/****************************************************************************
Copyright 2016  Martin Gräßlin <mgraesslin@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 KWAYLAND_CLIENT_TEXTINPUT_H
#define KWAYLAND_CLIENT_TEXTINPUT_H

#include <QObject>

#include <KWayland/Client/kwaylandclient_export.h>

struct wl_text_input;
struct wl_text_input_manager;
struct zwp_text_input_manager_v2;

namespace KWayland
{
namespace Client
{

class EventQueue;
class TextInputUnstableV0;
class Surface;
class Seat;

/**
 * @brief TextInput represents a Wayland interface for text input.
 *
 * The TextInput allows to have text composed by the Compositor and be sent to
 * the client.
 *
 * Depending on the interface the TextInputManager got created for this class
 * encapsulates one of the following interfaces:
 * @li wl_text_input
 * @li zwp_text_input_v2
 *
 * @since 5.23
 **/
class KWAYLANDCLIENT_EXPORT TextInput : public QObject
{
    Q_OBJECT
public:
    virtual ~TextInput();
    /**
     * @returns @c true if managing a resource.
     **/
    bool isValid() const;

    /**
     * @returns The Surface which has the text input focus on this TextInput.
     * @see entered
     * @see left
     **/
    Surface *enteredSurface() const;

    void setEventQueue(EventQueue *queue);
    EventQueue *eventQueue() const;

    /**
     * @returns whether the input panel (virtual keyboard) is currently visible on the screen
     * @see inputPanelStateChanged
     **/
    bool isInputPanelVisible() const;

    /**
     * Enable text input in a @p surface (usually when a text entry inside of it has focus).
     *
     * This can be called before or after a surface gets text (or keyboard) focus via the
     * enter event. Text input to a surface is only active when it has the current
     * text (or keyboard) focus and is enabled.
     * @see deactivate
     **/
    void enable(Surface *surface);

    /**
     * Disable text input in a @p surface (typically when there is no focus on any
     * text entry inside the surface).
     * @see enable
     **/
    void disable(Surface *surface);

    /**
     * Requests input panels (virtual keyboard) to show.
     * @see hideInputPanel
     **/
    void showInputPanel();

    /**
     * Requests input panels (virtual keyboard) to hide.
     * @see showInputPanel
     **/
    void hideInputPanel();

    /**
     * Should be called by an editor widget when the input state should be
     * reset, for example after the text was changed outside of the normal
     * input method flow.
     **/
    void reset();

    /**
     * Sets the plain surrounding text around the input position.
     *
     * @param text The text surrounding the cursor position
     * @param cursor Index in the text describing the cursor position
     * @param anchor Index of the selection anchor, if no selection same as cursor
     **/
    void setSurroundingText(const QString &text, quint32 cursor, quint32 anchor);

    /**
     * The possible states for a keyEvent.
     * @see keyEvent
     **/
    enum class KeyState {
        Pressed,
        Released
    };

    /**
     * ContentHint allows to modify the behavior of the text input.
     **/
    enum class ContentHint : uint32_t {
        /**
         * no special behaviour
         */
        None = 0,
        /**
         * suggest word completions
         */
        AutoCompletion = 1 << 0,
        /**
         * suggest word corrections
         */
        AutoCorrection = 1 << 1,
        /**
         * switch to uppercase letters at the start of a sentence
         */
        AutoCapitalization = 1 << 2,
        /**
         * prefer lowercase letters
         */
        LowerCase = 1 << 3,
        /**
         * prefer uppercase letters
         */
        UpperCase = 1 << 4,
        /**
         * prefer casing for titles and headings (can be language dependent)
         */
        TitleCase = 1 << 5,
        /**
         * characters should be hidden
         */
        HiddenText = 1 << 6,
        /**
         * typed text should not be stored
         */
        SensitiveData = 1 << 7,
        /**
         * just latin characters should be entered
         */
        Latin = 1 << 8,
        /**
         * the text input is multi line
         */
        MultiLine = 1 << 9
    };
    Q_DECLARE_FLAGS(ContentHints, ContentHint)

