/**
 * SPDX-FileCopyrightText: (C) 2005 Sébastien Laoût <slaout@linux62.org>
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#ifndef KCOLORCOMBO2_H
#define KCOLORCOMBO2_H

#include <KComboBox>

class QColor;
class QPixmap;

class QDragEnterEvent;
class QDropEvent;
class QMouseEvent;
class QKeyEvent;
class QPaintEvent;

class KColorPopup;

/**
 * @short A combobox to display or allow user selection of a color in a user-friendly way.
 *
 * A combobox widget that popup an array of colors for the user to easily pick a common color.\n
 * He/she can use the popup to quickly pick a reasonable color or open a color chooser dialog for a more precise choice.\n
 * The user can also choose a default color (the standard background color, text color, etc... it's to the programmer to make sense of this property).\n
 * \n
 * The user is also offered some facilities: like KColorButton he/she can copy a color or paste it
 * (with standard keyboard shortcuts, usually Ctrl+C and Ctrl+V), and he/she can drag or drop colors.
 *
 * @par Quick usage:
 * Just create a new KColorCombo2() with the initial color and eventually an allowed default color
 * (eg. palette().color(QPalette::Base) for a background color, palette().color(QPalette::Text)...).\n
 * You will be noticed of the color the user selects with the signal changed(), or you can use color() to get the color at any moment.\n
 * Note that they can return an invalid color (see QColor::isValid()) if the user chosen the default color (if he can choose that).\n
 * It's then easy to save in settings, but if you want the real color (even for the default), you can get it with effectiveColor().
 *
 * @par Notes about default color:
 * If you set a default color using Qt or KDE standard colors, the user can change them in the KDE Control Center,
 * but this widget willn't be update and will still show the old one.\n
 * To be noticed of such color change and then update the widget with the new standard color, you can use one of those two methods:
 * @code
 * void QWidgetDerivate::paletteChange(const QPalette &oldPalette) { // QWidgetDerivate is a parent or near custom widget
 *     theComboBox->setDefaultColor(theNewDefaultColor);
 *     QWidget::paletteChange(oldPalette);
 * }
 * @endcode
 * or connect the signal QApplication::kdisplayPaletteChanged() to a slot that will set the default color of this widget.
 *
 * @par Advanced usage:
 * By default, the combobox show a well balanced rainbow, OK for most usages, and you don't need to do anything for it to work.\n
 * You however can set your own color array by calling newColorArray() with the number of columns and rows.
 * Then, setColorAt() several times to fill the array.\n
 * This allow the most flexibility. But if you just want a rainbow with more or less colors, setRainbowPreset() is what you want.\n
 * If you worry about performance issues of creating a combobox with the default color array and then allocating another color array by yourself,
 * note that the default color array is not allocated in the constructor, but as soon as it is demanded (on first popup if no array has been
 * set before, or on first call of any accessors: colorAt(), columnCount(), setColorAt()...).
 * Finally, colorRectPixmap() and drawColorRect() allow to draw the color rounded-rectangle in other places for a consistent look.
 *
 * @see KGlobalSettings Use one of the static functions to get KDE standard colors for default values.
 * @see KColorButton    The same, but without the rainbow popup or the choice of a default color.
 * @see QColorDialog    The dialog that is shown when the user click the "Other..." entry.
 * @author Sébastien Laoût <slaout@linux62.org>
 *
 * @image html commoncolorselector.png "Common Color Selector ComboBox"
 */
class KColorCombo2 : public KComboBox
{
    Q_OBJECT
    Q_PROPERTY(QColor color READ color WRITE setColor NOTIFY colorChanged)
    Q_PROPERTY(QColor defaultColor READ defaultColor WRITE setDefaultColor NOTIFY defaultColorChanged)

public Q_SLOTS:
    /**
     * Change the selected color.\n
     * If the popup is open, it will not reflect the change. FIXME: Should it?
     * @param color The new selected color. Can be invalid to select the default one.\n
     *              If @p color is invalid and no default color is allowed, the function will keep the old one.
     */
    void setColor(const QColor &color);

    /**
     * Change the default color.
     * @param color The color to return if the user choose the default one. If it is not valid, the user willn't be allowed to choose a default one.
     * @see defaultColor() to get it.
     */
    void setDefaultColor(const QColor &color);
private Q_SLOTS:
    void popupClosed();
Q_SIGNALS:
    /**
     * Emitted when the color of the widget is changed, either with setColor() or via user selection.
     * @see color() to know the content of @p newColor.
     */
    void colorChanged(const QColor &newColor);

