/* This file is part of the KDE project
   Copyright (C) 2006 Martin Pfeiffer <hubipete@gmx.net>
                 2009 Jeremias Epperlein <jeeree@web.de>

   This library 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 of the License, or (at your option) any later version.

   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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/

#include "MultiscriptElement.h"

#include "AttributeManager.h"
#include "FormulaCursor.h"
#include "FormulaDebug.h"

#include <KoXmlWriter.h>
#include <KoXmlReader.h>

#include <QPainter>

MultiscriptElement::MultiscriptElement( BasicElement* parent ) : FixedElement( parent )
{
    m_baseElement = new RowElement( this );
}

MultiscriptElement::~MultiscriptElement()
{
    delete m_baseElement;
    //Delete all of the scripts
    while (!m_preScripts.isEmpty())
        delete m_preScripts.takeFirst();
    while (!m_postScripts.isEmpty())
        delete m_postScripts.takeFirst();
}

void MultiscriptElement::paint( QPainter& painter, AttributeManager* am )
{
    Q_UNUSED(painter)
    Q_UNUSED(am)
    /*do nothing as this element has no visual representation*/
}

void MultiscriptElement::ensureEvenNumberElements()
{
    if (m_postScripts.size() % 2 == 1) {
        // Odd number - add a None element to the end
        m_postScripts.append(nullptr);
    }
    if (m_preScripts.size() % 2 == 1) {
        // Odd number - add a None element to the end
        m_preScripts.append(nullptr);
    }
}

void MultiscriptElement::layout( const AttributeManager* am )
{
    // Get the minimum amount of shifting
    qreal subscriptshift   = am->doubleOf( "subscriptshift", this );
    qreal superscriptshift = am->doubleOf( "superscriptshift", this );
    //Add half a thin space between both sup and superscript, so there is a minimum
    //of a whole thin space between them.
    qreal halfthinspace   = am->layoutSpacing( this )/2.0;

    //First make sure that there are an even number of elements in both subscript and superscript
    ensureEvenNumberElements();

    // Go through all the superscripts (pre and post) and find the maximum heights;
    // BaseLine is the distance from the top to the baseline.
    // Depth is the distance from the baseline to the bottom
    qreal maxSuperScriptDepth     = 0.0;
    qreal maxSuperScriptBaseLine  = 0.0;
    qreal maxSubScriptDepth       = 0.0;
    qreal maxSubScriptBaseLine    = 0.0;
    bool isSuperscript = true;  //Toggle after each element time
    foreach( BasicElement *script, m_postScripts ) {
        isSuperscript = !isSuperscript;  //Toggle each time
        if(!script)
            continue;  // Null means no element - just a blank
        if(isSuperscript) {
            maxSuperScriptDepth = qMax( script->height() - script->baseLine(), maxSuperScriptDepth );
            maxSuperScriptBaseLine = qMax( script->baseLine(), maxSuperScriptBaseLine );
        } else {
            //Find out how much the subscript sticks below the baseline
            maxSubScriptDepth = qMax( script->height() - script->baseLine(), maxSubScriptDepth );
            maxSubScriptBaseLine = qMax( script->baseLine(), maxSubScriptBaseLine );
        }
    }
    foreach( BasicElement *script, m_preScripts ) {
        isSuperscript = !isSuperscript;  //Toggle each time
        if(!script)
            continue;  // Null means no element - just a blank
        if(isSuperscript) {
            maxSuperScriptDepth = qMax( script->height() - script->baseLine(), maxSuperScriptDepth );
            maxSuperScriptBaseLine = qMax( script->baseLine(), maxSuperScriptBaseLine );
        } else {
            //Find out how much the subscript sticks below the baseline
            maxSubScriptDepth = qMax( script->height() - script->baseLine(), maxSubScriptDepth );
            maxSubScriptBaseLine = qMax( script->baseLine(), maxSubScriptBaseLine );
        }
    }
    // The yOffsetBase is the amount the base element is moved down to make
    // room for the superscript
    qreal yOffsetBase = 0;
    if(maxSuperScriptDepth + maxSuperScriptBaseLine > 0) {
        yOffsetBase = maxSuperScriptDepth + maxSuperScriptBaseLine - m_baseElement->height()/2.0 + halfthinspace;
        yOffsetBase = qMax( yOffsetBase, superscriptshift );
    }
    // The yOffsetSub is the amount the subscript elements /baseline/ are moved down.
    qreal yOffsetSub = yOffsetBase + maxSubScriptBaseLine +
                qMax( m_baseElement->height()/2 + halfthinspace,
                      m_baseElement->height() - maxSubScriptBaseLine
                          + subscriptshift );

