/******************************************************************************
 * QSkinny - Copyright (C) 2016 Uwe Rathmann
 * This file may be used under the terms of the QSkinny License, Version 1.0
 *****************************************************************************/

#include "QskInputContext.h"
#include "QskInputPanel.h"
#include "QskInputPanelBox.h"

#include "QskLinearBox.h"
#include "QskDialog.h"
#include "QskPopup.h"
#include "QskWindow.h"
#include "QskEvent.h"
#include "QskQuick.h"

#include <QPointer>
#include <QGuiApplication>
#include <QMap>

QSK_QT_PRIVATE_BEGIN
#include <private/qguiapplication_p.h>
QSK_QT_PRIVATE_END

#include <qpa/qplatformintegration.h>
#include <qpa/qplatforminputcontext.h>

namespace
{
    class Panel final : public QskInputPanel
    {
    public:
        Panel( QQuickItem* parent = nullptr ):
            QskInputPanel( parent )
        {
            setAutoLayoutChildren( true );

            m_box = new QskInputPanelBox( this );

            connect( m_box, &QskInputPanelBox::keySelected,
                this, &QskInputPanel::keySelected );

            connect( m_box, &QskInputPanelBox::predictiveTextSelected,
                this, &QskInputPanel::predictiveTextSelected );
        }

        virtual void attachItem( QQuickItem* item ) override
        {
            m_box->attachInputItem( item );
        }

        virtual QQuickItem* inputProxy() const override
        {
            return m_box->inputProxy();
        }

        virtual void setPrompt( const QString& prompt ) override
        {
            m_box->setInputPrompt( prompt );
        }

        virtual void setPredictionEnabled( bool on ) override
        {
            m_box->setPanelHint( QskInputPanelBox::Prediction, on );
        }

        virtual void setPrediction( const QStringList& prediction ) override
        {
            m_box->setPrediction( prediction );
        }

    private:
        QskInputPanelBox* m_box;
    };

    class Channel
    {
    public:
        // item receiving the input
        QPointer< QQuickItem > item;

        // panel for inserting the input
        QPointer< QskInputPanel > panel;

        // popup or window embedding the panel
        QPointer< QskPopup > popup;
        QPointer< QskWindow > window;
    };

    class ChannelTable
    {
    public:
        inline Channel* currentChannel() const
        {
            const auto object = QGuiApplication::focusObject();
            return channel( qobject_cast< const QQuickItem* >( object ) );
        }

        inline Channel* channel( const QQuickWindow* window ) const
        {
            if ( window )
            {
                auto it = m_map.constFind( window );
                if ( it != m_map.constEnd() )
                    return const_cast< Channel* >( &it.value() );
            }

            return nullptr;
        }

        inline Channel* channel( const QQuickItem* item ) const
        {
            if ( item )
            {
                auto channel = this->channel( item->window() );
                if ( channel && channel->item == item )
                    return channel;
            }

            return nullptr;
        }

        inline Channel* ancestorChannel( const QQuickItem* item ) const
        {
            for ( auto it = m_map.constBegin();
                it != m_map.constEnd(); ++it )
            {
                if ( const auto panel = it.value().panel )
                {
                    if ( ( item == panel )
                        || qskIsAncestorOf( panel, item ) )
                    {
                        return const_cast< Channel*>( &it.value() );
                    }
                }
            }

            return nullptr;
        }

        inline Channel* insert( const QQuickWindow* window )
        {
            return &m_map[ window ];
        }

        inline void remove( const QQuickWindow* window )
        {
            m_map.remove( window );
        }

    private:
        QMap< const QQuickWindow*, Channel > m_map;
    };
}

static QPointer< QskInputContext > qskInputContext = nullptr;

static void qskSendToPlatformContext( QEvent::Type type )
{
    const auto platformInputContext =
        QGuiApplicationPrivate::platformIntegration()->inputContext();

    if ( platformInputContext )
    {
        QEvent event( type );
        QCoreApplication::sendEvent( platformInputContext, &event );
    }
}

static void qskInputContextHook()
{
    qAddPostRoutine( [] { delete qskInputContext; } );
}

