30 files changed, 3213 insertions, 0 deletions
diff --git a/src/study/CardEditDialog.cpp b/src/study/CardEditDialog.cpp
new file mode 100644
index 0000000..5dc47a3
--- /dev/null
+++ b/src/study/CardEditDialog.cpp
@@ -0,0 +1,119 @@
+#include "CardEditDialog.h"
+#include "IStudyWindow.h"
+#include "IStudyModel.h"
+#include "../dictionary/Card.h"
+#include "../dictionary/CardPack.h"
+#include "../dictionary/Dictionary.h"
+#include "../main-view/DictTableModel.h"
+#include "../main-view/DictTableView.h"
+#include "../main-view/CardFilterModel.h"
+#include "../main-view/MainWindow.h"
+
+#include <QSettings>
+#include <QCloseEvent>
+#include <QPushButton>
+#include <QVBoxLayout>
+#include <QHBoxLayout>
+#include <QHeaderView>
+#include <QVariant>
+
+CardEditDialog::CardEditDialog(Card* aCurCard, MainWindow* aMainWindow, IStudyWindow* aStudyWindow ):
+    QDialog( aStudyWindow ), m_cardEditModel( NULL ), m_cardEditView( NULL ), m_mainWindow( aMainWindow )
+    {
+    DictTableModel* tableModel = aStudyWindow->studyModel()->getDictModel();
+    if( !tableModel )
+        return;
+    
+    m_cardEditModel = new CardFilterModel( tableModel );
+    m_cardEditModel->setSourceModel( tableModel );
+    
+    const CardPack* cardPack = static_cast<const CardPack*>(aCurCard->getCardPack());
+    Q_ASSERT(cardPack);
+    m_dictionary = static_cast<const Dictionary*>(cardPack->dictionary());
+    Q_ASSERT( m_dictionary );
+    foreach( const DicRecord* record, aCurCard->getSourceRecords() )
+        {
+        int row = m_dictionary->indexOfRecord( const_cast<DicRecord*>( record ) );
+        if( row > -1 )
+            m_cardEditModel->addFilterRow( row );
+        }
+    
+    m_cardEditView = new DictTableView( m_cardEditModel, this );
+    m_cardEditView->setContextMenuPolicy( Qt::ActionsContextMenu );    
+    m_cardEditView->verticalHeader()->setContextMenuPolicy( Qt::ActionsContextMenu );
+    if( m_mainWindow )
+        {
+        m_cardEditView->addActions(m_mainWindow->getContextMenuActions());
+        m_cardEditView->verticalHeader()->addActions(m_mainWindow->getContextMenuActions());
+        connect( m_cardEditView->selectionModel(),
+            SIGNAL(selectionChanged(const QItemSelection&, const QItemSelection&)),
+            m_mainWindow, SLOT(updateSelectionActions()) );
+        }
+
+    QPushButton* dicWindowBtn = new QPushButton(tr("Go to dictionary window"));
+    connect( dicWindowBtn, SIGNAL(clicked()), SLOT(goToDictionaryWindow()));
+    QPushButton* closeBtn = new QPushButton(tr("Close"));
+    connect( closeBtn, SIGNAL(clicked()), SLOT(close()));
+    
+    QVBoxLayout* editLt = new QVBoxLayout;
+    editLt->addWidget( m_cardEditView );
+    QHBoxLayout* buttonsLt = new QHBoxLayout;
+    buttonsLt->addStretch( 1 );
+    buttonsLt->addWidget( dicWindowBtn );
+    buttonsLt->addWidget( closeBtn );
+    editLt->addLayout( buttonsLt );
+
+    setLayout( editLt );
+    setWindowTitle( QString(tr("Edit card: ", "In title of card edit view")) + aCurCard->getName() );
+    setWindowModality( Qt::WindowModal );
+    closeBtn->setFocus();
+    m_cardEditView->setCurrentIndex( m_cardEditModel->index(0, 0) );
+    
+    QSettings settings;
+    QVariant posVar = settings.value("cardeditview-pos");
+    if( !posVar.isNull() )
+        move( posVar.toPoint() );
+    resize( settings.value("cardeditview-size", QSize(CardEditViewWidth, CardEditViewHeight)).toSize() );
+    }
+
+CardEditDialog::~CardEditDialog()
+    {
+    delete m_cardEditView;
+    delete m_cardEditModel;
+    }
+
+void CardEditDialog::closeEvent( QCloseEvent* event )
+    {
+    QSettings settings;
+    settings.setValue("cardeditview-pos", pos());
+    settings.setValue("cardeditview-size", size());
+    event->accept();
+    }
+
+bool CardEditDialog::event( QEvent* event )
+    {
+    if( event->type() == QEvent::WindowActivate || event->type() == QEvent::WindowDeactivate )
+        {
+        m_mainWindow->updateSelectionActions();
+        return true;
+        }
+    return QDialog::event( event );
+    }
+
+const DictTableView* CardEditDialog::cardEditView() const
+    {
+    if( isActiveWindow() )
+        return m_cardEditView;
+    else
+        return NULL;
+    }
+
+void CardEditDialog::goToDictionaryWindow()
+    {
+    close();
+    QModelIndex curProxyIndex = m_cardEditView->currentIndex();
+    QModelIndex curSourceIndex = m_cardEditModel->mapToSource( curProxyIndex );
+    if( !m_dictionary )
+        return;
+    m_mainWindow->goToDictionaryRecord( m_dictionary, curSourceIndex.row() );
+    }
diff --git a/src/study/CardEditDialog.h b/src/study/CardEditDialog.h
new file mode 100644
index 0000000..3eb3d1b
--- /dev/null
+++ b/src/study/CardEditDialog.h
@@ -0,0 +1,42 @@
+#ifndef CARDEDITDIALOG_H
+#define CARDEDITDIALOG_H
+
+#include <QDialog>
+#include <QEvent>
+
+class Card;
+class Dictionary;
+class CardFilterModel;
+class DictTableView;
+class DictTableModel;
+class MainWindow;
+class IStudyWindow;
+
+class CardEditDialog : public QDialog
+{
+    Q_OBJECT
+    
+public:
+    CardEditDialog(Card* aCurCard, MainWindow* aMainWindow, IStudyWindow* aStudyWindow);
+    ~CardEditDialog();
+    
+    const DictTableView* cardEditView() const;    
+    
+protected:
+    void closeEvent( QCloseEvent* event );
+    bool event( QEvent* event );
+
+private slots:
+    void goToDictionaryWindow();    
+        
+private:
+    static const int CardEditViewHeight = 130;
+    static const int CardEditViewWidth = 600;
+    
+    const Dictionary* m_dictionary;
+    CardFilterModel* m_cardEditModel;
+    DictTableView* m_cardEditView;
+    MainWindow* m_mainWindow;
+};
+
+#endif
diff --git a/src/study/CardSideView.cpp b/src/study/CardSideView.cpp
new file mode 100644
index 0000000..8956210
--- /dev/null
+++ b/src/study/CardSideView.cpp
@@ -0,0 +1,205 @@
+#include "CardSideView.h"
+#include "../field-styles/FieldStyleFactory.h"
+#include "../dictionary/CardPack.h"
+#include "../dictionary/IDictionary.h"
+
+#include <QtCore>
+
+CardSideView::CardSideView( bool aMode ):
+    m_showMode(aMode), cardPack(NULL)
+{
+    setFrameStyle( QFrame::Plain | QFrame::Box );
+    setAlignment( Qt::AlignCenter );
+    setTextFormat( Qt::RichText );
+    setWordWrap( true );
+    setAutoFillBackground( true );
+    setPalette( FieldStyleFactory::inst()->cardBgColor );
+    newIcon = new QLabel(this);
+    newIcon->setPixmap(QPixmap(":/images/new-topright.png"));
+    updateNewIconPos();
+    newIcon->hide();
+}
+
+void CardSideView::setEnabled( bool aEnabled )
+    {
+    QLabel::setEnabled( aEnabled );
+    setBackgroundVisible( aEnabled );
+    }
+
+/** Cleans background and text */
+void CardSideView::setBackgroundVisible( bool aVisible )
+    {
+    if( aVisible )
+        QLabel::setEnabled( true );
+    setAutoFillBackground( aVisible );
+    setLineWidth( aVisible? 1 : 0 );
+    if( !aVisible )
+        setText("");
+    }
+
+void CardSideView::setPack(const CardPack* pack)
+    {
+    cardPack = pack;
+    }
+
+void CardSideView::setQstAnsr( const QString aQuestion, const QStringList aAnswers )
+    {
+    m_question = aQuestion;
+    m_answers = aAnswers;
+    updateText();
+    }
+
+void CardSideView::setQuestion( const QString aQuestion )
+    {
+    m_question = aQuestion;
+    updateText();
+    }
+
+void CardSideView::setShowMode( bool aMode )
+    {
+    m_showMode = aMode;
+    updateText();
+    }
+
+void CardSideView::updateText()
+{
+    setText(getFormattedText());
+}
+
+QString CardSideView::getFormattedText() const
+{
+    if(!cardPack)
+        return QString();
+    if(m_showMode == QstMode)
+        return getFormattedQuestion();
+    else
+        return getFormattedAnswer();
+}
+
+QString CardSideView::getFormattedQuestion() const
+{
+    const Field* qstField = cardPack->getQuestionField();
+    if(!qstField)
+        return QString();
+    return formattedField(m_question, qstField->style());
+}
+
+QString CardSideView::getFormattedAnswer() const
+{
+    QStringList formattedAnswers;
+    int i = 0;
+    foreach(const Field* field, cardPack->getAnswerFields())
+    {
+        QString text = getFormattedAnswerField(field, i);
+        if(i == 0)
+            text += "<br/>";
+        if(!text.isEmpty())
+            formattedAnswers << text;
+        i++;
+    }
+    return formattedAnswers.join("<br/>");
+}
+
+QString CardSideView::getFormattedAnswerField(const Field* field, int index) const
+{
+    if(!field)
+        return QString();
+    if(index >= m_answers.size())
+        return QString();
+    if(m_answers[index].isEmpty())
+        return QString();
+    return formattedField(m_answers[index], field->style() );
+}
+
+QString CardSideView::formattedField( const QString aField, const QString aStyle ) const
+    {
+    Q_ASSERT( cardPack );
+    QString text = static_cast<IDictionary*>(cardPack->dictionary())->
+        extendImagePaths( aField );
+    
+    FieldStyle fieldStyle =  FieldStyleFactory::inst()->getStyle( aStyle );
+    QString beginning("<span style=\"");
+    beginning += QString("font-family:'%1'").arg( fieldStyle.font.family() );
+    beginning += QString("; font-size:%1pt").arg( fieldStyle.font.pointSize() );
+    beginning += getHighlighting(fieldStyle);
+    beginning += "\">" + fieldStyle.prefix;
+    QString ending( fieldStyle.suffix + "</span>");
+
+    // Highlight keywords inside plain text. Ignore tags.