    /**
     * Emitted when the default color of the widget is changed with setDefaultColor()
     * @see defaultColor() to know the content of @p newDefaultColor.
     */
    void defaultColorChanged(const QColor &newDefaultColor);

public:
    /**
     * Constructs a color combobox with parent @p parent.
     * @param color         The initial selected color. If it is not valid, the default one will then be selected.\n
     *                      But if @p color is invalid and there is no default color, the result is undefined.
     * @param defaultColor  The color to return if the user choose the default one. If it is not valid, the user willn't be allowed to choose a default one.
     */
    KColorCombo2(const QColor &color, const QColor &defaultColor, QWidget *parent = nullptr);

    /**
     * Constructs a color combobox with parent @p parent.\n
     * The user is not allowed to choose a default color, unless you call setDefaultColor() later.
     * @param color         The initial selected color. If it is invalid, the result is undefined.
     */
    explicit KColorCombo2(const QColor &color, QWidget *parent = nullptr);

    /**
     * Destroys the combobox.
     */
    ~KColorCombo2() override;

    /**
     * Get the color chosen by the user.\n
     * Can be invalid, if the user chosen the default one.\n
     * Ideal to store it in settings for later recall.
     * @see effectiveColor() if you want the color to be always valid.
     */
    QColor color() const;

    /**
     * Return the color chosen by the user.\n
     * If the user chosen the default color, the default one is then returned, so the returned color is always valid.\n
     * Ideal to directly use to draw.
     * @see color() if you want to be notified of a default color choice.
     */
    QColor effectiveColor() const;

    /**
     * Returns the default color or an invalid color if no default color is set (if the user isn't allowed to choose a default color).
     * @see setDefaultColor() to change it.
     */
    QColor defaultColor() const;

    /**
     * Allocate a new color array of the specified dimension.\n
     * The new array will have invalid colors: you should then assign them one by one.\n
     * If one or both of the dimensions are negative or null, this function do nothing (both dimensions are always ensured to be at least equal to 1).
     * @param columnCount The number of columns of the array.
     * @param rowCount    The number of rows of the array.
     * @see setColorAt() to set all colors once the array have been created.
     */
    void newColorArray(int columnCount, int rowCount);

    /**
     * Get the number of columns in the array that the user can see to choose.
     * @see rowCount() for the number of rows, and colorAt() to get a color from the array.
     */
    int columnCount() const;

    /**
     * Get the number of rows in the array that the user can see to choose.
     * @see columnCount() for the number of columns, and colorAt() to get a color from the array.
     */
    int rowCount() const;

    /**
     * Set a color in the array at position (column,row).\n
     * If one or both of the indexes are out of range, this function do nothing.\n
     * @p column and @p row start from 0 to columnCount()-1 and columnRow()-1.
     *
     * @param column The x coordinate of the color to set or change.
     * @param row    The y coordinate of the color to set or change.
     * @param color  The color to assign at this position.
     */
    void setColorAt(int column, int row, const QColor &color);

    /**
     * Get a color in the array that the user can see to choose.\n
     * @p column and @p row start from 0 to columnCount()-1 and columnRow()-1.
     *
     * @return The asked color, or an invalid color if the index is out of limit of the array.
     * @see columnCount() and rowCount() to get the array dimensions.
     */
    QColor colorAt(int column, int row) /* const*/;

    /**
     * Fill the array of colors (that will be shown to the user in the popup that appears when he/she click the arrow) with a rainbow of different luminosity.\n
     * This rainbow representation have the advantage of being natural and well structured for a human to be able to select reasonable colors.\n
     * This function will allocate a color array by itself depending on the parameters (no need to call newColorArray()).
     * @param colorColumnCount The number of columns. The 360 possible colors of the rainbow will be split to take the wanted number of colors, equally
     * separated.
     * @param lightRowCount    There is always at least 1 row of colors: the "pure" colors: pure red, pure blue, pure green, pure fuchsia...\n
     *                         Additionally, you can add row on top: they will contain the same colors, but lighter.\n
     *                         The parameter @p lightRowCount specify how many different lighting grades should be shown (from near to white, but not white, to
     * "pure").
     * @param darkRowCount     Finally, on bottom of the row of "pure colors", you can put any variety of dark colors (from "pure", to near to black, but not
     * black).\n So, the number of rows is equal to @p lightRowCount + 1 + @p darkRowCount. On top are light colors, gradually going to dark ones on bottom.
     * @param withGray         If true, another column (so there will be @p colorColumnCount+1 columns) is added on the very-right of the popup
     *                         to show different gray values, matching the brightness of the sibling colors.
     *
     * The most acceptable parameters:
     * @li The default values are good to have the 7 colors of the rainbow + colors between them, and light/dark colors are well distinct.
     * @li If the color is a background color, you can set @p darkRowCount to 0, so only light colors are shown.
     * @li The inverse is true for text color choice: you can set @p lightRowCount to 0.
     * @li But be careful: some advanced users prefer white text on dark background, so you eg. can set @p lightRowCount to a big value and
     *     @p darkRowCount to a small one for a fewer choice of dark colors, but at least some ones.
     */
    void setRainbowPreset(int colorColumnCount = 12, int lightRowCount = 4, int darkRowCount = 4, bool withGray = true);
    // void setHsvPreset(QColor hue[], QColor saturation[], QColor value[], bool withGray = true);

