/* -*- indent-tabs-mode: nil; tab-width: 4; c-basic-offset: 4; -*-

   stacking.c for the Openbox window manager
   Copyright (c) 2006        Mikael Magnusson
   Copyright (c) 2003        Ben Jansens

   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.

   See the COPYING file for a copy of the GNU General Public License.
*/

#include "openbox.h"
#include "prop.h"
#include "screen.h"
#include "focus.h"
#include "client.h"
#include "group.h"
#include "frame.h"
#include "window.h"

GList  *stacking_list = NULL;

void stacking_set_list()
{
    Window *windows = NULL;
    GList *it;
    guint i = 0;

    /* on shutdown, don't update the properties, so that we can read it back
       in on startup and re-stack the windows as they were before we shut down
    */
    if (ob_state() == OB_STATE_EXITING) return;

    /* create an array of the window ids (from bottom to top,
       reverse order!) */
    if (stacking_list) {
        windows = g_new(Window, g_list_length(stacking_list));
        for (it = g_list_last(stacking_list); it; it = g_list_previous(it)) {
            if (WINDOW_IS_CLIENT(it->data))
                windows[i++] = WINDOW_AS_CLIENT(it->data)->window;
        }
    }

    PROP_SETA32(RootWindow(ob_display, ob_screen),
                net_client_list_stacking, window, (gulong*)windows, i);

    g_free(windows);
}

static void do_restack(GList *wins, GList *before)
{
    GList *it;
    Window *win;
    gint i;

#ifdef DEBUG
    GList *next;
    /* pls only restack stuff in the same layer at a time */
    for (it = wins; it; it = next) {
        next = g_list_next(it);
        if (!next) break;
        g_assert (window_layer(it->data) == window_layer(next->data));
    }
    if (before)
        g_assert(window_layer(it->data) >= window_layer(before->data));
#endif

    win = g_new(Window, g_list_length(wins) + 1);

    if (before == stacking_list)
        win[0] = screen_support_win;
    else if (!before)
        win[0] = window_top(g_list_last(stacking_list)->data);
    else
        win[0] = window_top(g_list_previous(before)->data);

    for (i = 1, it = wins; it; ++i, it = g_list_next(it)) {
        win[i] = window_top(it->data);
        g_assert(win[i] != None); /* better not call stacking shit before
                                     setting your top level window value */
        stacking_list = g_list_insert_before(stacking_list, before, it->data);
    }

#ifdef DEBUG
    /* some debug checking of the stacking list's order */
    for (it = stacking_list; ; it = next) {
        next = g_list_next(it);
        if (!next) break;
        g_assert(window_layer(it->data) >= window_layer(next->data));
    }
#endif

    XRestackWindows(ob_display, win, i);
    g_free(win);

    stacking_set_list();
}

static void do_raise(GList *wins)
{
    GList *it;
    GList *layer[OB_NUM_STACKING_LAYERS] = {NULL};
    gint i;

    for (it = wins; it; it = g_list_next(it)) {
        ObStackingLayer l;

        l = window_layer(it->data);
        layer[l] = g_list_append(layer[l], it->data);
    }

    it = stacking_list;
    for (i = OB_NUM_STACKING_LAYERS - 1; i >= 0; --i) {
        if (layer[i]) {
            for (; it; it = g_list_next(it)) {
                /* look for the top of the layer */
                if (window_layer(it->data) <= (ObStackingLayer) i)
                    break;
            }
            do_restack(layer[i], it);
            g_list_free(layer[i]);
        }
    }
}

static void do_lower(GList *wins)
{
    GList *it;
    GList *layer[OB_NUM_STACKING_LAYERS] = {NULL};
    gint i;

    for (it = wins; it; it = g_list_next(it)) {
        ObStackingLayer l;

        l = window_layer(it->data);
        layer[l] = g_list_append(layer[l], it->data);
    }

    it = stacking_list;
    for (i = OB_NUM_STACKING_LAYERS - 1; i >= 0; --i) {
        if (layer[i]) {
            for (; it; it = g_list_next(it)) {
                /* look for the top of the next layer down */
                if (window_layer(it->data) < (ObStackingLayer) i)
                    break;
            }
            do_restack(layer[i], it);
            g_list_free(layer[i]);
        }
    }
}

static void restack_windows(ObClient *selected, gboolean raise, gboolean group)
{
    GList *it, *last, *below, *above, *next;
    GList *wins = NULL;