    /**
     * The ContentPurpose allows to specify the primary purpose of a text input.
     *
     * This allows an input method to show special purpose input panels with
     * extra characters or to disallow some characters.
     */
    enum class ContentPurpose : uint32_t {
        /**
         * default input, allowing all characters
         */
        Normal,
        /**
         * allow only alphabetic characters
         **/
        Alpha,
        /**
         * allow only digits
         */
        Digits,
        /**
         * input a number (including decimal separator and sign)
         */
        Number,
        /**
         * input a phone number
         */
        Phone,
        /**
         * input an URL
         */
        Url,
        /**
         * input an email address
         **/
        Email,
        /**
         * input a name of a person
         */
        Name,
        /**
         * input a password
         */
        Password,
        /**
         * input a date
         */
        Date,
        /**
         * input a time
         */
        Time,
        /**
         * input a date and time
         */
        DateTime,
        /**
         * input for a terminal
         */
        Terminal
    };
    /**
     * Sets the content @p purpose and content @p hints.
     * While the @p purpose is the basic purpose of an input field, the @p hints flags allow
     * to modify some of the behavior.
     **/
    void setContentType(ContentHints hints, ContentPurpose purpose);

    /**
     * Sets the cursor outline @p rect in surface local coordinates.
     *
     * Allows the compositor to e.g. put a window with word suggestions
     * near the cursor.
     **/
    void setCursorRectangle(const QRect &rect);

    /**
     * Sets a specific @p language.
     *
     * This allows for example a virtual keyboard to show a language specific layout.
     * The @p language argument is a RFC-3066 format language tag.
     **/
    void setPreferredLanguage(const QString &language);

    /**
     * The text direction of input text.
     *
     * It is mainly needed for showing input cursor on correct side of the
     * editor when there is no input yet done and making sure neutral
     * direction text is laid out properly.
     * @see textDirectionChnaged
     **/
    Qt::LayoutDirection textDirection() const;

    /**
     * The language of the input text.
     *
     * As long as the server has not emitted the language, the code will be empty.
     *
     * @returns a RFC-3066 format language tag in utf-8.
     * @see languageChanged
     **/
    QByteArray language() const;

    /**
     * The cursor position inside the @link{composingText} (as byte offset) relative
     * to the start of the @link{composingText}.
     * If index is a negative number no cursor is shown.
     * @see composingText
     * @see composingTextChanged
     **/
    qint32 composingTextCursorPosition() const;

    /**
     * The currently being composed text around the @link{composingTextCursorPosition}.
     * @see composingTextCursorPosition
     * @see composingTextChanged
     **/
    QByteArray composingText() const;

    /**
     * The fallback text can be used to replace the @link{composingText} in some cases
     * (for example when losing focus).
     *
     * @see composingText
     * @see composingTextChanged
     **/
    QByteArray composingFallbackText() const;

    /**
     * The commit text to be inserted.
     *
     * The commit text might be empty if only text should be deleted or the cursor be moved.
     * @see cursorPosition
     * @see anchorPosition
     * @see deleteSurroundingText
     * @see committed
     **/
    QByteArray commitText() const;

    /**
     * The cursor position in bytes at which the @link{commitText} should be inserted.
     * @see committed
     **/
    qint32 cursorPosition() const;

    /**
     * The text between anchorPosition and @link(cursorPosition} should be selected.
     * @see cursorPosition
     * @see committed
     **/
    qint32 anchorPosition() const;

    /**
     * Holds the length before and after the cursor position to be deleted.
     **/
    struct DeleteSurroundingText {
        quint32 beforeLength;
        quint32 afterLength;
    };
    /**
     * @returns The lenght in bytes which should be deleted around the cursor position
     * @see committed
     **/
    DeleteSurroundingText deleteSurroundingText() const;

Q_SIGNALS:
    /**
     * Emitted whenever a Surface is focused on this TextInput.
     * @see enteredSurface
     * @see left
     **/
    void entered();
    /**
     * Emitted whenever a Surface loses the focus on this TextInput.
     * @see enteredSurface
     * @see entered
     **/
    void left();
    /**
     * Emitted whenever the state of the input panel (virtual keyboard changes).
     * @see isInputPanelVisible
     **/
    void inputPanelStateChanged();
    /**
     * Emitted whenver the text direction changes.
     * @see textDirection
     **/
    void textDirectionChanged();
    /**
     * Emitted whenever the language changes.
     * @see language
     **/
    void languageChanged();

    /**
     * Emitted when a key event was sent.
     * Key events are not used for normal text input operations, but for specific key symbols
     * which are not composable through text.
     *
     * @param xkbKeySym The XKB key symbol, not a key code
     * @param state Whether the event represents a press or release event
     * @param modifiers The hold modifiers on this event
     * @param time Timestamp of this event
     **/
    void keyEvent(quint32 xkbKeySym, KWayland::Client::TextInput::KeyState state, Qt::KeyboardModifiers modifiers, quint32 time);

