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

#ifndef RIPPLE_NODESTORE_H_INCLUDED
#define RIPPLE_NODESTORE_H_INCLUDED

/** Persistency layer for NodeObject
*/
// VFALCO TODO Move all definitions to the .cpp
class NodeStore : LeakChecked <NodeStore>
{
public:
    /** Back end used for the store.
    */
    class Backend
    {
    public:
        // VFALCO TODO Remove this, the backend should not be a shared
        //             object it should be ScopedPointer owned.
        //
        typedef boost::shared_ptr <Backend> pointer;

        Backend()                { ; }
        virtual ~Backend()       { ; }

        virtual std::string getDataBaseName() = 0;

        // Store/retrieve a single object
        // These functions must be thread safe
        virtual bool store(NodeObject::ref) = 0;
        virtual NodeObject::pointer retrieve(uint256 const &hash) = 0;

        // Store a group of objects
        // This function will only be called from a single thread
        virtual bool bulkStore(const std::vector< NodeObject::pointer >&) = 0;

        // Visit every object in the database
        // This function will only be called during an import operation
        virtual void visitAll(FUNCTION_TYPE<void (NodeObject::pointer)>) = 0;
    };

public:
    /** Factory to produce backends.
    */
    class BackendFactory
    {
    public:
        virtual ~BackendFactory () { }

        /** Retrieve the name of this factory.
        */
        virtual String getName () const = 0;

        /** Create an instance of this factory's backend.
        */
        virtual Backend* createInstance (HashMap <String, String> const& keyValueParameters) = 0;
    };

public:
    NodeStore (int cacheSize, int cacheAge);

    bool isLevelDB ()
    {
        return mLevelDB;
    }

    float getCacheHitRate ()
    {
        return mCache.getHitRate ();
    }

    bool store (NodeObjectType type, uint32 index, Blob const& data,
                uint256 const& hash)
    {
        if (mLevelDB)
            return storeLevelDB (type, index, data, hash);

        return storeSQLite (type, index, data, hash);
    }

    NodeObject::pointer retrieve (uint256 const& hash)
    {
        if (mLevelDB)
            return retrieveLevelDB (hash);

        return retrieveSQLite (hash);
    }

    bool storeSQLite (NodeObjectType type, uint32 index, Blob const& data,
                      uint256 const& hash);
    NodeObject::pointer retrieveSQLite (uint256 const& hash);
    void bulkWriteSQLite (Job&);

    bool storeLevelDB (NodeObjectType type, uint32 index, Blob const& data,
                       uint256 const& hash);
    NodeObject::pointer retrieveLevelDB (uint256 const& hash);
    void bulkWriteLevelDB (Job&);


    void waitWrite ();
    void tune (int size, int age);
    void sweep ()
    {
        mCache.sweep ();
        mNegativeCache.sweep ();
    }
    int getWriteLoad ();

    int import (const std::string& fileName);

private:
    static NodeObject::pointer LLRetrieve (uint256 const& hash, leveldb::DB* db);
    static void LLWrite (boost::shared_ptr<NodeObject> ptr, leveldb::DB* db);
    static void LLWrite (const std::vector< boost::shared_ptr<NodeObject> >& set, leveldb::DB* db);

private:
    TaggedCache<uint256, NodeObject, UptimeTimerAdapter>  mCache;
    KeyCache <uint256, UptimeTimerAdapter> mNegativeCache;

    boost::mutex                mWriteMutex;
    boost::condition_variable   mWriteCondition;
    int                         mWriteGeneration;
    int                         mWriteLoad;

    std::vector< boost::shared_ptr<NodeObject> > mWriteSet;
    bool mWritePending;
    bool mLevelDB;
    bool mEphemeralDB;
};

#endif