basic focus (without direction)

sway/commands.c

@@ -132,6 +132,7 @@ static struct cmd_handler handlers[] = {
 	{ "exec", cmd_exec },
 	{ "exec_always", cmd_exec_always },
 	{ "exit", cmd_exit },
+	{ "focus", cmd_focus },
 	{ "include", cmd_include },
 	{ "input", cmd_input },
 	{ "kill", cmd_kill },

sway/commands/focus.c

@@ -0,0 +1,32 @@
+#include <wlr/util/log.h>
+#include "log.h"
+#include "sway/input/input-manager.h"
+#include "sway/input/seat.h"
+#include "sway/view.h"
+#include "sway/commands.h"
+
+struct cmd_results *cmd_focus(int argc, char **argv) {
+	swayc_t *con = config->handler_context.current_container;
+	struct sway_seat *seat = config->handler_context.seat;
+
+	if (!sway_assert(seat, "'focus' command called without seat context")) {
+		return cmd_results_new(CMD_FAILURE, "focus",
+			"Command 'focus' called without seat context (this is a bug in sway)");
+	}
+
+	if (config->reading) {
+		return cmd_results_new(CMD_FAILURE, "focus",
+			"Command 'focus' cannot be used in the config file");
+	}
+	if (con == NULL) {
+		wlr_log(L_DEBUG, "no container to focus");
+		return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+	}
+
+	if (argc == 0) {
+		sway_seat_set_focus(seat, con);
+		return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+	}
+
+	return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}

sway/ipc-server.c

@@ -336,6 +336,7 @@ void ipc_client_handle_command(struct ipc_client *client) {
 	case IPC_COMMAND:
 	{
 		config_clear_handler_context(config);
+		config->handler_context.seat = input_manager_current_seat(input_manager);
 		struct cmd_results *results = handle_command(buf);
 		const char *json = cmd_results_to_json(results);
 		char reply[256];

sway/meson.build

@@ -10,6 +10,7 @@ sway_sources = files(
 	'commands/exit.c',
 	'commands/exec.c',
 	'commands/exec_always.c',
+	'commands/focus.c',
 	'commands/kill.c',
 	'commands/include.c',
 	'commands/input.c',