Create printer pkg, fix color force enable/disable

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

internal/printer/printer.go

@@ -0,0 +1,42 @@
+package printer
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/fatih/color"
+)
+
+var (
+	errorColor   = color.New(color.FgRed, color.Bold)
+	warningColor = color.New(color.FgYellow, color.Bold)
+	successColor = color.New(color.FgGreen)
+)
+
+func init() {
+	colors := UseColors()
+	if colors == nil {
+		return
+	}
+	if *colors {
+		errorColor.EnableColor()
+		warningColor.EnableColor()
+		successColor.EnableColor()
+	} else {
+		errorColor.DisableColor()
+		warningColor.DisableColor()
+		successColor.DisableColor()
+	}
+}
+
+func Error(w io.Writer, format string, args ...interface{}) {
+	fmt.Fprintf(w, color.RedString("error: ")+format+"\n", args...)
+}
+
+func Warning(w io.Writer, format string, args ...interface{}) {
+	fmt.Fprintf(w, color.YellowString("warning: ")+format+"\n", args...)
+}
+
+func Success(w io.Writer, format string, args ...interface{}) {
+	fmt.Fprintf(w, color.GreenString(fmt.Sprintf(format+"\n", args...)))
+}