    GList *group_modals = NULL;
    GList *group_trans = NULL;
    GList *modals = NULL;
    GList *trans = NULL;

    if (!raise && selected->transient_for) {
        GSList *top, *top_it;
        GSList *top_reorder = NULL;
        
        /* if it's a transient lowering, lower its parents so that we can lower
           this window, or it won't move */
        top = client_search_all_top_parents(selected);

        /* go thru stacking list backwards so we can use g_slist_prepend */
        for (it = g_list_last(stacking_list); it && top;
             it = g_list_previous(it))
            if ((top_it = g_slist_find(top, it->data))) {
                top_reorder = g_slist_prepend(top_reorder, top_it->data);
                top = g_slist_delete_link(top, top_it);
            }
        g_assert(top == NULL);

        /* call restack for each of these to lower them */
        for (top_it = top_reorder; top_it; top_it = g_slist_next(top_it))
            restack_windows(top_it->data, raise, group);
        return;
    }

    /* remove first so we can't run into ourself */
    it = g_list_find(stacking_list, selected);
    g_assert(it);
    stacking_list = g_list_delete_link(stacking_list, it);

    /* go from the bottom of the stacking list up */
    for (it = g_list_last(stacking_list); it; it = g_list_previous(it)) {
        if (WINDOW_IS_CLIENT(it->data)) {
            ObClient *ch = it->data;

            /* only move windows in the same stacking layer */
            if (ch->layer == selected->layer &&
                client_search_transient(selected, ch))
            {
                if (client_is_direct_child(selected, ch)) {
                    if (ch->modal)
                        modals = g_list_prepend(modals, ch);
                    else
                        trans = g_list_prepend(trans, ch);
                }
                else {
                    if (ch->modal)
                        group_modals = g_list_prepend(group_modals, ch);
                    else
                        group_trans = g_list_prepend(group_trans, ch);
                }
                stacking_list = g_list_delete_link(stacking_list, it);
            }
        }
    }

    /* put transients of the selected window right above it */
    wins = g_list_concat(modals, trans);
    wins = g_list_append(wins, selected);

    /* if selected window is transient for group then raise it above others */
    if (selected->transient_for == OB_TRAN_GROUP) {
        /* if it's modal, raise it above those also */
        if (selected->modal) {
            wins = g_list_concat(wins, group_modals);
            group_modals = NULL;
        }
        wins = g_list_concat(wins, group_trans);
        group_trans = NULL;
    }

    /* find where to put the selected window, start from bottom of list,
       this is the window below everything we are re-adding to the list */
    last = NULL;
    for (it = g_list_last(stacking_list); it; it = g_list_previous(it))
    {
        if (window_layer(it->data) < selected->layer)
            continue;
        /* if lowering, stop at the beginning of the layer */
        if (!raise)
            break;
        /* if raising, stop at the end of the layer */
        if (window_layer(it->data) > selected->layer)
            break;

        last = it;
    }

    /* save this position in the stacking list */
    below = last;

    /* find where to put the group transients, start from the top of list */
    for (it = stacking_list; it; it = g_list_next(it)) {
        /* skip past higher layers */
        if (window_layer(it->data) > selected->layer)
            continue;
        /* if we reach the end of the layer (how?) then don't go further */
        if (window_layer(it->data) < selected->layer)
            break;
        /* stop when we reach the first window in the group */
        if (WINDOW_IS_CLIENT(it->data)) {
            ObClient *c = it->data;
            if (c->group == selected->group)
                break;
        }
        /* if we don't hit any other group members, stop here because this
           is where we are putting the selected window (and its children) */
        if (it == below)
            break;
    }

    /* save this position, this is the top of the group of windows between the
       group transient ones we're restacking and the others up above that we're
       restacking

       we actually want to save 1 position _above_ that, for for loops to work
       nicely, so move back one position in the list while saving it
    */
    above = it ? g_list_previous(it) : g_list_last(stacking_list);

