/********************************************************************
 KWin - the KDE window manager
 This file is part of the KDE project.

Copyright (C) 1999, 2000 Matthias Ettrich <ettrich@kde.org>
Copyright (C) 2003 Lubos Lunak <l.lunak@kde.org>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/

// SELI zmenit doc

/*

 This file contains things relevant to stacking order and layers.

 Design:

 Normal unconstrained stacking order, as requested by the user (by clicking
 on windows to raise them, etc.), is in Workspace::unconstrained_stacking_order.
 That list shouldn't be used at all, except for building
 Workspace::stacking_order. The building is done
 in Workspace::constrainedStackingOrder(). Only Workspace::stackingOrder() should
 be used to get the stacking order, because it also checks the stacking order
 is up to date.
 All clients are also stored in Workspace::clients (except for isDesktop() clients,
 as those are very special, and are stored in Workspace::desktops), in the order
 the clients were created.

 Every window has one layer assigned in which it is. There are 6 layers,
 from bottom : DesktopLayer, BelowLayer, NormalLayer, DockLayer, AboveLayer
 and ActiveLayer (see also NETWM sect.7.10.). The layer a window is in depends
 on the window type, and on other things like whether the window is active.

 NET::Splash clients belong to the Normal layer. NET::TopMenu clients
 belong to Dock layer. Clients that are both NET::Dock and NET::KeepBelow
 are in the Normal layer in order to keep the 'allow window to cover
 the panel' Kicker setting to work as intended (this may look like a slight
 spec violation, but a) I have no better idea, b) the spec allows adjusting
 the stacking order if the WM thinks it's a good idea . We put all
 NET::KeepAbove above all Docks too, even though the spec suggests putting
 them in the same layer.

 Most transients are in the same layer as their mainwindow,
 see Workspace::constrainedStackingOrder(), they may also be in higher layers, but
 they should never be below their mainwindow.

 When some client attribute changes (above/below flag, transiency...),
 Workspace::updateClientLayer() should be called in order to make
 sure it's moved to the appropriate layer ClientList if needed.

 Currently the things that affect client in which layer a client
 belongs: KeepAbove/Keep Below flags, window type, fullscreen
 state and whether the client is active, mainclient (transiency).

 Make sure updateStackingOrder() is called in order to make
 Workspace::stackingOrder() up to date and propagated to the world.
 Using Workspace::blockStackingUpdates() (or the StackingUpdatesBlocker
 helper class) it's possible to temporarily disable updates
 and the stacking order will be updated once after it's allowed again.

*/

#include <assert.h>

#include <kdebug.h>

#include "utils.h"
#include "client.h"
#include "workspace.h"
#include "tabbox.h"
#include "group.h"
#include "rules.h"
#include "unmanaged.h"
#include "deleted.h"
#include "effects.h"
#include <QX11Info>
#include "composite.h"

namespace KWin
{

//*******************************
// Workspace
//*******************************

void Workspace::updateClientLayer(Client* c)
{
    if (c == NULL)
        return;
    if (c->layer() == c->belongsToLayer())
        return;
    StackingUpdatesBlocker blocker(this);
    c->invalidateLayer(); // invalidate, will be updated when doing restacking
    for (ClientList::ConstIterator it = c->transients().constBegin();
            it != c->transients().constEnd();
            ++it)
        updateClientLayer(*it);
}

void Workspace::updateStackingOrder(bool propagate_new_clients)
{
    if (block_stacking_updates > 0) {
        if (propagate_new_clients)
            blocked_propagating_new_clients = true;
        return;
    }
    ToplevelList new_stacking_order = constrainedStackingOrder();
    bool changed = (force_restacking || new_stacking_order != stacking_order);
    force_restacking = false;
    stacking_order = new_stacking_order;
#if 0
    kDebug(1212) << "stacking:" << changed;
    if (changed || propagate_new_clients) {
        for (ClientList::ConstIterator it = stacking_order.begin();
                it != stacking_order.end();
                ++it)
            kDebug(1212) << (void*)(*it) << *it << ":" << (*it)->layer();
    }
#endif
    if (changed || propagate_new_clients) {
        propagateClients(propagate_new_clients);
        if (m_compositor) {
            m_compositor->addRepaintFull();
        }

        if (active_client)
            active_client->updateMouseGrab();
    }
}

/*!
  Propagates the managed clients to the world.
  Called ONLY from updateStackingOrder().
 */
void Workspace::propagateClients(bool propagate_new_clients)
{
    Window *cl; // MW we should not assume WId and Window to be compatible
    // when passig pointers around.

