Keep a detached head in the branch switcher

1 file changed, 41 insertions, 0 deletions

diff --git a/source/ui-shared.c b/source/ui-shared.c
index cd822a0..85712bf 100644
--- a/source/ui-shared.c
+++ b/source/ui-shared.c
@@ -408,6 +408,45 @@ struct branch_option_data {
 	const char *selected;
 };
 
+/*
+ * Whether the head the request follows is one of the branches the switcher
+ * lists, remote ones included when those are shown. A head that is not, a
+ * raw commit id or a tag, would otherwise leave the select resting on the
+ * first branch, and submitting the form would quietly move the visitor there.
+ */
+static int head_is_listed_branch(void)
+{
+	struct ref_store *refs = get_main_ref_store(the_repository);
+	struct strbuf ref = STRBUF_INIT;
+	int found;
+
+	strbuf_addf(&ref, "refs/heads/%s", ctx.qry.head);
+	found = refs_ref_exists(refs, ref.buf);
+	if (!found && ctx.repo->enable_remote_branches) {
+		strbuf_reset(&ref);
+		strbuf_addf(&ref, "refs/remotes/%s", ctx.qry.head);
+		found = refs_ref_exists(refs, ref.buf);
+	}
+	strbuf_release(&ref);
+	return found;
+}
+
+static void print_detached_head_option(void)
+{
+	const char *head = ctx.qry.head;
+	struct object_id oid;
+	struct strbuf label = STRBUF_INIT;
+
+	// A head that is a full id reads better cut to the length the pinned
+	// entry uses.
+	if (strlen(head) == the_hash_algo->hexsz && !get_oid_hex(head, &oid))
+		strbuf_addf(&label, "%.*s (detached)", SHORT_HASH_LEN, head);
+	else
+		strbuf_addf(&label, "%s (detached)", head);
+	html_option(head, label.buf, head);
+	strbuf_release(&label);
+}
+
 static int print_branch_option(const struct reference *ref, void *data)
 {
 	struct branch_option_data *opt = data;
@@ -478,6 +517,8 @@ static void print_header(void)
 
 			html_option(hex, cgit_fmt("%.*s (detached)",
 						  SHORT_HASH_LEN, hex), hex);
+		} else if (!head_is_listed_branch()) {
+			print_detached_head_option();
 		}
 		refs_for_each_branch_ref(get_main_ref_store(the_repository),
 					 print_branch_option, &opt);