import GoogleMobileAds  
import UIKit 

class ResponsiveAdDelegateViewController: UIViewController, GADAdSizeDelegate {
  
  /// The custom banner size (320x480) switch.    
  @IBOutlet weak var GADAdSizeCustomBannerSwitch: UISwitch!   

  /// The medium rectangle size (300x250) switch.    
  @IBOutlet weak var GADAdSizeMediumRectangleSwitch: UISwitch! 
  
  /// The DFP banner view. It's DFPBannerView not GADBannerView right? 
  var bannerView: DFPBannerView!  

  override func viewDidLoad() {
    super.viewDidLoad()
    
    bannerView = DFPBannerView(adSize: kGADAdSizeMediumRectangle)  

    bannerView.delegate = self
    // You have to set ID and what's the view controller
    // Ad Unit ID has to be set up in DV360
    bannerView.adUnitID = "/6499/example/banner"
    bannerView.rootViewController = self
   
    // Ad Size Delegate, so adView can be called in the bottom
    bannerView.adSizeDelegate = self

    // Add it into the view
    addBannerViewToView(bannerView)

    // Let's load an ad into it (whenever you want to do it)
    bannerView.load(GADRequest())
  }

  func addBannerViewToView(_ bannerView: DFPBannerView) {
    bannerView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(bannerView)
    view.addConstraints(
      [NSLayoutConstraint(item: bannerView,
                          attribute: .bottom,
                          relatedBy: .equal,
                          toItem: bottomLayoutGuide,
                          attribute: .top,
                          multiplier: 1,
                          constant: 0),
       NSLayoutConstraint(item: bannerView,
                          attribute: .centerX,
                          relatedBy: .equal,
                          toItem: view,
                          attribute: .centerX,
                          multiplier: 1,
                          constant: 0)
      ])

     guard GADAdSizeCustomBannerSwitch.isOn ||     GADAdSizeMediumRectangleSwitch.isOn else {
       let alert = UIAlertView(title: "Load Ad Error",
          message: "Failed to load ad. Please select at least one ad size.",
          delegate: self,
          cancelButtonTitle: "OK")
       alert.alertViewStyle = .default
       alert.show()
       return
     }

     var adSizes = [NSValue]()
     
     // Let's add the valid Scroller Placement
     if GADAdSizeCustomBannerSwitch.isOn {
       let scrollerGADAdSize = GADAdSizeFromCGSize(CGSize(width: 320, height: 480))
       adSizes.append(NSValueFromGADAdSize(scrollerGADAdSize))
     }
     if GADAdSizeMediumRectangleSwitch.isOn {
       adSizes.append(NSValueFromGADAdSize(kGADAdSizeMediumRectangle))
     }

     bannerView.validAdSizes = adSizes
   }

   /// Called before the ad view changes to the new size.
   /// Initiated by the view delegate that's set via `bannerView.adSizeDelegate = self` above 
   func adView(_ bannerView: DFPBannerView, willChangeAdSizeTo size: GADAdSize) {
     // The bannerView calls this method on its adSizeDelegate object before the banner updates its
     // size, allowing the application to adjust any views that may be affected by the new ad size.
     print("Make your app layout changes here, if necessary. New banner ad size will be \(size\).")
   }
}

func updateBannerSize(_ bannerView: DFPBannerView, willChangeAdSizeTo size: GADAdSize) {
  let width = size.size.width
  let height = size.size.height
  let ratio = height/width
  
  let newWidth = view.bounds.width
  
  // We assume that 320 means full width and 300 means with 10px padding on left and right
  // Change the padding to what you have normal in your feed
  let feedPadding = 10
  if width != 320 {
     newWidth = newWidth - (feedPadding * 2)
  }
 
  let newHeight = ( newWidth * ratio )

  var frameRect = bannerView.frame
  frameRect.size.width = newWidth
  frameRect.size.height = newHeight
  bannerView.frame = frameRect
}

func adView(_ bannerView: DFPBannerView, willChangeAdSizeTo size: GADAdSize) {  
  ...
  
  updateBannerSize(bannerView, size)

  ...
}

class ResponsiveAdDelegateViewController: UIViewController, GADAppEventDelegate {
     func viewDidLoad() {
          ...
          bannerView.appEventDelegate = self
          ...
     }

     func adView(_ bannerView: DFPBannerView, didReceiveAppEvent name: String,
    withInfo info: String?) {
    if name == "ad.size" {
      guard let info = info else { return }
      
      // I'm using JSON String Parser defined below, use the one you prefer
      let size: AnyObject? = info.parseJSONString
      updateBannerSize(bannerView, GADAdSizeFromCGSize(CGSize(width: size.width, height: size.height)))
    }
  }
}

extension String {

    var parseJSONString: AnyObject? {

        let data = self.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)

        if let jsonData = data {
            // Will return an object or nil if JSON decoding fails
            return NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers, error: nil)
        } else {
            // Lossless conversion of the string was not possible
            return nil
        }
    }
}