+    if(m_showMode == AnsMode && fieldStyle.hasKeyword)
+        {
+        QString highlightedText;
+        int curPos = 0;
+        while( curPos < text.length() )
+            {
+            QString curText;
+            int beginTagPos = text.indexOf( "<", curPos );
+            if( beginTagPos > -1 )
+                curText = text.mid( curPos, beginTagPos - curPos ); // copy plain text
+            else
+                curText = text.mid( curPos, -1 ); // copy until end of string
+            curText = highlightKeyword(curText, fieldStyle);
+            highlightedText += curText;
+            if( beginTagPos == -1 )
+                break;
+            int endTagPos = text.indexOf( ">", beginTagPos );
+            if( endTagPos > -1 )
+                highlightedText += text.mid( beginTagPos, endTagPos - beginTagPos + 1 );    // copy tag
+            else
+                {
+                highlightedText += text.mid( curPos, -1 );  // copy until end of string
+                break;
+                }
+            curPos = endTagPos + 1;
+            }
+        text = highlightedText;
+        }
+
+    return beginning + text + ending;
+    }
+
+QString CardSideView::highlightKeyword( const QString aText, const FieldStyle& fieldStyle ) const
+    {
+    QString resText = aText;
+    if( !m_question.isEmpty() )
+        resText.replace(QRegExp( "\\b(\\w*" + QRegExp::escape( m_question ) + "\\w*)\\b",
+            Qt::CaseInsensitive ), "[\\1]");
+    QString spanBegin("<span style=\"");
+    spanBegin += getHighlighting(fieldStyle.getKeywordStyle()) + "\">";
+    resText.replace('[', spanBegin);
+    resText.replace( ']', "</span>" );
+    return resText;
+    }
+
+QString CardSideView::getHighlighting(const FieldStyle& fieldStyle) const
+{
+    QString res;
+    if(fieldStyle.color != Qt::black)
+        res += QString("; color:%1").arg(fieldStyle.color.name());
+    if(fieldStyle.font.bold())
+        res += "; font-weight:bold";
+    if(fieldStyle.font.italic())
+        res += "; font-style:italic";
+    return res;
+}
+
+QSize CardSideView::sizeHint() const
+{
+    return QSize(300, 200);
+}
+
+void CardSideView::updateNewIconPos()
+{
+    newIcon->move(rect().topRight() - QPoint(newIcon->width(), 0));
+}
+
+void CardSideView::showNewIcon(bool visible)
+{
+    newIcon->setVisible(visible);
+    updateNewIconPos();
+}
+
+void CardSideView::resizeEvent(QResizeEvent* /*event*/)
+{
+    updateNewIconPos();
+}
diff --git a/src/study/CardSideView.h b/src/study/CardSideView.h
new file mode 100644
index 0000000..c67ebe4
--- /dev/null
+++ b/src/study/CardSideView.h
@@ -0,0 +1,52 @@
+#ifndef CARDSIDEVIEW_H
+#define CARDSIDEVIEW_H
+
+#include <QLabel>
+
+class CardPack;
+class FieldStyle;
+class Field;
+
+class CardSideView : public QLabel
+{
+    Q_OBJECT
+public:
+    CardSideView( bool aMode = QstMode );
+    void setPack( const CardPack* pack );
+    void setQstAnsr( const QString aQuestion, const QStringList aAnswers );
+    void setQuestion( const QString aQuestion );
+    void setShowMode( bool aMode );
+    QSize sizeHint() const;
+    QString getFormattedText() const;
+    void showNewIcon(bool visible);
+
+public:
+    static const bool QstMode = true;
+    static const bool AnsMode = false;
+
+public slots:
+    void setEnabled( bool aEnabled );
+
+protected:
+    void resizeEvent(QResizeEvent* event);
+
+private:
+    void updateText();
+    void setBackgroundVisible( bool aVisible );
+    QString formattedField( const QString aField, const QString aStyle ) const;
+    QString highlightKeyword( const QString aText, const FieldStyle& fieldStyle ) const;
+    QString getHighlighting(const FieldStyle& fieldStyle) const;
+    QString getFormattedQuestion() const;
+    QString getFormattedAnswer() const;
+    QString getFormattedAnswerField(const Field* field, int index) const;
+    void updateNewIconPos();
+
+private:
+    bool m_showMode;
+    const CardPack* cardPack;
+    QString m_question;
+    QStringList m_answers;
+    QLabel* newIcon;
+};
+
+#endif
diff --git a/src/study/CardsStatusBar.cpp b/src/study/CardsStatusBar.cpp
new file mode 100644
index 0000000..e29f9f8
--- /dev/null
+++ b/src/study/CardsStatusBar.cpp
@@ -0,0 +1,82 @@
+#include "CardsStatusBar.h"
+
+const QStringList CardsStatusBar::Colors = {"green", "#fffd7c", "white", "#bd8d71"};
+
+CardsStatusBar::CardsStatusBar(QWidget* aParent) :
+    QWidget(aParent)
+{
+    setMinimumHeight(10);
+    setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
+}
+
+CardsStatusBar::~CardsStatusBar()
+{
+    delete painter;
+}
+
+void CardsStatusBar::paintEvent(QPaintEvent* aEvent)
+{
+    QWidget::paintEvent( aEvent );
+    if(values.isEmpty())
+        return;
+    max = getMax();
+
+    painter = new QPainter(this);
+    painter->setRenderHint(QPainter::Antialiasing);
+    painter->save();
+        
+    QPainterPath path;
+    path.addRoundedRect( rect(), Radius, Radius);
+    painter->setClipPath( path );
+
+    barRect = rect().adjusted(0, 0, 1, 0);
+
+    sectionLeft = rect().left();
+    for(int i = 0; i < values.size(); i++)
+        drawSection(i);
+
+    painter->restore();
+
+    painter->setPen(QPen("#7c7c7c"));
+    painter->drawRoundedRect(rect(), Radius, Radius);
+}
+
+int CardsStatusBar::getMax() const
+{
+    int max = 0;
+    foreach(int v, values)
+        max += v;
+    if(max == 0)
+        max = 1;
+    return max;
+}
+
+void CardsStatusBar::drawSection(int index)
+{
+    QRectF sectionRect = getSectionRect(index);
+    painter->setPen( Qt::NoPen );
+    painter->setBrush(getSectionGradient(index));
+    painter->drawRect(sectionRect);
+
+    painter->setPen(QPen(QBrush("#a7a7a7"), 0.5));
+    painter->drawLine(sectionRect.topRight(), sectionRect.bottomRight());
+
+    sectionLeft += sectionRect.width();
+}
+
+QLinearGradient CardsStatusBar::getSectionGradient(int index)
+{
+    QLinearGradient grad(barRect.topLeft(), barRect.bottomLeft());
+    grad.setColorAt( 0, Qt::white);
+    grad.setColorAt( 0.9, QColor(Colors[index]) );
+    return grad;
+}
+
+QRectF CardsStatusBar::getSectionRect(int index)
+{
+    QRectF sectionRect = barRect;
+    sectionRect.moveLeft(sectionLeft);
+    qreal sectionWidth = barRect.width() * values[index] / max;
+    sectionRect.setWidth(sectionWidth);
+    return sectionRect;
+}
diff --git a/src/study/CardsStatusBar.h b/src/study/CardsStatusBar.h
new file mode 100644
index 0000000..10344f7
--- /dev/null
+++ b/src/study/CardsStatusBar.h
@@ -0,0 +1,37 @@
+#ifndef CARDSSTATUSBAR_H
+#define CARDSSTATUSBAR_H
+
+#include <QtWidgets>
+
+class CardsStatusBar : public QWidget
+{
+    Q_OBJECT
+public:
+    static const QStringList Colors;
+
+public:
+    CardsStatusBar(QWidget* aParent = 0);
+    ~CardsStatusBar();
+    void setValues(const QList<int>& values) { this->values = values; update(); }
+
+protected:
+    virtual void paintEvent(QPaintEvent* aEvent);
+
+private:
+    int getMax() const;
+    void drawSection(int index);
+    QLinearGradient getSectionGradient(int index);
+    QRectF getSectionRect(int index);
+
+private:
+    static const int Radius = 6;
+
+private:
+    QList<int> values;
+    qreal max;
+    QRectF barRect;
+    QPainter* painter;
+    qreal sectionLeft;
+};
+
+#endif
diff --git a/src/study/IStudyModel.cpp b/src/study/IStudyModel.cpp
new file mode 100644
index 0000000..3194a71
--- /dev/null
+++ b/src/study/IStudyModel.cpp
@@ -0,0 +1,9 @@
+#include "IStudyModel.h"
+
+#include "../dictionary/CardPack.h"
+
+IStudyModel::IStudyModel( CardPack* aCardPack ):
+    cardPack(aCardPack), dictModel(NULL), curCardNum(-1)
+{
+}
+
diff --git a/src/study/IStudyModel.h b/src/study/IStudyModel.h
new file mode 100644
index 0000000..392ef01
--- /dev/null
+++ b/src/study/IStudyModel.h
@@ -0,0 +1,35 @@
+#ifndef ISTUDYMODEL_H
+#define ISTUDYMODEL_H
+
+#include <QObject>
+
+class Card;
+class CardPack;
+class DictTableModel;
+
+class IStudyModel: public QObject
+{
+Q_OBJECT
+
+public:
+    IStudyModel( CardPack* aCardPack );
+    virtual ~IStudyModel() {}
+
+public:
+    CardPack* getCardPack() { return cardPack; }
+    virtual Card* getCurCard() const = 0;
+    DictTableModel* getDictModel() const { return dictModel; }
+    
+    void setDictModel( DictTableModel* aModel ) { dictModel = aModel; }
+
+signals:
+    void nextCardSelected();
+    void curCardUpdated();
+
+protected:
+    CardPack* cardPack;
+    DictTableModel* dictModel;
+    int curCardNum;        ///< Number of the current card in this session, base=0.
+};
+
+#endif
diff --git a/src/study/IStudyWindow.cpp b/src/study/IStudyWindow.cpp
new file mode 100644
index 0000000..f918936
--- /dev/null
+++ b/src/study/IStudyWindow.cpp
@@ -0,0 +1,293 @@
+#include "IStudyWindow.h"
+
+#include <QCloseEvent>
+#include <QMessageBox>
+
+#include "IStudyModel.h"
+#include "CardSideView.h"
+#include "CardEditDialog.h"
+#include "../dictionary/Dictionary.h"
+#include "../dictionary/CardPack.h"
+#include "../main-view/MainWindow.h"
+
+const int IStudyWindow::AnsButtonPage = 0;
+const int IStudyWindow::AnsLabelPage = 1;
+const int IStudyWindow::CardPage = 0;
+const int IStudyWindow::MessagePage = 1;
+
+IStudyWindow::IStudyWindow(IStudyModel* aModel , QString aStudyName, QWidget *aParent):
+    m_model( aModel ), curCard( NULL ), state(StateAnswerHidden), m_studyName( aStudyName ),
+    m_parentWidget( aParent ), m_cardEditDialog( NULL )
+{
+    setMinimumWidth(MinWidth);
+    setMaximumWidth(MaxWidth);
+    setAttribute( Qt::WA_DeleteOnClose );
+    connect( m_model, SIGNAL(nextCardSelected()), SLOT(showNextCard()) );
+    connect( m_model, SIGNAL(curCardUpdated()), SLOT(updateCurCard()) );
+}
+
+IStudyWindow::~IStudyWindow()
+{
+    delete m_model;
+}
+
+void IStudyWindow::OnDictionaryRemoved()
+{
+    close();
+}
+
+void IStudyWindow::createUI()
+{
+    centralStackedLt = new QStackedLayout;
+    centralStackedLt->addWidget(createWrapper(createCardView()));
+    centralStackedLt->addWidget(createWrapper(createMessageLayout()));
+    centralStackedLt->setCurrentIndex(CardPage);
+    connect(centralStackedLt, SIGNAL(currentChanged(int)), SLOT(updateToolBarVisibility(int)));
+
+    QVBoxLayout* mainLayout = new QVBoxLayout;
+    mainLayout->addLayout(createUpperPanel());
+    mainLayout->addLayout(centralStackedLt);
+    mainLayout->addLayout(createLowerPanel());
+    setLayout(mainLayout);
+
+    ReadSettings();
+}
+
+QWidget* IStudyWindow::createWrapper(QBoxLayout* layout)
+{
+    QWidget* widget = new QWidget;
+    widget->setLayout(layout);
+    return widget;
+}
+
+QVBoxLayout* IStudyWindow::createMessageLayout()
+{
+    messageLabel = createMessageLabel();
+
+    QVBoxLayout* lt = new QVBoxLayout;
+    lt->setContentsMargins(QMargins());
+    lt->addStretch();
+    lt->addWidget(messageLabel);
+    lt->addStretch();
+    lt->addWidget(createClosePackButton(), 0, Qt::AlignHCenter);
+    lt->addStretch();
+    return lt;
+}
+
+QLabel* IStudyWindow::createMessageLabel()
+{
+    QLabel* label = new QLabel;
+    label->setAutoFillBackground(true);
+    label->setPalette(QPalette("#fafafa"));
+    label->setWordWrap(true);
+    label->setFrameStyle(QFrame::StyledPanel);
+    label->setMinimumHeight(200);
+    return label;
+}
+
+QPushButton* IStudyWindow::createClosePackButton()
+{
+    QPushButton* button = new QPushButton(tr("Close this pack"));
+    button->setFixedSize(BigButtonWidth, BigButtonHeight);
+    connect(button, SIGNAL(clicked()), SLOT(close()));
+    return button;
+}
+
+QHBoxLayout* IStudyWindow::createUpperPanel()
+{
+    editCardBtn = createEditCardButton();
+    deleteCardBtn = createDeleteCardButton();
+
+    QHBoxLayout* upperPanelLt = new QHBoxLayout;
+    upperPanelLt->addWidget(new QLabel(m_model->getCardPack()->id()));
+    upperPanelLt->addWidget(deleteCardBtn);
+    upperPanelLt->addWidget(editCardBtn);
+
+    return upperPanelLt;
+}
+
+QToolButton* IStudyWindow::createEditCardButton()
+{
+    QToolButton* button = new QToolButton( this );
+    button->setIcon( QIcon(":/images/pencil.png") );
+    button->setIconSize( QSize(ToolBarIconSize, ToolBarIconSize) );
+    button->setShortcut( tr("E", "Shortcut for 'Edit card' button") );
+    button->setToolTip( tr("Edit card")+" ("+button->shortcut().toString()+")" );
+    button->setFixedSize( ToolBarButtonSize, ToolBarButtonSize );
+    connect( button, SIGNAL(clicked()), SLOT(openCardEditDialog()) );
+    return button;
+}
+
+QToolButton* IStudyWindow::createDeleteCardButton()
+{
+    QToolButton* button = new QToolButton( this );
+    button->setIcon( QIcon(":/images/red-cross.png") );
+    button->setIconSize( QSize(ToolBarIconSize, ToolBarIconSize) );
+    button->setShortcut( tr("D", "Shortcut for 'Delete card' button") );
+    button->setToolTip( tr("Delete card")+" ("+button->shortcut().toString()+")" );
+    button->setFixedSize( ToolBarButtonSize, ToolBarButtonSize );
+    connect( button, SIGNAL(clicked()), SLOT(deleteCard()) );
+    return button;
+}
+
+QVBoxLayout* IStudyWindow::createCardView()
+{
+    questionLabel = new CardSideView( CardSideView::QstMode );
+    questionLabel->setPack( m_model->getCardPack() );
+
+    answerStackedLt = new QStackedLayout;
+    answerStackedLt->addWidget(createWrapper(createAnswerButtonLayout()));
+    answerStackedLt->addWidget(createWrapper(createAnswerLayout()));
+    answerStackedLt->setCurrentIndex(AnsButtonPage);
+
+    QVBoxLayout* cardViewLt = new QVBoxLayout;
+    cardViewLt->addWidget(questionLabel, 1);
+    cardViewLt->addLayout(answerStackedLt, 1);
+
+    return cardViewLt;
+}
+
+QBoxLayout* IStudyWindow::createAnswerButtonLayout()
+{
+    answerBtn = createAnswerButton();
+
+    QBoxLayout* lt = new QVBoxLayout;
+    lt->addStretch();
+    if(getAnswerEdit())
+        lt->addWidget(getAnswerEdit(), 0, Qt::AlignCenter);
+    lt->addWidget(answerBtn, 0, Qt::AlignCenter);
+    lt->addStretch();
+    return lt;
+}
+
+QPushButton* IStudyWindow::createAnswerButton()
+{
+    QPushButton* button = new QPushButton(QIcon(":/images/info.png"), tr("Show answer"));
+    button->setFixedSize(BigButtonWidth, BigButtonHeight);
+    button->setShortcut(Qt::Key_Return);
+    button->setToolTip(tr("Show answer") + ShortcutToStr(button) );
+    connect(button, SIGNAL(clicked()), SLOT(showAnswer()));
+    return button;
+}
+
+QBoxLayout* IStudyWindow::createAnswerLayout()
+{
+    answerLabel = new CardSideView( CardSideView::AnsMode );
+    answerLabel->setPack( m_model->getCardPack() );
+
+    QBoxLayout* lt = new QVBoxLayout;
+    lt->setContentsMargins(QMargins());
+    if(getUserAnswerLabel())
+        lt->addWidget(getUserAnswerLabel(), 1);
+    lt->addWidget(answerLabel, 1);
+    return lt;
+}
+
+const DictTableView* IStudyWindow::cardEditView() const
+    {
+    if( m_cardEditDialog )
+        return m_cardEditDialog->cardEditView();
+    else
+        return NULL;
+    }
+
+void IStudyWindow::openCardEditDialog()
+    {
+    if( m_cardEditDialog )  // already open
+        return;
+    Card* curCard = m_model->getCurCard();
+    Q_ASSERT( curCard );
+    MainWindow* mainWindow = dynamic_cast<MainWindow*>( m_parentWidget );
+    if( !mainWindow )
+        return;
+    m_cardEditDialog = new CardEditDialog( curCard, mainWindow, this );
+    m_cardEditDialog->exec();    
+    delete m_cardEditDialog;
+    m_cardEditDialog = NULL;
