// Copyright 2019 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.ui.activity;

using zx;

using OngoingActivityId = uint32;

/// The Tracker protocol collects evidence of user activity and uses this
/// evidence to set the system's activity state.
[Discoverable]
protocol Tracker {
    /// Reports a discrete activity such as a keystroke.
    /// |event_time| is in nanoseconds in the `CLOCK_MONOTONIC` time base.
    ReportDiscreteActivity(DiscreteActivity activity, zx.time event_time);

    /// Reports the start of an ongoing activity such as media playback.
    /// Returns a unique |activity_id| which is expected to be later passed
    /// to EndOngoingActivity.
    /// |start_time| is in nanoseconds in the `CLOCK_MONOTONIC` time base.
    StartOngoingActivity(OngoingActivity activity, zx.time start_time)
        -> (OngoingActivityId activity_id);

    /// Reports the end of an ongoing activity such as media playback.
    /// |activity_id| is the nonce which was returned by StartOngoingActivity.
    /// |end_time| is in nanoseconds in the `CLOCK_MONOTONIC` time base.
    EndOngoingActivity(OngoingActivityId activity_id, zx.time end_time);
};