/*
 *   Copyright 2006-2007 by Aaron Seigo <aseigo@kde.org>
 *   Copyright 2007 by Riccardo Iaconelli <riccardo@kde.org>
 *   Copyright 2008 by Ménard Alexis <darktears31@gmail.com>

 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as
 *   published by the Free Software Foundation; either version 2, 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 Library 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 PLASMA_APPLET_H
#define PLASMA_APPLET_H

#include <QObject>
#include <QKeySequence>
#include <QUrl>

#include <kconfiggroup.h>
#include <kplugininfo.h>

#include <plasma/plasma.h>
#include <plasma/version.h>
#include <plasma/framesvg.h>

class KActionCollection;
class KConfigLoader;

namespace Plasma
{

class AppletPrivate;
class Containment;
class DataEngine;
class Package;

/**
 * @class Applet plasma/applet.h <Plasma/Applet>
 *
 * @short The base Applet class
 *
 * Applet provides several important roles for add-ons widgets in Plasma.
 *
 * First, it is the base class for the plugin system and therefore is the
 * interface to applets for host applications. It also handles the life time
 * management of data engines (e.g. all data engines accessed via
 * Applet::dataEngine(const QString&) are properly deref'd on Applet
 * destruction), background painting (allowing for consistent and complex
 * look and feel in just one line of code for applets), loading and starting
 * of scripting support for each applet, providing access to the associated
 * plasmoid package (if any) and access to configuration data.
 *
 * See techbase.kde.org for tutorials on writing Applets using this class.
 */
class PLASMA_EXPORT Applet : public QObject
{
    Q_OBJECT
    Q_PROPERTY(Types::ItemStatus status READ status WRITE setStatus NOTIFY statusChanged)
    Q_PROPERTY(Types::ImmutabilityType immutability READ immutability WRITE setImmutability NOTIFY immutabilityChanged)
    Q_PROPERTY(Types::FormFactor formFactor READ formFactor NOTIFY formFactorChanged)
    Q_PROPERTY(Types::Location location READ location NOTIFY locationChanged)
    Q_PROPERTY(QString title READ title WRITE setTitle FINAL)
    Q_PROPERTY(QString icon READ icon WRITE setIcon FINAL)

public:
//CONSTRUCTORS
    /**
     * @param parent the QObject this applet is parented to
     * @param serviceId the name of the .desktop file containing the
     *      information about the widget
     * @param appletId a unique id used to differentiate between multiple
     *      instances of the same Applet type
     */
    explicit Applet(QObject *parent = 0, const QString &serviceId = QString(), uint appletId = 0);

    /**
     * @param parent the QObject this applet is parented to
     * @param info the plugin information object for this Applet
     * @param appletId a unique id used to differentiate between multiple
     *      instances of the same Applet type
     * @since 4.6
     */
    explicit Applet(const KPluginInfo &info, QObject *parent = 0, uint appletId = 0);

    ~Applet();

//BOOKKEEPING
    /**
     * @return the id of this applet
     */
    uint id() const;

    /**
     * @return The type of immutability of this applet
     */
    Types::ImmutabilityType immutability() const;

    /**
     * If for some reason, the applet fails to get up on its feet (the
     * library couldn't be loaded, necessary hardware support wasn't found,
     * etc..) this method returns the reason why, in an user-readable way.
     * @since 5.0
     **/
    QString launchErrorMessage() const;

    /**
     * If for some reason, the applet fails to get up on its feet (the
     * library couldn't be loaded, necessary hardware support wasn't found,
     * etc..) this method returns true.
     **/
    bool failedToLaunch() const;

    /**
     * @return true if destroy() was called; useful for Applets which should avoid
     * certain tasks if they are about to be deleted permanently
     */
    bool destroyed() const;

    /**
     * @return the Containment, if any, this applet belongs to
     **/
    Containment *containment() const;

    /**
     * @return true if this Applet is currently being used as a Containment, false otherwise
     */
    bool isContainment() const;

    /**
     * @return the status of the applet
     * @since 4.4
     */
    Types::ItemStatus status() const;

    /**
     * Returns the current form factor the applet is being displayed in.
     *
     * @see Plasma::FormFactor
     */
    Types::FormFactor formFactor() const;

    /**
     * Returns the location of the scene which is displaying applet.
     *
     * @see Plasma::Types::Location
     */
    Types::Location location() const;

