text: #ifndef _POSIX_C_SOURCE
  #define _POSIX_C_SOURCE 200809L
  #endif
  #include <assert.h>
  #include <stdlib.h>
  #include <wayland-server-protocol.h>
  #include <wayland-server.h>
  #include <wlr/types/wlr_surface.h>
  #include <wlr/types/wlr_wl_shell.h>
  #include <wlr/util/log.h>
  #include "util/signal.h"
  
  static const struct wlr_surface_role shell_surface_role;
  
  bool wlr_surface_is_wl_shell_surface(struct wlr_surface *surface) {
  	return surface->role == &shell_surface_role;
  }
  
  struct wlr_wl_shell_surface *wlr_wl_shell_surface_from_wlr_surface(
  		struct wlr_surface *surface) {
  	assert(wlr_surface_is_wl_shell_surface(surface));
  	return (struct wlr_wl_shell_surface *)surface->role_data;
  }
  
  static void shell_pointer_grab_end(struct wlr_seat_pointer_grab *grab) {
  	struct wlr_wl_shell_popup_grab *popup_grab = grab->data;
  
  	struct wlr_wl_shell_surface *popup, *tmp = NULL;
  	wl_list_for_each_safe(popup, tmp, &popup_grab->popups, grab_link) {
  		if (popup->popup_mapped) {
  			wl_shell_surface_send_popup_done(popup->resource);
  			popup->popup_mapped = false;
  		}
  	}
  
  	if (grab->seat->pointer_state.grab == grab) {
  		wlr_seat_pointer_end_grab(grab->seat);
  	}
  }
  
  static void shell_pointer_grab_maybe_end(struct wlr_seat_pointer_grab *grab) {
  	struct wlr_wl_shell_popup_grab *popup_grab = grab->data;
  
  	if (grab->seat->pointer_state.grab != grab) {
  		return;
  	}
  
  	bool has_mapped = false;
  
  	struct wlr_wl_shell_surface *popup, *tmp = NULL;
  	wl_list_for_each_safe(popup, tmp, &popup_grab->popups, grab_link) {
  		if (popup->popup_mapped) {
  			has_mapped = true;
  			break;
  		}
  	}
  
  	if (!has_mapped) {
  		shell_pointer_grab_end(grab);
  	}
  }
  
  static void shell_pointer_grab_enter(struct wlr_seat_pointer_grab *grab,
  		struct wlr_surface *surface, double sx, double sy) {
  	struct wlr_wl_shell_popup_grab *popup_grab = grab->data;
  	if (wl_resource_get_client(surface->resource) == popup_grab->client) {
  		wlr_seat_pointer_enter(grab->seat, surface, sx, sy);
  	} else {
  		wlr_seat_pointer_clear_focus(grab->seat);
  	}
  }
  
  static void shell_pointer_grab_motion(struct wlr_seat_pointer_grab *grab,
  		uint32_t time, double sx, double sy) {
  	wlr_seat_pointer_send_motion(grab->seat, time, sx, sy);
  }
  
  static uint32_t shell_pointer_grab_button(struct wlr_seat_pointer_grab *grab,
  		uint32_t time, uint32_t button, uint32_t state) {
  	uint32_t serial =
  		wlr_seat_pointer_send_button(grab->seat, time, button, state);
  	if (serial) {
  		return serial;
  	} else {
  		shell_pointer_grab_end(grab);
  		return 0;
  	}
  }
  
  static void shell_pointer_grab_cancel(struct wlr_seat_pointer_grab *grab) {
  	shell_pointer_grab_end(grab);
  }
  
  static void shell_pointer_grab_axis(struct wlr_seat_pointer_grab *grab,
  		uint32_t time, enum wlr_axis_orientation orientation, double value,
  		int32_t value_discrete, enum wlr_axis_source source) {
  	wlr_seat_pointer_send_axis(grab->seat, time, orientation, value,
  		value_discrete, source);
  }
  
  static const struct wlr_pointer_grab_interface shell_pointer_grab_impl = {
  	.enter = shell_pointer_grab_enter,
  	.motion = shell_pointer_grab_motion,
  	.button = shell_pointer_grab_button,
  	.cancel = shell_pointer_grab_cancel,
  	.axis = shell_pointer_grab_axis,
  };
  
