Implement rename workspace command

This implements the following commands:

* rename workspace to new_name
* rename workspace old_name to new_name
* rename workspace number n to new_name

4 files changed, 81 insertions, 0 deletions

diff --git a/include/sway/commands.h b/include/sway/commands.h
index 7b8c949b..75534163 100644
--- a/include/sway/commands.h
+++ b/include/sway/commands.h
@@ -131,6 +131,7 @@ sway_cmd cmd_output;
 sway_cmd cmd_permit;
 sway_cmd cmd_reject;
 sway_cmd cmd_reload;
+sway_cmd cmd_rename;
 sway_cmd cmd_resize;
 sway_cmd cmd_scratchpad;
 sway_cmd cmd_seamless_mouse;
diff --git a/sway/commands.c b/sway/commands.c
index 2115bd8c..6af3c5d0 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -167,6 +167,7 @@ static struct cmd_handler command_handlers[] = {
         { "move", cmd_move },
         { "opacity", cmd_opacity },
         { "reload", cmd_reload },
+        { "rename", cmd_rename },
         { "resize", cmd_resize },
         { "split", cmd_split },
         { "splith", cmd_splith },
diff --git a/sway/commands/rename.c b/sway/commands/rename.c
new file mode 100644
index 00000000..4be912a9
--- /dev/null
+++ b/sway/commands/rename.c
@@ -0,0 +1,78 @@
+#define _XOPEN_SOURCE 500
+#include <string.h>
+#include <strings.h>
+#include "log.h"
+#include "stringop.h"
+#include "sway/commands.h"
+#include "sway/config.h"
+#include "sway/ipc-server.h"
+#include "sway/tree/container.h"
+#include "sway/tree/workspace.h"
+
+static const char* expected_syntax =
+        "Expected 'rename workspace <old_name> to <new_name>' or "
+        "'rename workspace to <new_name>'";
+
+struct cmd_results *cmd_rename(int argc, char **argv) {
+        struct cmd_results *error = NULL;
+        if ((error = checkarg(argc, "rename", EXPECTED_AT_LEAST, 3))) {
+                return error;
+        }
+        if (strcasecmp(argv[0], "workspace") != 0) {
+                return cmd_results_new(CMD_INVALID, "rename", expected_syntax);
+        }
+
+        int argn = 1;
+        struct sway_container *workspace;
+
+        if (strcasecmp(argv[1], "to") == 0) {
+                // 'rename workspace to new_name'
+                workspace = config->handler_context.current_container;
+                if (workspace->type != C_WORKSPACE) {
+                        workspace = container_parent(workspace, C_WORKSPACE);
+                }
+        } else if (strcasecmp(argv[1], "number") == 0) {
+                // 'rename workspace number x to new_name'
+                workspace = workspace_by_number(argv[2]);
+                while (argn < argc && strcasecmp(argv[argn], "to") != 0) {
+                        ++argn;
+                }
+        } else {
+                // 'rename workspace old_name to new_name'
+                int end = argn;
+                while (end < argc && strcasecmp(argv[end], "to") != 0) {
+                        ++end;
+                }
+                char *old_name = join_args(argv + argn, end - argn);
+                workspace = workspace_by_name(old_name);
+                free(old_name);
+                argn = end;
+        }
+
+        if (!workspace) {
+                return cmd_results_new(CMD_INVALID, "rename",
+                                "There is no workspace with that name");
+        }
+
+        ++argn; // move past "to"
+
+        if (argn >= argc) {
+                return cmd_results_new(CMD_INVALID, "rename", expected_syntax);
+        }
+
+        char *new_name = join_args(argv + argn, argc - argn);
+        struct sway_container *tmp_workspace = workspace_by_name(new_name);
+        if (tmp_workspace) {
+                free(new_name);
+                return cmd_results_new(CMD_INVALID, "rename",
+                                "Workspace already exists");
+        }
+
+        wlr_log(L_DEBUG, "renaming workspace '%s' to '%s'", workspace->name, new_name);
+        free(workspace->name);
+        workspace->name = new_name;
+
+        ipc_event_workspace(NULL, workspace, "rename");
+
+        return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}
diff --git a/sway/meson.build b/sway/meson.build
index 67dbe3dd..f3c319ed 100644
--- a/sway/meson.build
+++ b/sway/meson.build
@@ -45,6 +45,7 @@ sway_sources = files(
         'commands/move.c',
         'commands/output.c',
         'commands/reload.c',
+        'commands/rename.c',
         'commands/resize.c',
         'commands/seat.c',
         'commands/seat/attach.c',