From 29dba445b4e6d762e80e1bd015a70cb362a7906e Mon Sep 17 00:00:00 2001
From: Christian Hopps <chopps@labn.net>
Date: Fri, 1 Mar 2024 08:48:47 -0500
Subject: [PATCH] lib: add automatic xpath-based completion

Signed-off-by: Christian Hopps <chopps@labn.net>
---
 lib/command.c | 22 ++++++++++++++++++++--
 lib/command.h |  1 +
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/lib/command.c b/lib/command.c
index fa260721dcb2..0288ab75995b 100644
--- a/lib/command.c
+++ b/lib/command.c
@@ -678,6 +678,21 @@ vector cmd_describe_command(vector vline, struct vty *vty, int *status)
 
 static struct list *varhandlers = NULL;
 
+static int __add_key_comp(const struct lyd_node *dnode, void *arg)
+{
+	const char *key_value = yang_dnode_get_string(dnode, NULL);
+
+	vector_set((vector)arg, XSTRDUP(MTYPE_COMPLETION, key_value));
+
+	return YANG_ITER_CONTINUE;
+}
+
+static void __get_list_keys(vector comps, const char *xpath)
+{
+	yang_dnode_iterate(__add_key_comp, comps,
+			   vty_shared_candidate_config->dnode, "%s", xpath);
+}
+
 void cmd_variable_complete(struct cmd_token *token, const char *arg,
 			   vector comps)
 {
@@ -694,7 +709,10 @@ void cmd_variable_complete(struct cmd_token *token, const char *arg,
 		if (cvh->varname && (!token->varname
 				     || strcmp(cvh->varname, token->varname)))
 			continue;
-		cvh->completions(tmpcomps, token);
+		if (cvh->xpath)
+			__get_list_keys(tmpcomps, cvh->xpath);
+		if (cvh->completions)
+			cvh->completions(tmpcomps, token);
 		break;
 	}
 
@@ -753,7 +771,7 @@ void cmd_variable_handler_register(const struct cmd_variable_handler *cvh)
 	if (!varhandlers)
 		return;
 
-	for (; cvh->completions; cvh++)
+	for (; cvh->completions || cvh->xpath; cvh++)
 		listnode_add(varhandlers, (void *)cvh);
 }
 
diff --git a/lib/command.h b/lib/command.h
index 04c66adb2688..ef1815c0bd51 100644
--- a/lib/command.h
+++ b/lib/command.h
@@ -636,6 +636,7 @@ extern void cmd_banner_motd_line(const char *line);
 
 struct cmd_variable_handler {
 	const char *tokenname, *varname;
+	const char *xpath;	/* fill comps from set of values at xpath */
 	void (*completions)(vector out, struct cmd_token *token);
 };