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#include "qlayout.h"

#include "private/qlayoutengine_p.h"

#include "qvector.h"

#include "qwidget.h"

#include <qlist.h>

#include <qalgorithms.h>

#include <qdebug.h>

QT_BEGIN_NAMESPACE

//#define QLAYOUT_EXTRA_DEBUG

typedef qint64 Fixed64;

static inline Fixed64 toFixed(int i) { return (Fixed64)i * 256; }

static inline int fRound(Fixed64 i) {

    return (i % 256 < 128) ? i / 256 : 1 + i / 256;

}

/*

  This is the main workhorse of the QGridLayout. It portions out

  available space to the chain's children.

  The calculation is done in fixed point: "fixed" variables are

  scaled by a factor of 256.

  If the layout runs "backwards" (i.e. RightToLeft or Up) the layout

  is computed mirror-reversed, and it's the caller's responsibility

  do reverse the values before use.

  chain contains input and output parameters describing the geometry.

  count is the count of items in the chain; pos and space give the

  interval (relative to parentWidget topLeft).

*/

void qGeomCalc(QVector<QLayoutStruct> &chain, int start, int count,

               int pos, int space, int spacer)

{

    int cHint = 0;

    int cMin = 0;

    int cMax = 0;

    int sumStretch = 0;

    int sumSpacing = 0;

    bool wannaGrow = false; // anyone who really wants to grow?

    //    bool canShrink = false; // anyone who could be persuaded to shrink?

    bool allEmptyNonstretch = true;

    int pendingSpacing = -1;

    int spacerCount = 0;

    int i;

    for (i = start; i < start + count; i++) {

        QLayoutStruct *data = &chain[i];

        data->done = false;

        cHint += data->smartSizeHint();

        cMin += data->minimumSize;

        cMax += data->maximumSize;

        sumStretch += data->stretch;

        if (!data->empty) {

            /*

                Using pendingSpacing, we ensure that the spacing for the last

                (non-empty) item is ignored.

            */

            if (pendingSpacing >= 0) {

                sumSpacing += pendingSpacing;

                ++spacerCount;

            }

            pendingSpacing = data->effectiveSpacer(spacer);

        }

        wannaGrow = wannaGrow || data->expansive || data->stretch > 0;

        allEmptyNonstretch = allEmptyNonstretch && !wannaGrow && data->empty;

    }

    int extraspace = 0;

    if (space < cMin + sumSpacing) {

        /*

          Less space than minimumSize; take from the biggest first

        */

        int minSize = cMin + sumSpacing;

        // shrink the spacers proportionally

        if (spacer >= 0) {

            spacer = minSize > 0 ? spacer * space / minSize : 0;

            sumSpacing = spacer * spacerCount;

        }

        QList<int> list;

        for (i = start; i < start + count; i++)

            list << chain.at(i).minimumSize;

        qSort(list);

        int space_left = space - sumSpacing;

        int sum = 0;

        int idx = 0;

        int space_used=0;

        int current = 0;

        while (idx < count && space_used < space_left) {

            current = list.at(idx);

            space_used = sum + current * (count - idx);

            sum += current;

            ++idx;

        }

        --idx;

        int deficit = space_used - space_left;

        int items = count - idx;

        /*

         * If we truncate all items to "current", we would get "deficit" too many pixels. Therefore, we have to remove

         * deficit/items from each item bigger than maxval. The actual value to remove is deficitPerItem + remainder/items

         * "rest" is the accumulated error from using integer arithmetic.

        */

        int deficitPerItem = deficit/items;

        int remainder = deficit % items;

        int maxval = current - deficitPerItem;

        int rest = 0;

        for (i = start; i < start + count; i++) {

            int maxv = maxval;

            rest += remainder;

            if (rest >= items) {

                maxv--;

                rest-=items;

            }

            QLayoutStruct *data = &chain[i];

            data->size = qMin(data->minimumSize, maxv);

            data->done = true;

        }

    } else if (space < cHint + sumSpacing) {

        /*

          Less space than smartSizeHint(), but more than minimumSize.

          Currently take space equally from each, as in Qt 2.x.

          Commented-out lines will give more space to stretchier

          items.

