package notify

const (
	recordStreamMetadataCapBatchAckKey  = "_notify.record_cap_batch_ack"
	recordStreamMetadataUseBatchAckKey  = "_notify.record_use_batch_ack"
	recordStreamMetadataCapHalfCloseKey = "_notify.record_cap_half_close"
	recordStreamMetadataUseHalfCloseKey = "_notify.record_use_half_close"
	recordStreamMetadataEnabledValue    = "1"
)

func advertiseRecordStreamOpenMetadata(metadata StreamMetadata) StreamMetadata {
	metadata = cloneStreamMetadata(metadata)
	if metadata == nil {
		metadata = make(StreamMetadata, 1)
	}
	delete(metadata, recordStreamMetadataUseHalfCloseKey)
	metadata[recordStreamMetadataCapBatchAckKey] = recordStreamMetadataEnabledValue
	metadata[recordStreamMetadataCapHalfCloseKey] = recordStreamMetadataEnabledValue
	return metadata
}

func negotiateRecordStreamOpenMetadata(channel StreamChannel, metadata StreamMetadata) (StreamMetadata, StreamMetadata) {
	metadata = cloneStreamMetadata(metadata)
	if normalizeStreamChannel(channel) != StreamRecordChannel {
		return metadata, nil
	}
	response := make(StreamMetadata)
	if metadata[recordStreamMetadataCapBatchAckKey] == recordStreamMetadataEnabledValue {
		metadata[recordStreamMetadataUseBatchAckKey] = recordStreamMetadataEnabledValue
		response[recordStreamMetadataUseBatchAckKey] = recordStreamMetadataEnabledValue
	}
	delete(metadata, recordStreamMetadataUseHalfCloseKey)
	if metadata[recordStreamMetadataCapHalfCloseKey] == recordStreamMetadataEnabledValue {
		metadata[recordStreamMetadataUseHalfCloseKey] = recordStreamMetadataEnabledValue
		response[recordStreamMetadataUseHalfCloseKey] = recordStreamMetadataEnabledValue
	}
	return metadata, response
}

func mergeStreamMetadata(base StreamMetadata, overlay StreamMetadata) StreamMetadata {
	if len(base) == 0 && len(overlay) == 0 {
		return nil
	}
	merged := cloneStreamMetadata(base)
	if merged == nil {
		merged = make(StreamMetadata, len(overlay))
	}
	for key, value := range overlay {
		merged[key] = value
	}
	return merged
}

func recordStreamUseBatchAck(metadata StreamMetadata) bool {
	return metadata[recordStreamMetadataUseBatchAckKey] == recordStreamMetadataEnabledValue
}

func recordStreamUseHalfClose(metadata StreamMetadata) bool {
	return metadata[recordStreamMetadataUseHalfCloseKey] == recordStreamMetadataEnabledValue
}