    // restack the windows according to the stacking order
    // 1 - supportWindow, 1 - topmenu_space, 8 - electric borders
    QVector<Window*> newWindowStack;
    // Stack all windows under the support window. The support window is
    // not used for anything (besides the NETWM property), and it's not shown,
    // but it was lowered after kwin startup. Stacking all clients below
    // it ensures that no client will be ever shown above override-redirect
    // windows (e.g. popups).
    newWindowStack << (Window*)supportWindow->winId();
#ifdef KWIN_BUILD_SCREENEDGES
    QVectorIterator<Window> it(m_screenEdge.windows());
    while (it.hasNext()) {
        if ((Window)it.next() != None) {
            newWindowStack << (Window*)&it;
        }
    }
#endif
    for (int i = stacking_order.size() - 1; i >= 0; i--) {
        Client *client = qobject_cast<Client*>(stacking_order.at(i));
        if (!client || client->hiddenPreview()) {
            continue;
        }

        if (client->inputId())
            // Stack the input window above the frame
            newWindowStack << (Window*)client->inputId();

        newWindowStack << (Window*)client->frameId();
    }

    // when having hidden previews, stack hidden windows below everything else
    // (as far as pure X stacking order is concerned), in order to avoid having
    // these windows that should be unmapped to interfere with other windows
    for (int i = stacking_order.size() - 1; i >= 0; i--) {
        Client *client = qobject_cast<Client*>(stacking_order.at(i));
        if (!client || !client->hiddenPreview())
            continue;
        newWindowStack << (Window*)client->frameId();
    }
    // TODO isn't it too inefficient to restack always all clients?
    // TODO don't restack not visible windows?
    assert(newWindowStack.at(0) == (Window*)supportWindow->winId());
    XRestackWindows(display(), (Window*)newWindowStack.data(), newWindowStack.count());

    int pos = 0;
    if (propagate_new_clients) {
        cl = new Window[ desktops.count() + clients.count()];
        // TODO this is still not completely in the map order
        for (ClientList::ConstIterator it = desktops.constBegin(); it != desktops.constEnd(); ++it)
            cl[pos++] = (*it)->window();
        for (ClientList::ConstIterator it = clients.constBegin(); it != clients.constEnd(); ++it)
            cl[pos++] = (*it)->window();
        rootInfo->setClientList(cl, pos);
        delete [] cl;
    }

    cl = new Window[ stacking_order.count()];
    pos = 0;
    for (ToplevelList::ConstIterator it = stacking_order.constBegin(); it != stacking_order.constEnd(); ++it) {
        if ((*it)->isClient())
            cl[pos++] = (*it)->window();
    }
    rootInfo->setClientListStacking(cl, pos);
    delete [] cl;

    // Make the cached stacking order invalid here, in case we need the new stacking order before we get
    // the matching event, due to X being asynchronous.
    x_stacking_dirty = true;
}

/*!
  Returns topmost visible client. Windows on the dock, the desktop
  or of any other special kind are excluded. Also if the window
  doesn't accept focus it's excluded.
 */
// TODO misleading name for this method, too many slightly different ways to use it
Client* Workspace::topClientOnDesktop(int desktop, int screen, bool unconstrained, bool only_normal) const
{
// TODO    Q_ASSERT( block_stacking_updates == 0 );
    ToplevelList list;
    if (!unconstrained)
        list = stacking_order;
    else
        list = unconstrained_stacking_order;
    for (int i = list.size() - 1;
            i >= 0;
            --i) {
        Client *c = qobject_cast<Client*>(list.at(i));
        if (!c) {
            continue;
        }
        if (c->isOnDesktop(desktop) && c->isShown(false) && c->isOnCurrentActivity()) {
            if (screen != -1 && c->screen() != screen)
                continue;
            if (!only_normal)
                return c;
            if (c->wantsTabFocus() && !c->isSpecialWindow())
                return c;
        }
    }
    return 0;
}