  static const struct wl_shell_surface_interface shell_surface_impl;
  
  static struct wlr_wl_shell_surface *shell_surface_from_resource(
  		struct wl_resource *resource) {
  	assert(wl_resource_instance_of(resource, &wl_shell_surface_interface,
  		&shell_surface_impl));
  	return wl_resource_get_user_data(resource);
  }
  
  static void shell_surface_protocol_pong(struct wl_client *client,
  		struct wl_resource *resource, uint32_t serial) {
  	wlr_log(WLR_DEBUG, "got shell surface pong");
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	if (surface->ping_serial != serial) {
  		return;
  	}
  
  	wl_event_source_timer_update(surface->ping_timer, 0);
  	surface->ping_serial = 0;
  }
  
  static void shell_surface_protocol_move(struct wl_client *client,
  		struct wl_resource *resource, struct wl_resource *seat_resource,
  		uint32_t serial) {
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	struct wlr_seat_client *seat = wlr_seat_client_from_resource(seat_resource);
  
  	if (!wlr_seat_validate_grab_serial(seat->seat, serial)) {
  		wlr_log(WLR_DEBUG, "invalid serial for grab");
  		return;
  	}
  
  	struct wlr_wl_shell_surface_move_event event = {
  		.surface = surface,
  		.seat = seat,
  		.serial = serial,
  	};
  
  	wlr_signal_emit_safe(&surface->events.request_move, &event);
  }
  
  static struct wlr_wl_shell_popup_grab *shell_popup_grab_from_seat(
  		struct wlr_wl_shell *shell, struct wlr_seat *seat) {
  	struct wlr_wl_shell_popup_grab *shell_grab;
  	wl_list_for_each(shell_grab, &shell->popup_grabs, link) {
  		if (shell_grab->seat == seat) {
  			return shell_grab;
  		}
  	}
  
  	shell_grab = calloc(1, sizeof(struct wlr_wl_shell_popup_grab));
  	if (!shell_grab) {
  		return NULL;
  	}
  
  	shell_grab->pointer_grab.data = shell_grab;
  	shell_grab->pointer_grab.interface = &shell_pointer_grab_impl;
  
  	wl_list_init(&shell_grab->popups);
  
  	wl_list_insert(&shell->popup_grabs, &shell_grab->link);
  	shell_grab->seat = seat;
  
  	return shell_grab;
  }
  
  static void shell_surface_destroy_popup_state(
  		struct wlr_wl_shell_surface *surface) {
  	if (surface->popup_state) {
  		wl_list_remove(&surface->grab_link);
  		struct wlr_wl_shell_popup_grab *grab =
  			shell_popup_grab_from_seat(surface->shell,
  					surface->popup_state->seat);
  		if (wl_list_empty(&grab->popups)) {
  			if (grab->seat->pointer_state.grab == &grab->pointer_grab) {
  				wlr_seat_pointer_end_grab(grab->seat);
  			}
  		}
  		free(surface->popup_state);
  		surface->popup_state = NULL;
  	}
  }
  
  static void shell_surface_protocol_resize(struct wl_client *client,
  		struct wl_resource *resource, struct wl_resource *seat_resource,
  		uint32_t serial, enum wl_shell_surface_resize edges) {
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	struct wlr_seat_client *seat = wlr_seat_client_from_resource(seat_resource);
  
  	if (!wlr_seat_validate_grab_serial(seat->seat, serial)) {
  		wlr_log(WLR_DEBUG, "invalid serial for grab");
  		return;
  	}
  
  	struct wlr_wl_shell_surface_resize_event event = {
  		.surface = surface,
  		.seat = seat,
  		.serial = serial,
  		.edges = edges,
  	};
  