//CONFIGURATION
    /**
    * Returns the KConfigGroup to access the applets configuration.
    *
    * This config object will write to an instance
    * specific config file named \<appletname\>\<instanceid\>rc
    * in the Plasma appdata directory.
    **/
    KConfigGroup config() const;

    /**
     * Returns a KConfigGroup object to be shared by all applets of this
     * type.
     *
     * This config object will write to an applet-specific config object
     * named plasma_\<appletname\>rc in the local config directory.
     */
    KConfigGroup globalConfig() const;

    /**
     * Returns the config skeleton object from this applet's package,
     * if any.
     *
     * @return config skeleton object, or 0 if none
     **/
    KConfigLoader *configScheme() const;

    /**
     * Saves state information about this applet that will
     * be accessed when next instantiated in the restore(KConfigGroup&) method.
     *
     * This method does not need to be reimplmented by Applet
     * subclasses, but can be useful for Applet specializations
     * (such as Containment) to do so.
     *
     * Applet subclasses may instead want to reimplement saveState().
     **/
    virtual void save(KConfigGroup &group) const;

    /**
     * Restores state information about this applet saved previously
     * in save(KConfigGroup&).
     *
     * This method does not need to be reimplmented by Applet
     * subclasses, but can be useful for Applet specializations
     * (such as Containment) to do so.
     **/
    virtual void restore(KConfigGroup &group);

    /**
     * @return true if the applet currently needs to be configured,
     *         otherwise, false
     */
    bool configurationRequired() const;

    /**
     * @return true when the configuration interface is being shown
     * @since 4.5
     */
    bool isUserConfiguring() const;

    /**
     * Tells the applet the user is configuring
     * @param configuring true if the configuration ui is showing
     */
    void setUserConfiguring(bool configuring);

//UTILS
    /**
     * Accessor for the associated Package object if any.
     * Generally, only Plasmoids come in a Package.
     *
     * @return the Package object, or an invalid one if none
     **/
    Package package() const;

    /**
     * Called when any of the geometry constraints have been updated.
     * This method calls constraintsEvent, which may be reimplemented,
     * once the Applet has been prepared for updating the constraints.
     *
     * @param constraints the type of constraints that were updated
     */
    void updateConstraints(Plasma::Types::Constraints constraints = Plasma::Types::AllConstraints);

//METADATA
    /**
     * @return metadata information about this plugin
     * @see KPluginInfo
     * @since 5.0
     */
    KPluginInfo pluginInfo() const;

    /**
     * Returns the user-visible title for the applet, as specified in the
     * Name field of the .desktop file. Can be changed with @see setTitle
     *
     * @since 5.0
     * @return the user-visible title for the applet.
     **/
    QString title() const;

    /**
     * Sets a custom title for this instance of the applet. E.g. a clock might
     * use the timezone as its name rather than the .desktop file
     *
     * @since 5.0
     * @param title the user-visible title for the applet.
     */
    void setTitle(const QString &title) const;

    /**
     * Attempts to load an applet from a package
     *
     * Returns a pointer to the applet if successful.
     * The caller takes responsibility for the applet, including
     * deleting it when no longer needed.
     *
     * @param path the path to the package
     * @param appletId unique ID to assign the applet, or zero to have one
     *        assigned automatically.
     * @return a pointer to the loaded applet, or 0 on load failure
     * @since 4.3
     **/
    static Applet *loadPlasmoid(const QString &path, uint appletId = 0);

    /**
     * @returns The icon name related to this applet
     * By default is the one in the plasmoid desktop file
     **/
    QString icon() const;

    /**
     * Sets an icon name for this applet
     * @param icon Freedesktop compatible icon name
     */
    void setIcon(const QString &icon);

//ACTIONS
    /**
     * Returns a list of context-related QAction instances.
     *
     * This is used e.g. within the \a DesktopView to display a
     * contextmenu.
     *
     * @return A list of actions. The default implementation returns an
     *         empty list.
     **/
    virtual QList<QAction *> contextualActions();

    /**
     * Returns the collection of actions for this Applet
     */
    KActionCollection *actions() const;

    /**
     * Sets the global shortcut to associate with this widget.
     */
    void setGlobalShortcut(const QKeySequence &shortcut);

    /**
     * @return the global shortcut associated with this wiget, or
     * an empty shortcut if no global shortcut is associated.
     */
    QKeySequence globalShortcut() const;