        */

        int n = count;

        int space_left = space - sumSpacing;

        int overdraft = cHint - space_left;

        // first give to the fixed ones:

        for (i = start; i < start + count; i++) {

            QLayoutStruct *data = &chain[i];

            if (!data->done

                 && data->minimumSize >= data->smartSizeHint()) {

                data->size = data->smartSizeHint();

                data->done = true;

                space_left -= data->smartSizeHint();

                // sumStretch -= data->stretch;

                n--;

            }

        }

        bool finished = n == 0;

        while (!finished) {

            finished = true;

            Fixed64 fp_over = toFixed(overdraft);

            Fixed64 fp_w = 0;

            for (i = start; i < start+count; i++) {

                QLayoutStruct *data = &chain[i];

                if (data->done)

                    continue;

                // if (sumStretch <= 0)

                fp_w += fp_over / n;

                // else

                //    fp_w += (fp_over * data->stretch) / sumStretch;

                int w = fRound(fp_w);

                data->size = data->smartSizeHint() - w;

                fp_w -= toFixed(w); // give the difference to the next

                if (data->size < data->minimumSize) {

                    data->done = true;

                    data->size = data->minimumSize;

                    finished = false;

                    overdraft -= data->smartSizeHint() - data->minimumSize;

                    // sumStretch -= data->stretch;

                    n--;

                    break;

                }

            }

        }

    } else { // extra space

        int n = count;

        int space_left = space - sumSpacing;

        // first give to the fixed ones, and handle non-expansiveness

        for (i = start; i < start + count; i++) {

            QLayoutStruct *data = &chain[i];

            if (!data->done

                && (data->maximumSize <= data->smartSizeHint()

                    || (wannaGrow && !data->expansive && data->stretch == 0)

                    || (!allEmptyNonstretch && data->empty &&

                        !data->expansive && data->stretch == 0))) {

                data->size = data->smartSizeHint();

                data->done = true;

                space_left -= data->size;

                sumStretch -= data->stretch;

                n--;

            }

        }

        extraspace = space_left;

        /*

          Do a trial distribution and calculate how much it is off.

          If there are more deficit pixels than surplus pixels, give

          the minimum size items what they need, and repeat.

          Otherwise give to the maximum size items, and repeat.

          Paul Olav Tvete has a wonderful mathematical proof of the

          correctness of this principle, but unfortunately this

          comment is too small to contain it.

        */

        int surplus, deficit;

        do {

            surplus = deficit = 0;

            Fixed64 fp_space = toFixed(space_left);

            Fixed64 fp_w = 0;

            for (i = start; i < start + count; i++) {

                QLayoutStruct *data = &chain[i];

                if (data->done)

                    continue;

                extraspace = 0;

                if (sumStretch <= 0)

                    fp_w += fp_space / n;

                else

                    fp_w += (fp_space * data->stretch) / sumStretch;

                int w = fRound(fp_w);

                data->size = w;

                fp_w -= toFixed(w); // give the difference to the next

                if (w < data->smartSizeHint()) {

                    deficit +=  data->smartSizeHint() - w;

                } else if (w > data->maximumSize) {

                    surplus += w - data->maximumSize;

                }

            }

            if (deficit > 0 && surplus <= deficit) {

                // give to the ones that have too little

                for (i = start; i < start+count; i++) {

                    QLayoutStruct *data = &chain[i];

                    if (!data->done && data->size < data->smartSizeHint()) {

                        data->size = data->smartSizeHint();

                        data->done = true;

                        space_left -= data->smartSizeHint();

                        sumStretch -= data->stretch;

                        n--;

                    }

                }

            }

            if (surplus > 0 && surplus >= deficit) {

                // take from the ones that have too much

                for (i = start; i < start + count; i++) {

                    QLayoutStruct *data = &chain[i];

                    if (!data->done && data->size > data->maximumSize) {

                        data->size = data->maximumSize;

                        data->done = true;

                        space_left -= data->maximumSize;

                        sumStretch -= data->stretch;

                        n--;

                    }

                }

            }

        } while (n > 0 && surplus != deficit);

        if (n == 0)

            extraspace = space_left;

    }

    /*

      As a last resort, we distribute the unwanted space equally

      among the spacers (counting the start and end of the chain). We

      could, but don't, attempt a sub-pixel allocation of the extra

      space.

