1//
2//  Helpers.swift
3//  BlinkReviewer
4//
5//  Created by Alex Chan on 08/06/2023.
6//
7
8import Foundation
9import Photos
10
11extension PHAsset {
12    /// Returns a list of all the albums that contain this asset.
13    func albums() -> [PHAssetCollection] {
14        var result: [PHAssetCollection] = []
15        
16        PHAssetCollection
17            .fetchAssetCollectionsContaining(self, with: .album, options: nil)
18            .enumerateObjects({ (collection, index, stop) in
19                result.append(collection)
20            })
21        
22        return result
23    }
24    
25    func originalFilename() -> String {
26        PHAssetResource.assetResources(for: self).first!.originalFilename
27    }
28
29    /// Returns true if an asset is in the given album, false otherwise.
30    private func isInAlbum(_ album: PHAssetCollection) -> Bool {
31        return albums().contains(where: { collection in
32            collection == album
33        })
34    }
35    
36    /// Remove a photo from an album.
37    ///
38    /// This expects to be run inside a performChangesAndWait change block;
39    /// see https://developer.apple.com/documentation/photokit/phphotolibrary/1620747-performchangesandwait.
40    func remove(fromAlbum album: PHAssetCollection) -> Void {
41      let changeAlbum =
42        PHAssetCollectionChangeRequest(for: album)!
43
44      changeAlbum.removeAssets([self] as NSFastEnumeration)
45    }
46
47    /// Add a photo to an album.
48    ///
49    /// This expects to be run inside a performChangesAndWait change block;
50    /// see https://developer.apple.com/documentation/photokit/phphotolibrary/1620747-performchangesandwait.
51    func add(toAlbum album: PHAssetCollection) -> Void {
52      let changeAlbum =
53        PHAssetCollectionChangeRequest(for: album)!
54
55      changeAlbum.addAssets([self] as NSFastEnumeration)
56    }
57    
58    /// Toggle a photo's inclusion in an album.
59    ///
60    /// If the photo is already in the album, remove it.  If the photo isn't
61    /// in the album, add it.
62    ///
63    /// This expects to be run inside a performChangesAndWait change block;
64    /// see https://developer.apple.com/documentation/photokit/phphotolibrary/1620747-performchangesandwait.
65    func toggle(inAlbum album: PHAssetCollection) -> Void {
66      let changeAlbum =
67        PHAssetCollectionChangeRequest(for: album)!
68
69      let assets = [self] as NSFastEnumeration
70
71      if self.isInAlbum(album) {
72        changeAlbum.removeAssets(assets)
73      } else {
74        changeAlbum.addAssets(assets)
75      }
76    }
77}