From df50aaee6c6ef4b51638fe22317e28234ffe8acc Mon Sep 17 00:00:00 2001
From: Trygve Laugstøl <trygvis@inamo.no>
Date: Wed, 7 Feb 2024 19:12:07 +0100
Subject: wip

---
 consumer.go | 74 ++++++++++++++++++++++++++++++++++++++++++-------------------
 producer.go |  1 -
 2 files changed, 51 insertions(+), 24 deletions(-)

diff --git a/consumer.go b/consumer.go
index b9c1b45..4047c4e 100644
--- a/consumer.go
+++ b/consumer.go
@@ -4,10 +4,10 @@ import (
 	"fmt"
 	"github.com/confluentinc/confluent-kafka-go/v2/kafka"
 	"kafka-sandbox/util"
+	"log"
 	"os"
 	"os/signal"
 	"syscall"
-	"time"
 )
 
 func main() {
@@ -23,23 +23,11 @@ func main() {
 	conf["auto.offset.reset"] = "earliest"
 
 	c, err := kafka.NewConsumer(&conf)
-
 	if err != nil {
 		fmt.Printf("Failed to create consumer: %s", err)
 		os.Exit(1)
 	}
 
-	partitions, err := c.Assignment()
-	if err != nil {
-		fmt.Printf("Failed to get assignments: %s", err)
-		os.Exit(1)
-	}
-
-	fmt.Printf("Consuming %d partitions: \n", len(partitions))
-	for i, partition := range partitions {
-		fmt.Printf(" #%d: %s\n", i+1, partition.String())
-	}
-
 	topic := "purchases"
 	err = c.SubscribeTopics([]string{topic}, nil)
 	// Set up a channel for handling Ctrl-C, etc
@@ -54,20 +42,60 @@ func main() {
 			fmt.Printf("Caught signal %v: terminating\n", sig)
 			run = false
 		default:
-			ev, err := c.ReadMessage(100 * time.Millisecond)
-			if err != nil {
-				// Errors are informational and automatically handled by the consumer
+			ev := c.Poll(100)
+			if ev == nil {
 				continue
 			}
-			fmt.Printf("%s %s %s: %+v, key = %-10s value = %s\n",
-				ev.TimestampType.String(),
-				ev.Timestamp.String(),
-				*ev.TopicPartition.Topic,
-				ev.Headers,
-				string(ev.Key),
-				string(ev.Value))
+
+			switch e := ev.(type) {
+			case *kafka.Message:
+				if e.TopicPartition.Error != nil {
+					onTopicPartitionError(e)
+				} else {
+					onMessage(e)
+				}
+			case kafka.OffsetsCommitted:
+				log.Println("Offsets committed")
+				for i, offset := range e.Offsets {
+					log.Printf(" %d: %s\n", i, offset.String())
+				}
+			case kafka.Error:
+				log.Fatalln(e)
+			default:
+				log.Printf("Unhandled message type: %s\n", e.String())
+			}
 		}
 	}
 
 	c.Close()
 }
+
+func onMessage(ev *kafka.Message) {
+	fmt.Printf("-------- %s\n", ev.TopicPartition.String())
+	fmt.Printf("%s %s: %s\n",
+		ev.TimestampType.String(),
+		ev.Timestamp.String(),
+		string(ev.Key))
+	for _, header := range ev.Headers {
+		fmt.Printf("%s: %s\n", header.Key, string(header.Value))
+	}
+	fmt.Printf("%s\n", string(ev.Value))
+}
+
+func onTopicPartitionError(e *kafka.Message) {
+	fmt.Printf("Partition error: %s\n", e.TopicPartition.String())
+}
+
+func showAssignment(err error, c *kafka.Consumer) error {
+	partitions, err := c.Assignment()
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("Consuming %d partitions: \n", len(partitions))
+	for i, partition := range partitions {
+		fmt.Printf(" #%d: %s\n", i+1, partition.String())
+	}
+
+	return nil
+}
diff --git a/producer.go b/producer.go
index f5392ae..2eb33d1 100644
--- a/producer.go
+++ b/producer.go
@@ -21,7 +21,6 @@ func main() {
 
 	topic := "purchases"
 	p, err := kafka.NewProducer(&conf)
-
 	if err != nil {
 		fmt.Printf("Failed to create producer: %s", err)
 		os.Exit(1)
-- 
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