//------------------------------------------------------------------------------
/*
    Copyright (c) 2011-2013, OpenCoin, Inc.
*/
//==============================================================================

class KeyvaDBBackendFactory::Backend : public NodeStore::Backend
{
private:
    typedef RecycledObjectPool <MemoryBlock> MemoryPool;
    typedef RecycledObjectPool <NodeStore::EncodedBlob> EncodedBlobPool;

public:
    Backend (size_t keyBytes,
             StringPairArray const& keyValues,
             NodeStore::Scheduler& scheduler)
        : m_keyBytes (keyBytes)
        , m_scheduler (scheduler)
        , m_path (keyValues ["path"])
        , m_db (KeyvaDB::New (
                    keyBytes,
                    3,
                    File::getCurrentWorkingDirectory().getChildFile (m_path).withFileExtension ("key"),
                    File::getCurrentWorkingDirectory().getChildFile (m_path).withFileExtension ("val")))
    {
    }

    ~Backend ()
    {
    }

    std::string getName ()
    {
        return m_path.toStdString ();
    }

    //--------------------------------------------------------------------------

    Status fetch (void const* key, NodeObject::Ptr* pObject)
    {
        pObject->reset ();

        Status status (ok);

        struct Callback : KeyvaDB::GetCallback
        {
            explicit Callback (MemoryBlock& block)
                : m_block (block)
            {
            }

            void* getStorageForValue (int valueBytes)
            {
                m_size = valueBytes;
                m_block.ensureSize (valueBytes);

                return m_block.getData ();
            }

            void const* getData () const noexcept
            {
                return m_block.getData ();
            }

            size_t getSize () const noexcept
            {
                return m_size;
            }

        private:
            MemoryBlock& m_block;
            size_t m_size;
        };

        MemoryPool::ScopedItem item (m_memoryPool);
        MemoryBlock& block (item.getObject ());

        Callback cb (block);

        // VFALCO TODO Can't we get KeyvaDB to provide a proper status?
        //
        bool const found = m_db->get (key, &cb);

        if (found)
        {
            NodeStore::DecodedBlob decoded (key, cb.getData (), cb.getSize ());

            if (decoded.wasOk ())
            {
                *pObject = decoded.createObject ();

                status = ok;
            }
            else
            {
                status = dataCorrupt;
            }
        }
        else
        {
            status = notFound;
        }

        return status;
    }

    void store (NodeObject::ref object)
    {
        EncodedBlobPool::ScopedItem item (m_blobPool);
        NodeStore::EncodedBlob& encoded (item.getObject ());

        encoded.prepare (object);

        m_db->put (encoded.getKey (), encoded.getData (), encoded.getSize ());
    }

    void storeBatch (NodeStore::Batch const& batch)
    {
        for (int i = 0; i < batch.size (); ++i)
            store (batch [i]);
    }

    void visitAll (VisitCallback& callback)
    {
        // VFALCO TODO Implement this!
        //
        bassertfalse;
        //m_db->visitAll ();
    }

    int getWriteLoad ()
    {
        // we dont do pending writes
        return 0;
    }

    //--------------------------------------------------------------------------

private:
    size_t const m_keyBytes;
    NodeStore::Scheduler& m_scheduler;
    String m_path;
    ScopedPointer <KeyvaDB> m_db;
    MemoryPool m_memoryPool;
    EncodedBlobPool m_blobPool;
};

//------------------------------------------------------------------------------

KeyvaDBBackendFactory::KeyvaDBBackendFactory ()
{
}

KeyvaDBBackendFactory::~KeyvaDBBackendFactory ()
{
}

KeyvaDBBackendFactory& KeyvaDBBackendFactory::getInstance ()
{
    static KeyvaDBBackendFactory instance;

    return instance;
}

String KeyvaDBBackendFactory::getName () const
{
    return "KeyvaDB";
}

NodeStore::Backend* KeyvaDBBackendFactory::createInstance (
    size_t keyBytes,
    StringPairArray const& keyValues,
    NodeStore::Scheduler& scheduler)
{
    return new KeyvaDBBackendFactory::Backend (keyBytes, keyValues, scheduler);
}

//------------------------------------------------------------------------------