persephone/Persephone/Controllers/AlbumViewController.swift

//
//  AlbumViewController.swift
//  Persephone
//
//  Created by Daniel Barber on 2019/2/08.
//  Copyright © 2019 Dan Barber. All rights reserved.
//

import Cocoa
import ReSwift
import Differ

class AlbumViewController: NSViewController,
                           NSCollectionViewDelegate,
                           NSCollectionViewDelegateFlowLayout {
  let paddingWidth: CGFloat = 40
  let gutterWidth: CGFloat = 20

  var dataSource = AlbumDataSource()

  override func viewDidLoad() {
    super.viewDidLoad()

    AppDelegate.store.subscribe(self) {
      $0.select { $0.albumListState }
    }

    albumScrollView.postsBoundsChangedNotifications = true

    albumCollectionView.dataSource = dataSource
  }

  override func viewWillLayout() {
    super.viewWillLayout()

    if let layout = albumCollectionView.collectionViewLayout as? AlbumViewLayout {
      layout.saveScrollPosition()
    }

    albumCollectionView.collectionViewLayout?.invalidateLayout()
  }

  override func viewDidLayout() {
    super.viewDidLayout()

    guard let layout = albumCollectionView.collectionViewLayout as? AlbumViewLayout
      else { return }

    layout.setScrollPosition()
  }

  override func observeValue(
    forKeyPath keyPath: String?,
    of object: Any?,
    change: [NSKeyValueChangeKey : Any]?,
    context: UnsafeMutableRawPointer?
    ) {
    switch keyPath {
    case "mpdLibraryDir":
      albumCollectionView.reloadData()
    case "fetchMissingArtworkFromInternet":
      AppDelegate.store.dispatch(ResetAlbumListCoverArtAction())
    default:
      break
    }
  }

  @IBOutlet var albumScrollView: NSScrollView!
  @IBOutlet var albumCollectionView: NSCollectionView!
}

extension AlbumViewController: StoreSubscriber {
  typealias StoreSubscriberStateType = AlbumListState

  func newState(state: StoreSubscriberStateType) {
    let oldAlbums = dataSource.albums
    dataSource.albums = state.albums
    albumCollectionView.animateItemChanges(
      oldData: oldAlbums,
      newData: dataSource.albums
    )
  }
}