Add the rev_labels template formatter

acmed/src/template.rs

@@ -1,12 +1,73 @@
 use acme_common::error::Error;
 use serde::Serialize;
+use serde_json::Value;
 use tinytemplate::TinyTemplate;
 
+macro_rules! default_format {
+    ($value: ident, $output: ident) => {{
+        $output.push_str(&$value.to_string());
+        Ok(())
+    }};
+}
+
+fn formatter_rev_labels(value: &Value, output: &mut String) -> tinytemplate::error::Result<()> {
+    match value {
+        Value::Null => Ok(()),
+        Value::Bool(v) => default_format!(v, output),
+        Value::Number(v) => default_format!(v, output),
+        Value::String(v) => {
+            let s = v.rsplit(".").collect::<Vec<&str>>().join(".");
+            output.push_str(&s);
+            Ok(())
+        }
+        _ => Ok(()),
+    }
+}
+
 pub fn render_template<T>(template: &str, data: &T) -> Result<String, Error>
 where
     T: Serialize,
 {
     let mut reg = TinyTemplate::new();
+    reg.add_formatter("rev_labels", formatter_rev_labels);
     reg.add_template("reg", template)?;
     Ok(reg.render("reg", data)?)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::render_template;
+    use serde::Serialize;
+
+    #[derive(Serialize)]
+    struct TplTest {
+        foo: String,
+        bar: u64,
+    }
+
+    #[test]
+    fn test_basic_template() {
+        let c = TplTest {
+            foo: String::from("test"),
+            bar: 42,
+        };
+        let tpl = "This is { foo } { bar -} !";
+        let rendered = render_template(tpl, &c);
+        assert!(rendered.is_ok());
+        let rendered = rendered.unwrap();
+        assert_eq!(rendered, "This is test 42!");
+    }
+
+    #[test]
+    fn test_formatter_rev_labels() {
+        let c = TplTest {
+            foo: String::from("mx1.example.org"),
+            bar: 42,
+        };
+        let tpl = "{ foo } - { foo | rev_labels }";
+        let rendered = render_template(tpl, &c);
+        assert!(rendered.is_ok());
+        let rendered = rendered.unwrap();
+        assert_eq!(rendered, "mx1.example.org - org.example.mx1");
+    }
+}

man/en/acmed.toml.5

@@ -669,6 +669,16 @@ For example,
 and
 .Dq 40s20h4h2s
 both represents a period of one day and forty-two seconds.
+.Sh TEMPLATE FORMATTERS
+In addition the the formatters provided by default by TinyTemplate, ACMEd provides the following formatters:
+.Bl -tag
+.It Pa rev_labels
+Reverts the labels of a domain name (eg:
+.Dq mx1.example.org
+becomes
+.Dq org.example.mx1
+).
+.El
 .Sh FILES
 .Bl -tag
 .It Pa /var/lib/acmed/accounts