Update color options to enum (#45)

cmd/flags.go

@@ -1,19 +1,33 @@
 package cmd
 
 import (
+	"os"
+
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"github.com/svix/svix-cli/pretty"
+	"github.com/svix/svix-cli/utils"
 	svix "github.com/svix/svix-libs/go"
 )
 
 func getPrinterOptions(cmd *cobra.Command) *pretty.PrinterOptions {
-	colorFlag := viper.GetBool("color")
-	if !colorFlag {
-		return nil
+	colorFlag := viper.GetString("color")
+	color := false
+	switch colorFlag {
+	case "always":
+		color = true
+	case "never":
+		color = false
+	default:
+		isTTY, _, err := utils.IsTTY(os.Stdout)
+		if err == nil {
+			// just defaults to false if an error occurs
+			color = isTTY
+		}
 	}
+
 	return &pretty.PrinterOptions{
-		Color: true,
+		Color: color,
 	}
 }
 

cmd/root.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"flag"
 	"fmt"
 	"net/url"
 	"os"
@@ -10,7 +11,7 @@ import (
 	"github.com/spf13/viper"
 
 	"github.com/svix/svix-cli/config"
-	"github.com/svix/svix-cli/utils"
+	"github.com/svix/svix-cli/flags"
 	"github.com/svix/svix-cli/version"
 	svix "github.com/svix/svix-libs/go"
 )
@@ -36,9 +37,10 @@ func init() {
 	rootCmd.Flags().BoolP("version", "v", false, "Get the version of the Svix CLI") // overrides default msg
 
 	// Global Flags
-	isTTY, _, err := utils.IsTTY(os.Stdout)
-	cobra.CheckErr(err)
-	rootCmd.PersistentFlags().Bool("color", isTTY, "colorize output json")              // on by default if TTY, off if not
+	color := "auto"
+	colorFlag := flags.NewEnum(&color, "auto", "always", "never")
+	flag.Var(colorFlag, "color", "auto|always|never")
+	rootCmd.PersistentFlags().AddGoFlag(flag.Lookup("color"))
 	cobra.CheckErr(viper.BindPFlag("color", rootCmd.PersistentFlags().Lookup("color"))) // allow color flag to be set in config
 
 	// Register Commands

flags/enum.go

@@ -0,0 +1,27 @@
+package flags
+
+import "fmt"
+
+type enum struct {
+	target  *string
+	options []string
+}
+
+func NewEnum(target *string, options ...string) *enum {
+	return &enum{target: target, options: options}
+}
+
+func (f *enum) String() string {
+	return *f.target
+}
+
+func (f *enum) Set(value string) error {
+	for _, v := range f.options {
+		if v == value {
+			*f.target = value
+			return nil
+		}
+	}
+
+	return fmt.Errorf("expected one of the following %q", f.options)
+}