// Copyright 2016 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;

/// Used by the clients of StoryProvider (SessionShell) to interact with a single
/// story. Created by StoryProvider.
///
/// If `StoryController` is closed, the `StoryState` associated with this story
/// does not change.
protocol StoryController {
    /// Gets information associated with the story.
    [Transitional = "Use GetInfo2 instead"]
    GetInfo() -> (StoryInfo info, StoryState state);
    /// For transition purposes only.
    [Transitional = "Only use while GetInfo2 is transitional"]
    GetInfo2() -> (StoryInfo2 info, StoryState state);

    /// Requests to run the story controlled by this `StoryController` instance.
    /// When the story starts, if not yet running, the view of the newly started
    /// story shell will be passed in a call to SessionShell.AttachView().
    RequestStart();

    /// Requests to stop the story controlled by this `StoryController`. If Start()
    /// requests are pending when this request is issued, the request is queued
    /// until the Start() requests complete. Before stopping the story, a snapshot
    /// of the story will be taken and saved. Returns when the story is stopped.
    Stop() -> ();

    /// Registers a watcher for changes of the story state.
    ///
    /// Note that stories can stop themselves at any time and it is advisable
    /// for the holder of a StoryController to provide a watcher.
    Watch(StoryWatcher watcher);

    /// Attach the `annotations` to the story.
    ///
    /// Existing annotations with the same key will be overwritten.
    Annotate(vector<Annotation>:MAX_ANNOTATIONS_PER_UPDATE annotations)
        -> () error AnnotationError;
};

/// Implemented by the client calling StoryController.Watch().
protocol StoryWatcher {
    /// Called with the current state right after registration, and subsequently
    /// when the state changes.
    OnStateChange(StoryState new_state);

    /// DEPRECATED
    OnModuleAdded(ModuleData module_data);

    /// DEPRECATED
    OnModuleFocused(vector<string> module_path);
};