/*
    Copyright (C) 2007 by Robert Knight <robertknight@gmail.com>
    Copyright (C) 1997,1998 by Lars Doelle <lars.doelle@on-line.de>

    Rewritten for QT4 by e_k <e_k at users.sourceforge.net>, Copyright (C)2008
    Copyright (C) 2012-2018 Jacob Dawid <jacob.dawid@cybercatalyst.com>

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

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

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

#ifndef TERMINALVIEW_H
#define TERMINALVIEW_H

// Qt
#include <QColor>
#include <QtCore/QPointer>
#include <QWidget>

// Konsole
#include "unix/Filter.h"
#include "unix/Character.h"

class QDrag;
class QDragEnterEvent;
class QDropEvent;
class QLabel;
class QTimer;
class QEvent;
class QFrame;
class QGridLayout;
class QKeyEvent;
class QScrollBar;
class QShowEvent;
class QHideEvent;
class QWidget;

extern unsigned short vt100_graphics[32];

class ScreenWindow;

/**
 * A widget which displays output from a terminal emulation and sends input keypresses and mouse activity
 * to the terminal.
 *
 * When the terminal emulation receives new output from the program running in the terminal,
 * it will update the display by calling updateImage().
 *
 * TODO More documentation
 */
class TerminalView : public QWidget
{
   Q_OBJECT

public:
    /** Constructs a new terminal display widget with the specified parent. */
    TerminalView(QWidget *parent = nullptr);
    virtual ~TerminalView();

    /** Returns the terminal color palette used by the display. */
    const ColorEntry* colorTable() const;
    /** Sets the terminal color palette used by the display. */
    void setColorTable(const ColorEntry table[]);
    /**
     * Sets the seed used to generate random colors for the display
     * (in color schemes that support them).
     */
    void setRandomSeed(uint seed);
    /**
     * Returns the seed used to generate random colors for the display
     * (in color schemes that support them).
     */
    uint randomSeed() const;


    /**
     * This enum describes the location where the scroll bar is positioned in the display widget.
     */
    enum ScrollBarPosition
    {
        /** Do not show the scroll bar. */
        NoScrollBar=0,
        /** Show the scroll bar on the left side of the display. */
        ScrollBarLeft=1,
        /** Show the scroll bar on the right side of the display. */
        ScrollBarRight=2
    };
    /**
     * Specifies whether the terminal display has a vertical scroll bar, and if so whether it
     * is shown on the left or right side of the display.
     */
    void setScrollBarPosition(ScrollBarPosition position);

    /**
     * Sets the current position and range of the display's scroll bar.
     *
     * @param cursor The position of the scroll bar's thumb.
     * @param lines The maximum value of the scroll bar.
     */
    void setScroll(int cursor, int lines);

    /**
     * Returns the display's filter chain.  When the image for the display is updated,
     * the text is passed through each filter in the chain.  Each filter can define
     * hotspots which correspond to certain strings (such as URLs or particular words).
     * Depending on the type of the hotspots created by the filter ( returned by Filter::Hotspot::type() )
     * the view will draw visual cues such as underlines on mouse-over for links or translucent
     * rectangles for markers.
     *
     * To add a new filter to the view, call:
     *      viewWidget->filterChain()->addFilter( filterObject );
     */
    FilterChain* filterChain() const;

    /**
     * Returns a list of menu actions created by the filters for the content
     * at the given @p position.
     */
    QList<QAction*> filterActions(const QPoint& position);

    /** Returns true if the cursor is set to blink or false otherwise. */
    bool blinkingCursor() { return _hasBlinkingCursor; }
    /** Specifies whether or not the cursor blinks. */
    void setBlinkingCursor(bool blink);
    void setBlinkingCursorState(bool blink);

    void setCtrlDrag(bool enable) { _ctrlDrag=enable; }
    bool ctrlDrag() { return _ctrlDrag; }

   /**
     *  This enum describes the methods for selecting text when
    *  the user triple-clicks within the display.
    */
   enum TripleClickMode
   {
      /** Select the whole line underneath the cursor. */
      SelectWholeLine,
      /** Select from the current cursor position to the end of the line. */
      SelectForwardsFromCursor
   };
    /** Sets how the text is selected when the user triple clicks within the display. */
    void setTripleClickMode(TripleClickMode mode) { _tripleClickMode = mode; }
   /** See setTripleClickSelectionMode() */
    TripleClickMode tripleClickMode() { return _tripleClickMode; }

    void setLineSpacing(uint);
    uint lineSpacing() const;

    void emitSelection(bool useXselection,bool appendReturn);

