Throttler&Debouncer.swift

import Foundation
import Alamofire

private extension Date {
    static func second(from referenceDate: Date) -> Int {
        return Int(Date().timeIntervalSince(referenceDate).rounded())
    }
}

public class Throttler { 
//http://danielemargutti.com/2017/10/19/throttle-in-swift/
    private var queue: DispatchQueue
    
    private var workItem: DispatchWorkItem = DispatchWorkItem(block: {})
    private var previousRun: Date = Date.distantPast
    private var maxInterval: Int
    private var previousRequest: Request?
    
    init(dispatch: DispatchQueue, seconds: Int) {
        self.queue = dispatch
        self.maxInterval = seconds
    }
    
    
    func throttle(completion: @escaping ()->Request?) {
        workItem.cancel()
        previousRequest?.cancel()

        workItem = DispatchWorkItem(){ [weak self] in
            guard let self = self else { return }
            self.previousRun = Date()
            self.previousRequest = completion()
        }
        
        let delay = Date.second(from: previousRun) > maxInterval ? 0 : maxInterval
        queue.asyncAfter(deadline: .now() + Double(delay), execute: workItem)
    }
}


public class Debouncer: NSObject {
    private var queue: DispatchQueue
    
    private var workItem: DispatchWorkItem = DispatchWorkItem(block: {})
    private var previousRequest: Request?
    
    init(dispatch: DispatchQueue) {
        self.queue = dispatch
    }
    
    func debounce(interval: DispatchTimeInterval, completion: @escaping ()->Request?) {
        workItem.cancel()
        previousRequest?.cancel()
        
        workItem = DispatchWorkItem() { [weak self] in
            guard let self = self else { return }
            self.previousRequest = completion()
        }
        
        queue.asyncAfter(deadline: .now() + interval, execute: workItem)
    }
}