handle inverse alias polarity

Author: apiraino

src/config.rs

@@ -265,9 +265,9 @@ impl RelabelConfig {
             // parse all tokens: if one matches an alias, extract the labels
             // else, it will assumed to be a valid label
             for tk in input.0.into_iter() {
-                let name = tk.label().as_str();
+                let name = tk.label() as &str;
                 if let Some(alias) = self.aliases.get(name) {
-                    let cmd = alias.to_command();
+                    let cmd = alias.to_command(matches!(tk, LabelDelta::Remove(_)));
                     deltas.extend(cmd.0);
                 } else {
                     deltas.push(tk);
@@ -290,12 +290,20 @@ pub(crate) struct RelabelAliasConfig {
 
 impl RelabelAliasConfig {
     /// Translate a RelabelAliasConfig into a RelabelCommand for GitHub consumption
-    pub fn to_command(&self) -> RelabelCommand {
+    pub fn to_command(&self, inverted: bool) -> RelabelCommand {
         let mut deltas = Vec::new();
-        for l in self.add_labels.iter() {
+        let mut add_labels = &self.add_labels;
+        let mut rem_labels = &self.rem_labels;
+
+        // if the polarity of the alias is inverted, swap labels before parsing the command
+        if inverted {
+            std::mem::swap(&mut add_labels, &mut rem_labels);
+        }
+
+        for l in add_labels.iter() {
             deltas.push(LabelDelta::Add(Label(l.into())));
         }
-        for l in self.rem_labels.iter() {
+        for l in rem_labels.iter() {
             deltas.push(LabelDelta::Remove(Label(l.into())));
         }
         RelabelCommand(deltas)
@@ -1145,9 +1153,9 @@ mod tests {
         assert_eq!(
             new_input,
             RelabelCommand(vec![
-                LabelDelta::Remove(Label("Alpha".into())),
                 LabelDelta::Add(Label("Bravo".into())),
                 LabelDelta::Add(Label("Charlie".into())),
+                LabelDelta::Remove(Label("Alpha".into())),
             ])
         );
     }