/***************************************************************************
 *   Copyright (C) 2005-09 by the Quassel Project                          *
 *   devel@quassel-irc.org                                                 *
 *                                                                         *
 *   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) version 3.                                           *
 *                                                                         *
 *   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.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

#ifndef _SETTINGSPAGE_H_
#define _SETTINGSPAGE_H_

#include <QWidget>

class QCheckBox;
class QComboBox;
class QSpinBox;

//! A SettingsPage is a page in the settings dialog.
/** The SettingsDlg provides suitable standard buttons, such as Ok, Apply, Cancel, Restore Defaults and Reset.
 *  Some pages might also be used in standalone dialogs or other containers. A SettingsPage provides suitable
 *  slots and signals to allow interaction with the container.
 *
 *  A derived class needs to keep track of its changed state. Whenever a child widget changes, it needs to be
 *  compared to its value in permanent storage, and the changed state updated accordingly by calling setChangedState().
 *  For most standard widgets, SettingsPage can do this automatically if desired. Such a child widget needs to have
 *  a dynamic property \c settingsKey that maps to the key in the client configuration file. This key is appended
 *  to settingsKey(), which must be set to a non-null value in a derived class. If the widget's key starts with '/',
 *  its key is treated as a global path starting from the root, rather than from settingsKey().
 *  A second dynamic property \c defaultValue can be defined in child widgets as well.
 *
 *  SettingsPage manages loading, saving, setting to default and setting the changed state for all automatic child widgets.
 *  Derived classes must be sure to call initAutoWidgets() *after* setupUi(); they also need to call the baseclass implementations
 *  of load(), save() and defaults() (preferably at the end of the derived function, since they call setChangedState(false)).
 *
 *  The following widgets can be handled for now:
 *    - QAbstractButton (isChecked(), e.g. for QCheckBox and QRadioButton)
 *    - QLineEdit, QTextEdit (text())
 *    - QComboBox (currentIndex())
 *    - QSpinBox (value())
 */
class SettingsPage : public QWidget {
  Q_OBJECT

public:
  SettingsPage(const QString &category, const QString &name, QWidget *parent = 0);
  virtual ~SettingsPage() {};

  //! The category of this settings page.
  inline virtual QString category() const { return _category; }

  //! The title of this settings page.
  inline virtual QString title() const { return _title; }

  //! The key this settings page stores its values under
  /** This needs to be overriden to enable automatic loading/saving/hasChanged checking of widgets.
   *  The child widgets' values will be stored in client settings under this key. Every widget that
   *  should be automatically handled needs to have a \c settingsKey property set, and should also provide
   *  a \c defaultValue property.
   *  You can return an empty string (as opposed to a null string) to use the config root as a base, and
   *  you can override this key for individual widgets by prefixing their SettingsKey with /.
   */
  inline virtual QString settingsKey() const { return QString(); }

  //! Derived classes need to define this and return true if they have default settings.
  /** If this method returns true, the "Restore Defaults" button in the SettingsDlg is
   *  enabled. You also need to provide an implementation of defaults() then.
   *
   * The default implementation returns false.
     */
  inline virtual bool hasDefaults() const { return false; }

  //! Check if there are changes in the page, compared to the state saved in permanent storage.
  inline bool hasChanged() const { return _changed || _autoWidgetsChanged; }

  //! Called immediately before save() is called.
  /** Derived classes should return false if saving is not possible (e.g. the current settings are invalid).
   *  \return false, if the SettingsPage cannot be saved in its current state.
   */
  inline virtual bool aboutToSave() { return true; }

  //! sets checked state depending on \checked and stores the value for later comparision
  static void load(QCheckBox *box, bool checked);
  static bool hasChanged(QCheckBox *box);
  static void load(QComboBox *box, int index);
  static bool hasChanged(QComboBox *box);
  static void load(QSpinBox *box, int value);
  static bool hasChanged(QSpinBox *box);

public slots:
  //! Save settings to permanent storage.
  /** This baseclass implementation saves the autoWidgets, so be sure to call it if you use
   *  this feature in your settingsPage!
   */
  virtual void save();

  //! Load settings from permanent storage, overriding any changes the user might have made in the dialog.
  /** This baseclass implementation loads the autoWidgets, so be sure to call it if you use
   *  this feature in your settingsPage!
   */
  virtual void load();

  //! Restore defaults, overriding any changes the user might have made in the dialog.
  /** This baseclass implementation loads the defaults of the autoWidgets (if available), so be sure
   *  to call it if you use this feature in your settingsPage!
   */
  virtual void defaults();

protected slots:
  //! Calling this slot is equivalent to calling setChangedState(true).
  inline void changed() { setChangedState(true); }

  //! This should be called whenever the widget state changes from unchanged to change or the other way round.
  void setChangedState(bool hasChanged = true);

protected:
  void initAutoWidgets();

signals:
  //! Emitted whenever the widget state changes.
  void changed(bool hasChanged);

private slots:
  // for auto stuff
  void autoWidgetHasChanged();

private:
  void findAutoWidgets(QObject *parent, QObjectList *widgetList) const;
  QByteArray autoWidgetPropertyName(QObject *widget) const;
  QString autoWidgetSettingsKey(QObject *widget) const;

  QString _category, _title;
  bool _changed, _autoWidgetsChanged;
  QObjectList _autoWidgets;
};



#endif
