refactor: extract core logic to a plain Go package

commands/render.go

@@ -0,0 +1,52 @@
+package commands
+
+import (
+	"encoding"
+	"encoding/json"
+	"io"
+
+	"gopkg.in/yaml.v3"
+)
+
+func render(w io.Writer, format string, v interface{}) error {
+	if format == "yaml" || format == "yml" {
+		return renderYAML(w, v)
+	}
+
+	if format == "json" {
+		return renderJSON(w, v)
+	}
+
+	if wt, ok := v.(io.WriterTo); ok {
+		_, err := wt.WriteTo(w)
+
+		return err
+	}
+
+	if tm, ok := v.(encoding.TextMarshaler); ok {
+		b, err := tm.MarshalText()
+		if err != nil {
+			return err
+		}
+
+		_, err = w.Write(b)
+
+		return err
+	}
+
+	return renderYAML(w, v)
+}
+
+func renderYAML(w io.Writer, v interface{}) error {
+	enc := yaml.NewEncoder(w)
+	enc.SetIndent(2)
+
+	return enc.Encode(v)
+}
+
+func renderJSON(w io.Writer, v interface{}) error {
+	enc := json.NewEncoder(w)
+	enc.SetIndent("", "  ")
+
+	return enc.Encode(v)
+}