feat(mobile): cache latest ios widget entry for fallback (#19824)

* cache the last image an ios widget fetched and use if a fetch fails in a future timeline build

* code review fixes

* downgrade pbx for flutter

* use cache in snapshots

Author: bwees

mobile/ios/WidgetExtension/EntryGenerators.swift

@@ -0,0 +1,161 @@
+import SwiftUI
+import WidgetKit
+
+typealias EntryMetadata = ImageEntry.Metadata
+
+struct ImageEntry: TimelineEntry {
+  let date: Date
+  var image: UIImage?
+  var metadata: Metadata = Metadata()
+
+  struct Metadata: Codable {
+    var subtitle: String? = nil
+    var error: WidgetError? = nil
+    var deepLink: URL? = nil
+  }
+
+  // Resizes the stored image to a maximum width of 450 pixels
+  mutating func resize() {
+    if image == nil || image!.size.height < 450 || image!.size.width < 450 {
+      return
+    }
+
+    image = image?.resized(toWidth: 450)
+
+    if image == nil {
+      metadata.error = .unableToResize
+    }
+  }
+
+  static func build(
+    api: ImmichAPI,
+    asset: Asset,
+    dateOffset: Int,
+    subtitle: String? = nil
+  )
+    async throws -> Self
+  {
+    let entryDate = Calendar.current.date(
+      byAdding: .minute,
+      value: dateOffset * 20,
+      to: Date.now
+    )!
+    let image = try await api.fetchImage(asset: asset)
+
+    return Self(
+      date: entryDate,
+      image: image,
+      metadata: EntryMetadata(
+        subtitle: subtitle,
+        deepLink: asset.deepLink
+      )
+    )
+  }
+
+  func cache(for key: String) throws {
+    if let containerURL = FileManager.default.containerURL(
+      forSecurityApplicationGroupIdentifier: IMMICH_SHARE_GROUP
+    ) {
+      let imageURL = containerURL.appendingPathComponent("\(key)_image.png")
+      let metadataURL = containerURL.appendingPathComponent(
+        "\(key)_metadata.json"
+      )
+
+      // build metadata JSON
+      let entryMetadata = try JSONEncoder().encode(self.metadata)
+
+      // write to disk
+      try self.image?.pngData()?.write(to: imageURL, options: .atomic)
+      try entryMetadata.write(to: metadataURL, options: .atomic)
+    }
+  }
+
+  static func loadCached(for key: String, at date: Date = Date.now)
+    -> ImageEntry?
+  {
+    if let containerURL = FileManager.default.containerURL(
+      forSecurityApplicationGroupIdentifier: IMMICH_SHARE_GROUP
+    ) {
+      let imageURL = containerURL.appendingPathComponent("\(key)_image.png")
+      let metadataURL = containerURL.appendingPathComponent(
+        "\(key)_metadata.json"
+      )
+
+      guard let imageData = try? Data(contentsOf: imageURL),
+        let metadataJSON = try? Data(contentsOf: metadataURL),
+        let decodedMetadata = try? JSONDecoder().decode(Metadata.self, from: metadataJSON)
+      else {
+        return nil
+      }
+
+      return ImageEntry(
+        date: date,
+        image: UIImage(data: imageData),
+        metadata: decodedMetadata
+      )
+    }
+
+    return nil
+  }
+
+  static func handleCacheFallback(
+    for key: String,
+    error: WidgetError = .fetchFailed
+  ) -> Timeline<ImageEntry> {
+    var timelineEntry = ImageEntry(
+      date: Date.now,
+      image: nil,
+      metadata: EntryMetadata(error: error)
+    )
+
+    // skip cache if album not found or no login
+    // we want to show these errors to the user since without intervention,
+    // it will never succeed
+    if error != .noLogin && error != .albumNotFound {
+      if let cachedEntry = ImageEntry.loadCached(for: key) {
+        timelineEntry = cachedEntry
+      }
+    }
+
+    return Timeline(entries: [timelineEntry], policy: .atEnd)
+  }
+}
+
+func generateRandomEntries(
+  api: ImmichAPI,
+  now: Date,
+  count: Int,
+  albumId: String? = nil,
+  subtitle: String? = nil
+)
+  async throws -> [ImageEntry]
+{
+
+  var entries: [ImageEntry] = []
+  let albumIds = albumId != nil ? [albumId!] : []
+
+  let randomAssets = try await api.fetchSearchResults(
+    with: SearchFilters(size: count, albumIds: albumIds)
+  )
+
+  await withTaskGroup(of: ImageEntry?.self) { group in
+    for (dateOffset, asset) in randomAssets.enumerated() {
+      group.addTask {
+        return try? await ImageEntry.build(
+          api: api,
+          asset: asset,
+          dateOffset: dateOffset,
+          subtitle: subtitle
+        )
+      }
+    }
+
+    for await result in group {
+      if let entry = result {
+        entries.append(entry)
+      }
+    }
+  }
+
+  return entries
+}

mobile/ios/WidgetExtension/ImageEntry.swift

@@ -1,35 +1,14 @@
 import SwiftUI
 import WidgetKit
 
-struct ImageEntry: TimelineEntry {
-  let date: Date
-  var image: UIImage?
-  var subtitle: String? = nil
-  var error: WidgetError? = nil
-  var deepLink: URL? = nil
-
-  // Resizes the stored image to a maximum width of 450 pixels
-  mutating func resize() {
-    if (image == nil || image!.size.height < 450 || image!.size.width < 450 ) {
-      return
-    }
-    
-    image = image?.resized(toWidth: 450)
-    
-    if image == nil {
-      error = .unableToResize
-    }
-  }
-}
-
 struct ImmichWidgetView: View {
   var entry: ImageEntry
 
