kafka

type Consumer interface {
	// Name returns the name of this consumer group.
	Name() string
	// Topics returns the names of the topics being consumed.
	Topics() ConsumerTopicList
	// Start starts the consumer
	Start() error
	// Stop stops the consumer
	Stop()
	// Closed returns a channel which will be closed after this consumer is completely shutdown
	Closed() <-chan struct{}
	// Messages return the message channel for this consumer
	Messages() <-chan Message
	// MergeDLQ consumes the offset ranges for the partitions from the DLQ topic for the specified ConsumerTopic
	// Topic should be the __dlq topic name.
	MergeDLQ(cluster, group, topic string, partition int32, offsetRange OffsetRange) error
}

type ConsumerConfig struct {
	// GroupName identifies your consumer group. Unless your application creates
	// multiple consumer groups (in which case it's suggested to have application name as
	// prefix of the group name), this should match your application name.
	GroupName string

	// TopicList is a list of consumer topics
	TopicList ConsumerTopicList

	// OffsetConfig is the offset-handling policy for this consumer group.
	Offsets struct {
		// Initial specifies the fallback offset configuration on consumer start.
		// The consumer will use the offsets persisted from its last run unless \
		// the offsets are too old or too new.
		Initial struct {
			// Offset is the initial offset to use if there is no previous offset
			// committed. Use OffsetNewest for high watermark and OffsetOldest for
			// low watermark. Defaults to OffsetOldest.
			Offset int64
		}

		// Commits a policy for committing consumer offsets to Kafka.
		Commits struct {
			// Enabled if you want the library to commit offsets on your behalf.
			// Defaults to true.
			//
			// The retry and dlq topic commit will always be committed for you since those topics are abstracted away from you.
			Enabled bool
		}
	}

	// Concurrency determines the number of concurrent messages to process.
	// When using the handler based API, this corresponds to the number of concurrent go
	// routines handler functions the library will run. Default is 1.
	Concurrency int

	// TLSConfig is the configuration to use for secure connections if
	// enabled (not nil) (defaults to disabled, nil).
	TLSConfig *tls.Config

	// SASLConfig is the configuration to use for SASL based auth
	SASLConfig *SASLConfig
}

type ConsumerTopic struct {
	Topic
	RetryQ     Topic
	DLQ        Topic
	MaxRetries int64 // MaxRetries = -1 for infinite retries.
}

type ConsumerTopicList []ConsumerTopic

type Message interface {
	zapcore.ObjectMarshaler

	// Key is a mutable reference to the message's key.
	Key() []byte
	// Value is a mutable reference to the message's value.
	Value() []byte
	// Topic is the topic from which the message was read.
	Topic() string
	// Partition is the ID of the partition from which the message was read.
	Partition() int32
	// Offset is the message's offset.
	Offset() int64
	// Timestamp returns the timestamp for this message
	Timestamp() time.Time
	// RetryCount is an incrementing integer denoting the number of times this message has been redelivered.
	// The first delivery of the message will be 0, incrementing on each subsequent redelivery.
	RetryCount() int64
	// Ack marks the message as successfully processed.
	Ack() error
	// Nack marks the message processing as failed and the message will be retried or sent to DLQ.
	Nack() error
	// NackToDLQ marks the message processing as failed and sends it immediately to DLQ.
	NackToDLQ() error
}

type NameResolver interface {
	// ResolveCluster returns a list of IP addresses for the brokers
	ResolveIPForCluster(cluster string) ([]string, error)
	// ResolveClusterForTopic returns the logical cluster names corresponding to a topic name
	//
	// It is possible for a topic to exist on multiple clusters in order to
	// transparently handle topic migration between clusters.
	// TODO (gteo): Remove to simplify API because not needed anymore
	ResolveClusterForTopic(topic string) ([]string, error)
}

type OffsetRange struct {
	// LowOffset is the low watermark for this offset range.
	// -1 indicates the value is not set.
	LowOffset int64
	// HighOffset is the high watermark for this offset range.
	// -1 indicates the value is not set.
	HighOffset int64
}

type SASLConfig struct {
	Enable    bool   `yaml:"enable"`
	User      string `yaml:"username"`
	Password  string `yaml:"password"`
	Mechanism string `yaml:"mechanism"`
}

type Topic struct {
	// Name for the topic
	Name string
	// Cluster is the logical name of the cluster to find this topic on.
	Cluster string
	// Delay is msg consumption delay applied on the topic.
	Delay time.Duration
}