+    Dictionary* dict = static_cast<Dictionary*>(m_model->getCardPack()->dictionary());
+    dict->save();
+    setWindowTitle(m_studyName + " - " + dict->shortName());
+    }
+
+void IStudyWindow::deleteCard()
+    {
+    QString question = m_model->getCurCard()->getQuestion();
+    QMessageBox::StandardButton pressedButton;
+    pressedButton = QMessageBox::question( this, tr("Delete card?"), tr("Delete card \"%1\"?").arg( question ),
+        QMessageBox::Yes | QMessageBox::No, QMessageBox::Yes );
+    if( pressedButton == QMessageBox::Yes )
+        static_cast<Dictionary*>(m_model->getCardPack()->dictionary())->
+            removeRecord( question );
+    }
+
+void IStudyWindow::showNextCard()
+{
+    Q_ASSERT( m_model );
+    if( curCard )
+        disconnect( curCard, 0, this, 0 );
+    curCard = m_model->getCurCard();
+    if( curCard )
+        {
+        connect( curCard, SIGNAL(answersChanged()), SLOT(updateCurCard()) );
+        connect( curCard, SIGNAL(destroyed()), SLOT(invalidateCurCard()) );
+        }
+    setWindowTitle( m_studyName + " - " +
+        static_cast<Dictionary*>(m_model->getCardPack()->dictionary())->shortName() );
+    setStateForNextCard();
+    processState();
+}
+
+void IStudyWindow::setStateForNextCard()
+    {
+    if( curCard )
+        state = StateAnswerHidden;
+    else
+        state = StateNoCards;
+    }
+
+void IStudyWindow::showAnswer()
+    {
+    answerStackedLt->setCurrentIndex( AnsLabelPage );
+    if( state == StateAnswerHidden )
+        state = StateAnswerVisible;
+    else
+        return;
+    processState();
+    }
+
+void IStudyWindow::updateCurCard()
+{
+    if( curCard )
+        disconnect( curCard, 0, this, 0 );
+    curCard = m_model->getCurCard();
+    if( curCard )
+        {
+        connect( curCard, SIGNAL(answersChanged()), SLOT(updateCurCard()) );
+        connect( curCard, SIGNAL(destroyed()), SLOT(invalidateCurCard()) );
+        }
+    setWindowTitle( m_studyName + " - " +
+        static_cast<Dictionary*>(m_model->getCardPack()->dictionary())->shortName() );
+    int origState = state;
+    if( state == StateAnswerHidden || state == StateAnswerVisible )
+        {
+        state = StateAnswerHidden;
+        processState();
+        }
+    if( origState == StateAnswerVisible )
+        {
+        state = StateAnswerVisible;
+        processState();
+        }
+}
+
+QString IStudyWindow::ShortcutToStr( QAbstractButton* aButton )
+{
+    return " (" + aButton->shortcut().toString( QKeySequence::NativeText ) + ")";
+}
+
+void IStudyWindow::updateToolBarVisibility(int index)
+{
+    bool visible = (index == CardPage);
+    deleteCardBtn->setVisible(visible);
+    editCardBtn->setVisible(visible);
+}
diff --git a/src/study/IStudyWindow.h b/src/study/IStudyWindow.h
new file mode 100644
index 0000000..1f0bd0d
--- /dev/null
+++ b/src/study/IStudyWindow.h
@@ -0,0 +1,107 @@
+#ifndef ISTUDYWINDOW_H
+#define ISTUDYWINDOW_H
+
+#include <QtCore>
+#include <QtWidgets>
+
+#include "../main-view/AppModel.h"
+
+class IStudyModel;
+class Card;
+class Dictionary;
+class QProgressBar;
+class CardSideView;
+class DictTableView;
+class CardEditDialog;
+
+class IStudyWindow: public QWidget
+{
+    Q_OBJECT
+
+protected:
+    enum
+        {
+        StateAnswerHidden,
+        StateAnswerVisible,
+        StateNoCards,
+        StatesNum
+        };
+
+public:
+    IStudyWindow(IStudyModel* aModel, QString aStudyName, QWidget* aParent);
+    virtual ~IStudyWindow();
+
+    AppModel::StudyType getStudyType() const { return studyType; }
+    IStudyModel* studyModel() const { return m_model; }
+    const DictTableView* cardEditView() const;
+
+protected:
+    void createUI();
+    virtual QVBoxLayout* createLowerPanel() = 0;
+    virtual void setStateForNextCard();
+    virtual void processState() = 0;
+    virtual void ReadSettings() = 0;
+    virtual QWidget* getAnswerEdit() { return NULL; }
+    virtual QWidget* getUserAnswerLabel() { return NULL; }
+    QString ShortcutToStr( QAbstractButton* aButton );
+    bool bigScreen() { return QApplication::desktop()->screenGeometry().height()> 250; }
+
+private:
+    QVBoxLayout* createMessageLayout();
+    QLabel* createMessageLabel();
+    QWidget* createWrapper(QBoxLayout* layout);
+    QPushButton* createClosePackButton();
+    QHBoxLayout* createUpperPanel();
+    QToolButton* createEditCardButton();
+    QToolButton* createDeleteCardButton();
+    QVBoxLayout* createCardView();    
+    QBoxLayout* createAnswerButtonLayout();
+    QPushButton* createAnswerButton();
+    QBoxLayout* createAnswerLayout();
+
+protected slots:
+    void OnDictionaryRemoved();
+    void showNextCard();    ///< Entry point for showing a new card
+    void showAnswer();      ///< Entry point for showing the answer
+    void updateCurCard();   ///< Update the card after pack re-generation
+    void invalidateCurCard() { curCard = NULL; }
+    void openCardEditDialog();
+    void deleteCard();
+    void updateToolBarVisibility(int index);
+    
+protected:
+    static const int AnsButtonPage;
+    static const int AnsLabelPage;
+    static const int CardPage;
+    static const int MessagePage;
+
+    AppModel::StudyType studyType;
+    IStudyModel* m_model;
+    const Card* curCard;
+    int state;
+
+    QString m_studyName;
+    QToolButton* editCardBtn;
+    QToolButton* deleteCardBtn;
+
+    QStackedLayout* centralStackedLt;
+    QLabel* messageLabel;
+
+    QStackedLayout* answerStackedLt;
+    QPushButton* answerBtn;
+    CardSideView* questionLabel;
+    CardSideView* answerLabel;
+
+private:
+    static const int MinWidth = 500;
+    static const int MaxWidth = 800;
+    static const int ToolBarButtonSize = 24;
+    static const int ToolBarIconSize = 16;
+    static const int BigButtonWidth = 160;
+    static const int BigButtonHeight = 50;
+
+    QWidget* m_parentWidget;
+    CardEditDialog* m_cardEditDialog;
+};
+
+#endif
diff --git a/src/study/NumberFrame.cpp b/src/study/NumberFrame.cpp
new file mode 100644
index 0000000..1d2a2e1
--- /dev/null
+++ b/src/study/NumberFrame.cpp
@@ -0,0 +1,40 @@
+#include "NumberFrame.h"
+
+NumberFrame::NumberFrame(QWidget* parent):
+    QLabel(parent)
+{
+    init();
+}
+
+void NumberFrame::init()
+{
+    setMinimumSize(MinWidth, MinHeight);
+    setAlignment(Qt::AlignCenter);
+    setFrameShape(QFrame::NoFrame);
+}
+
+void NumberFrame::setColor(const QColor& color)
+{
+    setPalette(QPalette(color));
+}
+
+void NumberFrame::setValue(int value)
+{
+    setMinimumWidth(value >= 100? MinWidth100: MinWidth);
+    setVisible(value > 0);
+    setText(QString::number(value));
+}
+
+void NumberFrame::paintEvent(QPaintEvent* event)
+{
+    QPainter painter(this);
+    painter.setRenderHint(QPainter::Antialiasing);
+
+    QPen pen("#7c7c7c");
+    pen.setWidthF(0.5);
+    painter.setPen(pen);
+    painter.setBrush(QBrush(palette().color(QPalette::Button)));
+    painter.drawRoundedRect(rect().adjusted(1, 1, -1, -1), Radius, Radius);
+
+    QLabel::paintEvent(event);
+}
diff --git a/src/study/NumberFrame.h b/src/study/NumberFrame.h
new file mode 100644
index 0000000..44161ca
--- /dev/null
+++ b/src/study/NumberFrame.h
@@ -0,0 +1,29 @@
+#ifndef NUMBER_FRAME_H
+#define NUMBER_FRAME_H
+
+#include <QtWidgets>
+
+class NumberFrame: public QLabel
+{
+public:
+    static const int MinWidth = 40;
+    static const int MinWidth100 = 50;
+
+public:
+    NumberFrame(QWidget* parent = 0);
+    void setColor(const QColor& color);
+    void setValue(int value);
+
+protected:
+    void paintEvent(QPaintEvent* event);
+
+private:
+    static const int Radius = 7;
+    static const int MinHeight = 16;
+
+private:
+    void init();
+
+};
+
+#endif
diff --git a/src/study/SpacedRepetitionModel.cpp b/src/study/SpacedRepetitionModel.cpp
new file mode 100644
index 0000000..e10299a
--- /dev/null
+++ b/src/study/SpacedRepetitionModel.cpp
@@ -0,0 +1,390 @@
+#include "SpacedRepetitionModel.h"
+
+#include <time.h>
+#include <QtDebug>
+#include <QtCore>
+
+#include "../dictionary/Dictionary.h"
+#include "../dictionary/Card.h"
+#include "../dictionary/CardPack.h"
+#include "../utils/IRandomGenerator.h"
+#include "../utils/TimeProvider.h"
+
+SpacedRepetitionModel::SpacedRepetitionModel(CardPack* aCardPack, IRandomGenerator* random):
+    IStudyModel(aCardPack),
+    curCard(NULL), settings(StudySettings::inst()), random(random)
+    {
+    srand(time(NULL));
+    curCardNum = 0;
+    connect(aCardPack, SIGNAL(cardsGenerated()), SLOT(updateStudyState()));
+    updateStudyState();
+    }
+
+SpacedRepetitionModel::~SpacedRepetitionModel()
+    {
+    saveStudy();
+	delete random;
+    }
+
+void SpacedRepetitionModel::saveStudy()
+    {
+    if(!cardPack)
+        return;
+    if(!cardPack->dictionary())
+        return;
+    cardPack->dictionary()->saveStudy();
+    }
+
+// Called after all cards are generated
+void SpacedRepetitionModel::updateStudyState()
+    {
+    curCard = cardPack->getCard( cardPack->findLastReviewedCard() );
+    curCardNum = 0;
+    if( !cardPack->curCardName().isEmpty() )
+        {
+        prevCard = curCard;
+        curCard = cardPack->getCard( cardPack->curCardName() );
+        if( curCard )
+            {
+            answerTime.start();
+            emit curCardUpdated();
+            }
+        else
+            {
+            curCard = prevCard;
+            pickNextCardAndNotify();
+            }
+        }
+    else
+        pickNextCardAndNotify();
+    }
+
+void SpacedRepetitionModel::scheduleCard(int newGrade)
+    {
+    if(!curCard)
+        return;
+    saveStudyRecord(createNewStudyRecord(newGrade));
+    curCardNum++;
+    pickNextCardAndNotify();
+    }
+
+StudyRecord SpacedRepetitionModel::createNewStudyRecord(int newGrade)
+{
+    StudyRecord prevStudy = curCard->getStudyRecord();
+    StudyRecord newStudy;
+
+    newStudy.grade = newGrade;
+    newStudy.level = getNewLevel(prevStudy, newGrade);
+    newStudy.easiness = getNewEasiness(prevStudy, newGrade);
+    newStudy.interval = getNextInterval(prevStudy, newStudy);
+    newStudy.date = TimeProvider::get();
+    newStudy.setRecallTime(curRecallTime / 1000.);
+    newStudy.setAnswerTime(answerTime.elapsed() / 1000.);
+    return newStudy;
+}
+
+int SpacedRepetitionModel::getNewLevel(const StudyRecord& prevStudy, int newGrade)
+{
+    int level = prevStudy.level;
+    switch(newGrade)
+    {
+    case StudyRecord::Unknown:
+    case StudyRecord::Incorrect:
+        level = StudyRecord::ShortLearning;
+        break;
+    case StudyRecord::Difficult:
+    case  StudyRecord::Good:
+        if(prevStudy.isOneDayOld())
+            level = StudyRecord::Repeating;
+        else
+            level++;
+        break;
+    case  StudyRecord::Easy:
+        level += 2;
+        break;
+    }
+    if(level > StudyRecord::LongLearning)
+        level = StudyRecord::Repeating;
+    return level;
+}
+
+double SpacedRepetitionModel::getNewEasiness(const StudyRecord& prevStudy,
+        int newGrade)
+{
+    switch(prevStudy.level)
+    {
+    case StudyRecord::ShortLearning:
+    case StudyRecord::LongLearning:
+        if(prevStudy.isOneDayOld())
+            return getChangeableEasiness(prevStudy, newGrade);
+        else
+            return prevStudy.easiness;
+    case StudyRecord::Repeating:
+        return getChangeableEasiness(prevStudy, newGrade);
+    default:
+        return prevStudy.easiness;
+    }
+}
+
+double SpacedRepetitionModel::getChangeableEasiness(const StudyRecord& prevStudy,
+        int newGrade) const
+{
+    double eas = prevStudy.easiness;
+    switch(newGrade)
+    {
+    case StudyRecord::Difficult:
+        eas += settings->difficultDelta;
+        break;
+    case StudyRecord::Easy:
+        eas += settings->easyDelta;
+        break;
+    default:
+        return prevStudy.easiness;
+    }
+    return limitEasiness(eas);
+}
+
+double SpacedRepetitionModel::limitEasiness(double eas) const
+{
+    if(eas < settings->minEasiness)
+        eas = settings->minEasiness;
+    else if(eas > settings->maxEasiness)
+        eas = settings->maxEasiness;
+    return eas;
+}
+
+double SpacedRepetitionModel::getNextInterval(const StudyRecord& prevStudy,
+        const StudyRecord& newStudy)
+{
+    switch(newStudy.level)
+    {
+    case StudyRecord::ShortLearning:
+        if(newStudy.grade == StudyRecord::Incorrect)
+            return settings->incorrectInterval;
+        else
+            return settings->unknownInterval;
+    case StudyRecord::LongLearning:
+        return settings->learningInterval;
+    case StudyRecord::Repeating:
+        return getNextRepeatingInterval(prevStudy, newStudy);
+    default:
+        return 0;
+    }
+}
+
+double SpacedRepetitionModel::getNextRepeatingInterval(const StudyRecord& prevStudy,
+        const StudyRecord& newStudy)
+{
+    switch(prevStudy.level)
+    {
+    case StudyRecord::ShortLearning:
+        return getNextRepeatingIntervalForShortLearning(prevStudy, newStudy);
+    case StudyRecord::LongLearning:
+        return getNextRepeatingIntervalForLongLearning(prevStudy, newStudy);
+    case StudyRecord::Repeating:
+        return getIncreasedInterval(prevStudy.interval, newStudy.easiness);
+    default:
+        return settings->nextDayInterval;
+    }
+}
+
+double SpacedRepetitionModel::getIncreasedInterval(double prevInterval,
+        double newEasiness)
+{
+    double interval = prevInterval * newEasiness;
+    interval += interval *
+            settings->schedRandomness * random->getInRange_11();
+    return interval;
+}
+
+double SpacedRepetitionModel::getNextRepeatingIntervalForShortLearning(
+        const StudyRecord& prevStudy,
+        const StudyRecord& newStudy)
+{
+    if(prevStudy.isOneDayOld())
+        return getIncreasedInterval(settings->nextDayInterval, newStudy.easiness);
+    else
+        return settings->nextDayInterval;
+}
+
+double SpacedRepetitionModel::getNextRepeatingIntervalForLongLearning(
+        const StudyRecord& prevStudy,
+        const StudyRecord& newStudy)
+{
+    if(prevStudy.isOneDayOld())
+        return getIncreasedInterval(settings->nextDayInterval, newStudy.easiness);
+    else if(newStudy.grade == StudyRecord::Easy)
+        return settings->twoDaysInterval;
+    else
+        return settings->nextDayInterval;
+}
+
+void SpacedRepetitionModel::saveStudyRecord(const StudyRecord& newStudy)
+{
+    cardPack->addStudyRecord(curCard->getQuestion(), newStudy);
+}
+
+QList<int> SpacedRepetitionModel::getAvailableGrades() const
+{
+    if(!curCard)
+        return {};
+    StudyRecord study = curCard->getStudyRecord();
+    switch(study.level)
+    {
+    case StudyRecord::New:
+        return {4, 5};
+    case StudyRecord::ShortLearning:
+    case StudyRecord::LongLearning:
+        if(study.isOneDayOld())
+            return {1, 2, 3, 4, 5};
+        else
+            return {1, 2, 4, 5};
+    case StudyRecord::Repeating:
+        return {1, 2, 3, 4, 5};
+    default:
+        return {};
+    }
+}
+
+bool SpacedRepetitionModel::isNew() const
+{
+    return curCard->getStudyRecord().level == StudyRecord::New;
+}
+
+void SpacedRepetitionModel::pickNextCardAndNotify()
+    {
+    answerTime.start();
+    pickNextCard();
+    if(curCard)
+        cardPack->setCurCard(curCard->getQuestion());
+    else
+        cardPack->setCurCard("");
+    // Notify the study window to show the selected card.
