NetworkOperation.swift

//
//  NetworkOperation.swift
//  OperationsTest
//
//  Created by Eugenio Baglieri on 11/04/17.
//  Copyright © 2017 Eugenio Baglieri. All rights reserved.
//

import Foundation

public enum NetworkError: Error {
    case badInput
    case noData
    case unacceptableResponse(Int)
}


public class NetworkOperation<Output>: Operation {
 
    public typealias Result = () -> Output
    public typealias CompletionHandler = (_ result: Result) -> Void
    
    let internalQueue: OperationQueue
    
    let requestOperation: RequestOperation
    
    let completion: CompletionHandler?
    
    init(environment: Environment, request: Request, completionHandler: CompletionHandler?) throws {
        requestOperation = RequestOperation(environment: environment, request: request)
        completion = CompletionHandler
        internalQueue = OperationQueue()
        internalQueue.delegate
        internalQueue.isSuspended = true
        super.init()
    }
    
    public override func execute() {
        guard isCancelled == false else { finish() }
        
        let decodeOperation = BlockOperation {
            let result = decodeResponse(requestOperation.response!)
        }
        
        let finishOperation = BlockOperation {
            DispatchQueue.main.async {
                completion? { result }
            }
            
        }
    }
    
    public func decodeResponse(_ response: Response) -> Result {
        fatalError("decodeResponse not overridden")
    }
    
}