/*
 * vim:ts=4:sw=4:expandtab
 */

#include "all.h"

struct Con *croot;
struct Con *focused;

struct all_cons_head all_cons = TAILQ_HEAD_INITIALIZER(all_cons);

/*
 * Loads tree from ~/.i3/_restart.json (used for in-place restarts).
 *
 */
bool tree_restore(const char *path, xcb_get_geometry_reply_t *geometry) {
    char *globbed = resolve_tilde(path);

    if (!path_exists(globbed)) {
        LOG("%s does not exist, not restoring tree\n", globbed);
        free(globbed);
        return false;
    }

    /* TODO: refactor the following */
    croot = con_new(NULL, NULL);
    croot->rect = (Rect){
        geometry->x,
        geometry->y,
        geometry->width,
        geometry->height
    };
    focused = croot;

    tree_append_json(globbed);

    printf("appended tree, using new root\n");
    croot = TAILQ_FIRST(&(croot->nodes_head));
    printf("new root = %p\n", croot);
    Con *out = TAILQ_FIRST(&(croot->nodes_head));
    printf("out = %p\n", out);
    Con *ws = TAILQ_FIRST(&(out->nodes_head));
    printf("ws = %p\n", ws);

    return true;
}

/*
 * Initializes the tree by creating the root node. The CT_OUTPUT Cons below the
 * root node are created in randr.c for each Output.
 *
 */
void tree_init(xcb_get_geometry_reply_t *geometry) {
    croot = con_new(NULL, NULL);
    FREE(croot->name);
    croot->name = "root";
    croot->type = CT_ROOT;
    croot->rect = (Rect){
        geometry->x,
        geometry->y,
        geometry->width,
        geometry->height
    };
}

/*
 * Opens an empty container in the current container
 *
 */
Con *tree_open_con(Con *con, i3Window *window) {
    if (con == NULL) {
        /* every focusable Con has a parent (outputs have parent root) */
        con = focused->parent;
        /* If the parent is an output, we are on a workspace. In this case,
         * the new container needs to be opened as a leaf of the workspace. */
        if (con->parent->type == CT_OUTPUT && con->type != CT_DOCKAREA) {
            con = focused;
        }

        /* If the currently focused container is a floating container, we
         * attach the new container to the currently focused spot in its
         * workspace. */
        if (con->type == CT_FLOATING_CON) {
            con = con_descend_tiling_focused(con->parent);
            if (con->type != CT_WORKSPACE)
                con = con->parent;
        }
        DLOG("con = %p\n", con);
    }

    assert(con != NULL);

    /* 3. create the container and attach it to its parent */
    Con *new = con_new(con, window);

    /* 4: re-calculate child->percent for each child */
    con_fix_percent(con);

    return new;
}

static bool _is_con_mapped(Con *con) {
    Con *child;

    TAILQ_FOREACH(child, &(con->nodes_head), nodes)
        if (_is_con_mapped(child))
            return true;

    return con->mapped;
}

/*
 * Closes the given container including all children.
 * Returns true if the container was killed or false if just WM_DELETE was sent
 * and the window is expected to kill itself.
 *
 */
bool tree_close(Con *con, kill_window_t kill_window, bool dont_kill_parent) {
    bool was_mapped = con->mapped;
    Con *parent = con->parent;

    if (!was_mapped) {
        /* Even if the container itself is not mapped, its children may be
         * mapped (for example split containers don't have a mapped window on
         * their own but usually contain mapped children). */
        was_mapped = _is_con_mapped(con);
    }

    /* Get the container which is next focused */
    Con *next = con_next_focused(con);
    DLOG("next = %p, focused = %p\n", next, focused);

    DLOG("closing %p, kill_window = %d\n", con, kill_window);
    Con *child, *nextchild;
    bool abort_kill = false;
    /* We cannot use TAILQ_FOREACH because the children get deleted
     * in their parent’s nodes_head */
    for (child = TAILQ_FIRST(&(con->nodes_head)); child; ) {
        nextchild = TAILQ_NEXT(child, nodes);
        DLOG("killing child=%p\n", child);
        if (!tree_close(child, kill_window, true))
            abort_kill = true;
        child = nextchild;
    }

    if (abort_kill) {
        DLOG("One of the children could not be killed immediately (WM_DELETE sent), aborting.\n");
        return false;
    }

    if (con->window != NULL) {
        if (kill_window != DONT_KILL_WINDOW) {
            x_window_kill(con->window->id, kill_window);
            return false;
        } else {
            xcb_void_cookie_t cookie;
            /* un-parent the window */
            cookie = xcb_reparent_window(conn, con->window->id, root, 0, 0);