// ASSOCIATED APPLICATION
    /**
     * Sets an application associated to this applet, that will be
     * regarded as a full view of what is represented in the applet
     *
     * @param string the name of the application. it can be
     *      \li a name understood by KService::serviceByDesktopName
     *        (e.g. "konqueror")
     *      \li a command in $PATH
     *      \li or an absolute path to an executable
     * @since 4.4
     */
    void setAssociatedApplication(const QString &string);

    /**
     * Sets a list of urls associated to this application,
     * they will be used as parameters for the associated application
     * @see setAssociatedApplication()
     *
     * @param urls
     */
    void setAssociatedApplicationUrls(const QList<QUrl> &urls);

    /**
     * @return the application associated to this applet
     * @since 4.4
     */
    QString associatedApplication() const;

    /**
     * @return the urls associated to this applet
     * @since 4.4
     */
    QList<QUrl> associatedApplicationUrls() const;

    /**
     * @return true if the applet has a valid associated application or urls
     * @since 4.4
     */
    bool hasValidAssociatedApplication() const;

//Completely UI-specific, remove or move to scriptengine
    /**
     * @return true if this plasmoid provides a GUI configuration
     **/
    bool hasConfigurationInterface() const;

Q_SIGNALS:
//BOOKEEPING
    /**
     * Emitted when the immutability changes
     * @since 4.4
     */
    void immutabilityChanged(Plasma::Types::ImmutabilityType immutable);

    /**
     * Emitted when the applet status changes
     * @since 4.4
     */
    void statusChanged(Plasma::Types::ItemStatus status);

//CONFIGURATION
    /**
     * Emitted when an applet has changed values in its configuration
     * and wishes for them to be saved at the next save point. As this implies
     * disk activity, this signal should be used with care.
     *
     * @note This does not need to be emitted from saveState by individual
     * applets.
     */
    void configNeedsSaving();

    /**
     * emitted when the config ui appears or disappears
     */
    void userConfiguringChanged(bool configuring);

//ACTIONS
    /**
     * Emitted when activation is requested due to, for example, a global
     * keyboard shortcut. By default the wiget is given focus.
     */
    void activated();

//TODO: fix usage in containment, port to QObject::destroyed
    /**
     * Emitted when the applet is deleted
     */
    void appletDeleted(Plasma::Applet *applet);

    /**
     * Emitted when the formfactor changes
     */
    void formFactorChanged(Plasma::Types::FormFactor formFactor);

    /**
     * Emitted when the location changes
     */
    void locationChanged(Plasma::Types::Location location);

public Q_SLOTS:
//BOOKKEEPING
    /**
     * Call this method when the applet fails to launch properly. An
     * optional reason can be provided.
     *
     * Not that all children items will be deleted when this method is
     * called. If you have pointers to these items, you will need to
     * reset them after calling this method.
     *
     * @param failed true when the applet failed, false when it succeeded
     * @param reason an optional reason to show the user why the applet
     *               failed to launch
     * @since 5.0
     **/
    void setLaunchErrorMessage(const QString &reason = QString());

    /**
     * Sets the immutability type for this applet (not immutable,
     * user immutable or system immutable)
     * @param immutable the new immutability type of this applet
     */
    void setImmutability(const Types::ImmutabilityType immutable);

    /**
     * Destroys the applet; it will be removed nicely and deleted.
     * Its configuration will also be deleted.
     * If you want to remove the Applet configuration, use this, don't just delete the Applet *
     */
    void destroy();

    /**
     * sets the status for this applet
     * @since 4.4
     */
    void setStatus(const Types::ItemStatus stat);

//CONFIGURATION
    /**
     * Called when applet configuration values have changed.
     */
    virtual void configChanged();

//UTILS
    /**
     * Sends all pending constraints updates to the applet. Will usually
     * be called automatically, but can also be called manually if needed.
     */
    void flushPendingConstraintsEvents();

    /**
     * This method is called once the applet is loaded and added to a Corona.
     * If the applet requires a Scene or has an particularly intensive
     * set of initialization routines to go through, consider implementing it
     * in this method instead of the constructor.
     *
     * Note: paintInterface may get called before init() depending on initialization
     * order. Painting is managed by the canvas (QGraphisScene), and may schedule a
     * paint event prior to init() being called.
     **/
    virtual void init();