    qreal xOffset = 0.0;  //We increment this as we go along, to keep track of where to place elements
    qreal lastSuperScriptWidth= 0.0;
    // Now we have all the information needed to start putting elements in place.
    // We start from the far left, and work to the far right.
    for( int i = m_preScripts.size()-1; i >= 0; i--) {
        //We start from the end, and work in.
        //m_preScripts[0] is subscript etc.  So even i is subscript, odd i is superscript
        if( i%2 == 0) {
            // i is even, so subscript
            if(!m_preScripts[i]) {
                xOffset += lastSuperScriptWidth;
            } else {
                // For a given vertical line, this is processed after the superscript
                qreal offset = qMax(qreal(0.0),
                                    (lastSuperScriptWidth - m_preScripts[i]->width()) / qreal(2.0));
                m_preScripts[i]->setOrigin( QPointF(
                            offset + xOffset,
                            yOffsetSub - m_preScripts[i]->baseLine() ) );
                xOffset += qMax(lastSuperScriptWidth, m_preScripts[i]->width());
            }
            if(i!=0)  //No halfthinspace between the first element and the base element
                xOffset += halfthinspace;
        } else {
            // i is odd, so superscript
            // For a given vertical line, we process the superscript first, then
            // the subscript.  We need to look at the subscript (i-1) as well
            // to find out how to align them
            if( !m_preScripts[i] )
                lastSuperScriptWidth = 0.0;
            else {
                lastSuperScriptWidth = m_preScripts[i]->width();
                qreal offset = 0.0;
                if(m_preScripts[i-1]) //the subscript directly below us.
                    offset = qMax(qreal(0.0), (m_preScripts[i-1]->width() - lastSuperScriptWidth)/qreal(2.0));
                m_preScripts[i]->setOrigin( QPointF(
                            offset + xOffset,
                            maxSuperScriptBaseLine - m_preScripts[i]->baseLine()));
            }
        }
    }

    //We have placed all the prescripts now.  So now place the base element
    m_baseElement->setOrigin( QPointF( xOffset, yOffsetBase ) );
    xOffset += m_baseElement->width();
    qreal lastSubScriptWidth = 0.0;
    //Now we can draw the post scripts.  This code is very similar, but this time we will parse
    //the subscript before the superscript
    for( int i = 0; i < m_postScripts.size(); i++) {
        //We start from the start, and work out.
        //m_preScripts[0] is subscript etc.  So even i is subscript, odd i is superscript
        if( i%2 == 0) {
            // i is even, so subscript
            // For a given vertical line, we process the subscript first, then
            // the superscript.  We need to look at the superscript (i+1) as well
            // to find out how to align them