Q_COREAPP_STARTUP_FUNCTION( qskInputContextHook )

void QskInputContext::setInstance( QskInputContext* inputContext )
{
    if ( inputContext != qskInputContext )
    {
        const auto oldContext = qskInputContext;
        qskInputContext = inputContext;

        if ( oldContext && oldContext->parent() == nullptr )
            delete oldContext;

        qskSendToPlatformContext( QEvent::PlatformPanel );
    }
}

QskInputContext* QskInputContext::instance()
{
    return qskInputContext;
}

class QskInputContext::PrivateData
{
public:

    inline QskInputPanel* createPanel( QskInputContext* context ) const
    {
        QskInputPanel* panel = nullptr;

        if ( this->factory )
            panel = this->factory->createPanel();

        if ( panel == nullptr )
            panel = new Panel();

        connect( panel, &QskInputPanel::visibleChanged,
            context, &QskInputContext::activeChanged );
            
        connect( panel, &QskInputPanel::localeChanged,
            context, [] { qskSendToPlatformContext( QEvent::LocaleChange ); } );

        return panel;
    }

    inline QskPopup* createPopup( QskInputPanel* panel ) const
    {
        auto popup = new QskPopup();

        popup->setAutoLayoutChildren( true );
        popup->setTransparentForPositioner( false );
        popup->setModal( true );

        auto box = new QskLinearBox( popup );
        box->addItem( panel );

        const auto alignment = panel->alignment() & Qt::AlignVertical_Mask;
        popup->setOverlay( alignment == Qt::AlignVCenter );

        switch( alignment )
        {
            case Qt::AlignTop:
            {
                box->setExtraSpacingAt( Qt::BottomEdge | Qt::LeftEdge | Qt::RightEdge );
                break;
            }
            case Qt::AlignVCenter:
            {
                box->setMargins( QMarginsF( 5, 5, 5, 5 ) );
                break;
            }

            case Qt::AlignBottom:
            default:
            {
                box->setExtraSpacingAt( Qt::TopEdge | Qt::LeftEdge | Qt::RightEdge );
            }
        }

        return popup;
    }

    inline QskWindow* createWindow( QskInputPanel* panel ) const
    {
        auto window = new QskWindow();

        window->setFlags( window->flags() & Qt::Dialog );
        //window->setModality( Qt::ApplicationModal );
        window->setAutoLayoutChildren( true );
    #if 0
        window->setFlags( Qt::Tool | Qt::WindowDoesNotAcceptFocus );
    #endif

        panel->setParentItem( window->contentItem() );

        return window;
    }

    ChannelTable channels;
    QPointer< QskInputContextFactory > factory;
};

QskInputContext::QskInputContext():
    m_data( new PrivateData() )
{
    setObjectName( "InputContext" );
}

QskInputContext::~QskInputContext()
{
}

void QskInputContext::setFactory( QskInputContextFactory* factory )
{
    if ( m_data->factory == factory )
        return;

    if ( m_data->factory && m_data->factory->parent() == this )
        delete m_data->factory;

    m_data->factory = factory;

    if ( factory && factory->parent() == nullptr )
        factory->setParent( this );
}

QskInputContextFactory* QskInputContext::factory() const
{
    return m_data->factory;
}

