syntax = "proto3";

package milvus.proto.streaming;

option go_package = "github.com/milvus-io/milvus/internal/proto/streamingpb";

import "milvus.proto";
import "google/protobuf/empty.proto";

//
// Common
//

// MessageID is the unique identifier of a message.
message MessageID {
    bytes id = 1;
}

// Message is the basic unit of communication between publisher and consumer.
message Message {
    bytes payload = 1;                   // message body
    map<string, string> properties = 2;  // message properties
}

// PChannelInfo is the information of a pchannel info, should only keep the basic info of a pchannel.
// It's used in many rpc and meta, so keep it simple.
message PChannelInfo {
    string name = 1;  // channel name
    int64 term =
        2;  // A monotonic increasing term, every time the channel is recovered or moved to another streamingnode, the term will increase by meta server.
}

// PChannelMetaHistory is the history meta information of a pchannel, should only keep the data that is necessary to persistent.
message PChannelMetaHistory {
    int64 term = 1;  // term when server assigned.
    StreamingNodeInfo node =
        2;  // streaming node that the channel is assigned to.
}

// PChannelMetaState
enum PChannelMetaState {
    PCHANNEL_META_STATE_UNKNOWN = 0;  // should never used.
    PCHANNEL_META_STATE_UNINITIALIZED =
        1;  // channel is uninitialized, never assgined to any streaming node.
    PCHANNEL_META_STATE_ASSIGNING =
        2;  // new term is allocated, but not determined to be assgined.
    PCHANNEL_META_STATE_ASSIGNED =
        3;  // channel is assigned to a streaming node.
    PCHANNEL_META_STATE_UNAVAILABLE =
        4;  // channel is unavailable at this term.
}

// PChannelMeta is the meta information of a pchannel, should only keep the data that is necessary to persistent.
// It's only used in meta, so do not use it in rpc.
message PChannelMeta {
    PChannelInfo channel = 1;    // keep the meta info that current assigned to.
    StreamingNodeInfo node = 2;  // nil if channel is not uninitialized.
    PChannelMetaState state = 3;  // state of the channel.
    repeated PChannelMetaHistory histories =
        4;  // keep the meta info history that used to be assigned to.
}

// VersionPair is the version pair of global and local.
message VersionPair {
    int64 global = 1;
    int64 local = 2;
}

//
// Milvus Service
//

service StreamingCoordStateService {
    rpc GetComponentStates(milvus.GetComponentStatesRequest)
        returns (milvus.ComponentStates) {
    }
}

service StreamingNodeStateService {
    rpc GetComponentStates(milvus.GetComponentStatesRequest)
        returns (milvus.ComponentStates) {
    }
}

//
// StreamingCoordAssignmentService
//

// StreamingCoordAssignmentService is the global log management service.
// Server: log coord. Running on every log node.
// Client: all log publish/consuming node.
service StreamingCoordAssignmentService {
    // AssignmentDiscover is used to discover all log nodes managed by the streamingcoord.
    // Channel assignment information will be pushed to client by stream.
    rpc AssignmentDiscover(stream AssignmentDiscoverRequest)
        returns (stream AssignmentDiscoverResponse) {
    }
}

// AssignmentDiscoverRequest is the request of Discovery
message AssignmentDiscoverRequest {
    oneof command {
        ReportAssignmentErrorRequest report_error =
            1;  // report streaming error, trigger reassign right now.
        CloseAssignmentDiscoverRequest close = 2;  // close the stream.
    }
}

// ReportAssignmentErrorRequest is the request to report assignment error happens.
message ReportAssignmentErrorRequest {
    PChannelInfo pchannel = 1;  // channel
    StreamingError err = 2;     // error happend on log node
}

// CloseAssignmentDiscoverRequest is the request to close the stream.
message CloseAssignmentDiscoverRequest {
}

// AssignmentDiscoverResponse is the response of Discovery
message AssignmentDiscoverResponse {
    oneof response {
        FullStreamingNodeAssignmentWithVersion full_assignment =
            1;  // all assignment info.
        // TODO: may be support partial assignment info in future.
        CloseAssignmentDiscoverResponse close = 2;
    }
}

// FullStreamingNodeAssignmentWithVersion is the full assignment info of a log node with version.
message FullStreamingNodeAssignmentWithVersion {
    VersionPair version = 1;
    repeated StreamingNodeAssignment assignments = 2;
}

message CloseAssignmentDiscoverResponse {
}

// StreamingNodeInfo is the information of a streaming node.
message StreamingNodeInfo {
    int64 server_id = 1;
    string address = 2;
}