    */

    int extra = extraspace / (spacerCount + 2);

    int p = pos + extra;

    for (i = start; i < start+count; i++) {

        QLayoutStruct *data = &chain[i];

        data->pos = p;

        p += data->size;

        if (!data->empty)

            p += data->effectiveSpacer(spacer) + extra;

    }

#ifdef QLAYOUT_EXTRA_DEBUG

    qDebug() << "qGeomCalc" << "start" << start <<  "count" << count <<  "pos" << pos

             <<  "space" << space <<  "spacer" << spacer;

    for (i = start; i < start + count; ++i) {

        qDebug() << i << ':' << chain[i].minimumSize << chain[i].smartSizeHint()

                 << chain[i].maximumSize << "stretch" << chain[i].stretch

                 << "empty" << chain[i].empty << "expansive" << chain[i].expansive

                 << "spacing" << chain[i].spacing;

        qDebug() << "result pos" << chain[i].pos << "size" << chain[i].size;

    }

#endif

}

Q_GUI_EXPORT QSize qSmartMinSize(const QSize &sizeHint, const QSize &minSizeHint,

                                 const QSize &minSize, const QSize &maxSize,

                                 const QSizePolicy &sizePolicy)

{

    QSize s(0, 0);

    if (sizePolicy.horizontalPolicy() != QSizePolicy::Ignored) {

        if (sizePolicy.horizontalPolicy() & QSizePolicy::ShrinkFlag)

            s.setWidth(minSizeHint.width());

        else

            s.setWidth(qMax(sizeHint.width(), minSizeHint.width()));

    }

    if (sizePolicy.verticalPolicy() != QSizePolicy::Ignored) {

        if (sizePolicy.verticalPolicy() & QSizePolicy::ShrinkFlag) {

            s.setHeight(minSizeHint.height());

        } else {

            s.setHeight(qMax(sizeHint.height(), minSizeHint.height()));

        }

    }

    s = s.boundedTo(maxSize);

    if (minSize.width() > 0)

        s.setWidth(minSize.width());

    if (minSize.height() > 0)

        s.setHeight(minSize.height());

    return s.expandedTo(QSize(0,0));

}

Q_GUI_EXPORT QSize qSmartMinSize(const QWidgetItem *i)

{

    QWidget *w = ((QWidgetItem *)i)->widget();

    return qSmartMinSize(w->sizeHint(), w->minimumSizeHint(),

                            w->minimumSize(), w->maximumSize(),

                            w->sizePolicy());

}

Q_GUI_EXPORT QSize qSmartMinSize(const QWidget *w)

{

    return qSmartMinSize(w->sizeHint(), w->minimumSizeHint(),

                            w->minimumSize(), w->maximumSize(),

                            w->sizePolicy());

}

Q_GUI_EXPORT QSize qSmartMaxSize(const QSize &sizeHint,

                                 const QSize &minSize, const QSize &maxSize,

                                 const QSizePolicy &sizePolicy, Qt::Alignment align)

{

    if (align & Qt::AlignHorizontal_Mask && align & Qt::AlignVertical_Mask)

        return QSize(QLAYOUTSIZE_MAX, QLAYOUTSIZE_MAX);

    QSize s = maxSize;

    QSize hint = sizeHint.expandedTo(minSize);

    if (s.width() == QWIDGETSIZE_MAX && !(align & Qt::AlignHorizontal_Mask))

        if (!(sizePolicy.horizontalPolicy() & QSizePolicy::GrowFlag))

            s.setWidth(hint.width());

    if (s.height() == QWIDGETSIZE_MAX && !(align & Qt::AlignVertical_Mask))

        if (!(sizePolicy.verticalPolicy() & QSizePolicy::GrowFlag))

            s.setHeight(hint.height());

    if (align & Qt::AlignHorizontal_Mask)

        s.setWidth(QLAYOUTSIZE_MAX);

    if (align & Qt::AlignVertical_Mask)

        s.setHeight(QLAYOUTSIZE_MAX);

    return s;

}

Q_GUI_EXPORT QSize qSmartMaxSize(const QWidgetItem *i, Qt::Alignment align)

{

    QWidget *w = ((QWidgetItem*)i)->widget();

    return qSmartMaxSize(w->sizeHint().expandedTo(w->minimumSizeHint()), w->minimumSize(), w->maximumSize(),

                            w->sizePolicy(), align);

}

Q_GUI_EXPORT QSize qSmartMaxSize(const QWidget *w, Qt::Alignment align)

{

    return qSmartMaxSize(w->sizeHint().expandedTo(w->minimumSizeHint()), w->minimumSize(), w->maximumSize(),

                            w->sizePolicy(), align);

}

Q_GUI_EXPORT int qSmartSpacing(const QLayout *layout, QStyle::PixelMetric pm)

{

    QObject *parent = layout->parent();

    if (!parent) {

        return -1;

    } else if (parent->isWidgetType()) {

        QWidget *pw = static_cast<QWidget *>(parent);

        return pw->style()->pixelMetric(pm, 0, pw);

    } else {

        return static_cast<QLayout *>(parent)->spacing();

    }

}

QT_END_NAMESPACE