Client* Workspace::findDesktop(bool topmost, int desktop) const
{
// TODO    Q_ASSERT( block_stacking_updates == 0 );
    if (topmost) {
        for (int i = stacking_order.size() - 1; i >= 0; i--) {
            Client *c = qobject_cast<Client*>(stacking_order.at(i));
            if (c && c->isOnDesktop(desktop) && c->isDesktop()
                    && c->isShown(true))
                return c;
        }
    } else { // bottom-most
        foreach (Toplevel * c, stacking_order) {
            Client *client = qobject_cast<Client*>(c);
            if (client && c->isOnDesktop(desktop) && c->isDesktop()
                    && client->isShown(true))
                return client;
        }
    }
    return NULL;
}

void Workspace::raiseOrLowerClient(Client *c)
{
    if (!c) return;
    Client* topmost = NULL;
// TODO    Q_ASSERT( block_stacking_updates == 0 );
    if (most_recently_raised && stacking_order.contains(most_recently_raised) &&
            most_recently_raised->isShown(true) && c->isOnCurrentDesktop())
        topmost = most_recently_raised;
    else
        topmost = topClientOnDesktop(c->isOnAllDesktops() ? VirtualDesktopManager::self()->current() : c->desktop(),
                                     options->isSeparateScreenFocus() ? c->screen() : -1);

    if (c == topmost)
        lowerClient(c);
    else
        raiseClient(c);
}


void Workspace::lowerClient(Client* c, bool nogroup)
{
    if (!c)
        return;

    c->cancelAutoRaise();

    StackingUpdatesBlocker blocker(this);

    unconstrained_stacking_order.removeAll(c);
    unconstrained_stacking_order.prepend(c);
    if (!nogroup && c->isTransient()) {
        // lower also all windows in the group, in their reversed stacking order
        ClientList wins = ensureStackingOrder(c->group()->members());
        for (int i = wins.size() - 1;
                i >= 0;
                --i) {
            if (wins[ i ] != c)
                lowerClient(wins[ i ], true);
        }
    }

    if (c == most_recently_raised)
        most_recently_raised = 0;
}

void Workspace::lowerClientWithinApplication(Client* c)
{
    if (!c)
        return;

    c->cancelAutoRaise();

    StackingUpdatesBlocker blocker(this);

    unconstrained_stacking_order.removeAll(c);
    bool lowered = false;
    // first try to put it below the bottom-most window of the application
    for (ToplevelList::Iterator it = unconstrained_stacking_order.begin();
            it != unconstrained_stacking_order.end();
            ++it) {
        Client *client = qobject_cast<Client*>(*it);
        if (!client) {
            continue;
        }
        if (Client::belongToSameApplication(client, c)) {
            unconstrained_stacking_order.insert(it, c);
            lowered = true;
            break;
        }
    }
    if (!lowered)
        unconstrained_stacking_order.prepend(c);
    // ignore mainwindows
}

void Workspace::raiseClient(Client* c, bool nogroup)
{
    if (!c)
        return;

    c->cancelAutoRaise();

    StackingUpdatesBlocker blocker(this);

    if (!nogroup && c->isTransient()) {
        ClientList transients;
        Client *transient_parent = c;
        while ((transient_parent = transient_parent->transientFor()))
            transients << transient_parent;
        foreach (transient_parent, transients)
            raiseClient(transient_parent, true);
    }

    unconstrained_stacking_order.removeAll(c);
    unconstrained_stacking_order.append(c);

    if (!c->isSpecialWindow()) {
        most_recently_raised = c;
        pending_take_activity = NULL;
    }
}

void Workspace::raiseClientWithinApplication(Client* c)
{
    if (!c)
        return;

    c->cancelAutoRaise();

    StackingUpdatesBlocker blocker(this);
    // ignore mainwindows

    // first try to put it above the top-most window of the application
    for (int i = unconstrained_stacking_order.size() - 1; i > -1 ; --i) {
        Client *other = qobject_cast<Client*>(unconstrained_stacking_order.at(i));
        if (!other) {
            continue;
        }
        if (other == c)     // don't lower it just because it asked to be raised
            return;
        if (Client::belongToSameApplication(other, c)) {
            unconstrained_stacking_order.removeAll(c);
            unconstrained_stacking_order.insert(unconstrained_stacking_order.indexOf(other) + 1, c);   // insert after the found one
            break;
        }
    }
}

