Capture completion hints in command metadata

completion.go

@@ -0,0 +1,55 @@
+package commandkit
+
+import commandmeta "gitea.maximumdirect.net/eric/CommandKit/internal/commandmeta"
+
+// CompletionChoice is a literal suggested value and its optional description.
+type CompletionChoice struct {
+	Value       string
+	Description string
+}
+
+// CompletionHint selects suggestions for a flag or positional value. Its zero
+// value requests no value suggestions; hints do not constrain accepted input.
+type CompletionHint struct {
+	kind    completionHintKind
+	choices []CompletionChoice
+}
+
+type completionHintKind uint8
+
+const (
+	completionNone completionHintKind = iota
+	completionChoices
+	completionFiles
+	completionDirectories
+)
+
+// CompleteChoices suggests literal values. The supplied slice is copied.
+func CompleteChoices(choices ...CompletionChoice) CompletionHint {
+	return CompletionHint{kind: completionChoices, choices: append([]CompletionChoice(nil), choices...)}
+}
+
+// CompleteFiles requests shell filename completion.
+func CompleteFiles() CompletionHint { return CompletionHint{kind: completionFiles} }
+
+// CompleteDirectories requests shell directory completion.
+func CompleteDirectories() CompletionHint { return CompletionHint{kind: completionDirectories} }
+
+// NoCompletion requests no value suggestions.
+func NoCompletion() CompletionHint { return CompletionHint{} }
+
+func bridgeCompletion(hint CompletionHint) commandmeta.CompletionHint {
+	result := commandmeta.CompletionHint{}
+	switch hint.kind {
+	case completionChoices:
+		result.Kind = commandmeta.CompletionChoices
+		for _, choice := range hint.choices {
+			result.Choices = append(result.Choices, commandmeta.CompletionChoice{Value: choice.Value, Description: choice.Description})
+		}
+	case completionFiles:
+		result.Kind = commandmeta.CompletionFiles
+	case completionDirectories:
+		result.Kind = commandmeta.CompletionDirectories
+	}
+	return result
+}