  	wlr_signal_emit_safe(&surface->events.request_resize, &event);
  }
  
  static void shell_surface_set_state(struct wlr_wl_shell_surface *surface,
  		enum wlr_wl_shell_surface_state state,
  		struct wlr_wl_shell_surface_transient_state *transient_state,
  		struct wlr_wl_shell_surface_popup_state *popup_state) {
  	surface->state = state;
  	free(surface->transient_state);
  	surface->transient_state = transient_state;
  	shell_surface_destroy_popup_state(surface);
  	surface->popup_state = popup_state;
  
  	wlr_signal_emit_safe(&surface->events.set_state, surface);
  }
  
  static void shell_surface_protocol_set_toplevel(struct wl_client *client,
  		struct wl_resource *resource) {
  	wlr_log(WLR_DEBUG, "got shell surface toplevel");
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	shell_surface_set_state(surface, WLR_WL_SHELL_SURFACE_STATE_TOPLEVEL, NULL,
  		NULL);
  }
  
  static void shell_surface_popup_set_parent(struct wlr_wl_shell_surface *surface,
  		struct wlr_wl_shell_surface *parent) {
  	assert(surface && surface->state == WLR_WL_SHELL_SURFACE_STATE_POPUP);
  	if (surface->parent == parent) {
  		return;
  	}
  	surface->parent = parent;
  	if (parent) {
  		wl_list_remove(&surface->popup_link);
  		wl_list_insert(&parent->popups, &surface->popup_link);
  		wlr_signal_emit_safe(&parent->events.new_popup, surface);
  	}
  }
  
  static struct wlr_wl_shell_surface *shell_find_shell_surface(
  		struct wlr_wl_shell *shell, struct wlr_surface *surface) {
  	if (surface) {
  		struct wlr_wl_shell_surface *wl_surface;
  		wl_list_for_each(wl_surface, &shell->surfaces, link) {
  			if (wl_surface->surface == surface) {
  				return wl_surface;
  			}
  		}
  	}
  	return NULL;
  }
  
  static void shell_surface_protocol_set_transient(struct wl_client *client,
  		struct wl_resource *resource, struct wl_resource *parent_resource,
  		int32_t x, int32_t y, enum wl_shell_surface_transient flags) {
  	wlr_log(WLR_DEBUG, "got shell surface transient");
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	struct wlr_surface *parent = wlr_surface_from_resource(parent_resource);
  	// TODO: check if parent_resource == NULL?
  
  	struct wlr_wl_shell_surface *wl_parent =
  		shell_find_shell_surface(surface->shell, parent);
  
  	if (!wl_parent) {
  		return;
  	}
  
  	struct wlr_wl_shell_surface_transient_state *transient_state =
  		calloc(1, sizeof(struct wlr_wl_shell_surface_transient_state));
  	if (transient_state == NULL) {
  		wl_client_post_no_memory(client);
  		return;
  	}
  
  	surface->parent = wl_parent;
  	transient_state->x = x;
  	transient_state->y = y;
  	transient_state->flags = flags;
  
  	shell_surface_set_state(surface, WLR_WL_SHELL_SURFACE_STATE_TRANSIENT,
  		transient_state, NULL);
  }
  
  static void shell_surface_protocol_set_fullscreen(struct wl_client *client,
  		struct wl_resource *resource,
  		enum wl_shell_surface_fullscreen_method method, uint32_t framerate,
  		struct wl_resource *output_resource) {
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	struct wlr_output *output = NULL;
  	if (output_resource != NULL) {
  		output = wlr_output_from_resource(output_resource);
  	}
  
  	shell_surface_set_state(surface, WLR_WL_SHELL_SURFACE_STATE_FULLSCREEN,
  		NULL, NULL);
  
  	struct wlr_wl_shell_surface_set_fullscreen_event event = {
  		.surface = surface,
  		.method = method,
  		.framerate = framerate,
  		.output = output,
  	};
  
  	wlr_signal_emit_safe(&surface->events.request_fullscreen, &event);
  }
  
  static void shell_surface_protocol_set_popup(struct wl_client *client,
  		struct wl_resource *resource, struct wl_resource *seat_resource,
  		uint32_t serial, struct wl_resource *parent_resource, int32_t x,
  		int32_t y, enum wl_shell_surface_transient flags) {
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	struct wlr_seat_client *seat_client =
  		wlr_seat_client_from_resource(seat_resource);
  	struct wlr_surface *parent = wlr_surface_from_resource(parent_resource);
  	struct wlr_wl_shell_popup_grab *grab =
  		shell_popup_grab_from_seat(surface->shell, seat_client->seat);
  	if (!grab) {
  		wl_client_post_no_memory(client);
  		return;
  	}
  
