/*
 * SPDX-FileCopyrightText: 2023 Contributors to the Eclipse Foundation
 *
 * See the NOTICE file(s) distributed with this work for additional
 * information regarding copyright ownership.
 * 
 * This program and the accompanying materials are made available under
 * the terms of the Apache License Version 2.0 which is available at
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * SPDX-FileType: SOURCE
 * SPDX-License-Identifier: Apache-2.0
 */
syntax = "proto3";

package uprotocol.core.usubscription.v3;

import "google/protobuf/any.proto";
import "google/protobuf/timestamp.proto";
import "uprotocol/v1/uri.proto";
import "uprotocol/uoptions.proto";

option java_package = "org.eclipse.uprotocol.core.usubscription.v3";
option java_outer_classname = "USubscriptionProto";
option java_multiple_files = true;

// Enables generation of generic service attributes in C++
option cc_generic_services = true;

// Subscription Service Interface definition
service uSubscription {
  option (uprotocol.service_name) = "core.usubscription"; // Service name
  option (uprotocol.service_version_major) = 3;
  option (uprotocol.service_version_minor) = 0;
  option (uprotocol.service_id) = 0;

  // uSubscription change Notification topic that sends the Update message
  option (uprotocol.notification_topic) = {
    id: 0x8000,
    name: "SubscriptionChange",
    message: "Update"
  };


  // A consumer (application) calls this API to subscribe to a topic.
  // What is passed is the SubscriptionRequest message containing the topic, the
  // subscriber's name, and any Subscription Attributes. This API returns a
  // SubscriptionResponse message containing the status of the request along with
  // any event delivery configuration
  // required to consume the event. Calling this API also registers the subscriber
  // to received subscription change notifications if ever the subscription state
  // changes.
  rpc Subscribe(SubscriptionRequest) returns (SubscriptionResponse) {
    option (uprotocol.method_id) = 1;
  }

  // The consumer no longer wishes to subscribe to a topic so it issues an
  // explicit unsubscribe request.
  rpc Unsubscribe(UnsubscribeRequest) returns (UnsubscribeResponse) {
    option (uprotocol.method_id) = 2;
  }

  // Fetch a list of subscriptions
  rpc FetchSubscriptions(FetchSubscriptionsRequest) returns (FetchSubscriptionsResponse) {
    option (uprotocol.method_id) = 3;
  }


  // Register to receive subscription change notifications that are published on the
  // 'up:/core.usubscription/3/subscriptions#Update'
  rpc RegisterForNotifications(NotificationsRequest) returns (NotificationsResponse) {
    option (uprotocol.method_id) = 6;
  }

  // Unregister for subscription change events
  rpc UnregisterForNotifications(NotificationsRequest) returns (NotificationsResponse) {
    option (uprotocol.method_id) = 7;
  }

  // Fetch a list of subscribers that are currently subscribed to a given topic.
  rpc FetchSubscribers(FetchSubscribersRequest) returns (FetchSubscribersResponse) {
    option (uprotocol.method_id) = 8;
  }

  // Reset subscriptions to and from the uSubscription Service.
  // This API is used between uSubscription services in order to flush and
  // reestablish subscriptions between devices. A uSubscription service might
  // ned to call this API if its database is flushed or corrupted (ex. factory
  // reset).
  // **__NOTE:__** This is a private API only for uSubscription services,
  // uEs can call Unsubscribe() to flush their own subscriptions.
  rpc Reset(ResetRequest) returns (ResetResponse) {
    option (uprotocol.method_id) = 9;
  }
}


// Additional subscription configurations information
message SubscribeAttributes {
  // When the subscription should expire (time in the future.
  // **__NOTE:__** If this field is missing, assumed to live forever
  google.protobuf.Timestamp expire = 1;

  // Any additional producer specific information that the consumer must send
  // inside of a subscription request
  repeated google.protobuf.Any details = 2;