void Workspace::raiseClientRequest(Client* c, NET::RequestSource src, Time timestamp)
{
    if (src == NET::FromTool || allowFullClientRaising(c, timestamp))
        raiseClient(c);
    else {
        raiseClientWithinApplication(c);
        c->demandAttention();
    }
}

void Workspace::lowerClientRequest(Client* c, NET::RequestSource src, Time /*timestamp*/)
{
    // If the client has support for all this focus stealing prevention stuff,
    // do only lowering within the application, as that's the more logical
    // variant of lowering when application requests it.
    // No demanding of attention here of course.
    if (src == NET::FromTool || !c->hasUserTimeSupport())
        lowerClient(c);
    else
        lowerClientWithinApplication(c);
}


void Workspace::restack(Client* c, Client* under)
{
    assert(unconstrained_stacking_order.contains(under));
    if (!Client::belongToSameApplication(under, c)) {
         // put in the stacking order below _all_ windows belonging to the active application
        for (int i = 0; i < unconstrained_stacking_order.size(); ++i) {
            Client *other = qobject_cast<Client*>(unconstrained_stacking_order.at(i));
            if (other && Client::belongToSameApplication(under, other)) {
                under = (c == other) ? 0 : other;
                break;
            }
        }
    }
    if (under) {
        unconstrained_stacking_order.removeAll(c);
        unconstrained_stacking_order.insert(unconstrained_stacking_order.indexOf(under), c);
    }

    assert(unconstrained_stacking_order.contains(c));
    for (uint desktop = 1; desktop <= VirtualDesktopManager::self()->count(); ++desktop) {
        // do for every virtual desktop to handle the case of onalldesktop windows
        if (c->wantsTabFocus() && c->isOnDesktop(desktop) && focus_chain[ desktop ].contains(under)) {
            if (Client::belongToSameApplication(under, c)) {
                // put it after the active window if it's the same app
                focus_chain[ desktop ].removeAll(c);
                focus_chain[ desktop ].insert(focus_chain[ desktop ].indexOf(under), c);
            } else {
                // put it in focus_chain[currentDesktop()] after all windows belonging to the active applicationa
                focus_chain[ desktop ].removeAll(c);
                for (int i = focus_chain[ desktop ].size() - 1; i >= 0; --i) {
                    if (Client::belongToSameApplication(under, focus_chain[ desktop ].at(i))) {
                        focus_chain[ desktop ].insert(i, c);
                        break;
                    }
                }
            }
        }
    }
    // the same for global_focus_chain
    if (c->wantsTabFocus() && global_focus_chain.contains(under)) {
        if (Client::belongToSameApplication(under, c)) {
            global_focus_chain.removeAll(c);
            global_focus_chain.insert(global_focus_chain.indexOf(under), c);
        } else {
            global_focus_chain.removeAll(c);
            for (int i = global_focus_chain.size() - 1; i >= 0; --i) {
                if (Client::belongToSameApplication(under, global_focus_chain.at(i))) {
                    global_focus_chain.insert(i, c);
                    break;
                }
            }
        }
    }
    updateStackingOrder();
}

void Workspace::restackClientUnderActive(Client* c)
{
    if (!active_client || active_client == c) {
        raiseClient(c);
        return;
    }
    restack(c, active_client);
}

void Workspace::restoreSessionStackingOrder(Client* c)
{
    if (c->sessionStackingOrder() < 0)
        return;
    StackingUpdatesBlocker blocker(this);
    unconstrained_stacking_order.removeAll(c);
    for (ToplevelList::Iterator it = unconstrained_stacking_order.begin();  // from bottom
            it != unconstrained_stacking_order.end();
            ++it) {
        Client *current = qobject_cast<Client*>(*it);
        if (!current) {
            continue;
        }
        if (current->sessionStackingOrder() > c->sessionStackingOrder()) {
            unconstrained_stacking_order.insert(it, c);
            return;
        }
    }
    unconstrained_stacking_order.append(c);
}

/*!
  Returns a stacking order based upon \a list that fulfills certain contained.
 */
ToplevelList Workspace::constrainedStackingOrder()
{
    ToplevelList layer[ NumLayers ];

