Swift

import Foundation

// Kiểu liệt kê đại diện cho trạng thái nguồn điện với kiểu giá trị
public enum DeviceState {
    case off
    case standby
    case active(powerUsageWatts: Double)
}

// Hợp đồng giao thức cho các thiết bị ngoại vi nhà thông minh
public protocol SmartDevice {
    var deviceID: String { get }
    var name: String { get set }
    var state: DeviceState { get }
    
    func turnOn()
    func turnOff()
}

// Triển khai cấu trúc cho một bóng đèn thông minh
public struct SmartBulb: SmartDevice {
    public let deviceID: String
    public var name: String
    public private(set) var state: DeviceState
    public var brightnessLevel: Int

    public init(deviceID: String, name: String, brightnessLevel: Int = 100) {
        self.deviceID = deviceID
        self.name = name
        self.brightnessLevel = brightnessLevel
        self.state = .off
    }

    public mutating func turnOn() {
        self.state = .active(powerUsageWatts: 9.5)
    }

    public mutating func turnOff() {
        self.state = .off
    }
}

import Foundation

public enum PurchaseResult {
    case success(transactionID: String, purchasedAt: Date)
    case pending
    case failed(errorDescription: String)
}

public protocol StoreServiceDelegate: AnyObject {
    func storeService(_ service: StoreManager, didUpdateResult result: PurchaseResult)
}

public final class StoreManager {
    public private(set) var activeSubscriptionID: String?
    public weak var delegate: StoreServiceDelegate?

    public init(activeSubscriptionID: String? = nil) {
        self.activeSubscriptionID = activeSubscriptionID
    }

    public func purchaseProduct(productID: String) {
        // Mô phỏng xử lý giao dịch
        let result = PurchaseResult.success(transactionID: "tx_99401", purchasedAt: Date())
        self.activeSubscriptionID = productID
        delegate?.storeService(self, didUpdateResult: result)
    }
}

import Foundation

public struct NotificationPayload {
    public let title: String
    public let body: String
    public let categoryIdentifier: String
    public let badgeCount: Int
}

public protocol NotificationDispatcher {
    func scheduleLocalNotification(payload: NotificationPayload, triggerInSeconds: TimeInterval)
}

// Mở rộng giao thức cung cấp hành vi mặc định
extension NotificationDispatcher {
    public func scheduleImmediate(payload: NotificationPayload) {
        scheduleLocalNotification(payload: payload, triggerInSeconds: 1.0)
    }
}

public final class APNsDispatcher: NotificationDispatcher {
    private let environment: String

    public init(environment: String = "production") {
        self.environment = environment
    }

    public func scheduleLocalNotification(payload: NotificationPayload, triggerInSeconds: TimeInterval) {
        print("Đã lên lịch '(payload.title)' trong (triggerInSeconds)s thông qua APNs ((environment))")
    }
}