            /* Ignore X11 errors for the ReparentWindow request.
             * X11 Errors are returned when the window was already destroyed */
            add_ignore_event(cookie.sequence, 0);

            /* We are no longer handling this window, thus set WM_STATE to
             * WM_STATE_WITHDRAWN (see ICCCM 4.1.3.1) */
            long data[] = { XCB_ICCCM_WM_STATE_WITHDRAWN, XCB_NONE };
            cookie = xcb_change_property(conn, XCB_PROP_MODE_REPLACE,
                        con->window->id, A_WM_STATE, A_WM_STATE, 32, 2, data);

            /* Ignore X11 errors for the ReparentWindow request.
             * X11 Errors are returned when the window was already destroyed */
            add_ignore_event(cookie.sequence, 0);
        }
        FREE(con->window->class_class);
        FREE(con->window->class_instance);
        FREE(con->window->name_x);
        FREE(con->window->name_json);
        free(con->window);
    }

    /* kill the X11 part of this container */
    x_con_kill(con);

    con_detach(con);
    if (con->type != CT_FLOATING_CON) {
        /* If the container is *not* floating, we might need to re-distribute
         * percentage values for the resized containers. */
        con_fix_percent(parent);
    }

    if (con_is_floating(con)) {
        Con *ws = con_get_workspace(con);
        DLOG("Container was floating, killing floating container\n");
        tree_close(parent, DONT_KILL_WINDOW, false);
        DLOG("parent container killed\n");
        if (con == focused) {
            DLOG("This is the focused container, i need to find another one to focus. I start looking at ws = %p\n", ws);
            /* go down the focus stack as far as possible */
            next = con_descend_focused(ws);

            dont_kill_parent = true;
            DLOG("Alright, focusing %p\n", next);
        } else {
            next = NULL;
        }
    }

    free(con->name);
    FREE(con->deco_render_params);
    TAILQ_REMOVE(&all_cons, con, all_cons);
    free(con);

    /* in the case of floating windows, we already focused another container
     * when closing the parent, so we can exit now. */
    if (!next) {
        DLOG("No next container, i will just exit now\n");
        return true;
    }

    if (was_mapped || con == focused) {
        if ((kill_window != DONT_KILL_WINDOW) || !dont_kill_parent || con == focused) {
            DLOG("focusing %p / %s\n", next, next->name);
            /* TODO: check if the container (or one of its children) was focused */
            if (next->type == CT_DOCKAREA) {
                /* Instead of focusing the dockarea, we need to restore focus to the workspace */
                con_focus(con_descend_focused(output_get_content(next->parent)));
            } else {
                con_focus(next);
            }
        }
        else {
            DLOG("not focusing because we're not killing anybody");
        }
    } else {
        DLOG("not focusing, was not mapped\n");
    }

    /* check if the parent container is empty now and close it */
    if (!dont_kill_parent)
        CALL(parent, on_remove_child);

    return true;
}

/*
 * Closes the current container using tree_close().
 *
 */
void tree_close_con(kill_window_t kill_window) {
    assert(focused != NULL);
    if (focused->type == CT_WORKSPACE) {
        LOG("Cannot close workspace\n");
        return;
    }

    /* There *should* be no possibility to focus outputs / root container */
    assert(focused->type != CT_OUTPUT);
    assert(focused->type != CT_ROOT);

    /* Kill con */
    tree_close(focused, kill_window, false);
}

/*
 * Splits (horizontally or vertically) the given container by creating a new
 * container which contains the old one and the future ones.
 *
 */
void tree_split(Con *con, orientation_t orientation) {
    /* for a workspace, we just need to change orientation */
    if (con->type == CT_WORKSPACE) {
        DLOG("Workspace, simply changing orientation to %d\n", orientation);
        con->orientation = orientation;
        return;
    }