#if 0
    kDebug(1212) << "stacking1:";
    for (ClientList::ConstIterator it = unconstrained_stacking_order.begin();
            it != unconstrained_stacking_order.end();
            ++it)
        kDebug(1212) << (void*)(*it) << *it << ":" << (*it)->layer();
#endif
    // build the order from layers
    QVector< QMap<Group*, Layer> > minimum_layer(numScreens());
    for (ToplevelList::ConstIterator it = unconstrained_stacking_order.constBegin(),
                                  end = unconstrained_stacking_order.constEnd(); it != end; ++it) {
        Layer l = (*it)->layer();

        const int screen = (*it)->screen();
        Client *c = qobject_cast<Client*>(*it);
        QMap< Group*, Layer >::iterator mLayer = minimum_layer[screen].find(c ? c->group() : NULL);
        if (mLayer != minimum_layer[screen].end()) {
            // If a window is raised above some other window in the same window group
            // which is in the ActiveLayer (i.e. it's fulscreened), make sure it stays
            // above that window (see #95731).
            if (*mLayer == ActiveLayer && (l == NormalLayer || l == AboveLayer))
                l = ActiveLayer;
            *mLayer = l;
        } else if (c) {
            minimum_layer[screen].insertMulti(c->group(), l);
        }
        layer[ l ].append(*it);
    }
    ToplevelList stacking;
    for (Layer lay = FirstLayer;
            lay < NumLayers;
            ++lay)
        stacking += layer[ lay ];
#if 0
    kDebug(1212) << "stacking2:";
    for (ClientList::ConstIterator it = stacking.begin();
            it != stacking.end();
            ++it)
        kDebug(1212) << (void*)(*it) << *it << ":" << (*it)->layer();
#endif
    // now keep transients above their mainwindows
    // TODO this could(?) use some optimization
    for (int i = stacking.size() - 1;
            i >= 0;
       ) {
        Client *current = qobject_cast<Client*>(stacking[i]);
        if (!current || !current->isTransient()) {
            --i;
            continue;
        }
        int i2 = -1;
        if (current->groupTransient()) {
            if (current->group()->members().count() > 0) {
                // find topmost client this one is transient for
                for (i2 = stacking.size() - 1;
                        i2 >= 0;
                        --i2) {
                    if (stacking[ i2 ] == stacking[ i ]) {
                        i2 = -1; // don't reorder, already the topmost in the group
                        break;
                    }
                    Client *c2 = qobject_cast<Client*>(stacking[ i2 ]);
                    if (!c2) {
                        continue;
                    }
                    if (c2->hasTransient(current, true)
                            && keepTransientAbove(c2, current))
                        break;
                }
            } // else i2 remains pointing at -1
        } else {
            for (i2 = stacking.size() - 1;
                    i2 >= 0;
                    --i2) {
                Client *c2 = qobject_cast<Client*>(stacking[ i2 ]);
                if (!c2) {
                    continue;
                }
                if (c2 == current) {
                    i2 = -1; // don't reorder, already on top of its mainwindow
                    break;
                }
                if (c2 == current->transientFor()
                        && keepTransientAbove(c2, current))
                    break;
            }
        }
        if (i2 == -1) {
            --i;
            continue;
        }
        stacking.removeAt(i);
        --i; // move onto the next item (for next for () iteration)
        --i2; // adjust index of the mainwindow after the remove above
        if (!current->transients().isEmpty())   // this one now can be possibly above its transients,
            i = i2; // so go again higher in the stack order and possibly move those transients again
        ++i2; // insert after (on top of) the mainwindow, it's ok if it2 is now stacking.end()
        stacking.insert(i2, current);
    }
#if 0
    kDebug(1212) << "stacking3:";
    for (ClientList::ConstIterator it = stacking.begin();
            it != stacking.end();
            ++it)
        kDebug(1212) << (void*)(*it) << *it << ":" << (*it)->layer();
    kDebug(1212) << "\n\n";
#endif
    return stacking;
}

void Workspace::blockStackingUpdates(bool block)
{
    if (block) {
        if (block_stacking_updates == 0)
            blocked_propagating_new_clients = false;
        ++block_stacking_updates;
    } else // !block
        if (--block_stacking_updates == 0) {
            updateStackingOrder(blocked_propagating_new_clients);
            if (effects)
                static_cast<EffectsHandlerImpl*>(effects)->checkInputWindowStacking();
        }
}