+    emit nextCardSelected();
+    }
+
+void SpacedRepetitionModel::pickNextCard()
+{
+    prevCard = curCard;
+    curCard = NULL;
+    pickActiveCard() ||
+        pickNewCard() ||
+        pickLearningCard();
+}
+
+bool SpacedRepetitionModel::mustRandomPickScheduledCard() const
+{
+    return random->getInRange_01() > settings->newCardsShare;
+}
+
+bool SpacedRepetitionModel::reachedNewCardsDayLimit() const
+{
+    return cardPack->getTodayNewCardsNum() >= settings->newCardsDayLimit;
+}
+
+bool SpacedRepetitionModel::pickActiveCard()
+{
+    QStringList activeCards = cardPack->getActiveCards();
+    if(activeCards.isEmpty())
+        return false;
+    if(pickPriorityActiveCard())
+        return true;
+    if(!mustPickScheduledCard())
+        return false;
+    curCard = cardPack->getCard(getRandomStr(activeCards));
+    return true;
+}
+
+bool SpacedRepetitionModel::pickPriorityActiveCard()
+{
+    QStringList priorityCards = cardPack->getPriorityActiveCards();
+    if(priorityCards.isEmpty())
+        return false;
+    QStringList smallestIntervals = cardPack->getSmallestIntervalCards(priorityCards);
+    curCard = cardPack->getCard(getRandomStr(smallestIntervals));
+    return true;
+}
+
+bool SpacedRepetitionModel::mustPickScheduledCard()
+{
+    bool noNewCards = cardPack->getNewCards().isEmpty();
+    if(noNewCards || reachedNewCardsDayLimit() ||
+        tooManyScheduledCards())
+        return true;
+    else
+        return mustRandomPickScheduledCard();
+}
+
+bool SpacedRepetitionModel::tooManyScheduledCards() const
+{
+    return cardPack->countScheduledForTodayCards() >= settings->limitForAddingNewCards;
+}
+
+bool SpacedRepetitionModel::pickNewCard()
+    {
+    if(reachedNewCardsDayLimit())
+        return false;
+    QStringList newCards = cardPack->getNewCards();
+    if(newCards.isEmpty())
+        return false;
+    QString cardName;
+    if(settings->showRandomly)
+        cardName = getRandomStr(newCards);
+    else
+        cardName = newCards.first();
+    curCard = cardPack->getCard(cardName);
+    return true;
+    }
+
+bool SpacedRepetitionModel::pickLearningCard()
+{
+    QStringList learningCards = cardPack->getLearningCards();
+    if(learningCards.isEmpty())
+        return false;
+    QStringList smallestIntervals = cardPack->getSmallestIntervalCards(learningCards);
+    curCard = cardPack->getCard(getRandomStr(smallestIntervals));
+    return true;
+}
+
+QString SpacedRepetitionModel::getRandomStr(const QStringList& list) const
+{
+    return list.at(random->getRand(list.size()));
+}
+
+/// New cards inside the reviewed ones still today
+int SpacedRepetitionModel::estimatedNewReviewedCardsToday() const
+    {
+    if(tooManyScheduledCards())
+        return 0;
+    int scheduledToday = cardPack->countScheduledForTodayCards();
+    int newRev = 0;
+    if( scheduledToday > 0 )
+        {
+        float newShare = settings->newCardsShare;
+        newRev = qRound( scheduledToday * newShare );
+        }
+    else
+        return 0;
+    
+    // Check for remained new cards in pack
+    int newCardsNum = cardPack->getNewCards().size();
+    if( newRev > newCardsNum )
+        newRev = newCardsNum;
+    
+    // Check for new cards day limit
+    int newCardsDayLimit = settings->newCardsDayLimit;
+    int todayReviewedNewCards = cardPack->getTodayNewCardsNum();
+    int remainedNewCardsLimit = newCardsDayLimit - todayReviewedNewCards;
+    if( newRev > remainedNewCardsLimit )
+        newRev = remainedNewCardsLimit;
+    
+    return newRev;
+    }
+
+/** Calculates number of candidate cards to be shown in the current session.
+  */
+int SpacedRepetitionModel::countTodayRemainingCards() const
+    {
+    int timeTriggered = cardPack->getActiveCards().size();
+    return timeTriggered + estimatedNewReviewedCardsToday();
+    }
diff --git a/src/study/SpacedRepetitionModel.h b/src/study/SpacedRepetitionModel.h
new file mode 100644
index 0000000..d39a1b8
--- /dev/null
+++ b/src/study/SpacedRepetitionModel.h
@@ -0,0 +1,79 @@
+#ifndef SPACEDREPETITIONMODEL_H
+#define SPACEDREPETITIONMODEL_H
+
+#include "IStudyModel.h"
+#include "StudyRecord.h"
+#include "StudySettings.h"
+
+#include <QMultiMap>
+#include <QTime>
+
+class CardPack;
+class IRandomGenerator;
+
+class SpacedRepetitionModel: public IStudyModel
+{
+    Q_OBJECT
+
+public:
+    static const int NewCardsDayLimit = 10;
+
+public:
+    SpacedRepetitionModel(CardPack* aCardPack, IRandomGenerator* random);
+    ~SpacedRepetitionModel();
+
+public:
+    Card* getCurCard() const { return curCard; }
+    QList<int> getAvailableGrades() const;
+    bool isNew() const;
+    void setRecallTime( int aTime ) { curRecallTime = aTime; }
+    int estimatedNewReviewedCardsToday() const;
+    int countTodayRemainingCards() const;
+
+public slots:
+    void scheduleCard(int newGrade);
+
+protected:
+    void pickNextCardAndNotify();
+
+private:
+    StudyRecord createNewStudyRecord(int newGrade);
+    int getNewLevel(const StudyRecord& prevStudy, int newGrade);
+    double getNewEasiness(const StudyRecord& prevStudy, int newGrade);
+    double getChangeableEasiness(const StudyRecord& prevStudy, int newGrade) const;
+    double limitEasiness(double eas) const;
+    double getNextInterval(const StudyRecord& prevStudy,
+            const StudyRecord& newStudy);
+    double getNextRepeatingInterval(const StudyRecord& prevStudy,
+            const StudyRecord& newStudy);
+    double getIncreasedInterval(double prevInterval, double newEasiness);
+    double getNextRepeatingIntervalForShortLearning(
+            const StudyRecord& prevStudy, const StudyRecord& newStudy);
+    double getNextRepeatingIntervalForLongLearning(
+            const StudyRecord& prevStudy, const StudyRecord& newStudy);
+    void saveStudyRecord(const StudyRecord& newStudy);
+    void pickNextCard();
+    bool pickNewCard();
+    QString getRandomStr(const QStringList& list) const;
+    bool reachedNewCardsDayLimit() const;
+    bool mustPickScheduledCard();
+    bool tooManyScheduledCards() const;
+    bool mustRandomPickScheduledCard() const;
+    bool pickActiveCard();
+    bool pickPriorityActiveCard();
+    bool pickLearningCard();
+    void saveStudy();
+    
+private slots:
+    void updateStudyState();
+
+private:
+    Card* curCard;   ///< The card selected for repetition
+    Card* prevCard;  ///< Previous reviewed card. Found in the study history.