  // Desired Sampling Period (measured in milliseconds) the subscriber wishes to receive events
  // for remote only topics. Device dispatchers (i.e. streamers) use this
  // attribute to reduce the publication rates of events sent between devices.
  // This attribute is commonly used for mobile/cloud subscribing to vehicle topics
  // that are published at a high rate.<br>
  // If the desired sampling period set by the subscriber is lower than the original publisher's
  // publication period, the attribute is ignored.<br>
  // **__NOTE:__** If this attribute is missing, the sampling period is set by the publisher.
  optional uint32 sample_period_ms = 3;
}


// Subscriber Identification Information
message SubscriberInfo {
  // subscriber URI containig the names and numbers of the
  // uE subscribing. Example represented in long form: `//device.domain/com.gm.app.hartley`
  uprotocol.v1.UUri uri = 1;

  // DEPRECATED: Any additional device specific subscriber information
  // repeated google.protobuf.Any details = 2;
  reserved 2;
}


// Subscription Status
message SubscriptionStatus {
  enum State {

    UNSUBSCRIBED = 0;         // Default state to indicate not subscribed

    SUBSCRIBE_PENDING = 1;    // Subscription is pending confirmation from remote
                              // uSubscription Service

    SUBSCRIBED = 2;           // Subscription has been successful

    UNSUBSCRIBE_PENDING = 3;  // Unsubscribe is pending confirmation from the
                              // remote uSubscription Service
  }

  reserved 2;

  // Subscription state
  State state = 1;

  // The Subscription status message
  string message = 3;
}


// How events will be delivered to the subscriber. Usage of this structure is
// device-dependent
message EventDeliveryConfig {
  // Identifier for the event delivery endpoint, ex. topic name for events to be published to
  // example for Azure uCloud: "SUBSCRIPTION_TOPIC"
  string id = 1;

  // What type of endpoint shall be used to deliver the events for said subscription
  // example for Azure uCloud: "Microsoft.EventHub/Namespaces/EventHubs"
  string type = 2;

  // Any additional configuration attributes
  map <string, google.protobuf.Any>  attributes = 3;
}


// Passed to Subscribe() contains the subscription request information
message SubscriptionRequest {
  // uProtocol uri topic to subscribe too
  uprotocol.v1.UUri topic = 1;

  // DEPRECATED: Subscribers's information (who is calling Subscribe) is not needed
  //SubscriberInfo subscriber = 2;
  reserved 2;

  // Additional subscription attributes
  SubscribeAttributes attributes = 3;
}


// Response message from the Subscribe() API
message SubscriptionResponse {
  // Current status of the subscription
  SubscriptionStatus status = 1;

  // Any platform (uDevice) specific additional event delivered configuration
  // information for how the subscriber should consume the published events.
  EventDeliveryConfig config = 2;

  // Subscription topic passed to SubscriptionRequest
  uprotocol.v1.UUri topic = 3;
}


// Passed to the Unsubscribe() API, the message contains the topic to unsubscribe
// to as well as the subscriber identification
message UnsubscribeRequest {
  // Topic to be unsubscribed to
  uprotocol.v1.UUri topic = 1;

  // DEPRECATED 0Subscriber identification is not needed
  // SubscriberInfo subscriber = 2;
  reserved 2;
}

// The (empty) response message representing the successful execution of the Unsubscribe operation.
message UnsubscribeResponse {}

// Passed to FetchSubscribers such that we can obtain a list of subscribers to
// a particular topic
message FetchSubscribersRequest {
  // Topic we wish to find the subscribers for
  uprotocol.v1.UUri topic = 1;

  // Offset in the fetch requests
  optional uint32 offset = 2;
}


// Returned from FetchSubscribers(), this message contains a repeated list of
// SubscriberInfo
message FetchSubscribersResponse {
  reserved 3;
  // List of subscribers
  repeated SubscriberInfo subscribers = 1;

  // Set to true if the batch did not return all records
  optional bool has_more_records = 2;
}


