package sarama

import (
	"crypto/rand"
	"log"
	"testing"
)

func assertPartitioningConsistent(t *testing.T, partitioner Partitioner, message *ProducerMessage, numPartitions int32) {
	choice, err := partitioner.Partition(message, numPartitions)
	if err != nil {
		t.Error(partitioner, err)
	}
	if choice < 0 || choice >= numPartitions {
		t.Error(partitioner, "returned partition", choice, "outside of range for", message)
	}
	for i := 1; i < 50; i++ {
		newChoice, err := partitioner.Partition(message, numPartitions)
		if err != nil {
			t.Error(partitioner, err)
		}
		if newChoice != choice {
			t.Error(partitioner, "returned partition", newChoice, "inconsistent with", choice, ".")
		}
	}
}

func TestRandomPartitioner(t *testing.T) {
	partitioner := NewRandomPartitioner("mytopic")

	choice, err := partitioner.Partition(nil, 1)
	if err != nil {
		t.Error(partitioner, err)
	}
	if choice != 0 {
		t.Error("Returned non-zero partition when only one available.")
	}

	for i := 1; i < 50; i++ {
		choice, err := partitioner.Partition(nil, 50)
		if err != nil {
			t.Error(partitioner, err)
		}
		if choice < 0 || choice >= 50 {
			t.Error("Returned partition", choice, "outside of range.")
		}
	}
}

func TestRoundRobinPartitioner(t *testing.T) {
	partitioner := NewRoundRobinPartitioner("mytopic")

	choice, err := partitioner.Partition(nil, 1)
	if err != nil {
		t.Error(partitioner, err)
	}
	if choice != 0 {
		t.Error("Returned non-zero partition when only one available.")
	}

	var i int32
	for i = 1; i < 50; i++ {
		choice, err := partitioner.Partition(nil, 7)
		if err != nil {
			t.Error(partitioner, err)
		}
		if choice != i%7 {
			t.Error("Returned partition", choice, "expecting", i%7)
		}
	}
}

func TestHashPartitioner(t *testing.T) {
	partitioner := NewHashPartitioner("mytopic")

	choice, err := partitioner.Partition(&ProducerMessage{}, 1)
	if err != nil {
		t.Error(partitioner, err)
	}
	if choice != 0 {
		t.Error("Returned non-zero partition when only one available.")
	}

	for i := 1; i < 50; i++ {
		choice, err := partitioner.Partition(&ProducerMessage{}, 50)
		if err != nil {
			t.Error(partitioner, err)
		}
		if choice < 0 || choice >= 50 {
			t.Error("Returned partition", choice, "outside of range for nil key.")
		}
	}

	buf := make([]byte, 256)
	for i := 1; i < 50; i++ {
		if _, err := rand.Read(buf); err != nil {
			t.Error(err)
		}
		assertPartitioningConsistent(t, partitioner, &ProducerMessage{Key: ByteEncoder(buf)}, 50)
	}
}

func TestManualPartitioner(t *testing.T) {
	partitioner := NewManualPartitioner("mytopic")

	choice, err := partitioner.Partition(&ProducerMessage{}, 1)
	if err != nil {
		t.Error(partitioner, err)
	}
	if choice != 0 {
		t.Error("Returned non-zero partition when only one available.")
	}

	for i := int32(1); i < 50; i++ {
		choice, err := partitioner.Partition(&ProducerMessage{Partition: i}, 50)
		if err != nil {
			t.Error(partitioner, err)
		}
		if choice != i {
			t.Error("Returned partition not the same as the input partition")
		}
	}
}

// By default, Sarama uses the message's key to consistently assign a partition to
// a message using hashing. If no key is set, a random partition will be chosen.
// This example shows how you can partition messages randomly, even when a key is set,
// by overriding Config.Producer.Partitioner.
func ExamplePartitioner_random() {
	config := NewConfig()
	config.Producer.Partitioner = NewRandomPartitioner

	producer, err := NewSyncProducer([]string{"localhost:9092"}, config)
	if err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err := producer.Close(); err != nil {
			log.Println("Failed to close producer:", err)
		}
	}()

	msg := &ProducerMessage{Topic: "test", Key: StringEncoder("key is set"), Value: StringEncoder("test")}
	partition, offset, err := producer.SendMessage(msg)
	if err != nil {
		log.Fatalln("Failed to produce message to kafka cluster.")
	}

	log.Printf("Produced message to partition %d with offset %d", partition, offset)
}

// This example shows how to assign partitions to your messages manually.
func ExamplePartitioner_manual() {
	config := NewConfig()

	// First, we tell the producer that we are going to partition ourselves.
	config.Producer.Partitioner = NewManualPartitioner

	producer, err := NewSyncProducer([]string{"localhost:9092"}, config)
	if err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err := producer.Close(); err != nil {
			log.Println("Failed to close producer:", err)
		}
	}()

	// Now, we set the Partition field of the ProducerMessage struct.
	msg := &ProducerMessage{Topic: "test", Partition: 6, Value: StringEncoder("test")}

	partition, offset, err := producer.SendMessage(msg)
	if err != nil {
		log.Fatalln("Failed to produce message to kafka cluster.")
	}

	if partition != 6 {
		log.Fatal("Message should have been produced to partition 6!")
	}

	log.Printf("Produced message to partition %d with offset %d", partition, offset)
}

// This example shows how to set a different partitioner depending on the topic.
func ExamplePartitioner_per_topic() {
	config := NewConfig()
	config.Producer.Partitioner = func(topic string) Partitioner {
		switch topic {
		case "access_log", "error_log":
			return NewRandomPartitioner(topic)

		default:
			return NewHashPartitioner(topic)
		}
	}

	// ...
}