// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.modular;

using fuchsia.ledger;
using fuchsia.sys;

// Provided to all component instances in their respective initialization
// information by the framework. For example, a Module gets it from its
// ModuleContext and an Agent gets it from its AgentContext.
[Discoverable]
interface ComponentContext {
    // Gets the Ledger associated with this component. This ledger instance is
    // unique to this component (nb. not the component instance) under this user.
    1: GetLedger(request<fuchsia.ledger.Ledger> request);

    // Used to start an agent in the user scope if it isn't already running, and
    // connect to it.
    2: ConnectToAgent(string url,
                      request<fuchsia.sys.ServiceProvider> incoming_services,
                      request<AgentController> controller);

    // Used to create or delete a message queue or retrieve an existing queue
    // identified by |name|. |name| is local to the calling component instance.
    3: ObtainMessageQueue(string name, request<MessageQueue> queue);
    4: DeleteMessageQueue(string name);

    // Gets a MessageSender service that can be used to send a message to a queue
    // identified by |queue_token|. Token for a MessageQueue is obtained from its
    // GetToken() method. The token is unique within the scope of the user, i.e.
    // it can be used by other component instances than the one that created the
    // message queue.
    5: GetMessageSender(string queue_token, request<MessageSender> sender);

    // Gets the EntityResolver service, which can be used to resolve an entity
    // reference to an Entity interface.
    6: GetEntityResolver(request<EntityResolver> request);

    // Creates a new entity from |type_to_data| such that duplicate types are
    // overriden by subsequent entries.
    //
    // This is a useful way to represent small immutable entities without having
    // to provide the entity using an Agent. The types and data together must be
    // within 16KB in size.
    7: CreateEntityWithData(vector<TypeToDataEntry> type_to_data)
           -> (string? entity_reference);

    // Gets the package name of this component.
    //
    // TODO(vardhan): MI4-939. This information should likely be exposed by a
    // lower level (component-level, or application level). This information is
    // most meant for a component to identify itself automatically when publishing
    // metrics.
    8: GetPackageName() -> (string package_name);
};

// Used by ComponentContext.CreateEntityWithData().
struct TypeToDataEntry {
    string type;
    string data;
};