// Subscription Message. Contains all the information about a subscription that
// is returned from FetchSubscriptions() API.
message Subscription {
  // Subscription topic
  uprotocol.v1.UUri topic = 1;

  // Information about the subscriber who changed their subscription
  SubscriberInfo subscriber = 2;

  // Current status of the subscription
  SubscriptionStatus status = 3;

  // Subscribers subscription attributes
  SubscribeAttributes attributes = 4;

  // Any platform (uDevice) specific additional event delivered configuration
  // information for how the subscriber should consume the published events.
  EventDeliveryConfig config = 5;
}


message FetchSubscriptionsRequest {
  oneof request {
    // Topic to register/unregister to receive subscription change notifications
    uprotocol.v1.UUri topic = 1;

    // Subscribers's information
    SubscriberInfo subscriber = 2;
  }

  // Offset in the fetch requests
  optional uint32 offset = 3;
}


// Results from FetchSubscriptions() API
message FetchSubscriptionsResponse {
  // Repeated list of subscriptions for a subscriber
  repeated Subscription subscriptions = 1;

  // Set to true if the batch did not return all records
  optional bool has_more_records = 2;
}


// Passed to the RegisterForSubscriptionChanges() and UnregisterForSubscriptionChanges()
// APIs this message includes the topic to register for subscription changes as well
// as information about the subscriber who wishes to receive said notifications
message NotificationsRequest {
  // Topic to register/unregister to receive subscription change notifications
  uprotocol.v1.UUri topic = 1;

  // DEPRECATED: Subscribers's information not used as only non-subscribers will call
  // this API (i.e. producers)
  // SubscriberInfo subscriber = 2;
  reserved 2;
}

// The (empty) response message representing the successful execution of the
// RegisterForSubscriptionChanges and UnregisterForSubscriptionChanges operations.
message NotificationsResponse {}

// Subscription Update Message.
// This Update message is sent from uSusbcription on the topic:
// '/core.usubscription/3/subscriptions#Update' whenever there is a change to
// a subscription. Subscribers automatically receive this notification along with
// any uE that called RegisterForNotifications().
message Update {
  // Subscribed topic whos state has changed
  uprotocol.v1.UUri topic = 1;

  // Information about the subscriber who changed their subscription
  SubscriberInfo subscriber = 2;

  // Current status of the subscription
  SubscriptionStatus status = 3;

  // Subscribers subscription attributes
  SubscribeAttributes attributes = 4;

  // Service meta-data option definitions - Resources
  enum Resources { subscriptions = 0; }
}



// Passive Subscription Mode.
// Passive subscriptions, in lieu of active ones, do not modify (the state) nor
// notify the publisher of the subscribers subscription. Passive subscriptions
// are a means to support observability frameworks to passively listen for
// events.
// *NOTE*: This attribute is an internal platform setting (for now) and not
// exposed as part of SubscribeAttributes.
message PassiveMode {
  bool enable = 1;    // Enable passive subscription mode
}


// Reset Subscriptions Request.
// Passed in the Reset() API this message contains the reason for the reset as
// well as the time before which all subscriptions should be reset.
message ResetRequest {
  // Reason for the reset
  optional Reason reason = 1;

  // Reset all subscriptions that are before this time, if omitted, the
  // current time is assumed
  optional google.protobuf.Timestamp before = 2;

  // The reason for triggering a reset, this is an optional attribute used
  // to provide insight as to why a reset occurred
  // More reasons will be added as we distill the business logic
  message Reason {
    Code code = 1;  // Reason code
    optional string message = 2; // Reason message

    // Reason code
    enum Code {
      UNSPECIFIED = 0;  // Default non-specified reason for issuing a reset
      FACTORY_RESET = 1;  // Factory reset
      CORRUPTED_DATA = 2;  // Corrupted data
    }
  }
}

// The (empty) response message representing the successful execution of the Reset operation.
message ResetResponse {}