/**
 * @file llmessagethrottle.cpp
 * @brief LLMessageThrottle class used for throttling messages.
 *
 * $LicenseInfo:firstyear=2004&license=viewerlgpl$
 * 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 "llhash.h"

#include "llmessagethrottle.h"
#include "llframetimer.h"

// This is used for the stl search_n function.
bool eq_message_throttle_entry(LLMessageThrottleEntry a, LLMessageThrottleEntry b)
        { return a.getHash() == b.getHash(); }

const U64 SEC_TO_USEC = 1000000;

// How long (in microseconds) each type of message stays in its throttle list.
const U64 MAX_MESSAGE_AGE[MTC_EOF] =
{
    10 * SEC_TO_USEC,   // MTC_VIEWER_ALERT
    10 * SEC_TO_USEC    // MTC_AGENT_ALERT
};

LLMessageThrottle::LLMessageThrottle()
{
}

LLMessageThrottle::~LLMessageThrottle()
{
}

void LLMessageThrottle::pruneEntries()
{
    // Go through each message category, and prune entries older than max age.
    S32 cat;
    for (cat = 0; cat < MTC_EOF; cat++)
    {
        message_list_t* message_list = &(mMessageList[cat]);

        // Use a reverse iterator, since entries on the back will be the oldest.
        message_list_reverse_iterator_t r_iterator  = message_list->rbegin();
        message_list_reverse_iterator_t r_last      = message_list->rend();

        // Look for the first entry younger than the maximum age.
        F32 max_age = (F32)MAX_MESSAGE_AGE[cat];
        bool found = false;
        while (r_iterator != r_last && !found)
        {
            if ( LLFrameTimer::getTotalTime() - (*r_iterator).getEntryTime() < max_age )
            {
                // We found a young enough entry.
                found = true;

                // Did we find at least one entry to remove?
                if (r_iterator != message_list->rbegin())
                {
                    // Yes, remove it.
                    message_list->erase(r_iterator.base(), message_list->end());
                }
            }
            else
            {
                r_iterator++;
            }
        }

        // If we didn't find any entries young enough to keep, remove them all.
        if (!found)
        {
            message_list->clear();
        }
    }
}

bool LLMessageThrottle::addViewerAlert(const LLUUID& to, const std::string& mesg)
{
    message_list_t* message_list = &(mMessageList[MTC_VIEWER_ALERT]);

    // Concatenate from,to,mesg into one string.
    std::ostringstream full_mesg;
    full_mesg << to << mesg;

    // Create an entry for this message.
    size_t hash = llhash(full_mesg.str().c_str());
    LLMessageThrottleEntry entry(hash, LLFrameTimer::getTotalTime());

    // Check if this message is already in the list.
    message_list_iterator_t found = std::search_n(message_list->begin(), message_list->end(),
                                                  1, entry, eq_message_throttle_entry);
    if (found == message_list->end())
    {
        // This message was not found.  Add it to the list.
        message_list->push_front(entry);
        return true;
    }
    else
    {
        // This message was already in the list.
        return false;
    }
}

bool LLMessageThrottle::addAgentAlert(const LLUUID& agent, const LLUUID& task, const std::string& mesg)
{
    message_list_t* message_list = &(mMessageList[MTC_AGENT_ALERT]);

    // Concatenate from,to,mesg into one string.
    std::ostringstream full_mesg;
    full_mesg << agent << task << mesg;

    // Create an entry for this message.
    size_t hash = llhash(full_mesg.str().c_str());
    LLMessageThrottleEntry entry(hash, LLFrameTimer::getTotalTime());

    // Check if this message is already in the list.
    message_list_iterator_t found = std::search_n(message_list->begin(), message_list->end(),
                                                  1, entry, eq_message_throttle_entry);
    if (found == message_list->end())
    {
        // This message was not found.  Add it to the list.
        message_list->push_front(entry);
        return true;
    }
    else
    {
        // This message was already in the list.
        return false;
    }
}