  	struct wlr_wl_shell_surface *wl_parent =
  		shell_find_shell_surface(surface->shell, parent);
  
  	if (surface->state == WLR_WL_SHELL_SURFACE_STATE_POPUP) {
  		surface->transient_state->x = x;
  		surface->transient_state->y = y;
  		shell_surface_popup_set_parent(surface, wl_parent);
  		grab->client = surface->client;
  		surface->popup_mapped = true;
  		wlr_seat_pointer_start_grab(seat_client->seat, &grab->pointer_grab);
  		return;
  	}
  
  	struct wlr_wl_shell_surface_transient_state *transient_state =
  		calloc(1, sizeof(struct wlr_wl_shell_surface_transient_state));
  	if (transient_state == NULL) {
  		wl_client_post_no_memory(client);
  		return;
  	}
  	transient_state->x = x;
  	transient_state->y = y;
  	transient_state->flags = flags;
  
  	struct wlr_wl_shell_surface_popup_state *popup_state =
  		calloc(1, sizeof(struct wlr_wl_shell_surface_popup_state));
  	if (popup_state == NULL) {
  		free(transient_state);
  		wl_client_post_no_memory(client);
  		return;
  	}
  	popup_state->seat = seat_client->seat;
  	popup_state->serial = serial;
  
  	shell_surface_set_state(surface, WLR_WL_SHELL_SURFACE_STATE_POPUP,
  		transient_state, popup_state);
  
  	shell_surface_popup_set_parent(surface, wl_parent);
  	grab->client = surface->client;
  	wl_list_insert(&grab->popups, &surface->grab_link);
  	surface->popup_mapped = true;
  	wlr_seat_pointer_start_grab(seat_client->seat, &grab->pointer_grab);
  }
  
  static void shell_surface_protocol_set_maximized(struct wl_client *client,
  		struct wl_resource *resource, struct wl_resource *output_resource) {
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	struct wlr_output *output = NULL;
  	if (output_resource != NULL) {
  		output = wlr_output_from_resource(output_resource);
  	}
  
  	shell_surface_set_state(surface, WLR_WL_SHELL_SURFACE_STATE_MAXIMIZED,
  		NULL, NULL);
  
  	struct wlr_wl_shell_surface_maximize_event event = {
  		.surface = surface,
  		.output = output,
  	};
  
  	wlr_signal_emit_safe(&surface->events.request_maximize, &event);
  }
  
  static void shell_surface_protocol_set_title(struct wl_client *client,
  		struct wl_resource *resource, const char *title) {
  	wlr_log(WLR_DEBUG, "new shell surface title: %s", title);
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  
  	char *tmp = strdup(title);
  	if (tmp == NULL) {
  		return;
  	}
  
  	free(surface->title);
  	surface->title = tmp;
  
  	wlr_signal_emit_safe(&surface->events.set_title, surface);
  }
  
  static void shell_surface_protocol_set_class(struct wl_client *client,
  		struct wl_resource *resource, const char *class) {
  	wlr_log(WLR_DEBUG, "new shell surface class: %s", class);
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  
  	char *tmp = strdup(class);
  	if (tmp == NULL) {
  		return;
  	}
  
  	free(surface->class);
  	surface->class = tmp;
  
  	wlr_signal_emit_safe(&surface->events.set_class, surface);
  }
  
  static const struct wl_shell_surface_interface shell_surface_impl = {
  	.pong = shell_surface_protocol_pong,
  	.move = shell_surface_protocol_move,
  	.resize = shell_surface_protocol_resize,
  	.set_toplevel = shell_surface_protocol_set_toplevel,
  	.set_transient = shell_surface_protocol_set_transient,
  	.set_fullscreen = shell_surface_protocol_set_fullscreen,
  	.set_popup = shell_surface_protocol_set_popup,
  	.set_maximized = shell_surface_protocol_set_maximized,
  	.set_title = shell_surface_protocol_set_title,
  	.set_class = shell_surface_protocol_set_class,
  };
  
