//

// JSONDownloader.swift

// JSONTutorial

//

// Created by Kapil Amagain on 5/11/17.

// Copyright © 2017 James Rochabrun. All rights reserved.

//

import Foundation

struct JSONDownloader {

//1)

let session: URLSession

init(configuration: URLSessionConfiguration) {

self.session = URLSession(configuration: configuration)

}

init() {

self.init(configuration: .default)

}

typealias JSON = [String: AnyObject]

typealias JSONTaskCompletionHandler = (Result<JSON>) -> ()

//4)

func jsonTask(with request: URLRequest, completionHandler completion: @escaping JSONTaskCompletionHandler) -> URLSessionDataTask {

let task = session.dataTask(with: request) { (data, response, error) in

guard let httpResponse = response as? HTTPURLResponse else {

completion(.Error(.requestFailed))

return

}

if httpResponse.statusCode == 200 {

if let data = data {

do {

if let json = try JSONSerialization.jsonObject(with: data, options: []) as? [String: AnyObject] {

DispatchQueue.main.async {

completion(.Success(json))

}

}

}

catch {

completion(.Error(.jsonConversionFailure))

}

} else {

completion(.Error(.invalidData))

}

} else {

completion(.Error(.responseUnsuccessful))

print("\(error)")

}

}

return task

}

}

enum Result<T> {

case Success(T)

case Error(ItunesAPIError)

}

enum ItunesAPIError: Error {

case requestFailed

case jsonConversionFailure

case invalidData

case responseUnsuccessful

case invalidURL

case jsonParsingFailure

}