/*
 * 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 <QVariant>
#include <QByteArray>
#include <functional>
#include <flatbuffers/flatbuffers.h>

/**
 * Defines how to convert qt primitives to flatbuffer ones
 */
template <class T>
flatbuffers::uoffset_t variantToProperty(const QVariant &, flatbuffers::FlatBufferBuilder &fbb);

/**
 * Defines how to convert flatbuffer primitives to qt ones
 */
template <typename T>
QVariant propertyToVariant(const flatbuffers::String *);


/**
 * The property mapper is a non-typesafe virtual dispatch.
 *
 * Instead of using an interface and requring each implementation to override
 * a virtual method per property, the property mapper can be filled with accessors
 * that extract the properties from resource types.
 */
template<typename BufferType>
class ReadPropertyMapper
{
public:
    virtual QVariant getProperty(const QByteArray &key, BufferType const *buffer) const
    {
        if (mReadAccessors.contains(key)) {
            auto accessor = mReadAccessors.value(key);
            return accessor(buffer);
        }
        return QVariant();
    }
    bool hasMapping(const QByteArray &key) const { return mReadAccessors.contains(key); }
    QList<QByteArray> availableProperties() const { return mReadAccessors.keys(); }
    void addMapping(const QByteArray &property, const std::function<QVariant(BufferType const *)> &mapping) {
        mReadAccessors.insert(property, mapping);
    }
private:
    QHash<QByteArray, std::function<QVariant(BufferType const *)> > mReadAccessors;
};

template<typename BufferBuilder>
class WritePropertyMapper
{
public:
    virtual void setProperty(const QByteArray &key, const QVariant &value, QList<std::function<void(BufferBuilder &)> > &builderCalls, flatbuffers::FlatBufferBuilder &fbb) const
    {
        if (mWriteAccessors.contains(key)) {
            auto accessor = mWriteAccessors.value(key);
            builderCalls << accessor(value, fbb);
        }
    }
    bool hasMapping(const QByteArray &key) const { return mWriteAccessors.contains(key); }
    void addMapping(const QByteArray &property, const std::function<std::function<void(BufferBuilder &)>(const QVariant &, flatbuffers::FlatBufferBuilder &)> &mapping) {
        mWriteAccessors.insert(property, mapping);
    }
private:
    QHash<QByteArray, std::function<std::function<void(BufferBuilder &)>(const QVariant &, flatbuffers::FlatBufferBuilder &)> > mWriteAccessors;
};