  static void shell_surface_destroy(struct wlr_wl_shell_surface *surface) {
  	wlr_signal_emit_safe(&surface->events.destroy, surface);
  	shell_surface_destroy_popup_state(surface);
  	wl_resource_set_user_data(surface->resource, NULL);
  
  	struct wlr_wl_shell_surface *child;
  	wl_list_for_each(child, &surface->popups, popup_link) {
  		shell_surface_popup_set_parent(child, NULL);
  	}
  	wl_list_remove(&surface->popup_link);
  
  	surface->surface->role_data = NULL;
  	wl_list_remove(&surface->link);
  	wl_list_remove(&surface->surface_destroy.link);
  	wl_event_source_remove(surface->ping_timer);
  	free(surface->transient_state);
  	free(surface->title);
  	free(surface->class);
  	free(surface);
  }
  
  static void shell_surface_resource_destroy(struct wl_resource *resource) {
  	struct wlr_wl_shell_surface *surface = shell_surface_from_resource(resource);
  	if (surface != NULL) {
  		shell_surface_destroy(surface);
  	}
  }
  
  static void shell_surface_handle_surface_destroy(struct wl_listener *listener,
  		void *data) {
  	struct wlr_wl_shell_surface *surface =
  		wl_container_of(listener, surface, surface_destroy);
  	shell_surface_destroy(surface);
  }
  
  static void shell_surface_role_commit(struct wlr_surface *wlr_surface) {
  	struct wlr_wl_shell_surface *surface =
  		wlr_wl_shell_surface_from_wlr_surface(wlr_surface);
  	if (surface == NULL) {
  		return;
  	}
  
  	if (!surface->configured &&
  			wlr_surface_has_buffer(surface->surface) &&
  			surface->state != WLR_WL_SHELL_SURFACE_STATE_NONE) {
  		surface->configured = true;
  		wlr_signal_emit_safe(&surface->shell->events.new_surface, surface);
  	}
  
  	if (surface->popup_mapped &&
  			surface->state == WLR_WL_SHELL_SURFACE_STATE_POPUP &&
  			!wlr_surface_has_buffer(surface->surface)) {
  		surface->popup_mapped = false;
  		struct wlr_wl_shell_popup_grab *grab =
  			shell_popup_grab_from_seat(surface->shell,
  				surface->popup_state->seat);
  		shell_pointer_grab_maybe_end(&grab->pointer_grab);
  	}
  }
  
  static const struct wlr_surface_role shell_surface_role = {
  	.name = "wl_shell_surface",
  	.commit = shell_surface_role_commit,
  };
  
  static int shell_surface_ping_timeout(void *user_data) {
  	struct wlr_wl_shell_surface *surface = user_data;
  	wlr_signal_emit_safe(&surface->events.ping_timeout, surface);
  
  	surface->ping_serial = 0;
  	return 1;
  }
  
  static const struct wl_shell_interface shell_impl;
  
  static struct wlr_wl_shell *shell_from_resource(
  		struct wl_resource *resource) {
  	assert(wl_resource_instance_of(resource, &wl_shell_interface, &shell_impl));
  	return wl_resource_get_user_data(resource);
  }
  
  static void shell_protocol_get_shell_surface(struct wl_client *client,
  		struct wl_resource *shell_resource, uint32_t id,
  		struct wl_resource *surface_resource) {
  	struct wlr_surface *surface = wlr_surface_from_resource(surface_resource);
  
  	struct wlr_wl_shell *wl_shell = shell_from_resource(shell_resource);
  	struct wlr_wl_shell_surface *wl_surface =
  		calloc(1, sizeof(struct wlr_wl_shell_surface));
  	if (wl_surface == NULL) {
  		wl_resource_post_no_memory(shell_resource);
  		return;
  	}
  
  	if (!wlr_surface_set_role(surface, &shell_surface_role, wl_surface,
  			shell_resource, WL_SHELL_ERROR_ROLE)) {
  		free(wl_surface);
  		return;
  	}
  
