Implement swap command

7 files changed, 218 insertions, 0 deletions

diff --git a/include/sway/commands.h b/include/sway/commands.h
index d39ac56c..365068ae 100644
--- a/include/sway/commands.h
+++ b/include/sway/commands.h
@@ -144,6 +144,7 @@ sway_cmd cmd_splitt;
 sway_cmd cmd_splitv;
 sway_cmd cmd_sticky;
 sway_cmd cmd_swaybg_command;
+sway_cmd cmd_swap;
 sway_cmd cmd_title_format;
 sway_cmd cmd_unmark;
 sway_cmd cmd_workspace;
diff --git a/include/sway/tree/layout.h b/include/sway/tree/layout.h
index cc999871..2e0f2abf 100644
--- a/include/sway/tree/layout.h
+++ b/include/sway/tree/layout.h
@@ -69,4 +69,6 @@ struct sway_container *container_split(struct sway_container *child,
 void container_recursive_resize(struct sway_container *container,
                 double amount, enum resize_edge edge);
 
+void container_swap(struct sway_container *con1, struct sway_container *con2);
+
 #endif
diff --git a/sway/commands.c b/sway/commands.c
index 6cba0a1c..c3728afd 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -186,6 +186,7 @@ static struct cmd_handler command_handlers[] = {
         { "splith", cmd_splith },
         { "splitt", cmd_splitt },
         { "splitv", cmd_splitv },
+        { "swap", cmd_swap },
         { "title_format", cmd_title_format },
         { "unmark", cmd_unmark },
 };
diff --git a/sway/commands/swap.c b/sway/commands/swap.c
new file mode 100644
index 00000000..e925ad33
--- /dev/null
+++ b/sway/commands/swap.c
@@ -0,0 +1,80 @@
+#include <strings.h>
+#include <wlr/util/log.h>
+#include "sway/commands.h"
+#include "sway/tree/layout.h"
+#include "sway/tree/view.h"
+#include "stringop.h"
+
+static const char* EXPECTED_SYNTAX =
+        "Expected 'swap container with id|con_id|mark <arg>'";
+
+static bool test_con_id(struct sway_container *container, void *con_id) {
+        return container->id == (size_t)con_id;
+}
+
+static bool test_id(struct sway_container *container, void *id) {
+        xcb_window_t *wid = id;
+        return (container->type == C_VIEW
+                        && container->sway_view->type == SWAY_VIEW_XWAYLAND
+                        && container->sway_view->wlr_xwayland_surface->window_id == *wid);
+}
+
+static bool test_mark(struct sway_container *container, void *mark) {
+        if (container->type == C_VIEW && container->sway_view->marks->length) {
+                return !list_seq_find(container->sway_view->marks,
+                                (int (*)(const void *, const void *))strcmp, mark);
+        }
+        return false;
+}
+
+struct cmd_results *cmd_swap(int argc, char **argv) {
+        struct cmd_results *error = NULL;
+        if ((error = checkarg(argc, "swap", EXPECTED_AT_LEAST, 4))) {
+                return error;
+        }
+
+        if (strcasecmp(argv[0], "container") || strcasecmp(argv[1], "with")) {
+                return cmd_results_new(CMD_INVALID, "swap", EXPECTED_SYNTAX);
+        }
+
+        struct sway_container *current = config->handler_context.current_container;
+        struct sway_container *other;
+
+        char *value = join_args(argv + 3, argc - 3);
+        if (strcasecmp(argv[2], "id") == 0) {
+                xcb_window_t id = strtol(value, NULL, 0);
+                other = container_find(&root_container, test_id, (void *)&id);
+        } else if (strcasecmp(argv[2], "con_id") == 0) {
+                size_t con_id = atoi(value);
+                other = container_find(&root_container, test_con_id, (void *)con_id);
+        } else if (strcasecmp(argv[2], "mark") == 0) {
+                other = container_find(&root_container, test_mark, (void *)value);
+        } else {
+                free(value);
+                return cmd_results_new(CMD_INVALID, "swap", EXPECTED_SYNTAX);
+        }
+
+        if (!other) {
+                error = cmd_results_new(CMD_FAILURE, "swap",
+                                "Failed to find %s '%s'", argv[2], value);
+        } else if (current->type < C_CONTAINER || other->type < C_CONTAINER) {
+                error = cmd_results_new(CMD_FAILURE, "swap",
+                                "Can only swap with containers and views");
+        } else if (container_has_anscestor(current, other)
+                        || container_has_anscestor(other, current)) {
+                error = cmd_results_new(CMD_FAILURE, "swap",
+                                "Cannot swap ancestor and descendant");
+        } else if (current->layout == L_FLOATING || other->layout == L_FLOATING) {
+                error = cmd_results_new(CMD_FAILURE, "swap",
+                                "Swapping with floating containers is not supported");
+        }
+
+        free(value);
+
+        if (error) {
+                return error;
+        }
+
+        container_swap(current, other);
+        return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}
diff --git a/sway/meson.build b/sway/meson.build
index 72347d51..9c942e8e 100644
--- a/sway/meson.build
+++ b/sway/meson.build
@@ -63,6 +63,7 @@ sway_sources = files(
         'commands/show_marks.c',
         'commands/split.c',
         'commands/swaybg_command.c',
+        'commands/swap.c',
         'commands/title_format.c',
         'commands/unmark.c',
         'commands/workspace.c',
diff --git a/sway/sway.5.scd b/sway/sway.5.scd
index ff138562..25a5eef5 100644
--- a/sway/sway.5.scd
+++ b/sway/sway.5.scd
@@ -167,6 +167,15 @@ They are expected to be used with *bindsym* or at runtime through *swaymsg*(1).
         "Sticks" a floating window to the current output so that it shows up on all
         workspaces.
 
