import SwiftUI
import Foundation

let global_endpoint = Endpoint2()

func timeString(from: TimeInterval) -> String {
   let minutes = Int(from) / 60
   let seconds = Int(from) % 60
   return String(format: "%04d:%02d", minutes, seconds)
}

struct ContentView: View {
   @State var timer: Timer?
   @State var elapsed: TimeInterval = 0
    var body: some View {
        VStack {
            Image(systemName: "globe")
                .imageScale(.large)
                .foregroundStyle(.tint)
            Text("Hello, world!")
            Text(timeString(from: elapsed))
               .font(.largeTitle)
               .padding()
            Button("Start Traffic") {
               TrafficController.shared.startEndpoint()
               timer = Timer.scheduledTimer(withTimeInterval: 0.01, repeats: true) { _ in
                  elapsed += 0.01
               }
            }
        }
        .padding()
    }
}

#Preview {
    ContentView()
}

class TrafficController: NSObject, URLSessionDataDelegate, URLSessionTaskDelegate {
   static let shared = TrafficController()
   static let ftp_url_string = "ftp://lanforge:lanforge@10.0.0.7/test-file10M.bin"

   private lazy var session: URLSession = {
      let configuration = URLSessionConfiguration.default
      return URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
   }()

   override init() {
      print("DEBUG: Called init for L4Handler!")
      super.init()
   }

   deinit {
      print("DEBUG: L4Handler deinit called. Deallocating both URLSession and URLSessionDelegate!")
   }

   func urlSession(_ session: URLSession, task: URLSessionTask,
                     didCompleteWithError error: Error?) {
       if let error = error {
         print("ERROR: got error in urlSession(didComplete): \(error)")
      }
   }

   func startEndpoint() {
      global_endpoint.session = session
      global_endpoint.startTest()
   }
}

class Endpoint2 {
   var session: URLSession!
   var worker: Task?

   init() {}

   // MARK -- Protocol API
   func startTest() {
      guard worker == nil else {
         return
      }
      worker = Task {
         while !Task.isCancelled {
            doTrafficRound()
            // hard code 2 URLs per second
            try await Task.sleep(nanoseconds: UInt64(0.2 * 1_000_000_000))
         }
      }
   }

   func stopTest() {
      guard let workerTask = worker else {
         print("ERROR: Cannot stop worker is already NULL")
         return
      }
      workerTask.cancel()
   }

   func doTrafficRound() {
      print("DEBUG: doing traffic round")
      if let url_object = URL(string: TrafficController.ftp_url_string) {
         let newTask = self.session.dataTask(with: url_object)
         newTask.resume()
      }
      else {
         print("DEBUG: Could not form URL from string: \(TrafficController.ftp_url_string)")
      }
   }
}