    /**
     * This enum describes the available shapes for the keyboard cursor.
     * See setKeyboardCursorShape()
     */
    enum KeyboardCursorShape
    {
        /** A rectangular block which covers the entire area of the cursor character. */
        BlockCursor,
        /**
         * A single flat line which occupies the space at the bottom of the cursor
         * character's area.
         */
        UnderlineCursor,
        /**
         * An cursor shaped like the capital letter 'I', similar to the IBeam
         * cursor used in Qt/KDE text editors.
         */
        IBeamCursor
    };
    /**
     * Sets the shape of the keyboard cursor.  This is the cursor drawn
     * at the position in the terminal where keyboard input will appear.
     *
     * In addition the terminal display widget also has a cursor for
     * the mouse pointer, which can be set using the QWidget::setCursor()
     * method.
     *
     * Defaults to BlockCursor
     */
    void setKeyboardCursorShape(KeyboardCursorShape shape);
    /**
     * Returns the shape of the keyboard cursor.  See setKeyboardCursorShape()
     */
    KeyboardCursorShape keyboardCursorShape() const;

    /**
     * Sets the color used to draw the keyboard cursor.
     *
     * The keyboard cursor defaults to using the foreground color of the character
     * underneath it.
     *
     * @param useForegroundColor If true, the cursor color will change to match
     * the foreground color of the character underneath it as it is moved, in this
     * case, the @p color parameter is ignored and the color of the character
     * under the cursor is inverted to ensure that it is still readable.
     * @param color The color to use to draw the cursor.  This is only taken into
     * account if @p useForegroundColor is false.
     */
    void setKeyboardCursorColor(bool useForegroundColor , const QColor& color);

    /**
     * Returns the color of the keyboard cursor, or an invalid color if the keyboard
     * cursor color is set to change according to the foreground color of the character
     * underneath it.
     */
    QColor keyboardCursorColor() const;

    /**
     * Returns the number of lines of text which can be displayed in the widget.
     *
     * This will depend upon the height of the widget and the current font.
     * See fontHeight()
     */
    int  lines()   { return _lines;   }
    /**
     * Returns the number of characters of text which can be displayed on
     * each line in the widget.
     *
     * This will depend upon the width of the widget and the current font.
     * See fontWidth()
     */
    int  columns() { return _columns; }

    /**
     * Returns the height of the characters in the font used to draw the text in the display.
     */
    int  fontHeight()   { return _fontHeight;   }
    /**
     * Returns the width of the characters in the display.
     * This assumes the use of a fixed-width font.
     */
    int  fontWidth()    { return _fontWidth; }

    void setSize(int cols, int lins);
    void setFixedSize(int cols, int lins);

    // reimplemented
    QSize sizeHint() const;

    /**
     * Sets which characters, in addition to letters and numbers,
     * are regarded as being part of a word for the purposes
     * of selecting words in the display by double clicking on them.
     *
     * The word boundaries occur at the first and last characters which
     * are either a letter, number, or a character in @p wc
     *
     * @param wc An array of characters which are to be considered parts
     * of a word ( in addition to letters and numbers ).
     */
    void setWordCharacters(const QString& wc);
    /**
     * Returns the characters which are considered part of a word for the
     * purpose of selecting words in the display with the mouse.
     *
     * @see setWordCharacters()
     */
    QString wordCharacters() { return _wordCharacters; }

    /**
     * Sets the type of effect used to alert the user when a 'bell' occurs in the
     * terminal session.
     *
     * The terminal session can trigger the bell effect by calling bell() with
     * the alert message.
     */
    void setBellMode(int mode);
    /**
     * Returns the type of effect used to alert the user when a 'bell' occurs in
     * the terminal session.
     *
     * See setBellMode()
     */
    int bellMode() { return _bellMode; }

    /**
     * This enum describes the different types of sounds and visual effects which
     * can be used to alert the user when a 'bell' occurs in the terminal
     * session.
     */
    enum BellMode
    {
        /** A system beep. */
        SystemBeepBell=0,
        /**
         * KDE notification.  This may play a sound, show a passive popup
         * or perform some other action depending on the user's settings.
         */
        NotifyBell=1,
        /** A silent, visual bell (eg. inverting the display's colors briefly) */
        VisualBell=2,
        /** No bell effects */
        NoBell=3
    };

    void setSelection(const QString &t);

    QString selectedText ();

    /**
     * Reimplemented.  Has no effect.  Use setVTFont() to change the font
     * used to draw characters in the display.
     */
    virtual void setFont(const QFont &);