  	wl_list_init(&wl_surface->grab_link);
  	wl_list_init(&wl_surface->popup_link);
  	wl_list_init(&wl_surface->popups);
  
  	wl_surface->shell = wl_shell;
  	wl_surface->client = client;
  	wl_surface->surface = surface;
  
  	wl_surface->resource = wl_resource_create(client,
  		&wl_shell_surface_interface, wl_resource_get_version(shell_resource),
  		id);
  	if (wl_surface->resource == NULL) {
  		free(wl_surface);
  		wl_resource_post_no_memory(shell_resource);
  		return;
  	}
  	wl_resource_set_implementation(wl_surface->resource,
  		&shell_surface_impl, wl_surface,
  		shell_surface_resource_destroy);
  
  	wlr_log(WLR_DEBUG, "new wl_shell %p (res %p)", wl_surface,
  		wl_surface->resource);
  
  	wl_signal_init(&wl_surface->events.destroy);
  	wl_signal_init(&wl_surface->events.ping_timeout);
  	wl_signal_init(&wl_surface->events.new_popup);
  	wl_signal_init(&wl_surface->events.request_move);
  	wl_signal_init(&wl_surface->events.request_resize);
  	wl_signal_init(&wl_surface->events.request_fullscreen);
  	wl_signal_init(&wl_surface->events.request_maximize);
  	wl_signal_init(&wl_surface->events.set_state);
  	wl_signal_init(&wl_surface->events.set_title);
  	wl_signal_init(&wl_surface->events.set_class);
  
  	wl_signal_add(&wl_surface->surface->events.destroy,
  		&wl_surface->surface_destroy);
  	wl_surface->surface_destroy.notify = shell_surface_handle_surface_destroy;
  
  	struct wl_display *display = wl_client_get_display(client);
  	struct wl_event_loop *loop = wl_display_get_event_loop(display);
  	wl_surface->ping_timer = wl_event_loop_add_timer(loop,
  		shell_surface_ping_timeout, wl_surface);
  	if (wl_surface->ping_timer == NULL) {
  		wl_client_post_no_memory(client);
  	}
  
  	wl_list_insert(&wl_shell->surfaces, &wl_surface->link);
  }
  
  static const struct wl_shell_interface shell_impl = {
  	.get_shell_surface = shell_protocol_get_shell_surface
  };
  
  static void shell_destroy(struct wl_resource *resource) {
  	wl_list_remove(wl_resource_get_link(resource));
  }
  
  static void shell_bind(struct wl_client *wl_client, void *data,
  		uint32_t version, uint32_t id) {
  	struct wlr_wl_shell *wl_shell = data;
  	assert(wl_client && wl_shell);
  
  	struct wl_resource *wl_resource = wl_resource_create(wl_client,
  		&wl_shell_interface, version, id);
  	if (wl_resource == NULL) {
  		wl_client_post_no_memory(wl_client);
  		return;
  	}
  	wl_resource_set_implementation(wl_resource, &shell_impl, wl_shell,
  		shell_destroy);
  	wl_list_insert(&wl_shell->resources, wl_resource_get_link(wl_resource));
  }
  
  static void handle_display_destroy(struct wl_listener *listener, void *data) {
  	struct wlr_wl_shell *wl_shell =
  		wl_container_of(listener, wl_shell, display_destroy);
  	wlr_wl_shell_destroy(wl_shell);
  }
  
  struct wlr_wl_shell *wlr_wl_shell_create(struct wl_display *display) {
  	struct wlr_wl_shell *wl_shell = calloc(1, sizeof(struct wlr_wl_shell));
  	if (!wl_shell) {
  		return NULL;
  	}
  	wl_shell->ping_timeout = 10000;
  	struct wl_global *global = wl_global_create(display, &wl_shell_interface,
  		1, wl_shell, shell_bind);
  	if (!global) {
  		free(wl_shell);
  		return NULL;
  	}
  	wl_shell->global = global;
  	wl_list_init(&wl_shell->resources);
  	wl_list_init(&wl_shell->surfaces);
  	wl_list_init(&wl_shell->popup_grabs);
  	wl_signal_init(&wl_shell->events.new_surface);
  
