/*
    Copyright (C) 2010 Klarlvdalens Datakonsult AB,
        a KDAB Group company, info@kdab.net,
        author Tobias Koenig <tokoe@kdab.com>

    This library is free software; you can redistribute it and/or modify it
    under the terms of the GNU Library General Public License as published by
    the Free Software Foundation; either version 2 of the License, or (at your
    option) any later version.

    This library 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 Library General Public
    License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to the
    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
    02110-1301, USA.
*/

#ifndef AKONADI_ENTITYFETCHWATCHER_H
#define AKONADI_ENTITYFETCHWATCHER_H

#include <QtCore/QObject>

class QAbstractItemModel;
class QModelIndex;

namespace AkonadiFuture {

/**
 * @short A class that encapsulates logic to wait for an entity to be completely loaded into a model.
 *
 * @author Tobias Koenig <tokoe@kde.org>
 */
class EntityFetchWatcher : public QObject
{
  Q_OBJECT

  public:
    /**
     * Creates a new entity fetch watcher.
     *
     * @param index The model index of the entity to wait for.
     * @param model The model to work on.
     * @param parent The parent object.
     */
    EntityFetchWatcher( const QModelIndex &index, const QAbstractItemModel *model, QObject *parent = 0 );

    /**
     * Destroys the entity fetch watcher.
     */
    ~EntityFetchWatcher();

    /**
     * Starts watching the collection.
     */
    void start();

  Q_SIGNALS:
    /**
     * This signal is emitted when the entity at the watched @p index has been loaded completely into
     * the model.
     */
    void entityFetched( const QModelIndex &index );

  private:
    //@cond PRIVATE
    class Private;
    Private* const d;

    Q_PRIVATE_SLOT( d, void dataChanged( const QModelIndex&, const QModelIndex& ) )
    //@endcond
};

}

#endif
/*
    Copyright (C) 2010 Klarlvdalens Datakonsult AB,
        a KDAB Group company, info@kdab.net,
        author Tobias Koenig <tokoe@kdab.com>

    This library is free software; you can redistribute it and/or modify it
    under the terms of the GNU Library General Public License as published by
    the Free Software Foundation; either version 2 of the License, or (at your
    option) any later version.

    This library 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 Library General Public
    License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to the
    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
    02110-1301, USA.
*/

#include "entityfetchwatcher.h"

#include <akonadi/collectionstatistics.h>
#include <akonadi/entitytreemodel.h>

#include <QtCore/QAbstractItemModel>
#include <QtCore/QTimer>

using namespace AkonadiFuture;

class EntityFetchWatcher::Private
{
  public:
    Private( EntityFetchWatcher *qq, const QModelIndex &index, const QAbstractItemModel *model )
      : q( qq ), mIndex( index ), mModel( model )
    {
    }

    void dataChanged( const QModelIndex &index, const QModelIndex& )
    {
      if ( index != mIndex )
        return;

      qDebug() << "dataChanged our index";
      if ( mIndex.data( Akonadi::EntityTreeModel::FetchStateRole ).toInt() == Akonadi::EntityTreeModel::IdleState ) {
        qDebug() << "our index is idle";
        q->disconnect( mModel, SIGNAL( dataChanged( const QModelIndex&, const QModelIndex& ) ),
                       q, SLOT( dataChanged( const QModelIndex&, const QModelIndex& ) ) );

        emit q->entityFetched( mIndex );

        q->deleteLater();
      } else {
        qDebug() << "our index is busy";
      }
    }

    EntityFetchWatcher *q;
    QPersistentModelIndex mIndex;
    const QAbstractItemModel *mModel;
};

EntityFetchWatcher::EntityFetchWatcher( const QModelIndex &index, const QAbstractItemModel *model, QObject *parent )
  : QObject( parent ), d( new Private( this, index, model ) )
{
  Q_ASSERT( d->mIndex.model() == d->mModel ); // make sure we work on the right indexes/model
  qDebug("EntityFetchWatcher::EntityFetchWatcher(%p)", this);
}

EntityFetchWatcher::~EntityFetchWatcher()
{
  qDebug("EntityFetchWatcher::~EntityFetchWatcher(%p)", this);
  delete d;
}

void EntityFetchWatcher::start()
{
  const Akonadi::Collection collection = d->mIndex.data( Akonadi::EntityTreeModel::CollectionRole ).value<Akonadi::Collection>();
  Q_ASSERT( collection.isValid() );

  if ( collection.statistics().count() == 0 ) {
    // no reason to wait, this collection does not contain any items
    emit entityFetched( d->mIndex );
    deleteLater();
    return;
  }

  // check if the loading has been finished already
  if ( d->mIndex.data( Akonadi::EntityTreeModel::FetchStateRole ).toInt() == Akonadi::EntityTreeModel::IdleState ) {
    emit entityFetched( d->mIndex );
    deleteLater();
    return;
  }


  // start our work
  connect( d->mModel, SIGNAL( dataChanged( const QModelIndex&, const QModelIndex& ) ),
           this, SLOT( dataChanged( const QModelIndex&, const QModelIndex& ) ) );
}

#include "entityfetchwatcher.moc"