    /** Returns the font used to draw characters in the display */
    QFont getVTFont() { return font(); }

    /**
     * Sets the font used to draw the display.  Has no effect if @p font
     * is larger than the size of the display itself.
     */
    void setVTFont(const QFont& font);


    /**
     * Specified whether terminal widget should be at read-only mode
     * Defaults to false.
     */
    void setReadOnly( bool readonly) { _readonly = readonly; }

    /**
     * Specified whether anti-aliasing of text in the terminal display
     * is enabled or not.  Defaults to enabled.
     */
    static void setAntialias( bool antialias ) { _antialiasText = antialias; }
    /**
     * Returns true if anti-aliasing of text in the terminal is enabled.
     */
    static bool antialias()                 { return _antialiasText;   }

    /**
     * Sets whether or not the current height and width of the
     * terminal in lines and columns is displayed whilst the widget
     * is being resized.
     */
    void setTerminalSizeHint(bool on) { _terminalSizeHint=on; }
    /**
     * Returns whether or not the current height and width of
     * the terminal in lines and columns is displayed whilst the widget
     * is being resized.
     */
    bool terminalSizeHint() { return _terminalSizeHint; }
    /**
     * Sets whether the terminal size display is shown briefly
     * after the widget is first shown.
     *
     * See setTerminalSizeHint() , isTerminalSizeHint()
     */
    void setTerminalSizeStartup(bool on) { _terminalSizeStartup=on; }

    /**
     * Sets the terminal screen section which is displayed in this widget.
     * When updateImage() is called, the display fetches the latest character image from the
     * the associated terminal screen window.
     *
     * In terms of the model-view paradigm, the ScreenWindow is the model which is rendered
     * by the TerminalDisplay.
     */
    void setScreenWindow( ScreenWindow* window );
    /** Returns the terminal screen section which is displayed in this widget.  See setScreenWindow() */
    ScreenWindow* screenWindow() const;

    /** Is called, when the terminal's visibility has changed in order to
     *  stop orstart timers etc.
     */
    void visibility_changed (bool visible);

public slots:

    /**
     * Updates the filters in the display's filter chain.  This will cause
     * the hotspots to be updated to match the current image.
     *
     * WARNING:  This function can be expensive depending on the
     * image size and number of filters in the filterChain()
     *
     * TODO - This API does not really allow efficient usage.  Revise it so
     * that the processing can be done in a better way.
     *
     * eg:
     *      - Area of interest may be known ( eg. mouse cursor hovering
     *      over an area )
     */
    void processFilters();

    /**
     * Causes the terminal display to fetch the latest character image from the associated
     * terminal screen ( see setScreenWindow() ) and redraw the display.
     */
    void updateImage();
    /**
     * Causes the terminal display to fetch the latest line status flags from the
     * associated terminal screen ( see setScreenWindow() ).
     */
    void updateLineProperties();

    /** Copies the selected text to the clipboard. */
    void copyClipboard (bool extra_interrupt);
    /**
     * Pastes the content of the clipboard into the
     * display.
     */
    void pasteClipboard();
    /**
     * Pastes the content of the selection into the
     * display.
     */
    void pasteSelection();

    /**
     * selects all content
     */
    void selectAll();

	 /**
	 * Causes the widget to display or hide a message informing the user that terminal
	 * output has been suspended (by using the flow control key combination Ctrl+S)
	 *
	 * @param suspended True if terminal output has been suspended and the warning message should
	 *				 	be shown or false to indicate that terminal output has been resumed and that
	 *				 	the warning message should disappear.
	 */
	void outputSuspended(bool suspended);

    /**
     * Sets whether the program whoose output is being displayed in the view
     * is interested in mouse events.
     *
     * If this is set to true, mouse signals will be emitted by the view when the user clicks, drags
     * or otherwise moves the mouse inside the view.
     * The user interaction needed to create selections will also change, and the user will be required
     * to hold down the shift key to create a selection or perform other mouse activities inside the
     * view area - since the program running in the terminal is being allowed to handle normal mouse
     * events itself.
     *
     * @param usesMouse Set to true if the program running in the terminal is interested in mouse events
     * or false otherwise.
     */
    void setUsesMouse(bool usesMouse);

    /** See setUsesMouse() */
    bool usesMouse() const;

signals:

    void interrupt_signal (void);

    /**
     * Emitted when the user presses a key whilst the terminal widget has focus.
     */
    void keyPressedSignal(QKeyEvent *e);