   var body: some View {
     if entry.image == nil {
       VStack {
         Image("LaunchImage")
-        Text(entry.error?.errorDescription ?? "")
+        Text(entry.metadata.error?.errorDescription ?? "")
           .minimumScaleFactor(0.25)
           .multilineTextAlignment(.center)
           .foregroundStyle(.secondary)
@@ -44,7 +23,7 @@ struct ImmichWidgetView: View {
         )
         VStack {
           Spacer()
-          if let subtitle = entry.subtitle {
+          if let subtitle = entry.metadata.subtitle {
             Text(subtitle)
               .foregroundColor(.white)
               .padding(8)
@@ -55,7 +34,7 @@ struct ImmichWidgetView: View {
         }
         .padding(16)
       }
-      .widgetURL(entry.deepLink)
+      .widgetURL(entry.metadata.deepLink)
     }
   }
 }
@@ -70,7 +49,9 @@ struct ImmichWidgetView: View {
     ImageEntry(
       date: date,
       image: UIImage(named: "ImmichLogo"),
-      subtitle: "1 year ago"
+      metadata: EntryMetadata(
+        subtitle: "1 year ago"
+      )
     )
   }
 )

mobile/ios/WidgetExtension/ImageWidgetView.swift

@@ -2,7 +2,7 @@ import Foundation
 import SwiftUI
 import WidgetKit
 
-enum WidgetError: Error {
+enum WidgetError: Error, Codable {
   case noLogin
   case fetchFailed
   case unknown
@@ -23,10 +23,10 @@ extension WidgetError: LocalizedError {
 
     case .albumNotFound:
       return "Album not found"
-        
+
     case .invalidURL:
       return "An invalid URL was used"
-        
+
     case .invalidImage:
       return "An invalid image was received"
 
@@ -46,7 +46,7 @@ enum AssetType: String, Codable {
 struct Asset: Codable {
   let id: String
   let type: AssetType
-  
+
   var deepLink: URL? {
     return URL(string: "immich://asset?id=\(id)")
   }
@@ -75,6 +75,8 @@ struct Album: Codable {
   let albumName: String
 }
 
+let IMMICH_SHARE_GROUP = "group.app.immich.share"
+
 // MARK: API
 
 class ImmichAPI {
@@ -86,7 +88,7 @@ class ImmichAPI {
 
   init() async throws {
     // fetch the credentials from the UserDefaults store that dart placed here
-    guard let defaults = UserDefaults(suiteName: "group.app.immich.share"),
+    guard let defaults = UserDefaults(suiteName: IMMICH_SHARE_GROUP),
       let serverURL = defaults.string(forKey: "widget_server_url"),
       let sessionKey = defaults.string(forKey: "widget_auth_token")
     else {
@@ -189,18 +191,25 @@ class ImmichAPI {
     else {
       throw .invalidURL
     }
-    
-    guard let imageSource = CGImageSourceCreateWithURL(fetchURL as CFURL, nil) else {
+
+    guard let imageSource = CGImageSourceCreateWithURL(fetchURL as CFURL, nil)
+    else {
       throw .invalidURL
     }
 
     let decodeOptions: [NSString: Any] = [
-        kCGImageSourceCreateThumbnailFromImageAlways: true,
-        kCGImageSourceThumbnailMaxPixelSize: 400,
-        kCGImageSourceCreateThumbnailWithTransform: true
+      kCGImageSourceCreateThumbnailFromImageAlways: true,
+      kCGImageSourceThumbnailMaxPixelSize: 400,
+      kCGImageSourceCreateThumbnailWithTransform: true,
     ]
-    
-    guard let thumbnail = CGImageSourceCreateThumbnailAtIndex(imageSource, 0, decodeOptions as CFDictionary) else {
+
+    guard
+      let thumbnail = CGImageSourceCreateThumbnailAtIndex(
+        imageSource,
+        0,
+        decodeOptions as CFDictionary
+      )
+    else {
       throw .fetchFailed
     }
 

mobile/ios/WidgetExtension/ImmichAPI.swift

@@ -7,14 +7,17 @@
 import UIKit
 
 extension UIImage {
-    /// Crops the image to ensure width and height do not exceed maxSize.
-    /// Keeps original aspect ratio and crops excess equally from edges (center crop).
-    func resized(toWidth width: CGFloat, isOpaque: Bool = true) -> UIImage? {
-      let canvas = CGSize(width: width, height: CGFloat(ceil(width/size.width * size.height)))
-      let format = imageRendererFormat
-      format.opaque = isOpaque
-      return UIGraphicsImageRenderer(size: canvas, format: format).image {
-        _ in draw(in: CGRect(origin: .zero, size: canvas))
-      }
+  /// Crops the image to ensure width and height do not exceed maxSize.
+  /// Keeps original aspect ratio and crops excess equally from edges (center crop).
+  func resized(toWidth width: CGFloat, isOpaque: Bool = true) -> UIImage? {
+    let canvas = CGSize(
+      width: width,
+      height: CGFloat(ceil(width / size.width * size.height))
+    )
+    let format = imageRendererFormat
+    format.opaque = isOpaque
+    return UIGraphicsImageRenderer(size: canvas, format: format).image {
+      _ in draw(in: CGRect(origin: .zero, size: canvas))
     }
+  }
 }