    Con *parent = con->parent;
    /* if we are in a container whose parent contains only one
     * child (its split functionality is unused so far), we just change the
     * orientation (more intuitive than splitting again) */
    if (con_num_children(parent) == 1) {
        parent->orientation = orientation;
        DLOG("Just changing orientation of existing container\n");
        return;
    }

    DLOG("Splitting in orientation %d\n", orientation);

    /* 2: replace it with a new Con */
    Con *new = con_new(NULL, NULL);
    TAILQ_REPLACE(&(parent->nodes_head), con, new, nodes);
    TAILQ_REPLACE(&(parent->focus_head), con, new, focused);
    new->parent = parent;
    new->orientation = orientation;

    /* 3: swap 'percent' (resize factor) */
    new->percent = con->percent;
    con->percent = 0.0;

    /* 4: add it as a child to the new Con */
    con_attach(con, new, false);
}

/*
 * Moves focus one level up.
 *
 */
void level_up() {
    /* We cannot go up when we are in fullscreen mode at the moment, that would
     * be totally not intuitive */
    if (focused->fullscreen_mode != CF_NONE) {
        LOG("Currently in fullscreen, not going up\n");
        return;
    }
    /* We can focus up to the workspace, but not any higher in the tree */
    if ((focused->parent->type != CT_CON &&
        focused->parent->type != CT_WORKSPACE) ||
        focused->type == CT_WORKSPACE) {
        LOG("Cannot go up any further\n");
        return;
    }
    con_focus(focused->parent);
}

/*
 * Moves focus one level down.
 *
 */
void level_down() {
    /* Go down the focus stack of the current node */
    Con *next = TAILQ_FIRST(&(focused->focus_head));
    if (next == TAILQ_END(&(focused->focus_head))) {
        printf("cannot go down\n");
        return;
    }
    con_focus(next);
}

static void mark_unmapped(Con *con) {
    Con *current;

    con->mapped = false;
    TAILQ_FOREACH(current, &(con->nodes_head), nodes)
        mark_unmapped(current);
    if (con->type == CT_WORKSPACE) {
        /* We need to call mark_unmapped on floating nodes aswell since we can
         * make containers floating. */
        TAILQ_FOREACH(current, &(con->floating_head), floating_windows)
            mark_unmapped(current);
    }
}

/*
 * Renders the tree, that is rendering all outputs using render_con() and
 * pushing the changes to X11 using x_push_changes().
 *
 */
void tree_render() {
    if (croot == NULL)
        return;

    DLOG("-- BEGIN RENDERING --\n");
    /* Reset map state for all nodes in tree */
    /* TODO: a nicer method to walk all nodes would be good, maybe? */
    mark_unmapped(croot);
    croot->mapped = true;

    render_con(croot, false);

    x_push_changes(croot);
    DLOG("-- END RENDERING --\n");
}

/*
 * Recursive function to walk the tree until a con can be found to focus.
 *
 */
static bool _tree_next(Con *con, char way, orientation_t orientation, bool wrap) {
    /* Stop recursing at workspaces */
    if (con->type == CT_WORKSPACE)
        return false;

    if (con->type == CT_FLOATING_CON) {
        /* TODO: implement focus for floating windows */
        return false;
    }

    Con *parent = con->parent;

    /* If the orientation does not match or there is no other con to focus, we
     * need to go higher in the hierarchy */
    if (con_orientation(parent) != orientation ||
        con_num_children(parent) == 1)
        return _tree_next(parent, way, orientation, wrap);

    Con *current = TAILQ_FIRST(&(parent->focus_head));
    /* TODO: when can the following happen (except for floating windows, which
     * are handled above)? */
    if (TAILQ_EMPTY(&(parent->nodes_head))) {
        DLOG("nothing to focus\n");
        return false;
    }

    Con *next;
    if (way == 'n')
        next = TAILQ_NEXT(current, nodes);
    else next = TAILQ_PREV(current, nodes_head, nodes);

    if (!next) {
        if (!config.force_focus_wrapping) {
            /* If there is no next/previous container, we check if we can focus one
             * when going higher (without wrapping, though). If so, we are done, if
             * not, we wrap */
            if (_tree_next(parent, way, orientation, false))
                return true;

            if (!wrap)
                return false;
        }

        if (way == 'n')
            next = TAILQ_FIRST(&(parent->nodes_head));
        else next = TAILQ_LAST(&(parent->nodes_head), nodes_head);
    }

