LivePhotoUtil.swift

//
//  LivePhotoUtil.swift
//  Blink
//
//  Created by Shane Vitarana on 6/2/17.
//  Copyright © 2017 Blink. All rights reserved.
//

import Alamofire
import BlinkApi
import Photos
import ReactiveSwift
import Result

final class LivePhotoUtil {
  let imageFileUrlProperty = MutableProperty<URL?>(nil)
  let videoFileUrlProperty = MutableProperty<URL?>(nil)
  let livePhotoComponents: Signal<(URL?, URL?), NoError>

  init() {
    livePhotoComponents = Property.combineLatest(imageFileUrlProperty, videoFileUrlProperty)
      .signal
  }

  func build(imageFileUrl: URL, videoFileUrl: URL) -> SignalProducer<PHLivePhoto, ClientError> {
    return SignalProducer { observer, _ in
      PHLivePhoto.request(
        withResourceFileURLs: [imageFileUrl, videoFileUrl],
        placeholderImage: nil,
        targetSize: .zero,
        contentMode: .default) { livePhoto, _ in
          guard let livePhoto = livePhoto else {
            observer.send(error: .livePhoto)
            return
          }
          observer.send(value: livePhoto)
      }
    }
  }

  func download(imageUrlString: String, videoUrlString: String) {
    download(urlString: imageUrlString, fileExtension: "jpg")
      .startWithResult { result in
        if let url = result.value {
          self.imageFileUrlProperty.value = url
        }
    }

    download(urlString: videoUrlString, fileExtension: "mov")
      .startWithResult { result in
        if let url = result.value {
          self.videoFileUrlProperty.value = url
        }
    }
  }
}

private extension LivePhotoUtil {
  func download(urlString: String, fileExtension: String) -> SignalProducer<URL, NoError> {
    return SignalProducer { observer, _ in
      let destination: DownloadRequest.DownloadFileDestination = { _, _ in
        let documentsURL = FileManager.default.urls(
          for: .documentDirectory,
          in: .userDomainMask)[0]
        let fileURL = documentsURL.appendingPathComponent("\(UUID().uuidString).\(fileExtension)")
        return (fileURL, [.removePreviousFile, .createIntermediateDirectories])
      }

      Alamofire.download(urlString, to: destination)
        .response { (response) in
          if response.error == nil, let fileUrl = response.destinationURL {
            observer.send(value: fileUrl)
          }
      }
    }
  }
}