            if(!m_postScripts[i]) {
                lastSubScriptWidth = 0.0;
            } else {
                lastSubScriptWidth = m_postScripts[i]->width();
                // For a given vertical line, this is processed after the superscript
                qreal offset = 0.0;
                if(m_postScripts.size() > i+1 && m_postScripts[i+1] != nullptr) //the subscript directly below us.
                    offset = qMax(qreal(0.0), (m_postScripts[i+1]->width() - lastSubScriptWidth)/qreal(2.0));
                m_postScripts[i]->setOrigin( QPointF(
                            offset + xOffset,
                            yOffsetSub - m_postScripts[i]->baseLine() ) );
            }
        } else {
            // i is odd, so superscript
           if( !m_postScripts[i] )
                xOffset += lastSubScriptWidth;
           else {
               qreal offset = qMax(qreal(0.0), (lastSubScriptWidth - m_postScripts[i]->width())/qreal(2.0));
               m_postScripts[i]->setOrigin( QPointF(
                            offset + xOffset,
                            maxSuperScriptBaseLine - m_postScripts[i]->baseLine()));
                xOffset += qMax(lastSubScriptWidth, m_postScripts[i]->width());
            }
           if(i != m_postScripts.size()-1)
               xOffset += halfthinspace; //Don't add an unneeded space at the very end
        }
    }


    //Finally, set our boundingbox
    setWidth( xOffset );
    setHeight( yOffsetSub + maxSubScriptDepth );
    setBaseLine( yOffsetBase + m_baseElement->baseLine() );
}

bool MultiscriptElement::acceptCursor( const FormulaCursor& cursor )
{
    Q_UNUSED( cursor )
    return false;
}

const QList<BasicElement*> MultiscriptElement::childElements() const
{
    QList<BasicElement*> list;

    list << m_baseElement;

    // postscript elements
    foreach( BasicElement* tmp, m_postScripts ) {
        if (tmp)
            list << tmp;
    }

    // prescript elements
#if 1
    foreach( BasicElement* tmp, m_preScripts ) {
        if (tmp)
            list << tmp;
    }
#else
    // What is this strange construction?
    for (int i = m_preScripts.count() - 2; i >= 0; i -= 2 ) {
        if (m_preScripts[i]) list << m_preScripts[i];
        if (m_preScripts[i+1]) list << m_preScripts[i+1];
    }
#endif

    return list;
}

QString MultiscriptElement::attributesDefaultValue( const QString& attribute ) const
{
    Q_UNUSED( attribute )
    return QString();
}

ElementType MultiscriptElement::elementType() const
{
    return MultiScript;
}

bool MultiscriptElement::readMathMLContent( const KoXmlElement& parent )
{
    QString name = parent.tagName().toLower();
    BasicElement* tmpElement = 0;
    KoXmlElement tmp;
    bool prescript = false; //When we see a mprescripts tag, we enable this
    bool baseElement = false;   // True when the base element is read.
    forEachElement( tmp, parent ) {
        if (tmp.tagName() == "none") {
            //In mathml, we read subscript, then superscript, etc.  To skip one,
            //you use "none"
            //To represent "none" we use a nullptr
            if(prescript)
                m_preScripts.append(nullptr);
            else
                m_postScripts.append(nullptr);
            continue;
        } else if (tmp.tagName() == "mprescripts") {
            prescript = true;
            //In mathml, when we see this tag, all the elements after it are
            // for prescripts
            continue;
        }

        tmpElement = ElementFactory::createElement( tmp.tagName(), this );
        if ( !tmpElement->readMathML( tmp ) )
            return false;

        // The very first element is the base
        if ( !baseElement ) {
            delete m_baseElement;
            m_baseElement = tmpElement;
            baseElement = true;
        }
        else if (prescript)
            m_preScripts.append( tmpElement );
        else
            m_postScripts.append( tmpElement );
    }

    ensureEvenNumberElements();
    Q_ASSERT(m_baseElement);  //We should have at least a BasicElement for the base
    return true;
}

