-color more similar to grep

cmd/circolog-tail/main.go

@@ -20,6 +20,39 @@ import (
 	"gopkg.in/mgo.v2/bson"
 )
 
+type BoolAuto uint
+
+const (
+	BoolAuto_NO   BoolAuto = iota
+	BoolAuto_YES  BoolAuto = iota
+	BoolAuto_AUTO BoolAuto = iota
+)
+
+func (b *BoolAuto) String() string {
+	switch *b {
+	case BoolAuto_NO:
+		return "no"
+	case BoolAuto_YES:
+		return "always"
+	case BoolAuto_AUTO:
+		return "auto"
+	}
+	return ""
+}
+func (b *BoolAuto) Set(s string) error {
+	switch s {
+	case "auto":
+		*b = BoolAuto_AUTO
+	case "always":
+		*b = BoolAuto_YES
+	case "no":
+		*b = BoolAuto_NO
+	default:
+		return fmt.Errorf("Invalid value %s", s)
+	}
+	return nil
+}
+
 func main() {
 	addr := flag.String("addr", "localhost:9080", "http service address")
 	querySocket := flag.String("socket", "", "Path to a unix domain socket for the HTTP server")
@@ -27,17 +60,11 @@ func main() {
 	var filter filtering.ExprValue
 	flag.Var(&filter, "where", "sql-like query to filter logs")
 	// TODO: change to color-mode=auto/no/always
-	noColor := flag.Bool("no-color", false, "disable colors")
+	hasColor := BoolAuto_AUTO
-	forceColor := flag.Bool("force-color", false, "force colors even on TTY")
+	flag.Var(&hasColor, "color", "dis/enable colors")
 	flag.Parse()
 
-	if *noColor && *forceColor {
+	if hasColor == BoolAuto_NO || (!isatty.IsTerminal(os.Stdout.Fd()) && hasColor != BoolAuto_YES) {
-		fmt.Fprintln(os.Stderr, "Can't use both -no-color and -force-color")
-		flag.Usage()
-		os.Exit(2)
-	}
-
-	if *noColor || (!isatty.IsTerminal(os.Stdout.Fd()) && !*forceColor) {
 		ansi.DisableColors(true)
 	}