+    int curRecallTime;        ///< Recall time of the current card, ms
+    QTime answerTime;        ///< Full answer time of the current card: recall + evaluation, ms    
+    StudySettings* settings;
+    IRandomGenerator* random;
+};
+
+#endif
diff --git a/src/study/SpacedRepetitionWindow.cpp b/src/study/SpacedRepetitionWindow.cpp
new file mode 100644
index 0000000..977b1ec
--- /dev/null
+++ b/src/study/SpacedRepetitionWindow.cpp
@@ -0,0 +1,380 @@
+#include "SpacedRepetitionWindow.h"
+#include "CardsStatusBar.h"
+#include "NumberFrame.h"
+#include "WarningPanel.h"
+#include "../dictionary/Dictionary.h"
+#include "../dictionary/Card.h"
+#include "../dictionary/CardPack.h"
+
+SpacedRepetitionWindow::SpacedRepetitionWindow( SpacedRepetitionModel* aModel, QWidget* aParent ):
+    IStudyWindow( aModel, tr("Spaced repetition"), aParent ),
+    exactAnswerLabel(NULL), exactAnswerEdit(NULL)
+{
+    usesExactAnswer = m_model->getCardPack()->getUsesExactAnswer();
+    studyType = AppModel::SpacedRepetition;
+    if(usesExactAnswer)
+        createExactAnswerWidget();
+    createUI(); // Can't call from parent constructor
+    setWindowIcon( QIcon(":/images/spaced-rep.png") );
+    dayCardsLimitShown = false;
+    showNextCard();
+}
+
+SpacedRepetitionWindow::~SpacedRepetitionWindow()
+{
+    WriteSettings();
+}
+
+void SpacedRepetitionWindow::createExactAnswerWidget()
+{
+    exactAnswerEdit = new QLineEdit;
+
+    exactAnswerLabel = new CardSideView;
+    exactAnswerLabel->setMaximumHeight(40);
+    exactAnswerLabel->setShowMode(CardSideView::AnsMode);
+    exactAnswerLabel->setPack(m_model->getCardPack());
+}
+
+QVBoxLayout* SpacedRepetitionWindow::createLowerPanel()
+{
+    warningPanel = new WarningPanel;
+
+    controlLt = new QVBoxLayout;
+    controlLt->addWidget(warningPanel);
+    controlLt->addLayout(createProgressLayout());
+    controlLt->addLayout(new QVBoxLayout);  // Grades layout
+
+    createGradeButtons();
+
+    return controlLt;
+}
+
+QBoxLayout* SpacedRepetitionWindow::createProgressLayout()
+{
+    QVBoxLayout* lt = new QVBoxLayout;
+    lt->setSpacing(3);
+    lt->addLayout(createStatsLayout());
+    lt->addLayout(createProgressBarLayout());
+    return lt;
+}
+
+QBoxLayout* SpacedRepetitionWindow::createStatsLayout()
+{
+    todayNewLabel = new NumberFrame;
+    todayNewLabel->setToolTip(tr("Today learned new cards"));
+    todayNewLabel->setColor("#c0d6ff");
+
+    learningCardsLabel = new NumberFrame;
+    learningCardsLabel->setToolTip(tr("Scheduled learning reviews:\n"
+            "new cards must be repeated today to learn"));
+    learningCardsLabel->setColor(CardsStatusBar::Colors[1]);
+
+    timeToNextLearningLabel = new QLabel;
+    timeToNextLearningLabel->setToolTip(tr("Time left to the next learning review"));
+
+    scheduledCardsLabel = new NumberFrame;
+    scheduledCardsLabel->setToolTip(tr("Scheduled cards for today"));
+    scheduledCardsLabel->setColor(CardsStatusBar::Colors[2]);
+
+    scheduledNewLabel = new NumberFrame;
+    scheduledNewLabel->setToolTip(tr("New scheduled cards for today:\n"
+            "new cards that will be shown between the scheduled ones"));
+    scheduledNewLabel->setColor("#bd8d71");
+
+    QHBoxLayout* lt = new QHBoxLayout;
+    lt->setSpacing(5);
+    lt->addWidget(todayNewLabel);
+    lt->addStretch();
+    lt->addWidget(learningCardsLabel);
+    lt->addWidget(timeToNextLearningLabel);
+    lt->addWidget(scheduledCardsLabel);
+    lt->addWidget(scheduledNewLabel);
+    return lt;
+}
+
+QBoxLayout* SpacedRepetitionWindow::createProgressBarLayout()
+{
+    progressLabel = new QLabel;
+    progressLabel->setToolTip(getProgressBarTooltip());
+
+    coloredProgressBar = new CardsStatusBar;
+    coloredProgressBar->setToolTip(progressLabel->toolTip());
+
+    QHBoxLayout* lt = new QHBoxLayout;
+    lt->setSpacing(5);
+    lt->addWidget(progressLabel);
+    lt->addWidget(coloredProgressBar);
+    return lt;
+}
+
+QString SpacedRepetitionWindow::getProgressBarTooltip()
+{
+    QString boxSpace;
+    for(int i = 0; i < 6; i++)
+        boxSpace += "&nbsp;";
+    QString colorBoxPattern = "<p><span style=\"background-color: %1;\">" +
+            boxSpace + "</span> &nbsp;";
+    QString pEnd = "</p>";
+
+    QStringList legendLines = {
+        tr("Reviewed cards"),
+        tr("Learning reviews"),
+        tr("Scheduled cards"),
+        tr("New cards for today")};
+    QString legend;
+    for(int i = 0; i < 4; i++)
+        legend += colorBoxPattern.arg(CardsStatusBar::Colors[i]) + legendLines[i] + pEnd;
+    return tr("Progress of reviews scheduled for today:") + legend;
+}
+
+void SpacedRepetitionWindow::createGradeButtons()
+{
+    cardGradedSM = new QSignalMapper(this);
+    connect( cardGradedSM, SIGNAL(mapped(int)),
+        qobject_cast<SpacedRepetitionModel*>(m_model), SLOT(scheduleCard(int)) );
+
+    gradeBtns[0] = createGradeButton(0, "question.png", tr("Unknown"),
+            tr("Completely forgotten card, couldn't recall the answer."));
+    gradeBtns[1] = createGradeButton(1, "red-stop.png", tr("Incorrect"),
+            tr("The answer is incorrect."));
+    gradeBtns[2] = createGradeButton(2, "blue-triangle-down.png", tr("Difficult"),
+            tr("It's difficult to recall the answer. The last interval was too long."));
+    gradeBtns[3] = createGradeButton(3, "green-tick.png", tr("Good"),
+            tr("The answer is recalled in couple of seconds. The last interval was good enough."));
+    gradeBtns[4] = createGradeButton(4, "green-triangle-up.png", tr("Easy"),
+            tr("The card is too easy, and recalled without any effort. The last interval was too short."));
+    goodBtn = gradeBtns[StudyRecord::Good - 1];
+}
+
+QPushButton* SpacedRepetitionWindow::createGradeButton(int i, const QString& iconName,
+        const QString& label, const QString& toolTip)
+{
+    QPushButton* btn = new QPushButton;
+    btn->setIcon(QIcon(":/images/" + iconName));
+    btn->setText(QString("%1 %2").arg(i + 1).arg(label));
+    btn->setToolTip("<p>" + toolTip);
+    btn->setShortcut( QString::number(i + 1) );
+    btn->setMinimumWidth(GradeButtonMinWidth);
+
+#if defined(Q_OS_WIN)
+    QFont font = btn->font();
+    font.setPointSize(12);
+    font.setFamily("Calibri");
+    btn->setFont(font);
+#endif
+
+    cardGradedSM->setMapping(btn, i + 1);
+    connect(btn, SIGNAL(clicked()), cardGradedSM, SLOT(map()));
+    return btn;
+}
+
+void SpacedRepetitionWindow::processState()
+{
+    setEnabledGradeButtons();
+    switch(state)
+        {
+        case StateAnswerHidden:
+            displayQuestion();
+            break;
+        case StateAnswerVisible:
+            displayAnswer();
+            break;
+        case StateNoCards:        
+            updateCardsProgress();
+            displayNoRemainedCards();
+            break;
+        }
+}
+
+void SpacedRepetitionWindow::setEnabledGradeButtons()
+{
+    for(int i = 0; i < StudyRecord::GradesNum; i++)
+        gradeBtns[i]->setEnabled(state == StateAnswerVisible);
+}
+
+void SpacedRepetitionWindow::displayQuestion()
+{
+    questionLabel->setQuestion( m_model->getCurCard()->getQuestion() );
+    answerStackedLt->setCurrentIndex( AnsButtonPage );
+    updateCardsProgress();
+    layoutGradeButtons();
+    focusAnswerWidget();
+    m_answerTime.start();
+    processIsNewCard();
+}
+
+void SpacedRepetitionWindow::layoutGradeButtons()
+{
+    QHBoxLayout* higherLt = new QHBoxLayout;
+    higherLt->addStretch();
+    putGradeButtonsIntoLayouts(higherLt);
+    higherLt->addStretch();
+    replaceGradesLayout(higherLt);
+    setGoodButtonText();
+}
+
+void SpacedRepetitionWindow::putGradeButtonsIntoLayouts(QBoxLayout* higherLt)
+{
+    QList<int> visibleGrades = static_cast<SpacedRepetitionModel*>(m_model)
+            ->getAvailableGrades();
+    for(int i = 0; i < StudyRecord::GradesNum; i++)
+    {
+        if(!visibleGrades.contains(i + 1))
+        {
+            gradeBtns[i]->setParent(NULL);
+            continue;
+        }
+        higherLt->addWidget(gradeBtns[i]);
+    }
+}
+
+void SpacedRepetitionWindow::replaceGradesLayout(QBoxLayout* higherLt)
+{
+    const int GradesLtIndex = 2;
+    delete controlLt->takeAt(GradesLtIndex);
+    controlLt->insertLayout(GradesLtIndex, higherLt);
+}
+
+void SpacedRepetitionWindow::setGoodButtonText()
+{
+    QList<int> visibleGrades = static_cast<SpacedRepetitionModel*>(m_model)
+            ->getAvailableGrades();
+    QString goodLabel = visibleGrades.size() == StudyRecord::GradesNum?
+                tr("Good") : tr("OK");
+    goodBtn->setText(QString("%1 %2").arg(StudyRecord::Good).arg(goodLabel));
+    goodBtn->setShortcut(QString::number(StudyRecord::Good));
+}
+
+void SpacedRepetitionWindow::focusAnswerWidget()
+{
+    if(usesExactAnswer)
+    {
+        exactAnswerEdit->clear();
+        exactAnswerEdit->setFocus();
+    }
+    else
+        answerBtn->setFocus();
+}
+
+void SpacedRepetitionWindow::processIsNewCard()
+{
+    questionLabel->showNewIcon(static_cast<SpacedRepetitionModel*>(m_model)->isNew());
+}
+
+void SpacedRepetitionWindow::displayAnswer()
+{
+    static_cast<SpacedRepetitionModel*>(m_model)->setRecallTime(m_answerTime.elapsed());
+    Card* card = m_model->getCurCard();
+    QStringList correctAnswers = card->getAnswers();
+    answerStackedLt->setCurrentIndex(AnsLabelPage);
+    if(usesExactAnswer)
+        showExactAnswer(correctAnswers);
+    answerLabel->setQstAnsr(card->getQuestion(), correctAnswers);
+    goodBtn->setFocus();
+}
+
+void SpacedRepetitionWindow::showExactAnswer(const QStringList& correctAnswers)
+{
+    if(static_cast<SpacedRepetitionModel*>(m_model)->isNew())
+    {
+        exactAnswerLabel->hide();
+        return;
+    }
+    else
+        exactAnswerLabel->show();
+    bool isCorrect = correctAnswers.first() == exactAnswerEdit->text().trimmed();
+    QString beginning("<span style=\"");
+    beginning += QString("color:%1").arg(isCorrect ? "green" : "red");
+    beginning += "\">";
+    QString answer = beginning + exactAnswerEdit->text() + "</span>";
+    exactAnswerLabel->setQstAnsr("", {answer});
+}
+
+void SpacedRepetitionWindow::updateCardsProgress()
+    {
+    CardPack* pack = m_model->getCardPack();
+    int todayReviewed = pack->getTodayReviewedCardsNum();
+    int todayNewReviewed = pack->getTodayNewCardsNum();
+    int activeRepeating = pack->getActiveRepeatingCardsNum();
+    int learningReviews = pack->getLearningReviewsNum();
+    int timeToNextLearning = pack->getTimeToNextLearning();
+    int scheduledNew = static_cast<SpacedRepetitionModel*>(m_model)->
+            estimatedNewReviewedCardsToday();
+    int allTodaysCards = todayReviewed + learningReviews +
+            activeRepeating + scheduledNew;
+
+    todayNewLabel->setVisible(todayNewReviewed > 0);
+    todayNewLabel->setValue(todayNewReviewed);
+    learningCardsLabel->setValue(learningReviews);
+
+    int minsToNextLearning = timeToNextLearning / 60;
+    timeToNextLearningLabel->setVisible(minsToNextLearning > 0);
+    timeToNextLearningLabel->setText(tr("(%1 min)").
+            arg(minsToNextLearning));
+
+    scheduledCardsLabel->setValue(activeRepeating);
+    scheduledNewLabel->setValue(scheduledNew);
+
+    progressLabel->setText(QString("%1/%2").
+            arg(todayReviewed).arg(allTodaysCards));
+    coloredProgressBar->setValues({todayReviewed, learningReviews,
+            activeRepeating, scheduledNew});
+
+    showLimitWarnings();
+}
+
+void SpacedRepetitionWindow::showLimitWarnings()
+{
+    if(warningPanel->isVisible())
+        return;
+    CardPack* pack = m_model->getCardPack();
+    if(dayLimitReached(pack->dictionary()->countTodaysAllCards()))
+    {
+        warningPanel->setText(tr("Day cards limit is reached: %1 cards.\n"
+            "It is recommended to stop studying this dictionary.")