    /**
     * A mouse event occurred.
     * @param button The mouse button (0 for left button, 1 for middle button, 2 for right button, 3 for release)
     * @param column The character column where the event occurred
     * @param line The character row where the event occurred
     * @param eventType The type of event.  0 for a mouse press / release or 1 for mouse motion
     */
    void mouseSignal(int button, int column, int line, int eventType);
    void changedFontMetricSignal(int height, int width);
    void changedContentSizeSignal(int height, int width);

    /**
     * Emitted when the user right clicks on the display, or right-clicks with the Shift
     * key held down if usesMouse() is true.
     *
     * This can be used to display a context menu.
     */
    void configureRequest( TerminalView*, int state, const QPoint& position );

   void isBusySelecting(bool);
   void sendStringToEmu(const char*);

   void tripleClicked( const QString& text );

   /**
    * Emitted when focus changes
    */
   void set_global_shortcuts_signal (bool);


protected:
    virtual void paintEvent( QPaintEvent * );

    void focusInEvent(QFocusEvent *focusEvent);
    void focusOutEvent(QFocusEvent *focusEvent);

    virtual void showEvent(QShowEvent*);
    virtual void hideEvent(QHideEvent*);
    virtual void resizeEvent(QResizeEvent*);

    virtual void fontChange(const QFont &font);

    virtual void keyPressEvent(QKeyEvent* event);
    virtual void mouseDoubleClickEvent(QMouseEvent* ev);
    virtual void mousePressEvent( QMouseEvent* );
    virtual void mouseReleaseEvent( QMouseEvent* );
    virtual void mouseMoveEvent( QMouseEvent* );
    virtual void extendSelection( const QPoint& pos );
    virtual void wheelEvent( QWheelEvent* );

    virtual bool focusNextPrevChild( bool next );

    // drag and drop
    virtual void dragEnterEvent(QDragEnterEvent* event);
    virtual void dropEvent(QDropEvent* event);
    void doDrag();
    enum DragState { diNone, diPending, diDragging };

    struct _dragInfo {
      DragState       state;
      QPoint          start;
      QDrag           *dragObject;
    } dragInfo;

    virtual int charClass(quint16) const;

    void clearImage();

    void mouseTripleClickEvent(QMouseEvent* ev);

    // reimplemented
    virtual void inputMethodEvent ( QInputMethodEvent* event );
    virtual QVariant inputMethodQuery( Qt::InputMethodQuery query ) const;

protected slots:

    void scrollBarPositionChanged(int value);
    void blinkEvent();
    void blinkCursorEvent();

    //Renables bell noises and visuals.  Used to disable further bells for a short period of time
    //after emitting the first in a sequence of bell events.
    void enableBell();

private slots:

    void swapColorTable();
    void tripleClickTimeout();  // resets possibleTripleClick

private:

    // -- Drawing helpers --

    // divides the part of the display specified by 'rect' into
    // fragments according to their colors and styles and calls
    // drawTextFragment() to draw the fragments
    void drawContents(QPainter &paint, const QRect &rect);
    // draws a section of text, all the text in this section
    // has a common color and style
    void drawTextFragment(QPainter& painter, const QRect& rect,
                          const QString& text, const Character* style);
    // draws the background for a text fragment
    // if useOpacitySetting is true then the color's alpha value will be set to
    // the display's transparency (set with setOpacity()), otherwise the background
    // will be drawn fully opaque
    void drawBackground(QPainter& painter, const QRect& rect, const QColor& color);
    // draws the cursor character
    void drawCursor(QPainter& painter, const QRect& rect , const QColor& foregroundColor,
                                       const QColor& backgroundColor , bool& invertColors);
    // draws the characters or line graphics in a text fragment
    void drawCharacters(QPainter& painter, const QRect& rect,  const QString& text,
                                           const Character* style, bool invertCharacterColor);
    // draws a string of line graphics
   void drawLineCharString(QPainter& painter, int x, int y,
                            const QString& str, const Character* attributes);

    // draws the preedit string for input methods
    void drawInputMethodPreeditString(QPainter& painter , const QRect& rect);

    // --

    // maps an area in the character image to an area on the widget
    QRect imageToWidget(const QRect& imageArea) const;

    // maps a point on the widget to the position ( ie. line and column )
    // of the character at that point.
    void getCharacterPosition(const QPoint& widgetPoint,int& line,int& column) const;

    // the area where the preedit string for input methods will be draw
    QRect preeditRect() const;

    // shows a notification window in the middle of the widget indicating the terminal's
    // current size in columns and lines
    void showResizeNotification();