// Ensure list is in stacking order
ClientList Workspace::ensureStackingOrder(const ClientList& list) const
{
// TODO    Q_ASSERT( block_stacking_updates == 0 );
    if (list.count() < 2)
        return list;
    // TODO is this worth optimizing?
    ClientList result = list;
    for (ToplevelList::ConstIterator it = stacking_order.constBegin();
            it != stacking_order.constEnd();
            ++it) {
        Client *c = qobject_cast<Client*>(*it);
        if (!c) {
            continue;
        }
        if (result.removeAll(c) != 0)
            result.append(c);
    }
    return result;
}

// check whether a transient should be actually kept above its mainwindow
// there may be some special cases where this rule shouldn't be enfored
bool Workspace::keepTransientAbove(const Client* mainwindow, const Client* transient)
{
    // #93832 - don't keep splashscreens above dialogs
    if (transient->isSplash() && mainwindow->isDialog())
        return false;
    // This is rather a hack for #76026. Don't keep non-modal dialogs above
    // the mainwindow, but only if they're group transient (since only such dialogs
    // have taskbar entry in Kicker). A proper way of doing this (both kwin and kicker)
    // needs to be found.
    if (transient->isDialog() && !transient->isModal() && transient->groupTransient())
        return false;
    // #63223 - don't keep transients above docks, because the dock is kept high,
    // and e.g. dialogs for them would be too high too
    if (mainwindow->isDock())
        return false;
    return true;
}

// Returns all windows in their stacking order on the root window.
ToplevelList Workspace::xStackingOrder() const
{
    if (!x_stacking_dirty)
        return x_stacking;
    x_stacking_dirty = false;
    x_stacking.clear();
    Window dummy;
    Window* windows = NULL;
    unsigned int count = 0;
    XQueryTree(display(), rootWindow(), &dummy, &dummy, &windows, &count);
    // use our own stacking order, not the X one, as they may differ
    foreach (Toplevel * c, stacking_order)
    x_stacking.append(c);
    for (unsigned int i = 0;
            i < count;
            ++i) {
        if (Unmanaged* c = findUnmanaged(WindowMatchPredicate(windows[ i ])))
            x_stacking.append(c);
    }
    if (windows != NULL)
        XFree(windows);
    if (m_compositor) {
        const_cast< Workspace* >(this)->m_compositor->checkUnredirect();
    }
    return x_stacking;
}

//*******************************
// Client
//*******************************

void Client::restackWindow(Window above, int detail, NET::RequestSource src, Time timestamp, bool send_event)
{
    Client *other = 0;
    if (detail == Opposite) {
        other = workspace()->findClient(WindowMatchPredicate(above));
        if (!other) {
            workspace()->raiseOrLowerClient(this);
            return;
        }
        ToplevelList::const_iterator  it = workspace()->stackingOrder().constBegin(),
                                    end = workspace()->stackingOrder().constEnd();
        while (it != end) {
            if (*it == this) {
                detail = Above;
                break;
            } else if (*it == other) {
                detail = Below;
                break;
            }
            ++it;
        }
    }
    else if (detail == TopIf) {
        other = workspace()->findClient(WindowMatchPredicate(above));
        if (other && other->geometry().intersects(geometry()))
            workspace()->raiseClientRequest(this, src, timestamp);
        return;
    }
    else if (detail == BottomIf) {
        other = workspace()->findClient(WindowMatchPredicate(above));
        if (other && other->geometry().intersects(geometry()))
            workspace()->lowerClientRequest(this, src, timestamp);
        return;
    }

    if (!other)
        other = workspace()->findClient(WindowMatchPredicate(above));

    if (other && detail == Above) {
        ToplevelList::const_iterator  it = workspace()->stackingOrder().constEnd(),
                                    begin = workspace()->stackingOrder().constBegin();
        while (--it != begin) {

            if (*it == other) { // the other one is top on stack
                it = begin; // invalidate
                src = NET::FromTool; // force
                break;
            }
            Client *c = qobject_cast<Client*>(*it);

            if (!c || !(  (*it)->isNormalWindow() && c->isShown(true) &&
                    (*it)->isOnCurrentDesktop() && (*it)->isOnCurrentActivity() && (*it)->isOnScreen(screen()) ))
                continue; // irrelevant clients

