//
//  ConnectionStatusViewPresenter.swift
//  PrivadoVPN
//
//  Created by Zhandos Bolatbekov on 08.07.2021.
//  Copyright © 2021 Privado LLC. All rights reserved.
//

import Foundation

final class ConnectionStatusViewPresenter: ConnectionStatusViewOutput {
    
    private enum Constants {
        
        enum LocalizedString {
            static let connecting = "connection.ipad.status.connecting"
            static let disconnecting = "connection.ipad.status.disconnecting"
        }
        
        static let animationInterval: TimeInterval = 0.5
    }
    
    weak var viewInput: ConnectionStatusViewInput?
    
    private var scheduler: Timer?
    private var statusText: String? {
        didSet {
            DispatchQueue.main.async { [weak self] in
                self?.viewInput?.updateConnectionStatus(title: self?.statusText)
            }
        }
    }
    
    init(session: Session) {
        
        session.vpnConnectionStateEmitter.addReaction { [weak self] state, _ -> ShouldContinueReceiveNotifications in
            
            switch state {
            case .connecting, .prepare:
                self?.statusText = NSLocalizedString(Constants.LocalizedString.connecting, comment: "Connecting") + "."
                self?.startAnimating()
                
            case .disconnecting:
                self?.statusText = NSLocalizedString(Constants.LocalizedString.disconnecting, comment: "Disconnecting") + "."
                self?.startAnimating()
                
            default:
                self?.statusText = nil
                self?.stopAnimating()
            }
            return self.isExist
        }
    }
    
    private func startAnimating() {
        guard !self.scheduler.isExist else { return }
        
        let scheduler = Timer.scheduledTimer(withTimeInterval: Constants.animationInterval, repeats: true) { [weak self] _ in
            self?.updateToNextState()
        }
        self.scheduler = scheduler
    }
    
    private func stopAnimating() {
        if let scheduler = self.scheduler {
            scheduler.invalidate()
            scheduler.fire()
        }
        
        self.scheduler = nil
    }
    
    private func updateToNextState() {
        guard var text = self.statusText else { return }
        if text.hasSuffix("...") {
            text.removeLast(2)
        } else {
            text += "."
        }
        self.statusText = text
    }
}