  	wl_shell->display_destroy.notify = handle_display_destroy;
  	wl_display_add_destroy_listener(display, &wl_shell->display_destroy);
  
  	return wl_shell;
  }
  
  void wlr_wl_shell_destroy(struct wlr_wl_shell *wlr_wl_shell) {
  	if (!wlr_wl_shell) {
  		return;
  	}
  	wl_list_remove(&wlr_wl_shell->display_destroy.link);
  	struct wl_resource *resource = NULL, *temp = NULL;
  	wl_resource_for_each_safe(resource, temp, &wlr_wl_shell->resources) {
  		// shell_destroy will remove the resource from the list
  		wl_resource_destroy(resource);
  	}
  	// TODO: destroy surfaces
  	wl_global_destroy(wlr_wl_shell->global);
  	free(wlr_wl_shell);
  }
  
  void wlr_wl_shell_surface_ping(struct wlr_wl_shell_surface *surface) {
  	if (surface->ping_serial != 0) {
  		// already pinged
  		return;
  	}
  
  	surface->ping_serial =
  		wl_display_next_serial(wl_client_get_display(surface->client));
  	wl_event_source_timer_update(surface->ping_timer,
  		surface->shell->ping_timeout);
  	wl_shell_surface_send_ping(surface->resource, surface->ping_serial);
  }
  
  void wlr_wl_shell_surface_configure(struct wlr_wl_shell_surface *surface,
  		uint32_t edges, int32_t width, int32_t height) {
  	wl_shell_surface_send_configure(surface->resource, edges, width, height);
  }
  
  struct wlr_surface *wlr_wl_shell_surface_surface_at(
  		struct wlr_wl_shell_surface *surface, double sx, double sy,
  		double *sub_sx, double *sub_sy) {
  	struct wlr_wl_shell_surface *popup;
  	wl_list_for_each(popup, &surface->popups, popup_link) {
  		if (!popup->popup_mapped) {
  			continue;
  		}
  
  		double popup_sx = popup->transient_state->x;
  		double popup_sy = popup->transient_state->y;
  		struct wlr_surface *sub = wlr_wl_shell_surface_surface_at(popup,
  			sx - popup_sx, sy - popup_sy, sub_sx, sub_sy);
  		if (sub != NULL) {
  			return sub;
  		}
  	}
  
  	return wlr_surface_surface_at(surface->surface, sx, sy, sub_sx, sub_sy);
  }
  
  struct wl_shell_surface_iterator_data {
  	wlr_surface_iterator_func_t user_iterator;
  	void *user_data;
  	int x, y;
  };
  
  static void wl_shell_surface_iterator(struct wlr_surface *surface,
  		int sx, int sy, void *data) {
  	struct wl_shell_surface_iterator_data *iter_data = data;
  	iter_data->user_iterator(surface, iter_data->x + sx, iter_data->y + sy,
  		iter_data->user_data);
  }
  
  static void wl_shell_surface_for_each_surface(
  		struct wlr_wl_shell_surface *surface, int x, int y,
  		wlr_surface_iterator_func_t iterator, void *user_data) {
  	struct wl_shell_surface_iterator_data data = {
  		.user_iterator = iterator,
  		.user_data = user_data,
  		.x = x, .y = y,
  	};
  	wlr_surface_for_each_surface(surface->surface, wl_shell_surface_iterator,
  		&data);
  
  	struct wlr_wl_shell_surface *popup;
  	wl_list_for_each(popup, &surface->popups, popup_link) {
  		double popup_x = popup->transient_state->x;
  		double popup_y = popup->transient_state->y;
  
  		wl_shell_surface_for_each_surface(popup, x + popup_x, y + popup_y,
  			iterator, user_data);
  	}
  }
  
  void wlr_wl_shell_surface_for_each_surface(struct wlr_wl_shell_surface *surface,
  		wlr_surface_iterator_func_t iterator, void *user_data) {
  	wl_shell_surface_for_each_surface(surface, 0, 0, iterator, user_data);
  }
  