            if (*(it - 1) == other)
                break; // "it" is the one above the target one, stack below "it"
        }

        if (it != begin && (*(it - 1) == other))
            other = qobject_cast<Client*>(*it);
        else
            other = 0;
    }

    if (other)
        workspace()->restack(this, other);
    else if (detail == Below)
        workspace()->lowerClientRequest(this, src, timestamp);
    else if (detail == Above)
        workspace()->raiseClientRequest(this, src, timestamp);

    if (send_event)
        sendSyntheticConfigureNotify();
}

void Client::setKeepAbove(bool b)
{
    b = rules()->checkKeepAbove(b);
    if (b && !rules()->checkKeepBelow(false))
        setKeepBelow(false);
    if (b == keepAbove()) {
        // force hint change if different
        if (bool(info->state() & NET::KeepAbove) != keepAbove())
            info->setState(keepAbove() ? NET::KeepAbove : 0, NET::KeepAbove);
        return;
    }
    keep_above = b;
    info->setState(keepAbove() ? NET::KeepAbove : 0, NET::KeepAbove);
    if (decoration != NULL)
        decoration->emitKeepAboveChanged(keepAbove());
    workspace()->updateClientLayer(this);
    updateWindowRules(Rules::Above);

    // Update states of all other windows in this group
    if (tabGroup())
        tabGroup()->updateStates(this, TabGroup::Layer);
    emit keepAboveChanged();
}

void Client::setKeepBelow(bool b)
{
    b = rules()->checkKeepBelow(b);
    if (b && !rules()->checkKeepAbove(false))
        setKeepAbove(false);
    if (b == keepBelow()) {
        // force hint change if different
        if (bool(info->state() & NET::KeepBelow) != keepBelow())
            info->setState(keepBelow() ? NET::KeepBelow : 0, NET::KeepBelow);
        return;
    }
    keep_below = b;
    info->setState(keepBelow() ? NET::KeepBelow : 0, NET::KeepBelow);
    if (decoration != NULL)
        decoration->emitKeepBelowChanged(keepBelow());
    workspace()->updateClientLayer(this);
    updateWindowRules(Rules::Below);

    // Update states of all other windows in this group
    if (tabGroup())
        tabGroup()->updateStates(this, TabGroup::Layer);
    emit keepBelowChanged();
}

Layer Client::layer() const
{
    if (in_layer == UnknownLayer)
        const_cast< Client* >(this)->in_layer = belongsToLayer();
    return in_layer;
}

Layer Client::belongsToLayer() const
{
    if (isDesktop())
        return DesktopLayer;
    if (isSplash())          // no damn annoying splashscreens
        return NormalLayer; // getting in the way of everything else
    if (isDock()) {
        // slight hack for the 'allow window to cover panel' Kicker setting
        // don't move keepbelow docks below normal window, but only to the same
        // layer, so that both may be raised to cover the other
        if (keepBelow())
            return NormalLayer;
        if (keepAbove()) // slight hack for the autohiding panels
            return AboveLayer;
        return DockLayer;
    }
    if (keepBelow())
        return BelowLayer;
    if (isActiveFullScreen())
        return ActiveLayer;
    if (keepAbove())
        return AboveLayer;
    return NormalLayer;
}

bool rec_checkTransientOnTop(const ClientList &transients, const Client *topmost)
{
    foreach (const Client *transient, transients) {
        if (transient == topmost || rec_checkTransientOnTop(transient->transients(), topmost)) {
            return true;
        }
    }
    return false;
}

bool Client::isActiveFullScreen() const
{
    if (!isFullScreen())
        return false;

//     const Client* ac = workspace()->mostRecentlyActivatedClient(); // instead of activeClient() - avoids flicker
//     if (!ac)
//         return false;
// not needed, for xinerama  -> && ( ac == this || this->group() == ac->group())

    // only raise fullscreen above docks if it's the topmost window in unconstrained stacking order,
    // i.e. the window set to be topmost by the user (also includes transients of the fullscreen window)
    const Client* top = workspace()->topClientOnDesktop(VirtualDesktopManager::self()->current(), screen(), true, false);
    if (!top)
        return false;

    // check whether we ...
    if (top == this)
        return true;
    // ... or one of our transients is topmost
    return rec_checkTransientOnTop(transients_list, top);
}

} // namespace