// Copyright 2022 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.
@available(platform="examples", added=1)
library fuchsia.examples.notificationhub;

/// The name of the Application.
alias AppName = string:64;
/// Number of milliseconds since the unix epoch.
alias Timestamp = uint64;
/// A URL.
alias Url = string:60000;

/// The settings for a Hub.
type Settings = flexible bits {
    /// Set to true if you want incoming messages to a hub to be rate-limited.
    SLOW_MODE = 0x1;
};

/// A message in the hub.
type Message = table {
    /// A unique id for the message.
    1: id uint64;
    /// The name of the Application that sent the message.
    2: from AppName;
    /// The time the message was sent, in unix time.
    3: time Timestamp;
    /// The contents of the message.
    4: content Content;
};

/// The contents of a message.
type Content = flexible union {
    /// The text contents of a message.
    1: text string:140;
    /// The contents of a banner message, supporting a banner image and text.
    2: banner table {
        /// The URL to the banner image.
        1: image Url;
        /// The text contents of the banner.
        2: text string:80;
    };
};

/// A representation of a single notification hub.
type Hub = table {
    /// The settings for the hub.
    1: settings Settings;
    /// The messages in the hub.
    2: messages vector<Message>:64;
};

/// All possible connection errors.
type ConnectionError = flexible enum {
    /// An error when the user is already connected to a given hub.
    ALREADY_CONNECTED = 1;
};

/// The NotificationHub protocol. Allows users to connect to a notification hub,
/// to recieve notifications. Supports multiple concurrent connections to
/// separate hubs.
protocol NotificationHub {
    /// Connect to a given app's notification hub.
    Connect(struct {
        /// The name of the app to connect to.
        app AppName;
    }) -> (Hub) error ConnectionError;
    /// Close all open connections to notification hubs.
    // We return a table for future flexibility. We can update this in the
    // future to return additional keyed data.
    Close() -> (table {});
};