// StreamingNodeAssignment is the assignment info of a streaming node.
message StreamingNodeAssignment {
    StreamingNodeInfo node = 1;
    repeated PChannelInfo channels = 2;
}

// DeliverPolicy is the policy to deliver message.
message DeliverPolicy {
    oneof policy {
        google.protobuf.Empty all = 1;     // deliver all messages.
        google.protobuf.Empty latest = 2;  // deliver the latest message.
        MessageID start_from =
            3;  // deliver message from this message id. [startFrom, ...]
        MessageID start_after =
            4;  // deliver message after this message id. (startAfter, ...]
    }
}

// DeliverFilter is the filter to deliver message.
message DeliverFilter {
    oneof filter {
        DeliverFilterTimeTickGT time_tick_gt = 1;
        DeliverFilterTimeTickGTE time_tick_gte = 2;
        DeliverFilterVChannel vchannel = 3;
    }
}

// DeliverFilterTimeTickGT is the filter to deliver message with time tick greater than this value.
message DeliverFilterTimeTickGT {
    uint64 time_tick =
        1;  // deliver message with time tick greater than this value.
}

// DeliverFilterTimeTickGTE is the filter to deliver message with time tick greater than or equal to this value.
message DeliverFilterTimeTickGTE {
    uint64 time_tick =
        1;  // deliver message with time tick greater than or equal to this value.
}

// DeliverFilterVChannel is the filter to deliver message with vchannel name.
message DeliverFilterVChannel {
    string vchannel = 1;  // deliver message with vchannel name.
}

// StreamingCode is the error code for log internal component.
enum StreamingCode {
    STREAMING_CODE_OK = 0;
    STREAMING_CODE_CHANNEL_EXIST = 1;           // channel already exist
    STREAMING_CODE_CHANNEL_NOT_EXIST = 2;       // channel not exist
    STREAMING_CODE_CHANNEL_FENCED = 3;          // channel is fenced
    STREAMING_CODE_ON_SHUTDOWN = 4;             // component is on shutdown
    STREAMING_CODE_INVALID_REQUEST_SEQ = 5;     // invalid request sequence
    STREAMING_CODE_UNMATCHED_CHANNEL_TERM = 6;  // unmatched channel term
    STREAMING_CODE_IGNORED_OPERATION = 7;       // ignored operation
    STREAMING_CODE_INNER = 8;                   // underlying service failure.
    STREAMING_CODE_EOF = 9;  // end of stream, generated by grpc status.
    STREAMING_CODE_INVAILD_ARGUMENT = 10;  // invalid argument
    STREAMING_CODE_UNKNOWN = 999;          // unknown error
}

// StreamingError is the error type for log internal component.
message StreamingError {
    StreamingCode code = 1;
    string cause = 2;
}

//
// StreamingNodeHandlerService
//

// StreamingNodeHandlerService is the service to handle log messages.
// All handler operation will be blocked until the channel is ready read or write on that log node.
// Server: all log node. Running on every log node.
// Client: all log produce or consuming node.
service StreamingNodeHandlerService {
    // Produce is a bi-directional streaming RPC to send messages to a channel.
    // All messages sent to a channel will be assigned a unique messageID.
    // The messageID is used to identify the message in the channel.
    // The messageID isn't promised to be monotonous increasing with the sequence of responsing.
    // Error:
    // If channel isn't assign to this log node, the RPC will return error CHANNEL_NOT_EXIST.
    // If channel is moving away to other log node, the RPC will return error CHANNEL_FENCED.
    rpc Produce(stream ProduceRequest) returns (stream ProduceResponse) {
    };

    // Consume is a server streaming RPC to receive messages from a channel.
    // All message after given startMessageID and excluding will be sent to the client by stream.
    // If no more message in the channel, the stream will be blocked until new message coming.
    // Error:
    // If channel isn't assign to this log node, the RPC will return error CHANNEL_NOT_EXIST.
    // If channel is moving away to other log node, the RPC will return error CHANNEL_FENCED.
    rpc Consume(stream ConsumeRequest) returns (stream ConsumeResponse) {
    };
}

// ProduceRequest is the request of the Produce RPC.
// Channel name will be passthrough in the header of stream bu not in the request body.
message ProduceRequest {
    oneof request {
        ProduceMessageRequest produce = 2;
        CloseProducerRequest close = 3;
    }
}

// CreateProducerRequest is the request of the CreateProducer RPC.
// CreateProducerRequest is passed in the header of stream.
message CreateProducerRequest {
    PChannelInfo pchannel = 1;
}

