/***

    Olive - Non-Linear Video Editor
    Copyright (C) 2019  Olive Team

    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 3 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, see <http://www.gnu.org/licenses/>.

***/

#ifndef LABELSLIDER_H
#define LABELSLIDER_H

#include <QLabel>
#include <QUndoCommand>

enum LabelSliderDisplayType {
  LABELSLIDER_NORMAL,
  LABELSLIDER_FRAMENUMBER,
  LABELSLIDER_PERCENT,
  LABELSLIDER_DECIBEL
};

/**
 * @brief The LabelSlider class
 *
 * A UI element that shows a number and can be dragged to increase/decrease its value or clicked to enter a specific
 * one.
 */
class LabelSlider : public QLabel
{
  Q_OBJECT
public:
  LabelSlider(QWidget* parent = nullptr);

  /**
     * @brief Set the display frame rate
     *
     * If the `display_type` is set to LABELSLIDER_FRAMENUMBER, this function sets how many frames per second the
     * timecode will be in.
     *
     * @param d
     */
  void set_frame_rate(double d);

  /**
     * @brief Sets the way to display the value
     *
     * * `LABELSLIDER_NORMAL` - Shows the value as a normal number
     * * `LABELSLIDER_FRAMENUMBER` - Shows the number as a timecode according to `config.timecode_view`. By default,
     * will render hh:mm:ss:ff
     * * `LABELSLIDER_PERCENT` - Shows the number as a percentage. 1.0 becomes "100%", 0.5 becomes 50%, etc.
     * * `LABELSLIDER_DECIBLE` - Shows the number as a decibel. 1.0 becomes "0 dB", 2.0 becames roughly "6 dB", 0.5
     * becomes roughly "-6 dB", etc.
     *
     * @param type
     *
     * The display type to set to. Should be a member of `enum LabelSliderDisplayType`.
     */
  void set_display_type(int type);

  /**
     * @brief Set the value
     * @param v
     *
     * Value to set to.
     *
     * @param userSet
     *
     * **TRUE** if this was called through a user action, **FALSE** if this was called through some other way. The
     * only difference is **TRUE** will emit a signal (valueChanged()) indicating that the value has changed, and
     * **FALSE** will not.
     */
  void set_value(double v, bool userSet);

  /**
     * @brief Set the default value
     *
     * If a default value is set, alt+clicking the LabelSlider will return to the default value.
     *
     * @param v
     *
     * Value to set as default
     */
  void set_default_value(double v);

  /**
     * @brief Set the minimum value
     *
     * If a minimum value is set, the value will never go below it. If the user manually sets a value lower than
     * the minimum, it will automatically snap to the minimum.
     *
     * @param v
     *
     * Value to set as minimum
     */
  void set_minimum_value(double v);

  /**
     * @brief Set the maximum value
     *
     * If a maximum value is set, the value will never go above it. If the user manually sets a value higher than
     * the maximum, it will automatically snap to the maximum.
     *
     * @param v
     *
     * Value to set as maximum
     */
  void set_maximum_value(double v);

  /**
     * @brief Returns the internal value as a double
     * @return The internal value. This will not respect the `display_type`, i.e. 100% will return as 1.0, 12dB will
     * return as 400%, and a timecode will return as a frame number.
     */
  double value();

  /**
     * @brief Returns whether a value has been set or not
     *
     * If a value has been entered by any means (i.e. if set_value() was called), this will be **TRUE**. If set_value()
     * has not been called and is_set() is **FALSE**, calling set_default_value() will automatically set the value
     * to the default value WITHOUT changing the is_set() state (i.e. it will still be **FALSE** and calling
     * set_default_value() again will change the current value again unless it's been changed through some other means
     * in that time).
     *
     * @return **TRUE** if a value has been set, **FALSE** if not.
     */
  bool is_set();

  /**
     * @brief Returns whether the user is currently dragging
     * @return **TRUE** if the user is dragging, **FALSE** if not.
     */
  bool is_dragging();

  /**
     * @brief Convert the internal value to a displayed string according to `display_type`
     * @return The internal value as a string
     */
  QString valueToString();

  /**
     * @brief Returns whatever value was set before the last set_value()
     *
     * For various reasons (largely undo capabilities) it is helpful to retrieve whatever the value was before the
     * current one. If the user dragged the current value, this will return the value just before the user started
     * dragging.
     *
     * @return The previous value
     */
  double getPreviousValue();

  /**
     * @brief Updates previous value
     *
     * Called internally to store the current value as the previous value in anticipation of an upcoming value change.
     * Can also be called externally (mainly for dragged EffectGizmos) in anticipation of an external change.
     */
  void set_previous_value();

  /**
     * @brief Set the display color
     * @param c
     *
     * Color to set to
     */
  void set_color(QString c = nullptr);

  /**
     * @brief Set how many decimal places to show for a floating-point number
     *
     * Defaults to 1
     */
  int decimal_places;
protected:
  void mousePressEvent(QMouseEvent *ev);
  void mouseMoveEvent(QMouseEvent *ev);
  void mouseReleaseEvent(QMouseEvent *ev);
private:
  double default_value;
  double internal_value;
  double drag_start_value;
  double previous_value;

  bool min_enabled;
  double min_value;
  bool max_enabled;
  double max_value;

  bool drag_start;
  bool drag_proc;
  int drag_start_x;
  int drag_start_y;

  bool set;

  int display_type;

  double frame_rate;

  /**
     * @brief Internal function to set the standard cursor (usually SizeHorCursor)
     */
  void set_default_cursor();

  /**
     * @brief Internal function to set the cursor while dragging (usually NoCursor aka invisible)
     */
  void set_active_cursor();
private slots:
  /**
   * @brief Context menu slot to be connected to QWidget::customContextMenuRequested(const QPoint&)
   *
   * @param pos
   *
   * Current cursor position
   */
  void show_context_menu(const QPoint& pos);

  /**
   * @brief Slot to reset current value to the default value
   */
  void reset_to_default_value();

  /**
   * @brief Show prompt asking for value
   *
   * Triggered when the user clicks on the LabelSlider without dragging or triggers right click > Edit.
   * Will show an input dialog asking for a new value to be entered manually. Asks for units in the selected
   * display type and converts them back to the internal value type.
   */
  void prompt_for_value();
signals:
  /**
     * @brief valueChanged signal
     *
     * Emitted if the value changed at it was instigated by the user.
     */
  void valueChanged();

  /**
     * @brief clicked signal
     *
     * Emitted if the user clicks on the LabelSlider in any way
     */
  void clicked();
};

#endif // LABELSLIDER_H