Add JSON output format for CLI commands

internal/cli/format.go

@@ -0,0 +1,22 @@
+package cli
+
+import (
+	"flag"
+	"fmt"
+	"io"
+
+	"gitea.maximumdirect.net/eric/distributor/internal/app"
+)
+
+func addFormatFlag(flags *flag.FlagSet) *string {
+	return flags.String("format", string(app.OutputFormatText), "output format: text or json")
+}
+
+func parseOutputFormat(stderr io.Writer, command, raw string) (app.OutputFormat, bool) {
+	format := app.OutputFormat(raw)
+	if err := app.ValidateOutputFormat(format); err != nil {
+		fmt.Fprintf(stderr, "%s: %s --format: %s\n", app.Name, command, err)
+		return "", false
+	}
+	return app.NormalizeOutputFormat(format), true
+}