feat(cmd/cup): support json output for cup config context

cmd/cup/config.go

@@ -18,22 +18,35 @@ func configCommand() *cli.Command {
 				return err
 			}
 
-			wr := writer()
-			fmt.Fprintln(wr, "NAME\tADDRESS\tNAMESPACE\tCURRENT\t")
-			for name, ctx := range cfg.Contexts {
+			type namedContext struct {
+				*config.Context
+				Name string `json:"name"`
+			}
+
+			enc, err := encoder(cfg, func(c *namedContext) [][]string {
 				var current string
-				if name == cfg.CurrentContext {
+				if c.Name == cfg.CurrentContext {
 					current = "*"
 				}
 
 				namespace := "default"
-				if ctx.Namespace != "" {
-					namespace = ctx.Namespace
+				if c.Namespace != "" {
+					namespace = c.Namespace
 				}
 
-				fmt.Fprintf(wr, "%s\t%s\t%s\t%s\t\n", name, ctx.Address, namespace, current)
+				return [][]string{{c.Name, c.Address, namespace, current}}
+			}, "NAME", "ADDRESS", "NAMESPACE", "CURRENT")
+			if err != nil {
+				return err
+			}
+
+			for name, ctx := range cfg.Contexts {
+				if err := enc.Encode(&namedContext{Name: name, Context: ctx}); err != nil {
+					return err
+				}
 			}
-			return wr.Flush()
+
+			return enc.Flush()
 		},
 		Subcommands: []*cli.Command{
 			{

cmd/cup/ctl.go

@@ -324,7 +324,7 @@ type tableEncoding[T any] struct {
 type rowsFn[T any] func(*T) [][]string
 
 func newTableEncoding[T any](rowFn rowsFn[T], headers ...string) *tableEncoding[T] {
-	return &tableEncoding[T]{Writer: writer(), rowFn: rowFn, headers: headers}
+	return &tableEncoding[T]{Writer: tabwriter.NewWriter(os.Stdout, 0, 0, 3, ' ', 0), rowFn: rowFn, headers: headers}
 }
 
 func (e *tableEncoding[T]) Encode(t *T) error {
@@ -431,7 +431,3 @@ func getDefintions(cfg config.Config, client *http.Client) (map[string]*core.Res
 
 	return definitions, nil
 }
-
-func writer() *tabwriter.Writer {
-	return tabwriter.NewWriter(os.Stdout, 0, 0, 3, ' ', 0)
-}