    /**
     * Emitted whenever the composing text and related states changed.
     * @see composingText
     * @see composingTextCursorPosition
     * @see composingFallbackText
     **/
    void composingTextChanged();

    /**
     * Emitted when the currently composing text got committed.
     * The @link{commitText} should get inserted at the @link{cursorPosition} and
     * the text around @link{deleteSurroundingText} should be deleted.
     *
     * @see commitText
     * @see cursorPosition
     * @see anchorPosition
     * @see deleteSurroundingText
     **/
    void committed();

protected:
    class Private;
    QScopedPointer<Private> d;
    explicit TextInput(Private *p, QObject *parent = nullptr);
};

/**
 * @brief Manager class for the TextInputManager interfaces.
 *
 * The TextInputManager supports multiple interfaces:
 * @li wl_text_input_manager
 * @li zwp_text_input_manager_v2
 *
 * Due to that it is different to other manager classes. It can only be created through
 * the corresponding factory method in Registry. A manual setup is not directly possible.
 *
 * The only task of a TextInputManager is to create TextInput for a given Seat.
 *
 * @since 5.23
 **/
class KWAYLANDCLIENT_EXPORT TextInputManager : public QObject
{
    Q_OBJECT
public:
    virtual ~TextInputManager();

    /**
     * Setup this TextInputManager to manage the @p textinputmanagerunstablev0.
     * When using Registry::createTextInputManager there is no need to call this
     * method.
     **/
    void setup(wl_text_input_manager *textinputmanagerunstablev0);
    /**
     * Setup this TextInputManager to manage the @p textinputmanagerunstablev0.
     * When using Registry::createTextInputManager there is no need to call this
     * method.
     **/
    void setup(zwp_text_input_manager_v2 *textinputmanagerunstablev2);
    /**
     * @returns @c true if managing a resource.
     **/
    bool isValid() const;
    /**
     * Releases the interface.
     * After the interface has been released the TextInputManager instance is no
     * longer valid and can be setup with another interface.
     **/
    void release();
    /**
     * Destroys the data held by this TextInputManager.
     * This method is supposed to be used when the connection to the Wayland
     * server goes away. If the connection is not valid anymore, it's not
     * possible to call release anymore as that calls into the Wayland
     * connection and the call would fail. This method cleans up the data, so
     * that the instance can be deleted or set up to a new  interface
     * once there is a new connection available.
     *
     * It is suggested to connect this method to ConnectionThread::connectionDied:
     * @code
     * connect(connection, &ConnectionThread::connectionDied, textinputmanager, &TextInputManager::destroy);
     * @endcode
     *
     * @see release
     **/
    void destroy();

    /**
     * Sets the @p queue to use for creating objects with this TextInputManager.
     **/
    void setEventQueue(EventQueue *queue);
    /**
     * @returns The event queue to use for creating objects with this TextInputManager.
     **/
    EventQueue *eventQueue();

    /**
     * Creates a TextInput for the @p seat.
     *
     * @param seat The Seat to create the TextInput for
     * @param parent The parent to use for the TextInput
     **/
    TextInput *createTextInput(Seat *seat, QObject *parent = nullptr);

    /**
     * @returns @c null if not for a wl_text_input_manager
     **/
    operator wl_text_input_manager*();
    /**
     * @returns @c null if not for a wl_text_input_manager
     **/
    operator wl_text_input_manager*() const;
    /**
     * @returns @c null if not for a zwp_text_input_manager_v2
     **/
    operator zwp_text_input_manager_v2*();
    /**
     * @returns @c null if not for a zwp_text_input_manager_v2
     **/
    operator zwp_text_input_manager_v2*() const;

Q_SIGNALS:
    /**
     * The corresponding global for this interface on the Registry got removed.
     *
     * This signal gets only emitted if the TextInputManager got created by
     * Registry::createTextInputManager
     **/
    void removed();

protected:
    class Private;
    explicit TextInputManager(Private *p, QObject *parent = nullptr);

    QScopedPointer<Private> d;
};

}
}

Q_DECLARE_METATYPE(KWayland::Client::TextInput::KeyState)
Q_DECLARE_METATYPE(KWayland::Client::TextInput::ContentHint)
Q_DECLARE_METATYPE(KWayland::Client::TextInput::ContentPurpose)
Q_DECLARE_METATYPE(KWayland::Client::TextInput::ContentHints)
Q_DECLARE_OPERATORS_FOR_FLAGS(KWayland::Client::TextInput::ContentHints)

#endif