+            .arg(StudySettings::inst()->cardsDayLimit));
+        warningPanel->show();
+        dayCardsLimitShown = true;
+    }
+}
+
+bool SpacedRepetitionWindow::dayLimitReached(int todayReviewed)
+{
+    return todayReviewed >= StudySettings::inst()->cardsDayLimit &&
+        !dayCardsLimitShown;
+}
+
+void SpacedRepetitionWindow::displayNoRemainedCards()
+{
+    centralStackedLt->setCurrentIndex(MessagePage);
+    messageLabel->setText(
+        QString("<div align=\"center\" style=\"font-size: 22pt; font-weight: bold\">") +
+        tr("All cards are reviewed") +
+        "</div>" + "<p align=\"center\" style=\"font-size: 11pt\">" +
+        tr("You can go to the next pack or dictionary, or open the Word drill.") +
+        "</p>");
+}
+
+void SpacedRepetitionWindow::ReadSettings()
+{
+    QSettings settings;
+    move( settings.value("spacedrep-pos", QPoint(PosX, PosY)).toPoint() );
+    resize( settings.value("spacedrep-size", QSize(Width, Height)).toSize() );
+}
+
+void SpacedRepetitionWindow::WriteSettings()
+{
+    QSettings settings;
+    settings.setValue("spacedrep-pos", pos());
+    settings.setValue("spacedrep-size", size());
+}
+
+QWidget* SpacedRepetitionWindow::getAnswerEdit()
+{
+    return exactAnswerEdit;
+}
+
+QWidget* SpacedRepetitionWindow::getUserAnswerLabel()
+{
+    return exactAnswerLabel;
+}
diff --git a/src/study/SpacedRepetitionWindow.h b/src/study/SpacedRepetitionWindow.h
new file mode 100644
index 0000000..942b7f2
--- /dev/null
+++ b/src/study/SpacedRepetitionWindow.h
@@ -0,0 +1,89 @@
+#ifndef SPACED_REPETITION_WINDOW_H
+#define SPACED_REPETITION_WINDOW_H
+
+#include <QtCore>
+#include <QtWidgets>
+
+#include "IStudyWindow.h"
+#include "StudyRecord.h"
+#include "StudySettings.h"
+#include "SpacedRepetitionModel.h"
+#include "CardSideView.h"
+
+class CardsStatusBar;
+class NumberFrame;
+class WarningPanel;
+
+class SpacedRepetitionWindow: public IStudyWindow
+{
+    Q_OBJECT
+    
+public:
+    SpacedRepetitionWindow( SpacedRepetitionModel* aModel, QWidget* aParent );
+    ~SpacedRepetitionWindow();
+
+protected:
+    QVBoxLayout*  createLowerPanel();
+    void processState();
+    void ReadSettings();
+    void WriteSettings();
+    QWidget* getAnswerEdit();
+    QWidget* getUserAnswerLabel();
+
+private:
+    static QString getProgressBarTooltip();
+
+private:
+    QBoxLayout* createProgressLayout();
+    QBoxLayout* createStatsLayout();
+    QBoxLayout* createProgressBarLayout();
+    void createGradeButtons();
+    QPushButton* createGradeButton(int i, const QString& iconName,
+            const QString& label, const QString& toolTip);
+    void setEnabledGradeButtons();
+    void layoutGradeButtons();
+    void putGradeButtonsIntoLayouts(QBoxLayout* higherLt);
+    void replaceGradesLayout(QBoxLayout* higherLt);
+    void setGoodButtonText();
+    void updateCardsProgress();
+    void displayAnswer();
+    void displayNoRemainedCards();
+    void showLimitWarnings();
+    bool dayLimitReached(int todayReviewed);
+    void createExactAnswerWidget();
+    void showExactAnswer(const QStringList& correctAnswers);
+    void focusAnswerWidget();
+    void processIsNewCard();
+
+private slots:
+    void displayQuestion();
+
+private:
+    static const int PosX = 200;
+    static const int PosY = 200;
+    static const int Width = 600;
+    static const int Height = 430;
+    static const int GradeButtonMinWidth = 100;
+
+private:
+    bool dayCardsLimitShown;
+
+    WarningPanel* warningPanel;
+    QLabel* progressLabel;
+    NumberFrame* todayNewLabel;
+    NumberFrame* learningCardsLabel;
+    QLabel* timeToNextLearningLabel;
+    NumberFrame* scheduledCardsLabel;
+    NumberFrame* scheduledNewLabel;
+    QVBoxLayout* controlLt;
+    CardsStatusBar* coloredProgressBar;
+    QPushButton* gradeBtns[StudyRecord::GradesNum];
+    QPushButton* goodBtn;
+    QSignalMapper* cardGradedSM;
+    bool usesExactAnswer;
+    CardSideView* exactAnswerLabel;
+    QLineEdit* exactAnswerEdit;
+    QTime m_answerTime;
+};
+
+#endif
diff --git a/src/study/StudyFileReader.cpp b/src/study/StudyFileReader.cpp
new file mode 100644
index 0000000..ecc4dbf
--- /dev/null
+++ b/src/study/StudyFileReader.cpp
@@ -0,0 +1,238 @@
+#include "StudyFileReader.h"
+#include "../dictionary/Dictionary.h"
+#include "../version.h"
+#include "../dictionary/CardPack.h"
+#include "../dictionary/DicRecord.h"
+
+#include <QMessageBox>
+
+const QString StudyFileReader::MinSupportedStudyVersion = "1.0";
+
+StudyFileReader::StudyFileReader( Dictionary* aDict ):
+    m_dict( aDict ), m_cardPack( NULL )
+    {
+    settings = StudySettings::inst();
+    }
+
+bool StudyFileReader::read( QIODevice* aDevice )
+    {
+    setDevice( aDevice );
+    while( !atEnd() )
+        {
+        readNext();
+        if( isStartElement() )
+            {
+            if( name() == "study" )
+                {
+                readStudy();
+                return !error();    // readStudy() processes all situations
+                }
+            else
+                raiseError( Dictionary::tr("The file is not a study file.") );
+            }
+        }
+    return !error();
+    }
+
+void StudyFileReader::readStudy()
+    {
+    Q_ASSERT( isStartElement() && name() == "study" );
+
+    m_studyVersion = attributes().value( "version" ).toString();
+    if(m_studyVersion >= MinSupportedStudyVersion)
+        readStudyCurrentVersion();
+    else
+        QMessageBox::warning( NULL, Dictionary::tr("Unsupported format"),
+            Dictionary::tr("The study file uses unsupported format %1.\n"
+                        "The minimum supported version is %2" )
+                        .arg( m_studyVersion )
+                        .arg( MinSupportedStudyVersion ) );
+    }
+
+void StudyFileReader::readUnknownElement()
+    {
+    Q_ASSERT( isStartElement() );
+     while( !atEnd() )
+        {
+        readNext();
+        if( isEndElement() )
+            break;
+        if( isStartElement() )
+            readUnknownElement();
+        }
+    }
+
+void StudyFileReader::readStudyCurrentVersion()
+    {
+    Q_ASSERT( isStartElement() && name() == "study" );
+
+    while( !atEnd() )
+        {
+        readNext();
+        if( isEndElement() )
+            break;
+        if( isStartElement() )
+            {
+            if( name() == "pack" )
+                readPack();
+            else
+                readUnknownElement();
+            }
+        }
+    if(m_studyVersion != STUDY_VERSION)
+        m_dict->setStudyModified();
+    }
+
+void StudyFileReader::readPack()
+    {
+    Q_ASSERT( isStartElement() && name() == "pack" );
+
+    QString id = attributes().value( "id" ).toString();
+    m_cardPack = m_dict->cardPack( id );
+    if( !m_cardPack )
+    {
+        skipCurrentElement();
+        return;
+    }
+    m_cardPack->setReadingStudyFile(true);
+
+    while( !atEnd() )
+        {
+        readNext();
+        if( isEndElement() )
+            break;
+        if( isStartElement() )
+            {
+            if( name() == "cur-card" )
+                {
+                Q_ASSERT( m_cardPack->curCardName().isEmpty() );
+                QString curCard = attributes().value( "id" ).toString();
+                if( !curCard.isEmpty() )
+                    m_cardPack->setCurCard( curCard );
+                readNext(); // read end of 'cur-card' element
+                Q_ASSERT( isEndElement() );
+                }
+            else if( name() == "c" )
+                readC();
+            else
+                readUnknownElement();
+            }
+        }
+
+    m_cardPack->setReadingStudyFile(false);
+    }
+
+void StudyFileReader::readC()
+    {
+    Q_ASSERT( isStartElement() && name() == "c" && m_cardPack );
+
+    m_cardId = attributes().value( "id" ).toString();
+
+    while( !atEnd() )
+        {
+        readNext();
+        if( isEndElement() )
+            break;
+        if( isStartElement() )
+            {
+            if( name() == "r" )
+                readR();
+            else
+                readUnknownElement();
+            }
+        }
+    }
+
+void StudyFileReader::readR()
+    {
+    Q_ASSERT( isStartElement() && name() == "r" );
+
+    StudyRecord study;
+    bool ok;    // for number conversions
+
+    QString date = attributes().value( "d" ).toString();
+    study.date = QDateTime::fromString( date, Qt::ISODate );
+
+    QString grade = attributes().value( "g" ).toString();
+    study.grade = grade.toInt( &ok );
+    if(m_studyVersion < "1.4" && study.grade < 3)
+        study.grade++;
+
+    QString easiness = attributes().value( "e" ).toString();
+    study.easiness = easiness.toFloat( &ok );
+    
+    QString time;
+    time = attributes().value( "t" ).toString();    // obsolete parameter
+    if(!time.isEmpty())
+        {
+        study.recallTime = time.toFloat( &ok );
+        Q_ASSERT( ok );
+        }
+
+    time = attributes().value( "rt" ).toString();
+    if(!time.isEmpty())
+        {
+        study.recallTime = time.toFloat( &ok );
+        if( study.recallTime > StudyRecord::MaxAnswerTime )
+            study.recallTime = StudyRecord::MaxAnswerTime;
+        Q_ASSERT( ok );
+        }
+
+    time = attributes().value( "at" ).toString();
+    if(!time.isEmpty())
+        {
+        study.answerTime = time.toFloat( &ok );
+        if( study.answerTime > StudyRecord::MaxAnswerTime )
+            study.answerTime = StudyRecord::MaxAnswerTime;
+        Q_ASSERT( ok );
+        }
+    
+    QString interval = attributes().value( "i" ).toString();
+    QString level = attributes().value( "l" ).toString();
+    if(!interval.isEmpty() && interval != "0")
+        {
+        study.interval = interval.toFloat();
+        if(!level.isEmpty())
+            study.level = level.toInt();
+        else
+            study.level = StudyRecord::Repeating;
+        if(m_studyVersion == "1.4")
+            fixupIncorrectGradeIn1_4(study);
+        }
+    else    // delayed card
+        {
+        QString cardsStr = attributes().value( "c" ).toString();
+        if( !cardsStr.isEmpty() )
+            {
+            int cardInterval = cardsStr.toInt();
+            if(cardInterval <= 7)
+                study.interval = settings->unknownInterval;
+            else
+                study.interval = settings->incorrectInterval;
+            }
+        else
+            study.interval = 0;
+        study.level = StudyRecord::ShortLearning;
+        }
+    
+    m_cardPack->addStudyRecord( m_cardId, study );
+
+    readElementText();  // read until element end
+    }
+
+void StudyFileReader::fixupIncorrectGradeIn1_4(StudyRecord& study)
+{
+    if(!(study.level == StudyRecord::ShortLearning &&
+            study.grade <= 3))
+        return;
+    if(equalDouble(study.interval, settings->unknownInterval))
+        study.grade = StudyRecord::Unknown;
+    else if(equalDouble(study.interval, settings->incorrectInterval))
+        study.grade = StudyRecord::Incorrect;
+}
+
+bool StudyFileReader::equalDouble(double a, double b)
+{
+    static const double Dif = 0.0001;
+    return fabs(a - b) < Dif;
+}
diff --git a/src/study/StudyFileReader.h b/src/study/StudyFileReader.h
new file mode 100644
index 0000000..2466fe3
--- /dev/null
+++ b/src/study/StudyFileReader.h
@@ -0,0 +1,44 @@
+#ifndef STUDYFILEREADER_H
+#define STUDYFILEREADER_H
+
+#include <QXmlStreamReader>
+#include <QList>
+#include <QString>
+
+#include "StudySettings.h"
+#include "StudyRecord.h"
+
+class Dictionary;
+class CardPack;
+class DicRecord;
+
+class StudyFileReader : public QXmlStreamReader
+{
+public:
+    StudyFileReader( Dictionary* aDict );
+    bool read( QIODevice* aDevice );
+
+private:
+    static const QString MinSupportedStudyVersion;
+
+private:
+    void readStudy();
+    void readUnknownElement();
+    void readStudyCurrentVersion();
+    void readPack();
+    void readC();
+    void readR();
+    void fixupIncorrectGradeIn1_4(StudyRecord& study);
+
+private:
+    static bool equalDouble(double a, double b);
+
+private:
+    Dictionary* m_dict;
+    QString m_studyVersion;
+    CardPack* m_cardPack;
+    QString m_cardId;
+    StudySettings* settings;
+};
+
+#endif // STUDYFILEREADER_H
diff --git a/src/study/StudyFileWriter.cpp b/src/study/StudyFileWriter.cpp
new file mode 100644
index 0000000..ab68d6f
--- /dev/null
+++ b/src/study/StudyFileWriter.cpp
@@ -0,0 +1,68 @@
+#include "StudyFileWriter.h"
+#include "StudySettings.h"
+#include "../dictionary/Dictionary.h"
+#include "../version.h"
+#include "../dictionary/CardPack.h"
+
+StudyFileWriter::StudyFileWriter( const Dictionary* aDict ):
+    m_dict( aDict )
+{
+    setAutoFormatting( true );
+}
+
+bool StudyFileWriter::write( QIODevice* aDevice )
+{
+    setDevice( aDevice );
+    writeStartDocument();
+    writeDTD( "<!DOCTYPE freshmemory-study>" );
+    writeStartElement("study");
+    writeAttribute( "version", STUDY_VERSION );
+
+    foreach( CardPack* pack, m_dict->cardPacks() )
+        writePack( pack );
+
+    writeEndDocument();
+    return true;
+}
+
+void StudyFileWriter::writePack( const CardPack* aPack )
+    {
+    QStringList cardIds = aPack->getCardQuestions();
+    if( cardIds.isEmpty() )
+        return; // Don't write empty pack
+    writeStartElement( "pack" );
+    writeAttribute( "id", aPack->id() );
+    if( !aPack->curCardName().isEmpty() )
+        { 
+        writeEmptyElement( "cur-card" );
+        writeAttribute( "id", aPack->curCardName() );
+        }
+    foreach( QString cardId, cardIds )
+        writeCard( cardId, aPack );
+    writeEndElement();
+    }
+
+void StudyFileWriter::writeCard( const QString& aCardId, const CardPack* aPack )
+    {
+    QList<StudyRecord> studyRecords( aPack->getStudyRecords( aCardId ) );
+    if( studyRecords.isEmpty() )   // Don't write cards without records
+        return;
+    writeStartElement( "c" );
+    writeAttribute( "id", aCardId );
+    // Take study records from the list in reverse order. The first is the most recent.
