//Handler
class Rescuer {
    fileprivate var next: Rescuer?
    fileprivate var code = -1

    //HandleRequest()
    func help(_ code: Int) {
        if (self.code == code) {
            toHelp()
        } else if (next != nil) {
            next!.help(code)
        }
    }

    fileprivate func toHelp() {}
}

//ConcreteHandler
class Firefighter: Rescuer {
    init(next: Rescuer?) {
        super.init()
        self.next = next
        self.code = 1
    }

    fileprivate override func toHelp() {
        print("call firefighters")
    }
}

//ConcreteHandler
class Police: Rescuer {
    init(next: Rescuer?) {
        super.init()
        self.next = next
        self.code = 2
    }

    fileprivate override func toHelp() {
        print("call the police")
    }
}

//ConcreteHandler
class Ambulance: Rescuer {
    init(next: Rescuer?) {
        super.init()
        self.next = next
        self.code = 3
    }

    fileprivate override func toHelp() {
        print("call an ambulance")
    }
}

let ambulance = Ambulance(next: nil)
let police = Police(next: ambulance)
let firefighter = Firefighter(next: police)
firefighter.help(1)
//printed: call firefighters
firefighter.help(2)
//printed: call the police
firefighter.help(3)
//printed: call an ambulance