/**
 * @file   llcapabilitylistener.cpp
 * @author Nat Goodspeed
 * @date   2009-01-07
 * @brief  Implementation for llcapabilitylistener.
 * 
 * $LicenseInfo:firstyear=2009&license=viewergpl$
 * Copyright (c) 2009, Linden Research, Inc.
 * $/LicenseInfo$
 */

// Precompiled header
#include "llviewerprecompiledheaders.h"
// associated header
#include "llcapabilitylistener.h"
// STL headers
#include <map>
// std headers
// external library headers
#include <boost/bind.hpp>
// other Linden headers
#include "stringize.h"
#include "llcapabilityprovider.h"

class LLCapabilityListener::CapabilityMappers: public LLSingleton<LLCapabilityListener::CapabilityMappers>
{
public:
    void registerMapper(const LLCapabilityListener::CapabilityMapper*);
    void unregisterMapper(const LLCapabilityListener::CapabilityMapper*);
    const LLCapabilityListener::CapabilityMapper* find(const std::string& cap) const;

    struct DupCapMapper: public std::runtime_error
    {
        DupCapMapper(const std::string& what):
            std::runtime_error(std::string("DupCapMapper: ") + what)
        {}
    };

private:
    friend class LLSingleton<LLCapabilityListener::CapabilityMappers>;
    CapabilityMappers();

    typedef std::map<std::string, const LLCapabilityListener::CapabilityMapper*> CapabilityMap;
    CapabilityMap mMap;
};

LLCapabilityListener::LLCapabilityListener(const std::string& name,
                                           LLMessageSystem* messageSystem,
                                           const LLCapabilityProvider& provider,
                                           const LLUUID& agentID,
                                           const LLUUID& sessionID):
    mEventPump(name),
    mMessageSystem(messageSystem),
    mProvider(provider),
    mAgentID(agentID),
    mSessionID(sessionID)
{
    mEventPump.listen("self", boost::bind(&LLCapabilityListener::capListener, this, _1));
}

bool LLCapabilityListener::capListener(const LLSD& request)
{
    // Extract what we want from the request object. We do it all up front
    // partly to document what we expect.
    LLSD::String cap(request["message"]);
    LLSD payload(request["payload"]);
    LLSD::String reply(request["reply"]);
    LLSD::String error(request["error"]);
    LLSD::Real timeout(request["timeout"]);
    // If the LLSD doesn't even have a "message" key, we doubt it was intended
    // for this listener.
    if (cap.empty())
    {
        LL_ERRS("capListener") << "capability request event without 'message' key to '"
                               << getCapAPI().getName()
                               << "' on region\n" << mProvider.getDescription()
                               << LL_ENDL;
        return false;               // in case fatal-error function isn't
    }
    // Establish default timeout. This test relies on LLSD::asReal() returning
    // exactly 0.0 for an undef value.
    if (! timeout)
    {
        timeout = HTTP_REQUEST_EXPIRY_SECS;
    }
    // Look up the url for the requested capability name.
    std::string url = mProvider.getCapability(cap);
    if (! url.empty())
    {
        // This capability is supported by the region to which we're talking.
        LLHTTPClient::post(url, payload,
                           new LLSDMessage::EventResponder(LLEventPumps::instance(),
                                                           request,
                                                           mProvider.getDescription(),
                                                           cap, reply, error),
                           LLSD(),  // headers
                           timeout);
    }
    else
    {
        // Capability not supported -- do we have a registered mapper?
        const CapabilityMapper* mapper = CapabilityMappers::instance().find(cap);
        if (! mapper)               // capability neither supported nor mapped
        {
            LL_ERRS("capListener") << "unsupported capability '" << cap << "' request to '"
                                   << getCapAPI().getName() << "' on region\n"
                                   << mProvider.getDescription()
                                   << LL_ENDL;
        }
        else if (! mapper->getReplyName().empty()) // mapper expects reply support
        {
            LL_ERRS("capListener") << "Mapper for capability '" << cap
                                   << "' requires unimplemented support for reply message '"
                                   << mapper->getReplyName()
                                   << "' on '" << getCapAPI().getName() << "' on region\n"
                                   << mProvider.getDescription()
                                   << LL_ENDL;
        }
        else
        {
            LL_INFOS("capListener") << "fallback invoked for capability '" << cap
                                    << "' request to '" << getCapAPI().getName()
                                    << "' on region\n" << mProvider.getDescription()
                                    << LL_ENDL;
            mapper->buildMessage(mMessageSystem, mAgentID, mSessionID, cap, payload);
            mMessageSystem->sendReliable(mProvider.getHost());
        }
    }
    return false;
}

LLCapabilityListener::CapabilityMapper::CapabilityMapper(const std::string& cap, const std::string& reply):
    mCapName(cap),
    mReplyName(reply)
{
    LLCapabilityListener::CapabilityMappers::instance().registerMapper(this);
}

LLCapabilityListener::CapabilityMapper::~CapabilityMapper()
{
    LLCapabilityListener::CapabilityMappers::instance().unregisterMapper(this);
}

LLSD LLCapabilityListener::CapabilityMapper::readResponse(LLMessageSystem* messageSystem) const
{
    return LLSD();
}

LLCapabilityListener::CapabilityMappers::CapabilityMappers() {}

void LLCapabilityListener::CapabilityMappers::registerMapper(const LLCapabilityListener::CapabilityMapper* mapper)
{
    // Try to insert a new map entry by which we can look up the passed mapper
    // instance.
    std::pair<CapabilityMap::iterator, bool> inserted =
        mMap.insert(CapabilityMap::value_type(mapper->getCapName(), mapper));
    // If we already have a mapper for that name, insert() merely located the
    // existing iterator and returned false. It is a coding error to try to
    // register more than one mapper for the same capability name.
    if (! inserted.second)
    {
        throw DupCapMapper(std::string("Duplicate capability name ") + mapper->getCapName());
    }
}

void LLCapabilityListener::CapabilityMappers::unregisterMapper(const LLCapabilityListener::CapabilityMapper* mapper)
{
    CapabilityMap::iterator found = mMap.find(mapper->getCapName());
    if (found != mMap.end())
    {
        mMap.erase(found);
    }
}

const LLCapabilityListener::CapabilityMapper*
LLCapabilityListener::CapabilityMappers::find(const std::string& cap) const
{
    CapabilityMap::const_iterator found = mMap.find(cap);
    if (found != mMap.end())
    {
        return found->second;
    }
    return NULL;
}