Networking.swift

//
//  IGNNetworking.swift
//  Unofficial Metacritic
//
//  Created by Jordan Morgan on 8/21/16.
//  Copyright © 2016 Dreaming In Binary, LLC. All rights reserved.
//

import Foundation
import UIKit

typealias JSONDictionary = [String: AnyObject]

class Networking : NSObject
{
    private let defaultSession:NSURLSession
    private var dataTask: NSURLSessionDataTask?
    
    //MARK: Initializers
    override init()
    {
        defaultSession = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration())
        super.init()
    }
    
    
    init(withAdditionalHeaders headers:[String:AnyObject])
    {
        let sessionConfiguration = NSURLSessionConfiguration.defaultSessionConfiguration()
        sessionConfiguration.HTTPAdditionalHeaders = headers
        defaultSession = NSURLSession(configuration: sessionConfiguration)
        super.init()
    }
    
    //MARK: GET
    internal func GET(with givenURL:NSURL, completion: (JSONDictionary?, NetworkError?) -> ())
    {
        UIApplication.sharedApplication().networkActivityIndicatorVisible = true
        
        if dataTask != nil
        {
            dataTask?.cancel()
        }
        
        dataTask = defaultSession.dataTaskWithURL(givenURL) { data, response, error in
            
            dispatch_async(dispatch_get_main_queue())
            {
                UIApplication.sharedApplication().networkActivityIndicatorVisible = false
            }
            
            if let error = error
            {
                completion(nil, NetworkError(message: error.localizedDescription, errorType: .GeneralError))
            }
            else if let httpResponse = response as? NSHTTPURLResponse
            {
                guard httpResponse.statusCode == 200 else
                {
                    completion(nil, NetworkError(message: "Received an unexpected response from the server.", errorType: .BadResponse))
                    return
                }
                
                do
                {
                    let json = try NSJSONSerialization.JSONObjectWithData(data!, options: .AllowFragments) as? NSDictionary
                    
                    if let response = json as? JSONDictionary
                    {
                        completion(response, nil)
                    }
                    else
                    {
                        completion(nil, NetworkError(message: "Unable to parse JSON.", errorType: .JSONSerialization))
                    }
                    
                }
                catch
                {
                    completion(nil, NetworkError(message: "Unable to parse JSON.", errorType: .JSONSerialization))
                }
                
            }
        }
        
        dataTask?.resume()
    }
    
    //MARK: POST String Sanitization
    private func sanitizeText(from query:String) -> String
    {
        let expectedCharSet = NSCharacterSet.URLQueryAllowedCharacterSet()
        return query.stringByAddingPercentEncodingWithAllowedCharacters(expectedCharSet)!
    }
}