//
  //  ALImageFetchingInteractor.swift
  //  ALImagePickerViewController
  //
  //  Created by Alex Littlejohn on 2015/06/09.
  //  Copyright (c) 2015 zero. All rights reserved.
  //
  
  import UIKit
  import Photos
  
  public typealias ImageFetcherSuccess = (PHFetchResult<PHAsset>) -> ()
  public typealias ImageFetcherFailure = (NSError) -> ()
  
  //extension PHFetchResult: Sequence {
  //    public func makeIterator() -> NSFastEnumerationIterator {
  //        return NSFastEnumerationIterator(self)
  //    }
  //}
  
  public class ImageFetcher {
  
      private var success: ImageFetcherSuccess?
      private var failure: ImageFetcherFailure?
      
      private var authRequested = false
      private let errorDomain = "com.zero.imageFetcher"
      
      let libraryQueue = DispatchQueue(label: "com.zero.ALCameraViewController.LibraryQueue");
      
      public init() { }
      
      public func onSuccess(_ success: @escaping ImageFetcherSuccess) -> Self {
          self.success = success
          return self
      }
      
      public func onFailure(_ failure: @escaping ImageFetcherFailure) -> Self {
          self.failure = failure
          return self
      }
      
      public func fetch() -> Self {
          _ = PhotoLibraryAuthorizer { error in
              if error == nil {
                  self.onAuthorized()
              } else {
                  self.failure?(error!)
              }
          }
          return self
      }
      
      private func onAuthorized() {
          let options = PHFetchOptions()
          options.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
          libraryQueue.async {
              let assets = PHAsset.fetchAssets(with: PHAssetMediaType.image, options: options)
              DispatchQueue.main.async {
                  self.success?(assets)
              }
          }
      }
  }