    /**
     * Returns a pixmap of a colored rounded-rectangle. The four corners are transparent.\n
     * Useful if you want to set such a rectangle as an icon for a menu entry, or for drag and drop operation...
     * @param color     The color of the rectangle. If the color is invalid, a rainbow is then drawn (like for the "Other..." entry in the popup).
     * @param isDefault True if @p color is the default one and should then be draw with a diagonal line.
     * @param width     The width of the rectangle pixmap to return.
     * @param height    The height of the rectangle pixmap to return.
     *
     * @see drawColorRect() if you need to draw it directly: it's faster.
     */
    QPixmap colorRectPixmap(const QColor &color, bool isDefault, int width, int height);

    /**
     * Draw an image of a colored rounded-rectangle.\n
     * This is like colorRectPixmap() but significantly faster because there is nothing to copy, and no transparency mask to create and apply.
     * @param painter   The painter where to draw the image.
     * @param x         The x coordinate on the @p painter where to draw the rectangle.
     * @param y         The y coordinate on the @p painter where to draw the rectangle.
     * @param color     The color of the rectangle. If the color is invalid, a rainbow is then drawn (like for the "Other..." entry in the popup).
     * @param isDefault True if @p color is the default one and should then be draw with a diagonal line.
     * @param width     The width of the rectangle pixmap to return.
     * @param height    The height of the rectangle pixmap to return.
     *
     * @see colorRectPixmap() to get a transparent pixmap of the rectangle.
     */
    void drawColorRect(QPainter &painter, int x, int y, const QColor &color, bool isDefault, int width, int height);

    /**
     * Get the height of a color rectangle for this combobox.\n
     * This is equal to the text height, regarding to the current font of this combobox.
     */
    int colorRectHeight() const;

    /**
     * Get the width of a color rectangle, depending of the @p height of it.\n
     * It typically return 1.4 * @p height for decent rectangle proportions.
     */
    int colorRectWidthForHeight(int height) const;

protected:
    void showPopup() override;
    void mouseMoveEvent(QMouseEvent *event) override;
    void dragEnterEvent(QDragEnterEvent *event) override;
    void dropEvent(QDropEvent *event) override;
    void keyPressEvent(QKeyEvent *event) override;
    virtual void fontChange(const QFont &oldFont);

private:
    /**
     * Initialization routine common to every constructors.\n
     * Constructors just have to initialize the KComboBox, m_color and m_defaultColor
     * and this function do the rest to complete the creation of this widget.
     */
    void init();

    /**
     * Free up all memory allocated for the color array.\n
     * But only if an array have previously been allocated, of course.
     */
    void deleteColorArray();

    /**
     * Update the only item of the combobox to mirror the new selected color.\n
     * Mainly called on init() and setColor().
     */
    void updateComboBox();

    KColorPopup *m_popup;
    QColor m_color;
    QColor m_defaultColor;
    QColor **m_colorArray;
    int m_columnCount;
    int m_rowCount;
    QPoint m_dragStartPos;

protected:
    /**
     * Keep place for future improvements without having to break binary compatibility.\n
     * Does nothing for the moment.
     */
    void virtual_hook(int id, void *data) override;

private:
    /**
     * Keep place for future improvements without having to break binary compatibility.
     */
    class KColorCombo2Private;

    KColorCombo2Private *d;
};

// TODO: setColorArray(QColor **, int, int) and use signals/slots ??

class KColorPopup : public QWidget
{
    Q_OBJECT
public:
    explicit KColorPopup(KColorCombo2 *parent);
    ~KColorPopup() override;
    void relayout(); // updateGeometry() ??
Q_SIGNALS:
    void closed();

protected:
    void paintEvent(QPaintEvent * /*event*/) override;
    void mouseMoveEvent(QMouseEvent *event) override;
    void mousePressEvent(QMouseEvent *event) override;
    void keyPressEvent(QKeyEvent *event) override;
    void doSelection();
    void validate();
    void updateCell(int column, int row);

    friend class KColorCombo2;

private:
    KColorCombo2 *m_selector;
    QPixmap *m_pixmap;
    int m_selectedRow;
    int m_selectedColumn;
    int m_columnOther;
    QColor m_otherColor;

    static const int MARGIN;
    static const int FRAME_WIDTH;
};

#endif // KCOLORCOMBO2_H