+    QListIterator<StudyRecord> it( studyRecords );
+    it.toBack();
+    while( it.hasPrevious() )
+        {
+        StudyRecord record = it.previous();
+        writeEmptyElement( "r" );
+        writeAttribute( "d", record.date.toString( Qt::ISODate ) );
+        writeAttribute( "l", QString::number( record.level ) );
+        writeAttribute( "g", QString::number( record.grade ) );
+        writeAttribute( "e", QString::number( record.easiness ) );
+        writeAttribute( "rt", QString::number( record.recallTime, 'g', 4 ) );
+        writeAttribute( "at", QString::number( record.answerTime, 'g', 4 ) );
+        writeAttribute( "i", QString::number( record.interval, 'g', 6 ) );
+        }
+    writeEndElement();  // <c />
+    }
diff --git a/src/study/StudyFileWriter.h b/src/study/StudyFileWriter.h
new file mode 100644
index 0000000..8800846
--- /dev/null
+++ b/src/study/StudyFileWriter.h
@@ -0,0 +1,26 @@
+#ifndef STUDYFILEWRITER_H
+#define STUDYFILEWRITER_H
+
+#include <QXmlStreamWriter>
+#include <QString>
+#include <QList>
+
+#include "StudyRecord.h"
+
+class Dictionary;
+class CardPack;
+
+class StudyFileWriter : public QXmlStreamWriter
+{
+public:
+    StudyFileWriter( const Dictionary* aDict );
+    bool write( QIODevice* aDevice );
+
+private:
+    void writePack( const CardPack* aPack );
+    void writeCard(const QString& aCardId, const CardPack* aPack );
+private:
+    const Dictionary* m_dict;
+};
+
+#endif // STUDYFILEWRITER_H
diff --git a/src/study/StudyRecord.cpp b/src/study/StudyRecord.cpp
new file mode 100644
index 0000000..330f572
--- /dev/null
+++ b/src/study/StudyRecord.cpp
@@ -0,0 +1,129 @@
+#include "StudyRecord.h"
+
+#include "StudySettings.h"
+#include "../utils/TimeProvider.h"
+
+ostream& operator<<(ostream& os, const StudyRecord& study)
+{
+    if(study.date <= QDateTime::currentDateTime())
+    {
+        const char* dateStr = study.date.toString(Qt::ISODate).toStdString().c_str();
+        os << "(" << dateStr <<
+            ", g" << study.grade << ", e" << study.easiness << ", " <<
+            "i" << study.interval << ")";
+    }
+    else
+        os << "(New card)";
+    return os;
+}
+
+// Create "new" study record
+StudyRecord::StudyRecord():
+    date(QDateTime()),
+    level(New),
+    interval(0),
+    grade(Unknown),
+    easiness(StudySettings::inst()->initEasiness),
+    recallTime(0),
+    answerTime(0)
+    {
+    }
+
+StudyRecord::StudyRecord(int level, int grade, double easiness, double interval):
+    date(QDateTime()),
+    recallTime(0),
+    answerTime(0)
+{
+    this->level = level;
+    this->interval = interval;
+    this->grade = grade;
+    this->easiness = easiness;
+}
+
+bool StudyRecord::operator==(const StudyRecord& aOther) const
+    {
+    return level == aOther.level &&
+        date == aOther.date &&
+        interval == aOther.interval &&
+        grade == aOther.grade &&
+        easiness == aOther.easiness;
+    }
+
+bool StudyRecord::timeTriggered() const
+{
+    if(date.isNull())
+        return false;
+    QDateTime nextRepetition = date.addSecs( (int)(interval * 60*60*24) );
+    return nextRepetition <= TimeProvider::get();
+}
+
+int StudyRecord::getSecsToNextRepetition() const
+{
+    if(date.isNull())
+        return 0;
+    QDateTime nextRepetition = date.addSecs( (int)(interval * 60*60*24) );
+    return TimeProvider::get().secsTo(nextRepetition);
+}
+
+bool StudyRecord::isOneDayOld() const
+{
+    return date.secsTo(TimeProvider::get()) / (60*60*24.) >=
+            StudySettings::inst()->nextDayInterval;
+}
+
+bool StudyRecord::isLearning() const
+{
+    return (level == ShortLearning || level == LongLearning) &&
+            !isOneDayOld();
+}
+
+int StudyRecord::getScheduledTodayReviews() const
+{
+    switch(level)
+    {
+    case New:
+        return 3;
+    case ShortLearning:
+        return 2;
+    case LongLearning:
+        return 1;
+    default:
+        return 0;
+    }
+}
+
+bool StudyRecord::isReviewedToday() const
+{
+    QDateTime recShiftedDate = shiftedDate(date);
+    QDateTime curShiftedDate = shiftedDate(QDateTime::currentDateTime());
+    return recShiftedDate.date() == curShiftedDate.date();
+}
+
+bool StudyRecord::isActivatedToday() const
+{
+    if(date.isNull())
+        return false;
+    QDateTime nextRepetition = date.addSecs( (int)(interval * 60*60*24) );
+    QDateTime shiftedNextRep = shiftedDate(nextRepetition);
+    QDateTime curShiftedDate = shiftedDate(QDateTime::currentDateTime());
+    return shiftedNextRep.date() <= curShiftedDate.date();
+}
+
+QDateTime StudyRecord::shiftedDate(const QDateTime& aDate)
+{
+    return aDate.addSecs(-60 * 60 * StudySettings::inst()->dayShift);
+}
+
+void StudyRecord::setRecallTime(double time)
+{
+    recallTime = time;
+    if(recallTime > MaxAnswerTime)
+        recallTime = MaxAnswerTime;
+}
+
+void StudyRecord::setAnswerTime(double time)
+{
+    answerTime = time;
+    if(answerTime > MaxAnswerTime)
+        answerTime = MaxAnswerTime;
+}
diff --git a/src/study/StudyRecord.h b/src/study/StudyRecord.h
new file mode 100644
index 0000000..abe7ef9
--- /dev/null
+++ b/src/study/StudyRecord.h
@@ -0,0 +1,62 @@
+#ifndef STUDYRECORD_H
+#define STUDYRECORD_H
+
+#include <iostream>
+#include <QDateTime>
+
+using std::ostream;
+
+class ScheduleParams;
+
+struct StudyRecord
+{
+public:
+    static const int MaxAnswerTime = 180;   // sec
+    enum Level
+    {
+        New = 1,
+        ShortLearning = 2,
+        LongLearning = 3,
+        Repeating = 10
+    };
+    enum Grade
+    {
+        Unknown = 1,
+        Incorrect = 2,
+        Difficult = 3,
+        Good = 4,
+        Easy = 5,
+        GradesNum = 5
+    };
+    
+public:
+    StudyRecord();
+    StudyRecord(int level, int grade, double easiness, double interval);
+
+    bool timeTriggered() const;
+    int getSecsToNextRepetition() const;
+    bool isOneDayOld() const;
+    bool isLearning() const;
+    int getScheduledTodayReviews() const;
+    bool isReviewedToday() const;
+    bool isActivatedToday() const;
+    bool operator==( const StudyRecord& aOther ) const;
+    void setRecallTime(double time);
+    void setAnswerTime(double time);
+
+private:
+    static QDateTime shiftedDate(const QDateTime& aDate);
+
+public:
+    QDateTime date;
+    int level;
+    double interval;     // days
+    int grade;
+    double easiness;
+    double recallTime;   // sec
+    double answerTime;   // Full answer time: recall + grading
+};
+
+ostream& operator<<(ostream& os, const StudyRecord& study);
+
+#endif
diff --git a/src/study/StudySettings.cpp b/src/study/StudySettings.cpp
new file mode 100644
index 0000000..c680f8e
--- /dev/null
+++ b/src/study/StudySettings.cpp
@@ -0,0 +1,93 @@
+#include "StudySettings.h"
+
+#include <QCoreApplication>
+#include <QStringList>
+#include <QtDebug>
+
+StudySettings::StudySettings()
+{
+    initDefaultStudy();
+}
+
+void StudySettings::initDefaultStudy()
+{
+    showRandomly = true;
+    newCardsShare = 0.2;
+    schedRandomness = 0.1;
+    cardsDayLimit = 80;
+    newCardsDayLimit = 10;
+    limitForAddingNewCards = 70;
+    dayShift = 3;
+
+    initEasiness = 2.5;
+    minEasiness = 1.3;
+    maxEasiness = 3.2;
+    difficultDelta = -0.14;
+    easyDelta = 0.1;
+
+    unknownInterval = 20./(24*60*60);
+    incorrectInterval = 1./(24*60);
+    learningInterval = 10./(24*60);
+    nextDayInterval = 0.9;
+    twoDaysInterval = 1.9;
+}
+
+StudySettings* StudySettings::inst()
+    {
+    static StudySettings instance;
+    return &instance;
+    }
+
+void StudySettings::load()
+    {
+    QSettings settings;
+    settings.beginGroup("Study");
+    loadStudy(settings);
+    settings.endGroup();
+    }
+
+void StudySettings::loadStudy(const QSettings& settings)
+{
+    showRandomly = settings.value("random", showRandomly).toBool();
+    newCardsShare = settings.value("new-cards-share", newCardsShare).toDouble();
+    schedRandomness =
+        settings.value("scheduling-randomness", schedRandomness).toDouble();
+    cardsDayLimit = settings.value("cards-daylimit", cardsDayLimit).toInt();
+    newCardsDayLimit = settings.value("new-cards-daylimit", newCardsDayLimit).toInt();
+    limitForAddingNewCards = settings.value("limit-for-adding-new-cards", limitForAddingNewCards).toInt();
+    dayShift = settings.value("dayshift", dayShift).toInt();
+
+    initEasiness = settings.value("init-easiness", initEasiness).toDouble();
+    minEasiness = settings.value("min-easiness", minEasiness).toDouble();
+    maxEasiness = settings.value("max-easiness", maxEasiness).toDouble();
+    difficultDelta = settings.value("difficult-delta", difficultDelta).toDouble();
+    easyDelta = settings.value("easy-delta", easyDelta).toDouble();
+    unknownInterval = settings.value("unknown-interval", unknownInterval).toDouble();
+    incorrectInterval = settings.value("incorrect-interval", incorrectInterval).toDouble();
+    learningInterval = settings.value("learning-interval", learningInterval).toDouble();
+    nextDayInterval = settings.value("next-day-interval", nextDayInterval).toDouble();
+}
+
+void StudySettings::save()
+    {
+    QSettings settings;
+    settings.beginGroup("Study");
+    settings.remove("");    // Remove old user settings
+    StudySettings defaults;
+    if(showRandomly != defaults.showRandomly)
+        settings.setValue( "random", showRandomly );
+    if(newCardsShare != defaults.newCardsShare)
+        settings.setValue( "new-cards-share", newCardsShare );
+    if(schedRandomness != defaults.schedRandomness)
+        settings.setValue( "scheduling-randomness", schedRandomness );
+    if(cardsDayLimit != defaults.cardsDayLimit)
+        settings.setValue( "cards-daylimit",cardsDayLimit );
+    if(newCardsDayLimit != defaults.newCardsDayLimit)
+        settings.setValue( "new-cards-daylimit", newCardsDayLimit );
+    if(limitForAddingNewCards != defaults.limitForAddingNewCards)
+        settings.setValue( "limit-for-adding-new-cards", limitForAddingNewCards );
+    if(dayShift != defaults.dayShift)
+        settings.setValue( "dayshift", dayShift );
+    settings.endGroup();
+}
+
diff --git a/src/study/StudySettings.h b/src/study/StudySettings.h
new file mode 100644
index 0000000..d65e8a7
--- /dev/null
+++ b/src/study/StudySettings.h
@@ -0,0 +1,40 @@
+#ifndef STUDYSETTINGS_H
+#define STUDYSETTINGS_H
+
+#include <QSettings>
+
+class StudySettings
+{
+public:
+    static StudySettings* inst();
+
+public:
+    StudySettings();
+    void save();
+    void load();
+
+private:
+    void loadUserSettings();
+    void initDefaultStudy();
+    void loadStudy(const QSettings& settings);
+
+public:
+    bool showRandomly;
+    double newCardsShare;
+    double schedRandomness;
+    int cardsDayLimit;
+    int newCardsDayLimit;
+    int limitForAddingNewCards;
+    int dayShift;   // in hours
+    double initEasiness;
+    double minEasiness;
+    double maxEasiness;
+    double difficultDelta;
+    double easyDelta;
+    double unknownInterval;
+    double incorrectInterval;
+    double learningInterval;    // Long learning level
+    double nextDayInterval;     // first repetition
+    double twoDaysInterval;     // easy first repetition
+};
+#endif
diff --git a/src/study/WarningPanel.cpp b/src/study/WarningPanel.cpp
new file mode 100644
index 0000000..9bf6122
--- /dev/null
+++ b/src/study/WarningPanel.cpp
@@ -0,0 +1,49 @@
+#include "WarningPanel.h"
+
+WarningPanel::WarningPanel(QWidget* parent):
+    QFrame(parent),
+    warningLabel(new QLabel)
+{
+    initPanel();
+    setLayout(createWarningLayout());
+}
+
+void WarningPanel::initPanel()
+{
+    setFrameStyle(QFrame::StyledPanel);
+    setPalette(QPalette("#ffffcc"));
+    setAutoFillBackground(true);
+    hide();
+}
+
+QHBoxLayout* WarningPanel::createWarningLayout()
+{
+    QHBoxLayout* warningLt = new QHBoxLayout;
+    warningLt->addWidget(createWarningIconLabel(), 0, Qt::AlignTop);
+    warningLt->addWidget(warningLabel, 1);
+    warningLt->addWidget(createWarningCloseButton(), 0, Qt::AlignTop);
+    return warningLt;
+}
+
+void WarningPanel::setText(const QString& text)
+{
+    warningLabel->setText(text);
+}
+
+QLabel* WarningPanel::createWarningIconLabel() const
+{
+    QLabel* label = new QLabel;
+    label->setPixmap( QPixmap(":/images/warning.png").scaled(
+        24, 24, Qt::KeepAspectRatio, Qt::SmoothTransformation ) );
+    return label;
+}
+
+QToolButton* WarningPanel::createWarningCloseButton() const
+{
+    QToolButton* button = new QToolButton;
+    button->setAutoRaise(true);
+    button->setIcon(QIcon(":/images/gray-cross.png"));
+    button->setShortcut(Qt::Key_Escape);
+    connect(button, SIGNAL(clicked()), this, SLOT(hide()));
+    return button;
+}
diff --git a/src/study/WarningPanel.h b/src/study/WarningPanel.h
new file mode 100644
index 0000000..f207843
--- /dev/null
+++ b/src/study/WarningPanel.h
@@ -0,0 +1,25 @@
+#ifndef WARNING_PANEL_H
+#define WARNING_PANEL_H
+
+#include <QtWidgets>
+
+class WarningPanel: public QFrame
+{
+    Q_OBJECT
+
+public:
+    WarningPanel(QWidget* parent = 0);
+    void setText(const QString& text);
+
+private:
+    QLabel* createWarningIconLabel() const;
+    QToolButton* createWarningCloseButton() const;
+    QHBoxLayout* createWarningLayout();
+    void initPanel();
+
+private:
+    QLabel* warningLabel;
+
+};
+
+#endif
diff --git a/src/study/WordDrillModel.cpp b/src/study/WordDrillModel.cpp
new file mode 100644
index 0000000..403535a
--- /dev/null
+++ b/src/study/WordDrillModel.cpp
@@ -0,0 +1,163 @@
+#include "WordDrillModel.h"
+#include "../dictionary/Card.h"
+#include "../dictionary/CardPack.h"
+#include "StudySettings.h"
+
+#include <stdlib.h>
+#include <time.h>
+
+WordDrillModel::WordDrillModel( CardPack* aCardPack ):
+    IStudyModel( aCardPack ), m_historyCurPackStart(0)
+    {
+    curCardNum = NoCardIndex;
+    srand( time(NULL) );
+    connect( aCardPack, SIGNAL(cardsGenerated()), SLOT(updateStudyState()) );
+
+    generateFreshPack();
+    pickNextCard();
+    }
+
+/** Get current card.
