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// Copyright 2023 Google LLC
// SPDX-License-Identifier: Apache-2.0
#![allow(dead_code)]

#[derive(Debug)]
/// 电梯系统中控制器必须响应的事件。
enum Event {
    /// 按下了某个按钮。
    ButtonPressed(Button),

    /// 轿厢已到达指定楼层。
    CarArrived(Floor),

    /// 轿厢门已打开。
    CarDoorOpened,

    /// 轿厢门已关闭。
    CarDoorClosed,
}

/// 楼层用整数表示。
type Floor = i32;

/// 行进方向。
#[derive(Debug)]
enum Direction {
    Up,
    Down,
}

/// 用户可操作的按钮。
#[derive(Debug)]
enum Button {
    /// 指定楼层电梯厅中的按钮。
    LobbyCall(Direction, Floor),

    /// 轿厢内的楼层按钮。
    CarFloor(Floor),
}

/// 轿厢已到达指定楼层。
fn car_arrived(floor: i32) -> Event {
    Event::CarArrived(floor)
}

/// 轿厢门已打开。
fn car_door_opened() -> Event {
    Event::CarDoorOpened
}

/// 轿厢门已关闭。
fn car_door_closed() -> Event {
    Event::CarDoorClosed
}

/// 某楼层电梯厅按下了方向按钮。
fn lobby_call_button_pressed(floor: i32, dir: Direction) -> Event {
    Event::ButtonPressed(Button::LobbyCall(dir, floor))
}

/// 轿厢内按下了楼层按钮。
fn car_floor_button_pressed(floor: i32) -> Event {
    Event::ButtonPressed(Button::CarFloor(floor))
}

fn main() {
    println!(
        "A ground floor passenger has pressed the up button: {:?}",
        lobby_call_button_pressed(0, Direction::Up)
    );
    println!("The car has arrived on the ground floor: {:?}", car_arrived(0));
    println!("The car door opened: {:?}", car_door_opened());
    println!(
        "A passenger has pressed the 3rd floor button: {:?}",
        car_floor_button_pressed(3)
    );
    println!("The car door closed: {:?}", car_door_closed());
    println!("The car has arrived on the 3rd floor: {:?}", car_arrived(3));
}