// ProduceMessageRequest is the request of the Produce RPC.
message ProduceMessageRequest {
    int64 request_id = 1;  // request id for reply.
    Message message = 2;   // message to be sent.
}

// CloseProducerRequest is the request of the CloseProducer RPC.
// After CloseProducerRequest is requested, no more ProduceRequest can be sent.
message CloseProducerRequest {
}

// ProduceResponse is the response of the Produce RPC.
message ProduceResponse {
    oneof response {
        CreateProducerResponse create = 1;
        ProduceMessageResponse produce = 2;
        CloseProducerResponse close = 3;
    }
}

// CreateProducerResponse is the result of the CreateProducer RPC.
message CreateProducerResponse {
    int64 producer_id =
        1;  // A unique producer id on streamingnode for this producer in streamingnode lifetime.
    // Is used to identify the producer in streamingnode for other unary grpc call at producer level.
}

message ProduceMessageResponse {
    int64 request_id = 1;
    oneof response {
        ProduceMessageResponseResult result = 2;
        StreamingError error = 3;
    }
}

// ProduceMessageResponseResult is the result of the produce message streaming RPC.
message ProduceMessageResponseResult {
    MessageID id = 1;  // the offset of the message in the channel
}

// CloseProducerResponse is the result of the CloseProducer RPC.
message CloseProducerResponse {
}

// ConsumeRequest is the request of the Consume RPC.
// Add more control block in future.
message ConsumeRequest {
    oneof request {
        CloseConsumerRequest close = 1;
    }
}

// CloseConsumerRequest is the request of the CloseConsumer RPC.
// After CloseConsumerRequest is requested, no more ConsumeRequest can be sent.
message CloseConsumerRequest {
}

// CreateConsumerRequest is the request of the CreateConsumer RPC.
// CreateConsumerRequest is passed in the header of stream.
message CreateConsumerRequest {
    PChannelInfo pchannel = 1;
    DeliverPolicy deliver_policy = 2;            // deliver policy.
    repeated DeliverFilter deliver_filters = 3;  // deliver filter.
}

// ConsumeResponse is the reponse of the Consume RPC.
message ConsumeResponse {
    oneof response {
        CreateConsumerResponse create = 1;
        ConsumeMessageReponse consume = 2;
        CloseConsumerResponse close = 3;
    }
}

message CreateConsumerResponse {
}

message ConsumeMessageReponse {
    MessageID id = 1;     // message id of message.
    Message message = 2;  // message to be consumed.
}

message CloseConsumerResponse {
}

//
// StreamingNodeManagerService
//

// StreamingNodeManagerService is the log manage operation on log node.
// Server: all log node. Running on every log node.
// Client: log coord. There should be only one client globally to call this service on all streamingnode.
service StreamingNodeManagerService {
    // Assign is a unary RPC to assign a channel on a log node.
    // Block until the channel assignd is ready to read or write on the log node.
    // Error:
    // If the channel already exists, return error with code CHANNEL_EXIST.
    rpc Assign(StreamingNodeManagerAssignRequest)
        returns (StreamingNodeManagerAssignResponse) {
    };

    // Remove is unary RPC to remove a channel on a log node.
    // Data of the channel on flying would be sent or flused as much as possible.
    // Block until the resource of channel is released on the log node.
    // New incoming request of handler of this channel will be rejected with special error.
    // Error:
    // If the channel does not exist, return error with code CHANNEL_NOT_EXIST.
    rpc Remove(StreamingNodeManagerRemoveRequest)
        returns (StreamingNodeManagerRemoveResponse) {
    };

    // rpc CollectStatus() ...
    // CollectStatus is unary RPC to collect all avaliable channel info and load balance info on a log node.
    // Used to recover channel info on log coord, collect balance info and health check.
    rpc CollectStatus(StreamingNodeManagerCollectStatusRequest)
        returns (StreamingNodeManagerCollectStatusResponse) {
    };
}

// StreamingManagerAssignRequest is the request message of Assign RPC.
message StreamingNodeManagerAssignRequest {
    PChannelInfo pchannel = 1;
}

message StreamingNodeManagerAssignResponse {
}

message StreamingNodeManagerRemoveRequest {
    PChannelInfo pchannel = 1;
}

message StreamingNodeManagerRemoveResponse {
}

message StreamingNodeManagerCollectStatusRequest {
}

message StreamingNodeBalanceAttributes {
    // TODO: traffic of pchannel or other things.
}

message StreamingNodeManagerCollectStatusResponse {
    StreamingNodeBalanceAttributes balance_attributes = 1;
}