public/fidl/fuchsia.modular/context/metadata.fidl

// 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;

// This struct serves two purposes. It is:
//
// 1) Used to expose metadata along with each context node when interfacing
// with clients either publishing, or retieving, context values.
//
// 2) Used while getting or querying for context values from a ContextReader to
// restrict the set of values returned by partially specifying a
// ContextMetadata struct.
//
// TODO(thatguy): Consider splitting these two purposes into their own structs
// if the dual-responsibility becomes difficult to manage.
struct ContextMetadata {
    StoryMetadata? story;
    ModuleMetadata? mod; // Annoyingly, "module" is a reserved word in FIDL.
    EntityMetadata? entity;
    LinkMetadata? link;

    // TODO(thatguy): Add Agent metadata.
};

struct StoryMetadata {
    string? id;
    FocusedState? focused;
    // TODO(thatguy): Add modular.StoryState
    // TODO(thatguy): Add visible state.
};

struct ModuleMetadata {
    string? url;
    vector<string>? path;
    FocusedState? focused;
};

struct EntityMetadata {
    string? topic;
    vector<string>? type;
};

struct LinkMetadata {
    // These fields are identical to those in modular.LinkPath. Can't use
    // modular.LinkPath directly because depending on lib/modular/fidl:link_path
    // causes issues with Dart bindings (they try to import the file from the
    // wrong package name), and depending on lib/modular/fidl causes a dependency
    // cycle (lib/context -> lib/module -> lib/user_intelligence -> lib/context).
    //
    // TODO(thatguy): Once we have FIDL2 (which will apparently fix the Dart
    // bindings problem), use LinkPath.
    vector<string>? module_path;
    string? name;
};

// bool type cannot be made optional (in StoryMetadata above), so we cannot
// differentiate between an unspecified value and false. So we have to create a
// struct with an enum in it to represent the boolean states, so that we can
// allow it to be null.
struct FocusedState {
    FocusedStateState state;
};

enum FocusedStateState {
    FOCUSED = 1;
    NOT_FOCUSED = 2;
};