void MultiscriptElement::writeMathMLContent( KoXmlWriter* writer, const QString& ns ) const
{
    m_baseElement->writeMathML( writer, ns );        // Just save the children in
                                                 // the right order
    foreach( BasicElement* tmp, m_postScripts ) {
        if(tmp)
            tmp->writeMathML( writer, ns );
        else {
            //We need to use a none element for missing elements in the super/sub scripts
            QString s = ns.isEmpty() ? QString::fromLatin1("none") : ns.toLatin1() + QString::fromLatin1(":none");
            writer->startElement(s.toLatin1());
            writer->endElement();
        }
    }
    if( m_preScripts.isEmpty() ) return;
    QString s = ns.isEmpty() ? QString::fromLatin1("mprescripts") : ns.toLatin1() + QString::fromLatin1(":mprescripts");
    writer->startElement(s.toLatin1());
    writer->endElement();
    foreach( BasicElement* tmp, m_preScripts ) {
        if(tmp)
            tmp->writeMathML( writer, ns );
        else {
            //We need to use a none element for missing elements in the super/sub scripts
            QString n = ns.isEmpty() ? QString::fromLatin1("none") : ns.toLatin1() + QString::fromLatin1(":none");
            writer->startElement(n.toLatin1());
            writer->endElement();
        }
    }
}

// int MultiscriptElement::length() const
// {
//     if (!m_postScripts.isEmpty() && m_postScripts.last()==0) {
//         //the last element is empty, so there are no cursor positions around it
//         return 2*(m_preScripts.count()+m_postScripts.count())-1;
//     } else {
//         return 2*(m_preScripts.count()+m_postScripts.count()+1)-1;
//     }
// }

bool MultiscriptElement::moveCursor ( FormulaCursor& newcursor, FormulaCursor& oldcursor )
{
    // grouppositions:  1 3   1 3
    //                  0 2 2 0 2
    //                  |     | |
    // pairs:           0 1   0 1
    //TODO: Fill this out

