/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

option java_package = "org.apache.hedwig.protocol";
option optimize_for = SPEED;
package Hedwig; 

enum ProtocolVersion{
    VERSION_ONE = 1;
}

// common structure to store header or properties
message Map {
    message Entry {
        optional string key  = 1;
        optional bytes value = 2;
    }
    repeated Entry entries = 1;
}

// message header
message MessageHeader {
    // user customized fields used for message filter
    optional Map properties = 1;
    // following are system properties in message header
    optional string messageType = 2;
}

/*
 * this is the structure that will be serialized
 */
message Message {
    required bytes body = 1;
    optional bytes srcRegion = 2;
    optional MessageSeqId msgId = 3;
    // message header
    optional MessageHeader header = 4;
}

message RegionSpecificSeqId {
    required bytes region = 1;
    required uint64 seqId = 2;
}
    
message MessageSeqId{
    optional uint64 localComponent = 1;
    repeated RegionSpecificSeqId remoteComponents = 2;    
}

enum OperationType{
    PUBLISH = 0;
    SUBSCRIBE = 1;
    CONSUME = 2;
    UNSUBSCRIBE = 3;
    
    //the following two are only used for the hedwig proxy
    START_DELIVERY = 4;
    STOP_DELIVERY = 5;
    // end for requests only used for hedwig proxy

    CLOSESUBSCRIPTION = 6;
}

/* A PubSubRequest is just a union of the various request types, with
 * an enum telling us which type it is. The same can also be done through 
 * extensions. We need one request type that we will deserialize into on 
 * the server side.
 */
message PubSubRequest{
    
    required ProtocolVersion protocolVersion = 1;
    required OperationType type = 2;
    repeated bytes triedServers = 3;
    required uint64 txnId = 4;
    optional bool shouldClaim = 5;
    required bytes topic = 6;
    //any authentication stuff and other general stuff here
    
    
    /* one entry for each type of request */
    optional PublishRequest publishRequest = 52; 
    optional SubscribeRequest subscribeRequest = 53;
    optional ConsumeRequest consumeRequest = 54;
    optional UnsubscribeRequest unsubscribeRequest = 55;
    optional StopDeliveryRequest stopDeliveryRequest = 56;
    optional StartDeliveryRequest startDeliveryRequest = 57;
    optional CloseSubscriptionRequest closeSubscriptionRequest = 58;
}



message PublishRequest{
    required Message msg = 2;
}

// record all preferences for a subscription,
// would be serialized to be stored in meta store
message SubscriptionPreferences {
    // user customized subscription options
    optional Map options = 1;

    ///
    /// system defined options
    ///

    // message bound
    optional uint32 messageBound = 2;
    // server-side message filter
    optional string messageFilter = 3;
    // message window size, this is the maximum number of messages 
    // which will be delivered without being consumed
    optional uint32 messageWindowSize = 4;
}

message SubscribeRequest{
    required bytes subscriberId = 2;

    enum CreateOrAttach{
        CREATE = 0;
        ATTACH = 1;
        CREATE_OR_ATTACH = 2;
    };
    optional CreateOrAttach createOrAttach = 3 [default = CREATE_OR_ATTACH];

    // wait for cross-regional subscriptions to be established before returning
    optional bool synchronous = 4 [default = false];
    // @Deprecated. set message bound in SubscriptionPreferences
    optional uint32 messageBound = 5;

    // subscription options
    optional SubscriptionPreferences preferences = 6;

    // force attach subscription which would kill existed channel
    // this option doesn't need to be persisted
    optional bool forceAttach = 7 [default = false];
}

// used in client only
// options are stored in SubscriptionPreferences structure
message SubscriptionOptions {
    // force attach subscription which would kill existed channel
    // this option doesn't need to be persisted
    optional bool forceAttach = 1 [default = false];
    optional SubscribeRequest.CreateOrAttach createOrAttach = 2 [default = CREATE_OR_ATTACH];
    optional uint32 messageBound = 3 [default = 0];
    // user customized subscription options
    optional Map options = 4;
    // server-side message filter
    optional string messageFilter = 5;
    // message window size, this is the maximum number of messages 
    // which will be delivered without being consumed
    optional uint32 messageWindowSize = 6;
    // enable resubscribe
    optional bool enableResubscribe = 7 [default = true];
}

