Compose discovery help through group aliases

help_view.go

@@ -17,7 +17,7 @@ func (a *App) helpView(route routeResult, snapshot *routingSnapshot) commandmeta
 		return view
 	}
 	if view.Discovery {
-		view.CommandAliases = discoveryHelpAliases(snapshot.commandAliases, route.discoveryPath)
+		view.CommandAliases = discoveryHelpAliases(snapshot, route)
 		view.FlagAliases = snapshot.discoveryFlags[route.discoveryPath.Key()].neutralRecords()
 		return view
 	}
@@ -30,17 +30,31 @@ func clonePath(path commandpath.Path) []string {
 	return append([]string(nil), path...)
 }
 
-func discoveryHelpAliases(aliases []commandmeta.CommandAlias, prefix commandpath.Path) []commandmeta.CommandAlias {
-	var result []commandmeta.CommandAlias
-	for _, alias := range aliases {
-		source := commandpath.FromTokens(alias.Source)
-		if len(source) <= len(prefix) || !source.HasPrefix(prefix) {
-			continue
+func discoveryHelpAliases(snapshot *routingSnapshot, route routeResult) []commandmeta.CommandAlias {
+	bySource := make(map[string]commandmeta.CommandAlias)
+	for _, prefix := range []commandpath.Path{route.enteredPath, route.discoveryPath} {
+		for _, alias := range snapshot.commandAliases {
+			source := commandpath.FromTokens(alias.Source)
+			if len(source) <= len(prefix) || !source.HasPrefix(prefix) {
+				continue
+			}
+			suffix := source[len(prefix):]
+			entered := append(route.enteredPath.Clone(), suffix...)
+			target := snapshot.aliases.Resolve(entered)
+			if traceCanonicalPath(snapshot.canonical, target).exact == nil {
+				continue
+			}
+			bySource[suffix.Key()] = commandmeta.CommandAlias{Source: clonePath(suffix), Target: clonePath(target)}
 		}
-		result = append(result, commandmeta.CommandAlias{
-			Source: clonePath(source[len(prefix):]),
-			Target: append([]string(nil), alias.Target...),
-		})
+	}
+	keys := make([]string, 0, len(bySource))
+	for key := range bySource {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	result := make([]commandmeta.CommandAlias, 0, len(keys))
+	for _, key := range keys {
+		result = append(result, bySource[key])
 	}
 	return result
 }