/*
    Copyright 2012 Frederik Gladhorn <gladhorn@kde.org>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) version 3, or any
    later version accepted by the membership of KDE e.V. (or its
    successor approved by the membership of KDE e.V.), which shall
    act as a proxy defined in Section 6 of version 3 of the license.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef QACCESSIBILITYCLIENT_REGISTRY_H
#define QACCESSIBILITYCLIENT_REGISTRY_H

#include <qobject.h>

#include "qaccessibilityclient_export.h"
#include "accessibleobject.h"
#include <QUrl>

#define accessibleRegistry (QAccessibleClient::Registry::instance())

namespace QAccessibleClient {

class RegistryPrivate;
class RegistryPrivateCacheApi;

/**
    This class represents the global accessibility registry.

    It provides information about running applications.
    All updates of accessible objects will result in signals emitted by this class.
*/
class QACCESSIBILITYCLIENT_EXPORT Registry : public QObject
{
    Q_OBJECT
    Q_ENUMS(EventListener)

public:

    /**
     This enum describes the different types of events that can be observed.
     */
    enum EventListener {
        NoEventListeners = 0x0,             /*!< No event listeners registered or wanted */
        Window = 0x1,                       /*!< Window changes, such as new applications being started */
        Focus = 0x2,                        /*!< Focus listener reacts to focus changes - see signal \sa focusChanged */
        //FocusPoint = 0x4,

        //BoundsChanged = 0x8,
        //LinkSelected = 0x10,
        StateChanged = 0x20,                /*!< State of the accessible changed - see signal \sa stateChanged */
        ChildrenChanged = 0x40,             /*!< Children changed - see signal \sa childrenChanged */
        VisibleDataChanged = 0x80,          /*!< Visibility of the accessible changed - see signal \sa visibleDataChanged */
        SelectionChanged = 0x100,           /*!< Selection changed  - see signal \sa selectionChanged */
        ModelChanged = 0x200,               /*!< The model changed - see signal \sa modelChanged */

        TextCaretMoved = 0x400,             /*!< The text caret moved its position - see signal \sa textCaretMoved */
        TextChanged = 0x800,                /*!< The text changed - see signal \sa textChanged */
        TextSelectionChanged = 0x1000,      /*!< The text selection changed - see signal \sa textSelectionChanged */
        PropertyChanged = 0x2000,           /*!< A property changed. See signals \sa accessibleNameChanged and \sa accessibleDescriptionChanged */
        //TextBoundsChanged = 0x2000,
        //TextAttributesChanged = 0x4000,
        //AttributesChanged = 0x8000,

        AllEventListeners = 0xffffffff      /*!< All possible event listeners */
    };
    Q_DECLARE_FLAGS(EventListeners, EventListener)

    /**
      Construct a Registry object with \a parent as QObject parent.
     */
    explicit Registry(QObject *parent = nullptr);
    /**
      Destroys this Registry.
     */
    ~Registry() override;

public Q_SLOTS:

    /**
        Returns true if the accessibility stack is enabled.

        This means that an atspi registry daemon is running and available as
        org.a11y.bus at the session dbus. The org.a11y.bus implments the
        org.a11y.Status dbus interface that offers the IsEnabled property. The
        \a isEnabled and \a setEnabled methods do read/write the boolean value
        of that org.a11y.Status.IsEnabled dbus property..
    */
    bool isEnabled() const;
    /**
      Activates accessibility when \a enabled and tells
      toolkits to provide updates such as focus changes.
     */
    void setEnabled(bool enable);

    /**
        Returns true if the screen reader is enabled.

        This means that there is potentially a screen reader, if installed,
        that is enabled or disabled. This allows to enable system wide a
        screen reader with just one switch.
    */
    bool isScreenReaderEnabled() const;
    /**
      Tells the system that a screen reader is \a enabled.
     */
    void setScreenReaderEnabled(bool enable);

    /**
        In order to get notified of changes in accessible applications
        it is neccessary to subscribe to the listeners that are relevant.

        This will unsubscribe all previously subscribed event listeners.
    */
    void subscribeEventListeners(const EventListeners &listeners) const;
    /**
      Returns the active event listeners.
     */
    EventListeners subscribedEventListeners() const;

    /**
        List of all currently running applications that
        expose an accessibility interface.
    */
    QList<AccessibleObject> applications() const;

    /**
        Creates the AccessibleObject for the \a url.

        This can be used to deserialize an AccessibleObject
        after passing it around as string.

        The returned QUrl returns a scheme of "accessibleobject".
    */
    AccessibleObject accessibleFromUrl(const QUrl &url) const;

Q_SIGNALS:

    /**
        Emitted if the \a isEnabled state changed.

        If the accessibility daemon got enabled or disabled either by us or
        ny someone else then this signal is emitted.
    */
    void enabledChanged(bool enabled);

    /**
        Emitted if the \a isScreenReaderEnabled state changed.

        If the screen reader enabled property got enabled or disabled either
        by us or by someone else then this signal is emitted.
    */
    void screenReaderEnabledChanged(bool enabled);

    /**
        Emitted if a AccessibleObject is created.

        This signal indicates that the \a AccessibleObject instance was
        created and is going to be added/attached.
    */
    void added(const QAccessibleClient::AccessibleObject &object);

    /**
        Emitted if a AccessibleObject is destroyed.

        This signal indicates that the \a AccessibleObject instance was
        destroyed and ended its life-time.
    */
    void removed(const QAccessibleClient::AccessibleObject &object);

    /**
        Emitted if a AccessibleObject is marked defunct.