message ConsumeRequest{
    required bytes subscriberId = 2;    
    required MessageSeqId msgId = 3;
    //the msgId is cumulative: all messages up to this id are marked as consumed
}

message UnsubscribeRequest{
    required bytes subscriberId = 2;
}

message CloseSubscriptionRequest {
    required bytes subscriberId = 2;
}

message StopDeliveryRequest{
    required bytes subscriberId = 2;
}

message StartDeliveryRequest{
    required bytes subscriberId = 2;
}

// Identify an event happened for a subscription
enum SubscriptionEvent {
    // topic has changed ownership (hub server down or topic released)
    TOPIC_MOVED = 1;
    // subscription is force closed by other subscribers
    SUBSCRIPTION_FORCED_CLOSED = 2;
}

// a response carries an event for a subscription sent to client
message SubscriptionEventResponse {
    optional SubscriptionEvent event = 1;
}

message PubSubResponse{
    required ProtocolVersion protocolVersion = 1;
    required StatusCode statusCode = 2;
    required uint64 txnId = 3;

    optional string statusMsg = 4;
    //in case of a status code of NOT_RESPONSIBLE_FOR_TOPIC, the status
    //message will contain the name of the host actually responsible 
    //for the topic
    
    //the following fields are sent in delivered messages
    optional Message message = 5;
    optional bytes topic = 6;
    optional bytes subscriberId = 7;

    // the following fields are sent by other requests
    optional ResponseBody responseBody = 8;
}

message PublishResponse {
    // If the request was a publish request, this was the message Id of the published message.
    required MessageSeqId publishedMsgId = 1;
}

message SubscribeResponse {
    optional SubscriptionPreferences preferences = 2;
}

message ResponseBody {
    optional PublishResponse publishResponse = 1;
    optional SubscribeResponse subscribeResponse = 2;
    optional SubscriptionEventResponse subscriptionEvent = 3;
}


enum StatusCode{
    SUCCESS = 0;
    
    //client-side errors (4xx)
    MALFORMED_REQUEST = 401;
    NO_SUCH_TOPIC = 402;
    CLIENT_ALREADY_SUBSCRIBED = 403;
    CLIENT_NOT_SUBSCRIBED = 404;
    COULD_NOT_CONNECT = 405;
    TOPIC_BUSY = 406;
    RESUBSCRIBE_EXCEPTION = 407;
    
    //server-side errors (5xx)
    NOT_RESPONSIBLE_FOR_TOPIC = 501;
    SERVICE_DOWN = 502;
    UNCERTAIN_STATE = 503;
    INVALID_MESSAGE_FILTER = 504;

    //server-side meta manager errors (52x)
    BAD_VERSION = 520;
    NO_TOPIC_PERSISTENCE_INFO = 521;
    TOPIC_PERSISTENCE_INFO_EXISTS = 522;
    NO_SUBSCRIPTION_STATE = 523;
    SUBSCRIPTION_STATE_EXISTS = 524;
    NO_TOPIC_OWNER_INFO = 525;
    TOPIC_OWNER_INFO_EXISTS = 526;

    //For all unexpected error conditions
    UNEXPECTED_CONDITION = 600;
    
    COMPOSITE = 700;
}
  
//What follows is not the server client protocol, but server-internal structures that are serialized in ZK  
//They should eventually be moved into the server 
    
message SubscriptionState {
    required MessageSeqId msgId = 1;
    // @Deprecated.
    // It is a bad idea to put fields that don't change frequently
    // together with fields that change frequently
    // so move it to subscription preferences structure
    optional uint32 messageBound = 2;
}

message SubscriptionData {
    optional SubscriptionState state = 1;
    optional SubscriptionPreferences preferences = 2;
}

message LedgerRange{
    required uint64 ledgerId = 1;
    optional MessageSeqId endSeqIdIncluded = 2;
    optional uint64 startSeqIdIncluded = 3;
}

message LedgerRanges{
    repeated LedgerRange ranges = 1;
}

message ManagerMeta {
    required string managerImpl = 2;
    required uint32 managerVersion = 3;
}

message HubInfoData {
    required string hostname = 2;
    required uint64 czxid = 3;
}

message HubLoadData {
    required uint64 numTopics = 2;
}