ViewController.swift

//
//  ViewController.swift
//  RxSwiftExample
//
//  Created by Eunyeong Kim on 2020/05/27.
//  Copyright © 2020 Eunyeong Kim. All rights reserved.
//

import UIKit
import RxSwift
import RxCocoa

struct PhotoWriter {
    static func save(_ image: UIImage) -> Single<String> {
        Single.create { observer in
            return Disposables.create()
        }
    }
}

final class PhotosViewController: UIViewController {
    private let subject = PublishSubject<UIImage>()
    var selectedPhotos: Observable<UIImage> {
        return subject.asObservable()
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        subject.onCompleted()
    }

    private func selectImage(_ image: UIImage) {
        subject.onNext(image)
    }
}

final class ViewController: UIViewController {
    private let disposeBag = DisposeBag()
    private let images = BehaviorRelay<[UIImage]>(value: [])

    private let previewImage = UIImage()

    private let photosVC = PhotosViewController()

    override func viewDidLoad() {
        super.viewDidLoad()

        photosVC.selectedPhotos
            .subscribe(
                onNext: { [weak self] image in
                    self?.images.accept(self?.images.value ?? [] + [image])
                }
            )
            .disposed(by: disposeBag)

        images.subscribe { images in
            print(images.element?.count ?? "")
        }.disposed(by: disposeBag)
    }

}

private extension ViewController {
    func addImage(newImage: UIImage) {
        images.accept(images.value + [newImage])
    }

    func clearImages() {
        images.accept([])
    }

    func showMessage() {
        didTapCloseButton()
            .subscribe(
                onCompleted: { [weak self] in
                    self?.saveImage()
                    // self?.previewImage = nil
                    // closeVC()
                },
                onError: { error in
                    print(error)
                }
            )
            .disposed(by: disposeBag)
    }

    func didTapCloseButton() -> Completable {
        Completable.create { completable in
            return Disposables.create()
        }
    }

    func saveImage() {
        PhotoWriter.save(previewImage)
            .subscribe(
                onSuccess: { id in
                    print("Saved Photo ID is \(id)")
                }) { error in
                    print(error)
                }
            .disposed(by: disposeBag)
    }
}