    /* 3: focus choice comes in here. at the moment we will go down
     * until we find a window */
    /* TODO: check for window, atm we only go down as far as possible */
    con_focus(con_descend_focused(next));
    return true;
}

/*
 * Changes focus in the given way (next/previous) and given orientation
 * (horizontal/vertical).
 *
 */
void tree_next(char way, orientation_t orientation) {
    _tree_next(focused, way, orientation, true);
}

/*
 * tree_flatten() removes pairs of redundant split containers, e.g.:
 *       [workspace, horizontal]
 *   [v-split]           [child3]
 *   [h-split]
 * [child1] [child2]
 * In this example, the v-split and h-split container are redundant.
 * Such a situation can be created by moving containers in a direction which is
 * not the orientation of their parent container. i3 needs to create a new
 * split container then and if you move containers this way multiple times,
 * redundant chains of split-containers can be the result.
 *
 */
void tree_flatten(Con *con) {
    Con *current, *child, *parent = con->parent;
    DLOG("Checking if I can flatten con = %p / %s\n", con, con->name);

    /* We only consider normal containers without windows */
    if (con->type != CT_CON || con->window != NULL)
        goto recurse;

    /* Ensure it got only one child */
    child = TAILQ_FIRST(&(con->nodes_head));
    if (child == NULL || TAILQ_NEXT(child, nodes) != NULL)
        goto recurse;

    /* The child must have a different orientation than the con but the same as
     * the con’s parent to be redundant */
    if (con->orientation == NO_ORIENTATION ||
        child->orientation == NO_ORIENTATION ||
        con->orientation == child->orientation ||
        child->orientation != parent->orientation)
        goto recurse;

    DLOG("Alright, I have to flatten this situation now. Stay calm.\n");
    /* 1: save focus */
    Con *focus_next = TAILQ_FIRST(&(child->focus_head));

    DLOG("detaching...\n");
    /* 2: re-attach the children to the parent before con */
    while (!TAILQ_EMPTY(&(child->nodes_head))) {
        current = TAILQ_FIRST(&(child->nodes_head));
        DLOG("detaching current=%p / %s\n", current, current->name);
        con_detach(current);
        DLOG("re-attaching\n");
        /* We don’t use con_attach() here because for a CT_CON, the special
         * case handling of con_attach() does not trigger. So all it would do
         * is calling TAILQ_INSERT_AFTER, but with the wrong container. So we
         * directly use the TAILQ macros. */
        current->parent = parent;
        TAILQ_INSERT_BEFORE(con, current, nodes);
        DLOG("attaching to focus list\n");
        TAILQ_INSERT_TAIL(&(parent->focus_head), current, focused);
        current->percent = con->percent;
    }
    DLOG("re-attached all\n");

    /* 3: restore focus, if con was focused */
    if (focus_next != NULL &&
        TAILQ_FIRST(&(parent->focus_head)) == con) {
        DLOG("restoring focus to focus_next=%p\n", focus_next);
        TAILQ_REMOVE(&(parent->focus_head), focus_next, focused);
        TAILQ_INSERT_HEAD(&(parent->focus_head), focus_next, focused);
        DLOG("restored focus.\n");
    }

    /* 4: close the redundant cons */
    DLOG("closing redundant cons\n");
    tree_close(con, DONT_KILL_WINDOW, true);

    /* Well, we got to abort the recursion here because we destroyed the
     * container. However, if tree_flatten() is called sufficiently often,
     * there can’t be the situation of having two pairs of redundant containers
     * at once. Therefore, we can safely abort the recursion on this level
     * after flattening. */
    return;

recurse:
    /* We cannot use normal foreach here because tree_flatten might close the
     * current container. */
    current = TAILQ_FIRST(&(con->nodes_head));
    while (current != NULL) {
        Con *next = TAILQ_NEXT(current, nodes);
        tree_flatten(current);
        current = next;
    }

    current = TAILQ_FIRST(&(con->floating_head));
    while (current != NULL) {
        Con *next = TAILQ_NEXT(current, floating_windows);
        tree_flatten(current);
        current = next;
    }
}