Use command line parser

examples/admin_list_consumer_groups/admin_list_consumer_groups.go

@@ -19,71 +19,62 @@ package main
 
 import (
 	"context"
+	"flag"
 	"fmt"
 	"os"
+	"strings"
 	"time"
 
 	"github.com/confluentinc/confluent-kafka-go/v2/kafka"
 )
 
-func usage(message string) {
+func usage(message string, fs *flag.FlagSet) {
 	if message != "" {
 		fmt.Fprintf(os.Stderr,
 			message)
 	}
-	fmt.Fprintf(os.Stderr,
-		"Usage: %s <bootstrap-servers> [-states <state1> <state2> ...] [-types <type1> <type2> ...] \n", os.Args[0])
+	fs.Usage()
 	os.Exit(1)
 }
 
-func parseListConsumerGroupsArgs() (states []kafka.ConsumerGroupState, types []kafka.ConsumerGroupType) {
-	if len(os.Args) > 2 {
-		args := os.Args[2:]
-		stateArray := false
-		typeArray := false
-		lastArray := 0
-		for _, arg := range args {
-			if arg == "-states" {
-				if stateArray {
-					usage("Cannot pass the states flag (-states) more than once.\n")
-				}
-				lastArray = 1
-				stateArray = true
-			} else if arg == "-types" {
-				if typeArray {
-					usage("Cannot pass the types flag (-types) more than once.\n")
-				}
-				lastArray = 2
-				typeArray = true
-			} else {
-				if lastArray == 1 {
-					state, _ := kafka.ConsumerGroupStateFromString(arg)
-					if state == kafka.ConsumerGroupStateUnknown {
-						usage(fmt.Sprintf("Given state %s is not a valid state\n", arg))
-					}
-					states = append(states, state)
-				} else if lastArray == 2 {
-					groupType := kafka.ConsumerGroupTypeFromString(arg)
-					if groupType == kafka.ConsumerGroupTypeUnknown {
-						usage(fmt.Sprintf("Given type %s is not a valid type\n", arg))
-					}
-					types = append(types, groupType)
-				} else {
-					usage(fmt.Sprintf("Unknown argument: %s\n", arg))
-				}
+func parseListConsumerGroupsArgs() (
+	bootstrapServers string,
+	states []kafka.ConsumerGroupState,
+	types []kafka.ConsumerGroupType,
+) {
+	var statesString, typesString string
+	fs := flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+	fs.StringVar(&bootstrapServers, "b", "localhost:9092", "Bootstrap servers")
+	fs.StringVar(&statesString, "states", "", "States to match")
+	fs.StringVar(&typesString, "types", "", "Types to match")
+	fs.Parse(os.Args[1:])
+
+	if statesString != "" {
+		for _, stateString := range strings.Split(statesString, ",") {
+			state, _ := kafka.ConsumerGroupStateFromString(stateString)
+			if state == kafka.ConsumerGroupStateUnknown {
+				usage(fmt.Sprintf("Given state %s is not a valid state\n",
+					stateString), fs)
 			}
+			states = append(states, state)
+		}
+	}
+	if typesString != "" {
+		for _, typeString := range strings.Split(typesString, ",") {
+			groupType := kafka.ConsumerGroupTypeFromString(typeString)
+			if groupType == kafka.ConsumerGroupTypeUnknown {
+				usage(fmt.Sprintf("Given type %s is not a valid type\n",
+					typeString), fs)
+			}
+			types = append(types, groupType)
 		}
 	}
 	return
 }
 
 func main() {
 
-	if len(os.Args) < 2 {
-		usage("")
-	}
-	bootstrapServers := os.Args[1]
-	states, types := parseListConsumerGroupsArgs()
+	bootstrapServers, states, types := parseListConsumerGroupsArgs()
 
 	// Create a new AdminClient.
 	a, err := kafka.NewAdminClient(&kafka.ConfigMap{"bootstrap.servers": bootstrapServers})