//ASSOCIATED APPLICATION
    /**
    * Open the application associated to this applet, if it's not set
    * but some urls are, open those urls with the proper application
    * for their mimetype
    * @see setAssociatedApplication()
    * @see setAssociatedApplicationUrls()
    * @since 4.4
    */
    void runAssociatedApplication();

protected:
//CONSTRUCTORS
    /**
     * This constructor is to be used with the plugin loading systems
     * found in KPluginInfo and KService. The argument list is expected
     * to have two elements: the KService service ID for the desktop entry
     * and an applet ID which must be a base 10 number.
     *
     * @param parent a QObject parent; you probably want to pass in 0
     * @param args a list of strings containing two entries: the service id
     *      and the applet id
     */
    Applet(QObject *parent, const QVariantList &args);

//CONFIGURATION
    /**
     * When called, the Applet should write any information needed as part
     * of the Applet's running state to the configuration object in config()
     * and/or globalConfig().
     *
     * Applets that always sync their settings/state with the config
     * objects when these settings/states change do not need to reimplement
     * this method.
     **/
    virtual void saveState(KConfigGroup &config) const;

    /**
     * Sets whether or not this applet provides a user interface for
     * configuring the applet.
     *
     * It defaults to false, and if true is passed in you should
     * also reimplement createConfigurationInterface()
     *
     * @param hasInterface whether or not there is a user interface available
     **/
    void setHasConfigurationInterface(bool hasInterface);

    /**
     * When the applet needs to be configured before being usable, this
     * method can be called to show a standard interface prompting the user
     * to configure the applet
     *
     * @param needsConfiguring true if the applet needs to be configured,
     *                         or false if it doesn't
     * @param reason a translated message for the user explaining that the
     *               applet needs configuring; this should note what needs
     *               to be configured
     */
    void setConfigurationRequired(bool needsConfiguring, const QString &reason = QString());

//UTILS
    /**
     * Called when any of the constraints for the applet have been updated. These constraints
     * range from notifying when the applet has officially "started up" to when geometry changes
     * to when the form factor changes.
     *
     * Each constraint that has been changed is passed in the constraints flag.
     * All of the constraints and how they work is documented in the @see Plasma::Constraints
     * enumeration.
     *
     * On applet creation, this is always called prior to painting and can be used as an
     * opportunity to layout the widget, calculate sizings, etc.
     *
     * Do not call update() from this method; an update() will be triggered
     * at the appropriate time for the applet.
     *
     * @param constraints the type of constraints that were updated
     * @property constraint
     */
    virtual void constraintsEvent(Plasma::Types::Constraints constraints);

//TODO: timerEvent should go into AppletPrivate
    /**
     * Reimplemented from QObject
     */
    void timerEvent(QTimerEvent *event);

private:
    /**
     * @internal This constructor is to be used with the Package loading system.
     *
     * @param parent a QObject parent; you probably want to pass in 0
     * @param args a list of strings containing two entries: the service id
     *      and the applet id
     * @since 4.3
     */
    Applet(const QString &packagePath, uint appletId);

    Q_PRIVATE_SLOT(d, void cleanUpAndDelete())
    Q_PRIVATE_SLOT(d, void askDestroy())
    Q_PRIVATE_SLOT(d, void updateShortcuts())
    Q_PRIVATE_SLOT(d, void globalShortcutChanged())
    Q_PRIVATE_SLOT(d, void propagateConfigChanged())
    Q_PRIVATE_SLOT(d, void requestConfiguration())

    AppletPrivate *const d;

    //Corona needs to access setLaunchErrorMessage and init
    friend class Corona;
    friend class CoronaPrivate;
    friend class Containment;
    friend class ContainmentPrivate;
    friend class AppletScript;
    friend class AppletPrivate;
    friend class AccessAppletJobPrivate;
    friend class GraphicsViewAppletPrivate;
    friend class PluginLoader;
    friend class AssociatedApplicationManager;
};

} // Plasma namespace

/**
 * Register an applet when it is contained in a loadable module
 */
#define K_EXPORT_PLASMA_APPLET(libname, classname) \
    K_PLUGIN_FACTORY(factory, registerPlugin<classname>();) \
    K_EXPORT_PLUGIN_VERSION(PLASMA_VERSION)

#endif // multiple inclusion guard
