#ifndef WORDDRILLMODEL_H
#define WORDDRILLMODEL_H

#include "IStudyModel.h"

#include <QStringList>

/** Model of Word Drill study tool.
 *
 * At the beginning of a test, the model generates a fresh pack of valid cards: #m_freshPack. In course of the test,
 * cards one-by-one are randomly taken from the fresh pack and moved to the history pack #m_cardHistory.
 * The part of history, which belongs to the current pack (recently generated new pack), is separated from older
 * cards with property #m_historyCurPackStart.
 * The current card can be obtained with #curCard(), it is taken from the history. When the fresh pack is finished
 * and the next card required, new fresh pack is generated.
 *
 * All used cards over all pack iterations are saved to the history.
 * The user can travel back and forth along the history with goBack() and goForward(). In this case #m_curCardNum
 * increases or decreases.
 */

class WordDrillModel: public IStudyModel
{
Q_OBJECT

public:
    WordDrillModel( CardPack* aCardPack );

    Card* getCurCard() const;
    bool canGoBack();
    bool canGoForward();

    int getCurCardNum() const { return curCardNum; }
    int historySize() const {return m_cardHistory.size(); }

private:
    void generateFreshPack();
    void cleanHistoryFromRemovedCards();

public slots:
    void pickNextCard();
    bool goBack();
    bool goForward();
    
private slots:
    void updateStudyState();

private:    
    static const int NoCardIndex = -1;

private:
    /** Fresh cards. The cards that were not shown yet (in the current iteration). Not own.*/
    QStringList m_freshPack;

    /// List of all shown cards. Not own.
    QStringList m_cardHistory;

    /// The start index of the current pack in the history
    int m_historyCurPackStart;    
};

#endif