+*swap* container with id|con\_id|mark <arg>
+        Swaps the position, geometry, and fullscreen status of two containers. The
+        first container can be selected either by criteria or focus. The second
+        container can be selected by _id_, _con\_id_, or _mark_. _id_ can only be
+        used with xwayland views. If the first container has focus, it will retain
+        focus unless it is moved to a different workspace or the second container
+        becomes fullscreen on the same workspace as the first container. In either
+        of those cases, the second container will gain focus.
+
 The following commands may be used either in the configuration file or at
 runtime.
 
diff --git a/sway/tree/layout.c b/sway/tree/layout.c
index 21cec529..624d5516 100644
--- a/sway/tree/layout.c
+++ b/sway/tree/layout.c
@@ -882,3 +882,127 @@ void container_recursive_resize(struct sway_container *container,
                 }
         }
 }
+
+static void swap_places(struct sway_container *con1,
+                struct sway_container *con2) {
+        struct sway_container *temp = malloc(sizeof(struct sway_container));
+        temp->x = con1->x;
+        temp->y = con1->y;
+        temp->width = con1->width;
+        temp->height = con1->height;
+        temp->parent = con1->parent;
+
+        con1->x = con2->x;
+        con1->y = con2->y;
+        con1->width = con2->width;
+        con1->height = con2->height;
+
+        con2->x = temp->x;
+        con2->y = temp->y;
+        con2->width = temp->width;
+        con2->height = temp->height;
+
+        int temp_index = index_child(con1);
+        container_insert_child(con2->parent, con1, index_child(con2));
+        container_insert_child(temp->parent, con2, temp_index);
+
+        free(temp);
+}
+
+static void swap_focus(struct sway_container *con1,
+                struct sway_container *con2, struct sway_seat *seat,
+                struct sway_container *focus) {
+        if (focus == con1 || focus == con2) {
+                struct sway_container *ws1 = container_parent(con1, C_WORKSPACE);
+                struct sway_container *ws2 = container_parent(con2, C_WORKSPACE);
+                if (focus == con1 && (con2->parent->layout == L_TABBED
+                                        || con2->parent->layout == L_STACKED)) {
+                        if (workspace_is_visible(ws2)) {
+                                seat_set_focus_warp(seat, con2, false);
+                        }
+                        seat_set_focus(seat, ws1 != ws2 ? con2 : con1);
+                } else if (focus == con2 && (con1->parent->layout == L_TABBED
+                                        || con1->parent->layout == L_STACKED)) {
+                        if (workspace_is_visible(ws1)) {
+                                seat_set_focus_warp(seat, con1, false);
+                        }
+                        seat_set_focus(seat, ws1 != ws2 ? con1 : con2);
+                } else if (ws1 != ws2) {
+                        seat_set_focus(seat, focus == con1 ? con2 : con1);
+                } else {
+                        seat_set_focus(seat, focus);
+                }
+        } else {
+                seat_set_focus(seat, focus);
+        }
+}
+
+void container_swap(struct sway_container *con1, struct sway_container *con2) {
+        if (!sway_assert(con1 && con2, "Cannot swap with nothing")) {
+                return;
+        }
+        if (!sway_assert(con1->type >= C_CONTAINER && con2->type >= C_CONTAINER,
+                                "Can only swap containers and views")) {
+                return;
+        }
+        if (!sway_assert(!container_has_anscestor(con1, con2)
+                                && !container_has_anscestor(con2, con1),
+                                "Cannot swap anscestor and descendant")) {
+                return;
+        }
+        if (!sway_assert(con1->layout != L_FLOATING && con2->layout != L_FLOATING,
+                                "Swapping with floating containers is not supported")) {
+                return;
+        }
+
+        wlr_log(L_DEBUG, "Swapping containers %zu and %zu", con1->id, con2->id);
+
+        int fs1 = con1->type == C_VIEW && con1->sway_view->is_fullscreen;
+        int fs2 = con2->type == C_VIEW && con2->sway_view->is_fullscreen;
+        if (fs1) {
+                view_set_fullscreen(con1->sway_view, false);
+        }
+        if (fs2) {
+                view_set_fullscreen(con2->sway_view, false);
+        }
+
+        struct sway_seat *seat = input_manager_get_default_seat(input_manager);
+        struct sway_container *focus = seat_get_focus(seat);
+        struct sway_container *vis1 = container_parent(
+                        seat_get_focus_inactive(seat, container_parent(con1, C_OUTPUT)),
+                        C_WORKSPACE);
+        struct sway_container *vis2 = container_parent(
+                        seat_get_focus_inactive(seat, container_parent(con2, C_OUTPUT)),
+                        C_WORKSPACE);
+
+        char *stored_prev_name = NULL;
+        if (prev_workspace_name) {
+                stored_prev_name = strdup(prev_workspace_name);
+        }
+
+        swap_places(con1, con2);
+
+        if (!workspace_is_visible(vis1)) {
+                seat_set_focus(seat, seat_get_focus_inactive(seat, vis1));
+        }
+        if (!workspace_is_visible(vis2)) {
+                seat_set_focus(seat, seat_get_focus_inactive(seat, vis2));
+        }
+
+        swap_focus(con1, con2, seat, focus);
+
+        if (stored_prev_name) {
+                free(prev_workspace_name);
+                prev_workspace_name = stored_prev_name;
+        }
+
+        arrange_children_of(con1->parent);
+        arrange_children_of(con2->parent);
+
+        if (fs1 && con2->type == C_VIEW) {
+                view_set_fullscreen(con2->sway_view, true);
+        }
+        if (fs2 && con1->type == C_VIEW) {
+                view_set_fullscreen(con1->sway_view, true);
+        }
+}