//
//  UpdateWalletStateService.swift
//  Malinka
//
//  Created by Juraldinio on 11/14/22.
//  Copyright © 2022 NUT.Tech. All rights reserved.
//

import Foundation
import Combine
import WalletKit

final class UpdateWalletStateService {
    
    // MARK: - Constants
    
    private enum Constants {
        static let timerInterval = 3
        static let maximumRefreshCount = 5
    }
    
    // MARK: - Properties
    
    private let status: CurrentValueSubject<WalletKit.Wallet, Never>
    private var timerPublisher: DispatchTimer?
    private var refreshStatus: AnyCancellable?
    
    var statusPublisher: AnyPublisher<WalletKit.Wallet, Never> { self.status.eraseToAnyPublisher() }
    
    // MARK: - Init
    
    init(bank: Bank, wallet: WalletKit.Wallet) {
        
        self.status = CurrentValueSubject<WalletKit.Wallet, Never>(wallet)
        
        let publisher = Publishers.timer(queue: DispatchQueue.global(qos: .background),
                                         interval: .seconds(Constants.timerInterval),
                                         times: .max(Constants.maximumRefreshCount))
        self.timerPublisher = publisher
        
        self.refreshStatus = publisher.sink(receiveCompletion: { [weak self] _ in
            self?.status.send(wallet)
            self?.status.send(completion: .finished)
        }, receiveValue: { [weak self] _ in
            self?.updateState(for: wallet, in: bank)
        })
        
    }
    
    // MARK: - Private
    
    private func updateState(for wallet: WalletKit.Wallet, in bank: Bank) {

        Task {
            try await bank.refreshStatus(wallet: wallet)
        }
        
        self.status.send(wallet)
        
        guard wallet.isOnCreationState else {
            self.refreshStatus?.cancel()
            self.refreshStatus = nil
            self.status.send(completion: .finished)
            return
        }
    }
}