength-desired_read_position, mChunkSize);

    if (fdata_size < 0)
    {
        LL_WARNS("Xfer") << "negative data size in xfer send, aborting" << LL_ENDL;
        abort(LL_ERR_EOF);
        return;
    }

    if (((U32)(desired_read_position + fdata_size) >= (U32)mBufferLength) && (mBufferContainsEOF))
    {
        last_packet = true;
    }

    if (packet_num)
    {
        num_copy = llmin(fdata_size, (S32)sizeof(fdata_buf));
        num_copy = llmin(num_copy, (S32)(mBufferLength - desired_read_position));
        if (num_copy > 0)
        {
            memcpy(fdata_buf,&mBuffer[desired_read_position],num_copy); /*Flawfinder: ignore*/
        }
    }
    else
    {
        // if we're the first packet, encode size as an additional S32
        // at start of data.
        num_copy = llmin(fdata_size, (S32)(sizeof(fdata_buf)-sizeof(S32)));
        num_copy = llmin(
            num_copy,
            (S32)(mBufferLength - desired_read_position));
        if (num_copy > 0)
        {
            memcpy( /*Flawfinder: ignore*/
                fdata_buf + sizeof(S32),
                &mBuffer[desired_read_position],
                num_copy);
        }
        fdata_size += sizeof(S32);
        htolememcpy(fdata_buf,&mXferSize, MVT_S32, sizeof(S32));
    }

    S32 encoded_packetnum = encodePacketNum(packet_num,last_packet);

    if (fdata_size)
    {
        // send the packet
        gMessageSystem->newMessageFast(_PREHASH_SendXferPacket);
        gMessageSystem->nextBlockFast(_PREHASH_XferID);

        gMessageSystem->addU64Fast(_PREHASH_ID, mID);
        gMessageSystem->addU32Fast(_PREHASH_Packet, encoded_packetnum);

        gMessageSystem->nextBlockFast(_PREHASH_DataPacket);
        gMessageSystem->addBinaryDataFast(_PREHASH_Data, &fdata_buf,fdata_size);

        S32 sent_something = gMessageSystem->sendMessage(mRemoteHost);
        if (sent_something == 0)
        {
            abort(LL_ERR_CIRCUIT_GONE);
            return;
        }

        ACKTimer.reset();
        mWaitingForACK = true;
    }
    if (last_packet)
    {
        mStatus = e_LL_XFER_COMPLETE;
    }
    else
    {
        mStatus = e_LL_XFER_IN_PROGRESS;
    }
}

///////////////////////////////////////////////////////////

void LLXfer::sendNextPacket()
{
    mRetries = 0;
    sendPacket(++mPacketNum);
}

///////////////////////////////////////////////////////////

void LLXfer::resendLastPacket()
{
    mRetries++;
    sendPacket(mPacketNum);
}

///////////////////////////////////////////////////////////

S32 LLXfer::processEOF()
{
    S32 retval = 0;

    mStatus = e_LL_XFER_COMPLETE;

    if (LL_ERR_NOERR == mCallbackResult)
    {
        LL_INFOS("Xfer") << "xfer from " << mRemoteHost << " complete: " << getFileName()
                << LL_ENDL;
    }
    else
    {
        LL_INFOS("Xfer") << "xfer from " << mRemoteHost << " failed, code "
                << mCallbackResult << ": " << getFileName() << LL_ENDL;
    }

    if (mCallback)
    {
        mCallback(mCallbackDataHandle,mCallbackResult, LLExtStat::NONE);
    }

    return(retval);
}

///////////////////////////////////////////////////////////

S32 LLXfer::encodePacketNum(S32 packet_num, bool is_EOF)
{
    if (is_EOF)
    {
        packet_num |= 0x80000000;
    }
    return packet_num;
}

///////////////////////////////////////////////////////////

void LLXfer::abort (S32 result_code)
{
    mCallbackResult = result_code;

    LL_INFOS("Xfer") << "Aborting xfer from " << mRemoteHost << " named " << getFileName()
            << " - error: " << result_code << LL_ENDL;

    if (result_code != LL_ERR_CIRCUIT_GONE)
    {
        gMessageSystem->newMessageFast(_PREHASH_AbortXfer);
        gMessageSystem->nextBlockFast(_PREHASH_XferID);
        gMessageSystem->addU64Fast(_PREHASH_ID, mID);
        gMessageSystem->addS32Fast(_PREHASH_Result, result_code);

        gMessageSystem->sendMessage(mRemoteHost);
    }

    mStatus = e_LL_XFER_ABORTED;
}


///////////////////////////////////////////////////////////

std::string LLXfer::getFileName()
{
    return U64_to_str(mID);
}

///////////////////////////////////////////////////////////

U32 LLXfer::getXferTypeTag()
{
    return 0;
}

///////////////////////////////////////////////////////////

S32 LLXfer::getMaxBufferSize ()
{
    return(mXferSize);
}


std::ostream& operator<< (std::ostream& os, LLXfer &hh)
{
    os << hh.getFileName() ;
    return os;
}