QskTextPredictor* QskInputContext::textPredictor( const QLocale& locale )
{
    if ( m_data->factory )
        return m_data->factory->createPredictor( locale );

    return nullptr;
}

void QskInputContext::update( const QQuickItem* item, Qt::InputMethodQueries queries )
{
    if ( item == nullptr )
    {
        // those are coming from QQuickWindow based on focus changes
        item = qobject_cast< QQuickItem* >( QGuiApplication::focusObject() );
    }

    auto channel = m_data->channels.channel( item );
    if ( channel == nullptr )
        return;

    if ( queries & Qt::ImEnabled )
    {
        QInputMethodQueryEvent event( Qt::ImEnabled );
        QCoreApplication::sendEvent( channel->item, &event );

        if ( !event.value( Qt::ImEnabled ).toBool() )
        {
            hidePanel( item );
            return;
        }
    }

    channel->panel->updateInputPanel( queries );
}

QRectF QskInputContext::panelRect() const
{
    /*
        As we can have more than panel at the same time we
        better don't return any geometry
     */
    
    return QRectF();
}

void QskInputContext::showPanel( const QQuickItem* item )
{
    if ( item == nullptr )
        return;

    if ( m_data->channels.ancestorChannel( item ) )
    {
        // We are inside of an existing panel
        return;
    }

    if ( auto channel = m_data->channels.channel( item->window() ) )
    {
        if ( channel->item == item )
            return;

        hidePanel( channel->item );
    }

    auto panel = m_data->createPanel( this );

    auto channel = m_data->channels.insert( item->window() );
    channel->item = const_cast< QQuickItem*>( item );
    channel->panel = panel;

    if ( QskDialog::instance()->policy() == QskDialog::TopLevelWindow )
    {
        // The input panel is embedded in a top level window

        auto window = m_data->createWindow( panel );

        QSize size = window->effectivePreferredSize();
        if ( size.isEmpty() )
        {
            // no idea, may be something based on the screen size
            size = QSize( 800, 240 );
        }

        window->resize( size );
        window->show();

        window->setDeleteOnClose( true );

        channel->window = window;
    }
    else
    {
        // The input panel is embedded in a popup

        auto popup = m_data->createPopup( panel );

        popup->setParentItem( item->window()->contentItem() );
        popup->setParent( this );
#if 1
        popup->setVisible( true );
#endif

        channel->popup = popup;
    }

    panel->attachInputItem( const_cast< QQuickItem* >( item ) );
}

void QskInputContext::hidePanel( const QQuickItem* item )
{
    if ( item == nullptr )
        return;

    if ( auto channel = m_data->channels.channel( item ) )
    {
        if ( channel->popup )
            channel->popup->deleteLater();

        if ( channel->window )
            channel->window->close(); // deleteOnClose is set

        m_data->channels.remove( item->window() );
    }
}

void QskInputContext::setInputPanelVisible( const QQuickItem* item, bool on )
{
    // called from inside the controls

    if ( item == nullptr )
        item = qobject_cast< QQuickItem* >( QGuiApplication::focusObject() );

    if ( item )
    {
        if ( on )
            showPanel( item );
        else
            hidePanel( item );
    }
}

bool QskInputContext::isInputPanelVisible() const
{
    return m_data->channels.currentChannel() != nullptr;
}

QLocale QskInputContext::locale() const
{
    if ( auto channel = m_data->channels.currentChannel() )
    {
        if ( channel->panel )
            return channel->panel->locale();
    }

    return QLocale();
}

void QskInputContext::setFocusObject( QObject* )
{
}

void QskInputContext::invokeAction(
    QInputMethod::Action, int cursorPosition )
{
    // called from qquicktextinput/qquicktextedit
    Q_UNUSED( cursorPosition );
}

void QskInputContext::commitPrediction( bool )
{
    /*
        called, when the input item loses the focus.
        As it it should be possible to navigate inside of the
        panel what should we do here ?
     */
}

QskInputContextFactory::QskInputContextFactory( QObject* parent ):
    QObject( parent )
{
}

QskInputContextFactory::~QskInputContextFactory()
{
}

QskTextPredictor* QskInputContextFactory::createPredictor( const QLocale& ) const
{
    return nullptr;
}

QskInputPanel* QskInputContextFactory::createPanel() const
{
    return new Panel();
}

#include "moc_QskInputContext.cpp"