        This signal indicates that the \a AccessibleObject became invalid
        and does not point any longer to any valid accessible object.
    */
    void defunct(const QAccessibleClient::AccessibleObject &object);

    /// Emitted when a window is created
    void windowCreated(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is destroyed
    void windowDestroyed(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is closed
    void windowClosed(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is reparented
    void windowReparented(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is minimized
    void windowMinimized(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is maximized
    void windowMaximized(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is restored to normal size
    void windowRestored(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is activated
    void windowActivated(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is deactivated
    void windowDeactivated(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a desktop window is created
    void windowDesktopCreated(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a desktop window is destroyed
    void windowDesktopDestroyed(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is raised
    void windowRaised(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is lowered
    void windowLowered(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is moved
    void windowMoved(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is resized
    void windowResized(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is shaded
    void windowShaded(const QAccessibleClient::AccessibleObject &object);
    /// Emitted when a window is unshaded
    void windowUnshaded(const QAccessibleClient::AccessibleObject &object);

    //void boundsChanged(const QAccessibleClient::AccessibleObject &object);
    //void linkSelected(const QAccessibleClient::AccessibleObject &object);

    /**
        \brief Notifies about a state change in an object.

        The \a state of \a object has change.
        If the state is now set \a active is true, otherwise the state was removed.
     */
    void stateChanged(const QAccessibleClient::AccessibleObject &object, const QString &state, bool active);

    /**
        \brief Notifies about a new AccessibleObject

        The childAdded signal is emitted when a new accessible object is created.
        This signal depends on the implementation of the server side and is not
        reliable for all applications.
        The parameter \a childIndex is the index of the child that has been added.
        \sa AccessibleObject::child(), childRemoved()
     */
    void childAdded(const QAccessibleClient::AccessibleObject &parent, int childIndex);

    /**
        \brief Notifies that an AccessibleObject has been removed

        The parameter \a childIndex is the index of the child that has been removed.
        \sa AccessibleObject::child(), childAdded()
     */
    void childRemoved(const QAccessibleClient::AccessibleObject &parent, int childIndex);

    /**
      \brief Notifies that the \a object's visible data changed.
     */
    void visibleDataChanged(const QAccessibleClient::AccessibleObject &object);

    /**
      \brief Notifies that the \a object's selection changed.
     */
    void selectionChanged(const QAccessibleClient::AccessibleObject &object);

    /**
      \brief Notifies that the \a object's table model changed.
     */
    void modelChanged(const QAccessibleClient::AccessibleObject &object);

    /**
        \brief Emitted when the focus changed.

        When subscribed to the Focus EventListener then this signal is emitted
        every time the focus changes. \a object is the newly focused AccessibleObject.
    */
    void focusChanged(const QAccessibleClient::AccessibleObject &object);

    /**
        \brief Emitted when the text cared moved.

        When subscribed to the TextCaretMoved EventListener then this signal
        is emitted every time the caret in an accessible object that implements
        a text-interface (like QLineEdit, QTextArea and QComboBox) moved to
        another position.
    */
    void textCaretMoved(const QAccessibleClient::AccessibleObject &object, int pos);

    /**
        \brief Emitted when the text selection changed.

        When subscribed to the TextSelectionChanged EventListener then this signal
        is emitted every time the selection in an accessible object that implements
        a text-interface (like QLineEdit, QTextArea and QComboBox) changed.
    */
    void textSelectionChanged(const QAccessibleClient::AccessibleObject &object);


    /**
        \brief Emitted when an accessible name changes

        When subscribed to the PropertyChanged EventListener, this signal is emitted
        whenever the accessible-name property changes its value.
    */
    void accessibleNameChanged(const QAccessibleClient::AccessibleObject &object);

    /**
        \brief Emitted when an accessible description changes

        When subscribed to the PropertyChanged EventListener, this signal is emitted
        whenever the accessible-description property changes its value.
    */
    void accessibleDescriptionChanged(const QAccessibleClient::AccessibleObject &object);

    /**
        \brief Emitted when an object's text was changed.

        The new text will be \a text. The change starts at \a startOffset and goes to \a endOffset.

        \sa textInserted, textRemoved
    */
    void textChanged(const QAccessibleClient::AccessibleObject &object, const QString& text, int startOffset, int endOffset);

    /**
        \brief Emitted when text was inserted in an object's text.

        The new text will be \a text. The change starts at \a startOffset and goes to \a endOffset.

        \sa textInserted, textRemoved
    */
    void textInserted(const QAccessibleClient::AccessibleObject &object, const QString& text, int startOffset, int endOffset);

    /**
        \brief Emitted when an object's text was removed.

        The removed text will be \a text, but this string may be emtpy for some implementations.
        The removal starts at \a startOffset and goes to \a endOffset.

        \sa textInserted, textRemoved
    */
    void textRemoved(const QAccessibleClient::AccessibleObject &object, const QString& text, int startOffset, int endOffset);

    //void textBoundsChanged(const QAccessibleClient::AccessibleObject &object);
    //void textAttributesChanged(const QAccessibleClient::AccessibleObject &object);
    //void attributesChanged(const QAccessibleClient::AccessibleObject &object);

private:
    Q_DISABLE_COPY(Registry)
    RegistryPrivate *d;
    friend class RegistryPrivate;
    friend class RegistryPrivateCacheApi;

    enum CacheType { NoCache, WeakCache};
    CacheType cacheType() const;
    void setCacheType(CacheType type);
    AccessibleObject clientCacheObject(const QString &id) const;
    QStringList clientCacheObjects() const;
    void clearClientCache();
};

Q_DECLARE_OPERATORS_FOR_FLAGS(Registry::EventListeners)

}

#endif
