/**
* A piece of a class int he PL Swift
* Swift is "null-safe"; it cannot have null pointer exceptions
* because every variable is either allowed to be null, or
* not. On any that is allowed, you must explicitly code to
* prevent NPEs.
**/

import Foundation
class RowerFakerClass: NSObject {

    var rowerView : RowerView?  //? indicated null is allowed
    var counter : Int = 0 // may not be null
    var timer = Timer()  // type inference

    func startTimer() {
        if (!timer.idle()) { //since timer is guaranteed to be non-null can check if it is use without fear
            self.timer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true, block: { _ in
            self.sendStroke()
        }) 
        } 
    }
    
    func sendStroke() {
        counter = counter+1
        if let rv = rowerView {  // here must confirm that rowerView is not null before using it.
        // variables created using let are immutable
        // why is this important here?
            let rowerData = RowerData(cc: counter, sd: startDate!)
            rv.notify(data: rowerData)
        }
    }
}