    int childposition=newcursor.position()/2;
    //this should be cached
    int prescriptCount=0;
    foreach (BasicElement* tmp, m_preScripts) {
        if (tmp) {
            prescriptCount++;
        }
    }
    if (childposition==prescriptCount) {
        //we are in BasePosition
        if (newcursor.direction()==MoveUp || newcursor.direction()==MoveDown) {
            return false;
        }
        if (m_postScripts.isEmpty() && m_preScripts.isEmpty()) {
            //this should not happen
            return moveSingleSituation(newcursor,oldcursor,
                                        childElements().indexOf(m_baseElement));
        }
        if (newcursor.direction()==MoveLeft) {
            if (!m_preScripts.isEmpty()) {
                // we search for the first non nullptr element to the left
                int i;
                for (i=0; i<m_preScripts.count(); i++) {
                    if (m_preScripts[i]) {
                        break;
                    }
                }
                if ((i<m_preScripts.count()) && m_preScripts[i]) {
                    return moveHorSituation(newcursor,oldcursor,
                                             childElements().indexOf(m_preScripts[i]),
                                             childElements().indexOf(m_baseElement));
                }
            }
            return moveSingleSituation(newcursor,oldcursor,0);
        } else if (newcursor.direction()==MoveRight) {
            if (!m_postScripts.isEmpty()) {
                // we search for the first non nullptr element to the left
                int i;
                for (i=0; i<m_postScripts.count(); i++) {
                    if (m_postScripts[i]) {
                        break;
                    }
                }
                if (m_postScripts[i]) {
                    return moveHorSituation(newcursor,oldcursor,
                                             childElements().indexOf(m_baseElement),
                                             childElements().indexOf(m_postScripts[i]));
                }
            }
            return moveSingleSituation(newcursor,oldcursor,
                                        childElements().indexOf(m_baseElement));
        }
    } else {
        int groupposition;
        bool prescript=true;
        if (childposition<prescriptCount) {
                //determine the position in the pre-/postscripts we are in
                groupposition=m_preScripts.indexOf(childElements()[childposition]);
        } else {
                groupposition=m_postScripts.indexOf(childElements()[childposition]);
                prescript=false;
        }
        int pair=groupposition/2;
        if (newcursor.direction()==MoveUp || newcursor.direction()==MoveDown) {
//             debugFormula << groupposition<<" - "<<prescriptCount<< "-" <<pair;
            if (prescript) {
                if (m_preScripts[pair*2] && m_preScripts[pair*2+1]) {
                    return moveVertSituation(newcursor,oldcursor,
                                              childElements().indexOf(m_preScripts[pair*2+1]),
                                              childElements().indexOf(m_preScripts[pair*2]));
                } else {
                    return false;
                }
            } else {
                if (m_postScripts[pair*2] && m_postScripts[pair*2+1]) {
                    return moveVertSituation(newcursor,oldcursor,
                                              childElements().indexOf(m_postScripts[pair*2+1]),
                                              childElements().indexOf(m_postScripts[pair*2]));
                } else {
                    return false;
                }
            }
        } else if (newcursor.direction()==MoveLeft) {
            if (prescript) {
                //we are in the prescripts
                int i=groupposition+2;
                if (!((i<m_preScripts.count()) && m_preScripts[i])) {
                    for (i=groupposition+1; i<m_preScripts.count(); i++) {
                        if (m_preScripts[i]) {
                            break;
                        }
                    }
                }
                if ((i<m_preScripts.count()) && m_preScripts[i]) {
                    return moveHorSituation(newcursor,oldcursor,
                                             childElements().indexOf(m_preScripts[i]),
                                             childElements().indexOf(m_preScripts[groupposition]));
                } else {
                    return moveSingleSituation(newcursor,oldcursor,
                                                childElements().indexOf(m_preScripts[groupposition]));
                }
            } else {
                //we are in the postscripts
                int i=groupposition-1;
                if (!(i>=0) && m_postScripts[i]) {
                    for (i=groupposition-2; i>=0; i--) {
                        if (m_postScripts[i]) {
                            break;
                        }
                    }
                }
                if ((i>=0) && m_postScripts[i]) {
                    return moveHorSituation(newcursor,oldcursor,
                                             childElements().indexOf(m_postScripts[i]),
                                             childElements().indexOf(m_postScripts[groupposition]));
                } else {
                    return moveHorSituation(newcursor,oldcursor,
                                             childElements().indexOf(m_baseElement),
                                             childElements().indexOf(elementNext(newcursor.position())));
                }
            }
        } else if (newcursor.direction()==MoveRight) {
            if (prescript) {
                //we are in the prescripts
                int i=groupposition-2;
                if (!((i>=0) && m_preScripts[i])) {
                    for (i=groupposition-1; i>=0; i--) {
                        if (m_preScripts[i]) {
                            break;
                        }
                    }
                }
                if ((i>=0) && m_preScripts[i]) {
//                    debugFormula << "Going from "<< groupposition <<" to " <<i;
                    return moveHorSituation(newcursor,oldcursor,
                                             childElements().indexOf(m_preScripts[groupposition]),
                                             childElements().indexOf(m_preScripts[i]));
                } else {
                    return moveHorSituation(newcursor,oldcursor,
                                             childElements().indexOf(elementNext(newcursor.position())),
                                             childElements().indexOf(m_baseElement));
                }
            } else {
                //we are in the postscripts
                int i=groupposition+2;
                if (!((i<m_postScripts.count()) && m_postScripts[i])) {
                    for (i=groupposition+1; i<m_postScripts.count(); i++) {
                        if (m_postScripts[i]) {
                            break;
                        }
                    }
                }
                if ((i<m_postScripts.count()) && m_postScripts[i]) {
                    return moveHorSituation(newcursor,oldcursor,
                                             childElements().indexOf(m_postScripts[groupposition]),
                                             childElements().indexOf(m_postScripts[i]));
                } else {
                    return moveSingleSituation(newcursor,oldcursor,
                                                childElements().indexOf(m_preScripts[groupposition]));
                }
            }
        }
    }
    return false;
}

bool MultiscriptElement::setCursorTo ( FormulaCursor& cursor, QPointF point )
{
    if (cursor.isSelecting()) {
        return false;
    }
    foreach (BasicElement* tmp, childElements()) {
        if (tmp->boundingRect().contains(point)) {
            return tmp->setCursorTo(cursor,point-tmp->origin());
        }
    }
    return m_baseElement->setCursorTo(cursor,point-m_baseElement->origin());
}