RefreshTokenLogic.swift

//: Playground - noun: a place where people can play

import UIKit

var str = "Hello, playground"


struct Token {
    
    var value: String
    
    func isValid() -> Token? {
        
        return self
    }
}

typealias TokenRequestCallback = Token? -> Void

class AuthManager {
    
    private var listOfTokenRequests: [TokenRequestCallback] = []
    private var isFetchingNewTokenFromNetwork: Bool = false
    private var currentToken: Token?
    
    private func refreshToken(completion: Token -> Void ) {
        
        fatalError("To be implemented")
    }
    
    private func getValidToken(completion: TokenRequestCallback) {
        
        if self.isFetchingNewTokenFromNetwork { return }
        
        if let validToken = self.currentToken?.isValid() {
            
            completion(validToken)
        } else {
            
            self.refreshToken{ refreshedToken in
                
                self.isFetchingNewTokenFromNetwork = false
                
                self.currentToken = refreshedToken
                completion(refreshedToken)
            }
            
            self.isFetchingNewTokenFromNetwork = true
        }
    }
    
    internal func onAskingForToken(handler: TokenRequestCallback) {
        
        dispatch_sync(dispatch_get_main_queue()) {
            
            self.listOfTokenRequests.append(handler)
            
            self.getValidToken { token in
                
                self.listOfTokenRequests.map { $0(token) }
                self.listOfTokenRequests.removeAll()
            }
        }
    }
}