+  * If the current card doesn't exist any more, find the next valid card.
+  */
+
+Card* WordDrillModel::getCurCard() const
+    {
+    if( m_cardHistory.isEmpty() || curCardNum < 0 )   // No cards in the pack
+        return NULL;
+    if( curCardNum >= m_cardHistory.size() )
+        return NULL;
+    QString cardName = m_cardHistory.at(curCardNum);
+    return cardPack->getCard( cardName );
+    }
+
+void WordDrillModel::updateStudyState()
+    {
+    generateFreshPack();
+    cleanHistoryFromRemovedCards();
+    if( getCurCard() )
+        emit curCardUpdated();
+    else
+        pickNextCard();
+    }
+
+void WordDrillModel::generateFreshPack()
+    {
+    m_freshPack = cardPack->getCardQuestions();
+    // Remove already reviewed cards
+    if( m_historyCurPackStart >= m_cardHistory.size() )
+        return;
+    foreach( QString reviewedCard, m_cardHistory.mid( m_historyCurPackStart ) )
+        m_freshPack.removeAll( reviewedCard );
+    }
+
+void WordDrillModel::cleanHistoryFromRemovedCards()
+    {
+    if( m_cardHistory.isEmpty() )
+        return;
+    bool cardsRemoved = false;
+    QMutableStringListIterator it( m_cardHistory );
+    int i = 0;
+    while( it.hasNext() )
+        {
+        QString cardName = it.next();
+        if( !cardPack->containsQuestion( cardName ) )
+            {
+            it.remove();
+            cardsRemoved = true;
+            if( i < curCardNum )
+                curCardNum--;
+            }
+        i++;
+        }
+    if( cardsRemoved )
+        {
+        if( curCardNum >= m_cardHistory.size() )
+            curCardNum = m_cardHistory.size() - 1;
+        emit nextCardSelected();
+        }
+    }
+
+
+/** Picks a random card. Removes the selected card from the fresh pack and adds it to the history.
+ * Thus, the new card is the last entry in the history.
+ * This function guarantees that the new card's question will be different from the previous one, unless there is no choice.
+ *
+ * Updates #m_curCardNum.
+ */
+void WordDrillModel::pickNextCard()
+    {
+    QString selectedCardName;
+    const Card* selectedCard = NULL;
+    do
+        {
+        if( m_freshPack.isEmpty() )  // No fresh cards
+            {
+            m_historyCurPackStart = m_cardHistory.size(); // Refers beyond the history pack
+            generateFreshPack();
+            if( m_freshPack.isEmpty() )  // Still no any cards available - no useful cards in the dictionary or it's empty
+                {
+                curCardNum = NoCardIndex;
+                emit nextCardSelected();
+                return;
+                }
+            }
+        if( m_freshPack.size() == 1 )    // Only 1 fresh card, no choice
+            selectedCardName = m_freshPack.takeFirst();
+        else
+            {
+            int selectedCardNum;
+            if( StudySettings::inst()->showRandomly )
+                selectedCardNum = rand() % m_freshPack.size();
+            else
+                selectedCardNum = 0;
+            if( !m_cardHistory.isEmpty() )
+                while( m_freshPack[ selectedCardNum ] == m_cardHistory.last() ) // The new question must be different from the current one
+                    {
+                    selectedCardNum++;
+                    selectedCardNum %= m_freshPack.size();
+                    }
+            selectedCardName = m_freshPack.takeAt( selectedCardNum );
+            }
+        selectedCard = cardPack->getCard( selectedCardName );
+        }
+    while( !selectedCard );
+    m_cardHistory << selectedCardName;
+    curCardNum = m_cardHistory.size() - 1;
+    emit nextCardSelected();
+    }
+
+/** Go back along the history line.
+ * @return true, if the transition was successful
+ */
+bool WordDrillModel::goBack()
+    {
+    if( !canGoBack() )
+        return false;
+    curCardNum--;
+    emit nextCardSelected();
+    return true;
+    }
+
+/** Go forward along the history line.
+ * @return true, if the transition was successful
+ */
+bool WordDrillModel::goForward()
+    {
+    if( !canGoForward() )
+        return false;
+    curCardNum++;
+    emit nextCardSelected();
+    return true;
+    }
+
+bool WordDrillModel::canGoBack()
+    {
+    return curCardNum > 0;
+    }
+
+bool WordDrillModel::canGoForward()
+    {
+    return curCardNum < m_cardHistory.size() - 1;
+    }
+
diff --git a/src/study/WordDrillModel.h b/src/study/WordDrillModel.h
new file mode 100644
index 0000000..7db780a
--- /dev/null
+++ b/src/study/WordDrillModel.h
@@ -0,0 +1,62 @@
+#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
diff --git a/src/study/WordDrillWindow.cpp b/src/study/WordDrillWindow.cpp
new file mode 100644
index 0000000..dd13bd1
--- /dev/null
+++ b/src/study/WordDrillWindow.cpp
@@ -0,0 +1,180 @@
+#include "WordDrillWindow.h"
+#include "WordDrillModel.h"
+#include "../dictionary/Card.h"
+#include "../dictionary/CardPack.h"
+#include "CardSideView.h"
+
+WordDrillWindow::WordDrillWindow( WordDrillModel* aModel, QWidget* aParent ):
+    IStudyWindow(aModel, tr("Word drill"), aParent)
+{
+    studyType = AppModel::WordDrill;
+    createUI(); // Can't call from parent constructor
+    setWindowIcon( QIcon(":/images/word-drill.png") );
+    showNextCard();
+}
+
+WordDrillWindow::~WordDrillWindow()
+{
+    WriteSettings();
+}
+
+QVBoxLayout* WordDrillWindow::createLowerPanel()
+{
+    QHBoxLayout* cardNumLayout = new QHBoxLayout;
+    iCardNumLabel = new QLabel;
+    iCardNumLabel->setAlignment( Qt::AlignVCenter );
+    iCardNumLabel->setToolTip(tr("Current card / All cards"));
+    iProgressBar = new QProgressBar;
+    iProgressBar->setTextVisible( false );
+    iProgressBar->setMaximumHeight( iProgressBar->sizeHint().height()/2 );
+    iProgressBar->setToolTip(tr("Progress of reviewing cards"));
+    iShowAnswersCB = new QCheckBox(tr("Show answers"));
+    iShowAnswersCB->setShortcut( tr("S", "Shortcut for 'Show answers' checkbox") );
+    iShowAnswersCB->setChecked( true );
+    connect( iShowAnswersCB, SIGNAL(stateChanged(int)), this, SLOT(ToggleAnswer()) );
+
+    cardNumLayout->addWidget( iCardNumLabel );
+    cardNumLayout->addWidget( iProgressBar );
+    cardNumLayout->addWidget( iShowAnswersCB );
+
+    iBackBtn = new QPushButton( QIcon(":/images/back.png"), tr("Back"), this);
+    iBackBtn->setShortcut( Qt::Key_Left );
+    iBackBtn->setToolTip( tr("Go back in history") + ShortcutToStr( iBackBtn ) );
+    connect( iBackBtn, SIGNAL(clicked()), qobject_cast<WordDrillModel*>(m_model), SLOT(goBack()) );
+
+    iForwardBtn = new QPushButton( QIcon(":/images/forward.png"), tr("Forward"), this);
+    iForwardBtn->setShortcut( Qt::Key_Right );
+    iForwardBtn->setToolTip( tr("Go forward in history") + ShortcutToStr( iForwardBtn ) );
+    connect( iForwardBtn, SIGNAL(clicked()), qobject_cast<WordDrillModel*>(m_model), SLOT(goForward()) );
+
+    iNextBtn = new QPushButton( QIcon(":/images/next.png"), tr("Next"), this);
+    iNextBtn->setShortcut( Qt::Key_Return );
+    iNextBtn->setToolTip( tr("Show next card (Enter)") );
+    connect( iNextBtn, SIGNAL(clicked()), qobject_cast<WordDrillModel*>(m_model), SLOT(pickNextCard()) );
+
+    QHBoxLayout* controlLt = new QHBoxLayout;
+    controlLt->addWidget( iBackBtn );
+    controlLt->addWidget( iForwardBtn );
+    controlLt->addWidget( iNextBtn );
+
+    QVBoxLayout* lowerPanelLt = new QVBoxLayout;
+    lowerPanelLt->addLayout( cardNumLayout );
+    if( bigScreen() )
+        lowerPanelLt->addLayout( controlLt );
+
+    return lowerPanelLt;
+}
+
+void WordDrillWindow::setStateForNextCard()
+{
+    if( m_model->getCurCard() )
+        state = iShowAnswersCB->isChecked()? StateAnswerVisible: StateAnswerHidden;
+    else
+        state = StateNoCards;
+ }
+
+void WordDrillWindow::processState()
+{
+if( state == StateAnswerHidden || state == StateAnswerVisible )
+    {
+    centralStackedLt->setCurrentIndex( CardPage );
+    DisplayCardNum();
+    UpdateButtons();
+    }
+switch( state )
+    {
+    case StateAnswerHidden:
+        questionLabel->setQuestion( m_model->getCurCard()->getQuestion() );
+        answerStackedLt->setCurrentIndex( AnsButtonPage );
+        answerBtn->setFocus();
+        break;
+    case StateAnswerVisible:
+        {
+        Card* card = m_model->getCurCard();
+        if( iShowAnswersCB->isChecked() )   // StateAnswerHidden was skipped
+            questionLabel->setQuestion( card->getQuestion() );
+        answerStackedLt->setCurrentIndex( AnsLabelPage );
+        answerLabel->setQstAnsr( card->getQuestion(), card->getAnswers() );
+        iNextBtn->setFocus();
+        break;
+        }
+    case StateNoCards:
+        centralStackedLt->setCurrentIndex(MessagePage);
+        messageLabel->setText(
+                QString("<div align=\"center\" style=\"font-size: 22pt; font-weight: bold\">") +
+                tr("No cards available") + "</div>");
+        break;
+    }
+}
+
+void WordDrillWindow::DisplayCardNum()
+{
+int curCardIndex = qobject_cast<WordDrillModel*>(m_model)->getCurCardNum();
+int curCardNum = curCardIndex + 1;
+int historySize = qobject_cast<WordDrillModel*>(m_model)->historySize();
+int packSize = m_model->getCardPack()->cardsNum();
+
+int curCardNumInPack = curCardIndex % packSize + 1;
+int passNum;
+if( packSize > 0 )
+    passNum = curCardIndex / packSize + 1;
+else
+    passNum = 1;
+QString cardNumStr = QString("%1/%2").arg( curCardNumInPack ).arg( packSize );
+QString passIconStr = "<img src=\":/images/passes.png\"/>";
+if( passNum > 1 )
+    cardNumStr += " " + passIconStr + QString::number( passNum );
+if( curCardNum < historySize && packSize > 0 )
+    {
+    int lastCardIndex = historySize - 1;
+    int lastCardNumInPack = lastCardIndex % packSize + 1;
+    cardNumStr += " (" + QString::number( lastCardNumInPack );
+    int sessionPassNum = lastCardIndex / packSize + 1;
+    if( sessionPassNum > 1 )
+        cardNumStr += " " + passIconStr + QString::number( sessionPassNum );
+    cardNumStr += ")";
+    }
+
+iCardNumLabel->setText( cardNumStr );
+iProgressBar->setMaximum( packSize );
+iProgressBar->setValue( curCardNumInPack );
+}
+
+void WordDrillWindow::UpdateButtons()
+{
+iBackBtn->setEnabled( qobject_cast<WordDrillModel*>(m_model)->canGoBack() );
+iForwardBtn->setEnabled( qobject_cast<WordDrillModel*>(m_model)->canGoForward() );
+}
+
+void WordDrillWindow::ToggleAnswer()
+{
+if( !m_model->getCurCard() )
+    return;
+answerStackedLt->setCurrentIndex( iShowAnswersCB->isChecked()? AnsLabelPage: AnsButtonPage );
+switch( state )
+    {
+    case StateAnswerHidden:
+        state = StateAnswerVisible;
+        break;
+    case StateAnswerVisible:
+        state = iShowAnswersCB->isChecked()? StateAnswerVisible: StateAnswerHidden;
+        break;
+    default:
+        return;
+    }
+processState();
+}
+
+void WordDrillWindow::ReadSettings()
+{
+QSettings settings;
+move( settings.value("worddrill-pos", QPoint(PosX, PosY)).toPoint() );
+resize( settings.value("worddrill-size", QSize(Width, Height)).toSize() );
+}
+
+void WordDrillWindow::WriteSettings()
+{
+QSettings settings;
+settings.setValue("worddrill-pos", pos());
+settings.setValue("worddrill-size", size());
+}
diff --git a/src/study/WordDrillWindow.h b/src/study/WordDrillWindow.h
new file mode 100644
index 0000000..ed421e9
--- /dev/null
+++ b/src/study/WordDrillWindow.h
@@ -0,0 +1,46 @@
+#ifndef WORDDRILLWINDOW_H
+#define WORDDRILLWINDOW_H
+
+#include <QtWidgets>
+#include "IStudyWindow.h"
+
+class WordDrillModel;
+
+class WordDrillWindow: public IStudyWindow
+{
+    Q_OBJECT
+
+public:
+    WordDrillWindow( WordDrillModel* aModel, QWidget* aParent );
+    ~WordDrillWindow();
+
+protected:
+    QVBoxLayout*  createLowerPanel();
+    void setStateForNextCard();
+    void processState();
+    void ReadSettings();
+    void WriteSettings();
+
+private:
+    void DisplayCardNum();
+    void UpdateButtons();
+
+private slots:
+    void ToggleAnswer();
+
+private:
+    static const int PosX = 200;
+    static const int PosY = 200;
+    static const int Width = 600;
+    static const int Height = 350;
+
+private:
+    QLabel* iCardNumLabel;
+    QProgressBar* iProgressBar;
+    QCheckBox* iShowAnswersCB;
+    QPushButton* iBackBtn;
+    QPushButton* iForwardBtn;
+    QPushButton* iNextBtn;
+};
+
+#endif