/*
Package types provides access to the types and constants that the Kafka protocol uses,
since they are needed by all levels of the saramago stack.
*/
package types

// KError is the type of error that can be returned directly by the Kafka broker.
// See https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-ErrorCodes
type KError int16

const (
	NO_ERROR                    KError = 0
	UNKNOWN                     KError = -1
	OFFSET_OUT_OF_RANGE         KError = 1
	INVALID_MESSAGE             KError = 2
	UNKNOWN_TOPIC_OR_PARTITION  KError = 3
	INVALID_MESSAGE_SIZE        KError = 4
	LEADER_NOT_AVAILABLE        KError = 5
	NOT_LEADER_FOR_PARTITION    KError = 6
	REQUEST_TIMED_OUT           KError = 7
	BROKER_NOT_AVAILABLE        KError = 8
	REPLICA_NOT_AVAILABLE       KError = 9
	MESSAGE_SIZE_TOO_LARGE      KError = 10
	STALE_CONTROLLER_EPOCH_CODE KError = 11
	OFFSET_METADATA_TOO_LARGE   KError = 12
)

func (err KError) Error() string {
	// Error messages stolen/adapted from
	// https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol
	switch err {
	case NO_ERROR:
		return "kafka server: Not an error, why are you printing me?"
	case UNKNOWN:
		return "kafka server: Unexpected (unknown?) server error."
	case OFFSET_OUT_OF_RANGE:
		return "kafka server: The requested offset is outside the range of offsets maintained by the server for the given topic/partition."
	case INVALID_MESSAGE:
		return "kafka server: Message contents does not match its CRC."
	case UNKNOWN_TOPIC_OR_PARTITION:
		return "kafka server: Request was for a topic or partition that does not exist on this broker."
	case INVALID_MESSAGE_SIZE:
		return "kafka server: The message has a negative size."
	case LEADER_NOT_AVAILABLE:
		return "kafka server: In the middle of a leadership election, there is currently no leader for this partition and hence it is unavailable for writes."
	case NOT_LEADER_FOR_PARTITION:
		return "kafka server: Tried to send a message to a replica that is not the leader for some partition. Your metadata is out of date."
	case REQUEST_TIMED_OUT:
		return "kafka server: Request exceeded the user-specified time limit in the request."
	case BROKER_NOT_AVAILABLE:
		return "kafka server: Broker not available. Not a client facing error, we should never receive this!!!"
	case REPLICA_NOT_AVAILABLE:
		return "kafka server: Replica not available. What is the difference between this and LeaderNotAvailable?"
	case MESSAGE_SIZE_TOO_LARGE:
		return "kafka server: Message was too large, server rejected it to avoid allocation error."
	case STALE_CONTROLLER_EPOCH_CODE:
		return "kafka server: Stale controller epoch code. ???"
	case OFFSET_METADATA_TOO_LARGE:
		return "kafka server: Specified a string larger than the configured maximum for offset metadata."
	default:
		return "Unknown error, how did this happen?"
	}
}

// CompressionCodec represents the various compression codecs recognized by Kafka in messages.
type CompressionCodec int8

const (
	COMPRESSION_NONE   CompressionCodec = 0
	COMPRESSION_GZIP   CompressionCodec = 1
	COMPRESSION_SNAPPY CompressionCodec = 2
)

// RequiredAcks is used in Produce Requests to tell the broker how many replica acknowledgements
// it must see before responding. Any positive int16 value is valid, or the constants defined here.
type RequiredAcks int16

const (
	NO_RESPONSE    RequiredAcks = 0  // Don't send any response, the TCP ACK is all you get.
	WAIT_FOR_LOCAL RequiredAcks = 1  // Wait for only the local commit to succeed before responding.
	WAIT_FOR_ALL   RequiredAcks = -1 // Wait for all replicas to commit before responding.
)

// OffsetTime is used in Offset Requests to ask for all messages before a certain time. Any positive int64
// value will be interpreted as milliseconds, or use the special constants defined here.
type OffsetTime int64

const (
	// Ask for the latest offsets.
	LATEST_OFFSETS OffsetTime = -1
	// Ask for the earliest available offset. Note that because offsets are pulled in descending order,
	// asking for the earliest offset will always return you a single element.
	EARLIEST_OFFSET OffsetTime = -2
)