//    Copyright (C) 2018-2019 Jakub Melka
//
//    This file is part of PdfForQt.
//
//    PdfForQt is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Lesser General Public License as published by
//    the Free Software Foundation, either version 3 of the License, or
//    (at your option) any later version.
//
//    PdfForQt is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Lesser General Public License for more details.
//
//    You should have received a copy of the GNU Lesser General Public License
//    along with PDFForQt.  If not, see <https://www.gnu.org/licenses/>.


#ifndef PDFDRAWWIDGET_H
#define PDFDRAWWIDGET_H

#include "pdfglobal.h"
#include "pdfrenderer.h"

#include <QWidget>
#include <QScrollBar>
#include <QOpenGLWidget>

namespace pdf
{
class PDFDocument;
class PDFDrawWidget;
class PDFDrawWidgetProxy;

class IDrawWidget
{
public:
    virtual ~IDrawWidget() = default;

    virtual QWidget* getWidget() = 0;

    /// Returns page indices, which are currently displayed in the widget
    virtual std::vector<PDFInteger> getCurrentPages() const = 0;
};

class PDFFORQTLIBSHARED_EXPORT PDFWidget : public QWidget
{
    Q_OBJECT

public:
    /// Constructs new PDFWidget.
    /// \param engine Rendering engine type
    /// \param samplesCount Samples count for rendering engine MSAA antialiasing
    explicit PDFWidget(RendererEngine engine, int samplesCount, QWidget* parent);
    virtual ~PDFWidget() override;

    using PageRenderingErrors = std::map<PDFInteger, QList<PDFRenderError>>;

    /// Sets the document to be viewed in this widget. Document can be nullptr,
    /// in that case, widget contents are cleared. Optional content activity can be nullptr,
    /// if this occurs, no content is suppressed.
    /// \param document Document
    /// \param optionalContentActivity Optional content activity
    void setDocument(const PDFDocument* document, const PDFOptionalContentActivity* optionalContentActivity);

    /// Update rendering engine according the settings
    /// \param engine Engine type
    /// \param samplesCount Samples count for rendering engine MSAA antialiasing
    void updateRenderer(RendererEngine engine, int samplesCount);

    IDrawWidget* getDrawWidget() const { return m_drawWidget; }
    QScrollBar* getHorizontalScrollbar() const { return m_horizontalScrollBar; }
    QScrollBar* getVerticalScrollbar() const { return m_verticalScrollBar; }
    PDFDrawWidgetProxy* getDrawWidgetProxy() const { return m_proxy; }
    const PageRenderingErrors* getPageRenderingErrors() const { return &m_pageRenderingErrors; }
    int getPageRenderingErrorCount() const;

signals:
    void pageRenderingErrorsChanged(PDFInteger pageIndex, int errorsCount);

private:
    void onRenderingError(PDFInteger pageIndex, const QList<PDFRenderError>& errors);

    IDrawWidget* createDrawWidget(RendererEngine rendererEngine, int samplesCount);

    IDrawWidget* m_drawWidget;
    QScrollBar* m_horizontalScrollBar;
    QScrollBar* m_verticalScrollBar;
    PDFDrawWidgetProxy* m_proxy;
    PageRenderingErrors m_pageRenderingErrors;
};

template<typename BaseWidget>
class PDFDrawWidgetBase : public BaseWidget, public IDrawWidget
{
public:
    explicit PDFDrawWidgetBase(PDFWidget* widget, QWidget* parent);
    virtual ~PDFDrawWidgetBase() override = default;

    /// Returns page indices, which are currently displayed in the widget
    virtual std::vector<PDFInteger> getCurrentPages() const override;

    virtual QSize minimumSizeHint() const override;
    virtual QWidget* getWidget() override { return this; }

protected:
    virtual void keyPressEvent(QKeyEvent* event) override;
    virtual void mousePressEvent(QMouseEvent* event) override;
    virtual void mouseReleaseEvent(QMouseEvent* event) override;
    virtual void mouseMoveEvent(QMouseEvent* event) override;
    virtual void wheelEvent(QWheelEvent* event) override;

    PDFWidget* getPDFWidget() const { return m_widget; }

private:
    enum class MouseOperation
    {
        None,
        Translate
    };

    /// Performs the mouse operation (under the current mouse position)
    /// \param currentMousePosition Current position of the mouse
    void performMouseOperation(QPoint currentMousePosition);

    PDFWidget* m_widget;
    QPoint m_lastMousePosition;
    MouseOperation m_mouseOperation;
};

class PDFOpenGLDrawWidget : public PDFDrawWidgetBase<QOpenGLWidget>
{
    Q_OBJECT

private:
    using BaseClass = PDFDrawWidgetBase<QOpenGLWidget>;

public:
    explicit PDFOpenGLDrawWidget(PDFWidget* widget, int samplesCount, QWidget* parent);
    virtual ~PDFOpenGLDrawWidget() override;

protected:
    virtual void resizeGL(int w, int h) override;
    virtual void initializeGL() override;
    virtual void paintGL() override;
};

class PDFDrawWidget : public PDFDrawWidgetBase<QWidget>
{
    Q_OBJECT

private:
    using BaseClass = PDFDrawWidgetBase<QWidget>;

public:
    explicit PDFDrawWidget(PDFWidget* widget, QWidget* parent);
    virtual ~PDFDrawWidget() override;

protected:
    virtual void paintEvent(QPaintEvent* event) override;
    virtual void resizeEvent(QResizeEvent* event) override;
};

extern template class PDFDrawWidgetBase<QOpenGLWidget>;
extern template class PDFDrawWidgetBase<QWidget>;

}   // namespace pdf

#endif // PDFDRAWWIDGET_H