/*
 * Copyright (C) 2014 Christian Mollekopf <chrigi_1@fastmail.fm>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the
 *   Free Software Foundation, Inc.,
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
 */
#pragma once

#include <QByteArray>

#include "query.h"
#include "domainadaptor.h"
#include "entitybuffer.h"
#include "log.h"
#include "storage.h"
#include "resultset.h"
#include "resultprovider.h"
#include "definitions.h"

/**
 * Wraps storage, entity adaptor factory and indexes into one.
 * 
 */
class EntityStorageBase
{
public:
    typedef std::function<ResultSet (const Akonadi2::Query &query, Akonadi2::Storage::Transaction &transaction, QSet<QByteArray> &remainingFilters)> InitialResultLoader;
    typedef std::function<ResultSet (qint64 baseRevision, const Akonadi2::Query &query, Akonadi2::Storage::Transaction &transaction, QSet<QByteArray> &remainingFilters)> IncrementalResultLoader;
    typedef std::function<void(const Akonadi2::Storage::Transaction &transaction, const QByteArray &key, const std::function<void(const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &, Akonadi2::Operation)> &resultCallback)> EntityReader;

    /**
     * Returns the initial result set that still needs to be filtered.
     *
     * To make this efficient indexes should be chosen that are as selective as possible.
     */
    InitialResultLoader loadInitialResultSet;
    /**
     * Returns the incremental result set that still needs to be filtered.
     */
    IncrementalResultLoader loadIncrementalResultSet;

    /**
     * Loads a single entity by uid from storage.
     */
    EntityReader readEntity;

protected:
    EntityStorageBase(const QByteArray &instanceIdentifier)
        : mResourceInstanceIdentifier(instanceIdentifier)
    {

    }

    virtual Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr copy(const Akonadi2::ApplicationDomain::ApplicationDomainType &) = 0;

    ResultSet getResultSet(const Akonadi2::Query &query, Akonadi2::Storage::Transaction &transaction, qint64 baseRevision);

    QByteArray mResourceInstanceIdentifier;

private:
    ResultSet filteredSet(const ResultSet &resultSet, const std::function<bool(const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &domainObject)> &filter, const Akonadi2::Storage::Transaction &transaction, bool isInitialQuery);
};

template<typename DomainType>
class EntityStorage : public EntityStorageBase
{

public:

    EntityStorage(const QByteArray &instanceIdentifier)
        : EntityStorageBase(instanceIdentifier)
    {
    }

protected:
    Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr copy(const Akonadi2::ApplicationDomain::ApplicationDomainType &object) Q_DECL_OVERRIDE
    {
        return Akonadi2::ApplicationDomain::ApplicationDomainType::getInMemoryRepresentation<DomainType>(object);
    }

public:

    virtual qint64 read(const Akonadi2::Query &query, qint64 baseRevision, const QSharedPointer<Akonadi2::ResultProvider<typename DomainType::Ptr> > &resultProvider)
    {
        Akonadi2::Storage storage(Akonadi2::storageLocation(), mResourceInstanceIdentifier);
        storage.setDefaultErrorHandler([](const Akonadi2::Storage::Error &error) {
            Warning() << "Error during query: " << error.store << error.message;
        });

        auto transaction = storage.createTransaction(Akonadi2::Storage::ReadOnly);

        Log() << "Querying" << baseRevision << Akonadi2::Storage::maxRevision(transaction);
        auto resultSet = getResultSet(query, transaction, baseRevision);
        while(resultSet.next([this, resultProvider](const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &value, Akonadi2::Operation operation) -> bool {
            switch (operation) {
            case Akonadi2::Operation_Creation:
                Trace() << "Got creation";
                resultProvider->add(copy(*value).template staticCast<DomainType>());
                break;
            case Akonadi2::Operation_Modification:
                Trace() << "Got modification";
                resultProvider->modify(copy(*value).template staticCast<DomainType>());
                break;
            case Akonadi2::Operation_Removal:
                Trace() << "Got removal";
                resultProvider->remove(copy(*value).template staticCast<DomainType>());
                break;
            }
            return true;
        })){};
        return Akonadi2::Storage::maxRevision(transaction);
    }

};