// 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.buttons;
using zx;

/// ButtonType should the same as BUTTONS_ID_... in metadata/buttons.h
type ButtonType = strict enum : uint8 {
    VOLUME_UP = 0;
    VOLUME_DOWN = 1;
    RESET = 2;
    MUTE = 3;
    PLAY_PAUSE = 4;
    KEY_A = 5;
    KEY_M = 6;
    CAM_MUTE = 7;
    MAX = 8;
};

/// Protocol for other devices to get the state of buttons and register for
/// notifications of state change.
@discoverable
protocol Buttons {
    /// Gets the state of the button requested.
    /// `type` : Button type.
    /// @Returns: `pressed` : True if button is pressed.
    GetState(struct {
        type ButtonType;
    }) -> (struct {
        pressed bool;
    });

    /// Registers to receive notifications of a state change for some buttons.
    /// `types` : Bitmask which indicates the interested buttons. 0 means not
    ///           interested, 1 means interested. Bit position corresponds to
    ///           ButtonType, e.g. (1 << VOLUME_UP) means notify only when
    ///           the state of the VOLUME_UP button changes. Types not listed
    ///           in subsequent calls are removed.
    /// @Returns: `status` : ZX_OK if succeeds.
    RegisterNotify(struct {
        types uint8;
    }) -> (struct {}) error zx.status;

    /// Notify event. Called when state of previously registered button changes.
    /// `type` : Button type.
    /// `pressed` : True if button is pressed.
    -> OnNotify(struct {
        type ButtonType;
        pressed bool;
    });
};