Caps-iOS/CapCollector/Presentation/ImageSelector.swift

//
//  ListViewController.swift
//  CapFinder
//
//  Created by User on 22.02.18.
//  Copyright © 2018 User. All rights reserved.
//

import UIKit
import SwiftyDropbox

class ImageSelector: UIViewController {

    // MARK: - Constants

    /// The number of items per row
    private let itemsPerRow: CGFloat = 3
    
    override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
        return .portrait
    }
    
    override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation {
        return .portrait
    }
    
    override var shouldAutorotate: Bool {
        return false
    }

    // MARK: - CollectionView

    private var images = [UIImage?]()

    var cap: Cap!

    @IBOutlet weak var collection: UICollectionView!

    // MARK: - Life cycle

    override func viewDidLoad() {
        super.viewDidLoad()

        collection.dataSource = self
        collection.delegate = self
    }

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

        downloadImages()
    }

    // MARK: Image download

    private func downloadImages() {
        images = [UIImage?](repeating: nil, count: cap.count)
        event("\(cap.count) images for cap \(cap.id)")
        for number in 0..<cap.count {
            cap.downloadImage(number) { image in
                self.images[number] = image
                self.collection.reloadItems(at: [IndexPath(row: number, section: 0)])
            }
        }
    }

    // MARK: Select

    private func selectedImage(nr: Int) {
        guard images[nr] != nil else {
            return
        }
        
        let tempId = cap.count
        let tempFile = "/Images/\(cap.id)/\(cap.id)-\(tempId).jpg"
        let oldFile = "/Images/\(cap.id)/\(cap.id)-0.jpg"
        let newFile = "/Images/\(cap.id)/\(cap.id)-\(nr).jpg"
        guard oldFile != newFile else {
            return
        }
        DropboxController.shared.move(file: oldFile, to: tempFile) { success in
            guard success else {
                self.error("Could not move \(oldFile) to \(tempFile)")
                return
            }
            DropboxController.shared.move(file: newFile, to: oldFile) { success in
                guard success else {
                    self.error("Could not move \(newFile) to \(oldFile)")
                    return
                }
                DropboxController.shared.move(file: tempFile, to: newFile) { success in
                    if !success {
                        self.error("Could not move \(tempFile) to \(newFile)")
                    }
                    self.finish(with: nr)
                }
            }
        }
    }

    private func finish(with nr: Int) {
        let image = images[nr]!
        guard cap.save(mainImage: image) else {
            return
        }
        event("Successfully switched image")
    }
}

// MARK: - UICollectionViewDataSource

extension ImageSelector: UICollectionViewDataSource {

    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return images.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(
            withReuseIdentifier: "Image",
            for: indexPath) as! ImageCell

        cell.capView.image = images[indexPath.row]
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        selectedImage(nr: indexPath.row)
        navigationController?.popViewController(animated: true)
    }
}

// MARK: - UICollectionViewDelegateFlowLayout

extension ImageSelector : UICollectionViewDelegateFlowLayout {

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {
        let widthPerItem = collectionView.frame.width / itemsPerRow
        return CGSize(width: widthPerItem, height: widthPerItem)
    }

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
    }

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 0
    }
}

extension ImageSelector: Logger {

    static let logToken = "[ImageSelector]"
}