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

#include "QskRichTextRenderer.h"
#include "QskTextColors.h"
#include "QskTextOptions.h"

#include <QQuickWindow>
#include <QGlobalStatic>

QSK_QT_PRIVATE_BEGIN
#include <private/qquicktext_p.h>
#include <private/qquicktext_p_p.h>
QSK_QT_PRIVATE_END

#include <limits>

namespace
{
    class TextItem final : public QQuickText
    {
    public:
        TextItem()
        {
            // fonts are supposed to be defined in the application skin and we
            // probably don't want to have them scaled
            setFontSizeMode( QQuickText::FixedSize );

#if 0
            setAntialiasing( true );
            setRenderType( QQuickText::QtRendering );
            setPadding( 0 );

            setMinimumPixelSize();
            setMinimumPointSize();

            // also something, that should be defined in an application skin
            setLineHeightMode( ... );
            setLineHeight();
#endif
        }

        inline void setAlignment( Qt::Alignment alignment )
        {
            setHAlign( ( QQuickText::HAlignment ) ( int( alignment ) & 0x0f ) );
            setVAlign( ( QQuickText::VAlignment ) ( int( alignment ) & 0xf0 ) );
        }

        inline void setOptions( const QskTextOptions& options )
        {
            // what about Qt::TextShowMnemonic ???
            setTextFormat( ( QQuickText::TextFormat ) options.format() );
            setElideMode( ( QQuickText::TextElideMode ) options.elideMode() );
            setMaximumLineCount( options.maximumLineCount() );
            setWrapMode( static_cast< QQuickText::WrapMode >( options.wrapMode() ) );
        }

        void begin() { classBegin(); }
        void end() { componentComplete(); }

        QRectF layedOutTextRect() const
        {
            auto that = const_cast< TextItem* >( this );
            return QQuickTextPrivate::get( that )->layedOutTextRect;
        }

        void updateTextNode( QQuickWindow* window, QSGNode* parentNode )
        {
            QQuickItemPrivate::get( this )->refWindow( window );

            while ( parentNode->firstChild() )
                delete parentNode->firstChild(); 

            auto node = QQuickText::updatePaintNode( nullptr, nullptr );
            node->reparentChildNodesTo( parentNode );
            delete node;

            QQuickItemPrivate::get( this )->derefWindow();
        }

    protected:
        virtual QSGNode* updatePaintNode(
            QSGNode*, UpdatePaintNodeData* ) override final
        {
            Q_ASSERT( false );
            return nullptr;
        }
    };
}

/*
    size requests and rendering might be from different threads and we
    better use different items as we might end up in events internally
    being sent, that leads to crashes because of it
 */
Q_GLOBAL_STATIC( TextItem, qskRenderHelper )
Q_GLOBAL_STATIC( TextItem, qskLayoutHelper )

QSizeF QskRichTextRenderer::textSize( const QString& text,
    const QFont& font, const QskTextOptions& options )
{
    auto& item = *qskLayoutHelper;

    item.begin();

    item.setFont( font );
    item.setOptions( options );

    item.setWidth( -1 );
    item.setText( text );

    item.end();

    return QSizeF( item.implicitWidth(), item.implicitHeight() );
}

QRectF QskRichTextRenderer::textRect( const QString& text,
    const QFont& font, const QskTextOptions& options, const QSizeF& size )
{
    auto& textItem = *qskLayoutHelper;

    textItem.begin();

    textItem.setFont( font );
    textItem.setOptions( options );
    textItem.setAlignment( Qt::Alignment() );

    textItem.setWidth( size.width() );
    textItem.setHeight( size.height() );

    textItem.setText( text );

    textItem.end();

    return textItem.layedOutTextRect();
}

void QskRichTextRenderer::updateNode( const QString& text,
    const QFont& font, const QskTextOptions& options,
    Qsk::TextStyle style, const QskTextColors& colors,
    Qt::Alignment alignment, const QRectF& rect,
    const QQuickItem* item, QSGTransformNode* node )
{
    // are we killing internal caches of QQuickText, when always using
    // the same item for the creation the text nodes. TODO ... 

    auto& textItem = *qskRenderHelper;

    textItem.begin();

    textItem.setBottomPadding( 0 );
    textItem.setTopPadding( 0 );
    textItem.setFont( font );
    textItem.setOptions( options );
    textItem.setAlignment( alignment );

#if 0
    // the position of textItem seems to have no effect
    // on the position of the node. We do it by translation later.

    textItem.setX( rect.x() );
    textItem.setY( rect.y() );
#endif

    if ( rect.width() != item->width() ||
        rect.height() != item->height() )
    {
        textItem.setWidth( rect.width() );
        textItem.setHeight( rect.height() );
        textItem.doLayout();
    }

    textItem.setColor( colors.textColor );
    textItem.setStyle( static_cast< QQuickText::TextStyle >( style ) );
    textItem.setStyleColor( colors.styleColor );
    textItem.setLinkColor( colors.linkColor );

    textItem.setText( text );

    textItem.end();

    if ( alignment & Qt::AlignVCenter )
    {
        /*
            We need to have a stable algo for rounding the text base line,
            so that texts don't start wobbling, when processing transitions
            between margins/paddings. We manipulate the layout code
            by adding some padding, so that the position of base line 
            gets always floored.
         */
        auto d = QQuickTextPrivate::get( &textItem );

        const qreal h = d->layedOutTextRect.height() + d->lineHeightOffset();

        if ( static_cast< int >( rect.height() - h ) % 2 )
        {
            if ( static_cast<int>( h ) % 2 )
                d->extra.value().bottomPadding = 1;
            else
                d->extra.value().topPadding = 1;
        }
    }

    textItem.updateTextNode( item->window(), node );
    textItem.setText( QString::null );
}