    // scrolls the image by a number of lines.
    // 'lines' may be positive ( to scroll the image down )
    // or negative ( to scroll the image up )
    // 'region' is the part of the image to scroll - currently only
    // the top, bottom and height of 'region' are taken into account,
    // the left and right are ignored.
    void scrollImage(int lines , const QRect& region);

    void calcGeometry();
    void propagateSize();
    void updateImageSize();
    void makeImage();

    void paintFilters(QPainter& painter);

	// returns a region covering all of the areas of the widget which contain
	// a hotspot
	QRegion hotSpotRegion() const;

	// returns the position of the cursor in columns and lines
	QPoint cursorPosition() const;

    // the window onto the terminal screen which this display
    // is currently showing.
    QPointer<ScreenWindow> _screenWindow;

    bool _allowBell;

    QGridLayout* _gridLayout;

    bool _fixedFont; // has fixed pitch

    double  _fontHeight;     // height
    double  _fontWidth;     // width
    //type double to decrease rounding errors

    int  _fontAscent;     // ascend

    int _leftMargin;    // offset
    int _topMargin;    // offset

    int _lines;      // the number of lines that can be displayed in the widget
    int _columns;    // the number of columns that can be displayed in the widget

    int _usedLines;  // the number of lines that are actually being used, this will be less
                    // than 'lines' if the character image provided with setImage() is smaller
                    // than the maximum image size which can be displayed

    int _usedColumns; // the number of columns that are actually being used, this will be less
                     // than 'columns' if the character image provided with setImage() is smaller
                     // than the maximum image size which can be displayed

    int _contentHeight;
    int _contentWidth;
    Character* _image; // [lines][columns]
               // only the area [usedLines][usedColumns] in the image contains valid data

    int _imageSize;
    QVector<LineProperty> _lineProperties;

    ColorEntry _colorTable[TABLE_COLORS];
    uint _randomSeed;

    bool _resizing;
    bool _terminalSizeHint;
    bool _terminalSizeStartup;
    bool _mouseMarks;

    QPoint  _iPntSel; // initial selection point
    QPoint  _pntSel; // current selection point
    QPoint  _tripleSelBegin; // help avoid flicker
    int     _actSel; // selection state
    bool    _wordSelectionMode;
    bool    _lineSelectionMode;
    bool    _preserveLineBreaks;
    bool    _columnSelectionMode;

    QClipboard*  _clipboard;
    QScrollBar* _scrollBar;
    ScrollBarPosition _scrollbarLocation;
    QString     _wordCharacters;
    int         _bellMode;

    bool _blinking;   // hide text in paintEvent
    bool _hasBlinker; // has characters to blink
    bool _cursorBlinking;     // hide cursor in paintEvent
    bool _hasBlinkingCursor;  // has blinking cursor enabled
    bool _ctrlDrag;           // require Ctrl key for drag
    TripleClickMode _tripleClickMode;
    bool _isFixedSize; //Columns / lines are locked.
    QTimer* _blinkTimer;  // active when hasBlinker
    QTimer* _blinkCursorTimer;  // active when hasBlinkingCursor
    QTimer* _process_filter_timer;  // active when visible, filter processing

//    KMenu* _drop;
    QString _dropText;
    int _dndFileCount;

    bool _possibleTripleClick;  // is set in mouseDoubleClickEvent and deleted
                               // after QApplication::doubleClickInterval() delay


    QLabel* _resizeWidget;
    QTimer* _resizeTimer;

   bool _flowControlWarningEnabled;

    //widgets related to the warning message that appears when the user presses Ctrl+S to suspend
    //terminal output - informing them what has happened and how to resume output
    QLabel* _outputSuspendedLabel;

    uint _lineSpacing;

    bool _colorsInverted; // true during visual bell

    QSize _size;

    QRgb _blendColor;

    // list of filters currently applied to the display.  used for links and
    // search highlight
    TerminalImageFilterChain* _filterChain;
    QRect _mouseOverHotspotArea;

    KeyboardCursorShape _cursorShape;

    // custom cursor color.  if this is invalid then the foreground
    // color of the character under the cursor is used
    QColor _cursorColor;


    struct InputMethodData
    {
        QString preeditString;
        QRect previousPreeditRect;
    };
    InputMethodData _inputMethodData;

    static bool _antialiasText;   // do we antialias or not

    //the delay in milliseconds between redrawing blinking text
    static const int BLINK_DELAY = 500;
   static const int DEFAULT_LEFT_MARGIN = 2;
   static const int DEFAULT_TOP_MARGIN = 2;

    bool _readonly;
};

#endif // TERMINALVIEW_H