    /* put the windows inside the gap to the other windows we're stacking
       into the restacking list, go from the bottom up so that we can use
       g_list_prepend */
    if (below) it = g_list_previous(below);
    else       it = g_list_last(stacking_list);
    for (; it != above; it = next) {
        next = g_list_previous(it);
        wins = g_list_prepend(wins, it->data);
        stacking_list = g_list_delete_link(stacking_list, it);
    }

    /* group transients go above the rest of the stuff acquired to now */
    wins = g_list_concat(group_trans, wins);
    /* group modals go on the very top */
    wins = g_list_concat(group_modals, wins);

    do_restack(wins, below);
    g_list_free(wins);
}

void stacking_raise(ObWindow *window, gboolean group)
{
    if (WINDOW_IS_CLIENT(window)) {
        ObClient *selected;
        selected = WINDOW_AS_CLIENT(window);
        restack_windows(selected, TRUE, group);
    } else {
        GList *wins;
        wins = g_list_append(NULL, window);
        stacking_list = g_list_remove(stacking_list, window);
        do_raise(wins);
        g_list_free(wins);
    }
}

void stacking_lower(ObWindow *window, gboolean group)
{
    if (WINDOW_IS_CLIENT(window)) {
        ObClient *selected;
        selected = WINDOW_AS_CLIENT(window);
        restack_windows(selected, FALSE, group);
    } else {
        GList *wins;
        wins = g_list_append(NULL, window);
        stacking_list = g_list_remove(stacking_list, window);
        do_lower(wins);
        g_list_free(wins);
    }
}

void stacking_below(ObWindow *window, ObWindow *below)
{
    GList *wins, *before;

    if (window_layer(window) != window_layer(below))
        return;

    wins = g_list_append(NULL, window);
    stacking_list = g_list_remove(stacking_list, window);
    before = g_list_next(g_list_find(stacking_list, below));
    do_restack(wins, before);
    g_list_free(wins);
}

void stacking_add(ObWindow *win)
{
    g_assert(screen_support_win != None); /* make sure I dont break this in the
                                             future */

    stacking_list = g_list_append(stacking_list, win);
    stacking_raise(win, FALSE);
}

void stacking_add_nonintrusive(ObWindow *win)
{
    ObClient *client;
    ObClient *parent = NULL;
    GList *it_below = NULL;

    if (!WINDOW_IS_CLIENT(win)) {
        stacking_add(win); /* no special rules for others */
        return;
    }

    client = WINDOW_AS_CLIENT(win);

    /* insert above its highest parent */
    if (client->transient_for) {
        if (client->transient_for != OB_TRAN_GROUP) {
            parent = client->transient_for;
        } else {
            GSList *sit;
            GList *it;

            if (client->group)
                for (it = stacking_list; !parent && it; it = g_list_next(it)) {
                    if ((sit = g_slist_find(client->group->members, it->data)))
                for (sit = client->group->members; !parent && sit;
                     sit = g_slist_next(sit))
                {
                    ObClient *c = sit->data;
                    /* checking transient_for prevents infinate loops! */
                    if (sit->data == it->data && !c->transient_for)
                        parent = it->data;
                }
            }
        }
    }

    if (!(it_below = g_list_find(stacking_list, parent))) {
        /* no parent to put above, try find the focused client to go
           under */
        if (focus_client && focus_client->layer == client->layer) {
            if ((it_below = g_list_find(stacking_list, focus_client)))
                it_below = it_below->next;
        }
    }
    if (!it_below) {
        /* out of ideas, just add it normally... */
        stacking_add(win);
    } else {
        /* make sure it's not in the wrong layer though ! */
        for (; it_below; it_below = g_list_next(it_below))
        {
            /* stop when the window is not in a higher layer than the window
               it is going above (it_below) */
            if (client->layer >= window_layer(it_below->data))
                break;
        }
        for (; it_below != stacking_list;
             it_below = g_list_previous(it_below))
        {
            /* stop when the window is not in a lower layer than the
               window it is going under (it_above) */
            GList *it_above = g_list_previous(it_below);
            if (client->layer <= window_layer(it_above->data))
                break;
        }

        GList *wins = g_list_append(NULL, win);
        do_restack(wins, it_below);
        g_list_free(wins);
    }
}