Merge pull request #308 from MacMagazine/fix/feed-category-reconciliation

fix(#297): reconcile FeedDB category membership on each fetch

Author: cassio-rossi

MacMagazine/Features/FeedLibrary/Sources/FeedLibrary/Services/StorageService.swift

@@ -21,6 +21,24 @@ extension Database {
         save(feed: feed, in: sharedModelContainer.mainContext)
     }
 
+    /// Saves category-specific fetch results and reconciles stale category membership.
+    ///
+    /// Each group's synthetic category key (`NewsCategory.filterKey`) is added to matching posts
+    /// as usual, then removed from any locally stored post whose `pubDate` falls inside the
+    /// group's fetched date range but which the fetch no longer returned - covering the case
+    /// where the server removed a post from that category (e.g. a de-highlighted post).
+    @MainActor
+    func save(feed groups: [(category: NewsCategory, posts: [FeedDB])]) {
+        let ctx = sharedModelContainer.mainContext
+        for group in groups {
+            group.posts.forEach {
+                _ = save(feed: $0, in: ctx)
+            }
+            reconcile(category: group.category, fetched: group.posts, in: ctx)
+        }
+        FeedDB.deduplicate(using: ctx)
+    }
+
     @MainActor
     private func save(feed: FeedDB, in ctx: ModelContext) -> FeedDB {
         let postId = feed.postId
@@ -44,6 +62,37 @@ extension Database {
         try? ctx.save()
         return feed
     }
+
+    /// Categories whose membership is reconciled (added and removed) on each fetch.
+    ///
+    /// `.news` is excluded: it represents the unfiltered feed, so removal has no meaning there
+    /// and its date window is the widest, making false-positive removals most likely.
+    private static let reconcilableCategories: Set<NewsCategory> = [
+        .highlights, .appletv, .reviews, .tutorials, .rumors
+    ]
+
+    @MainActor
+    private func reconcile(category: NewsCategory, fetched: [FeedDB], in ctx: ModelContext) {
+        guard Self.reconcilableCategories.contains(category),
+              let windowStart = fetched.map(\.pubDate).min(),
+              let windowEnd = fetched.map(\.pubDate).max() else { return }
+
+        let key = category.filterKey
+        let fetchedIds = Set(fetched.map(\.postId))
+        let descriptor = FetchDescriptor<FeedDB>(
+            predicate: #Predicate { $0.pubDate >= windowStart && $0.pubDate <= windowEnd }
+        )
+
+        guard let candidates = try? ctx.fetch(descriptor) else { return }
+        let stale = candidates.filter { $0.categories.contains(key) && !fetchedIds.contains($0.postId) }
+        guard !stale.isEmpty else { return }
+
+        for post in stale {
+            post.categories.removeAll { $0 == key }
+            post.modifiedAt = Date()
+        }
+        try? ctx.save()
+    }
 }
 
 // MARK: - Podcast -

MacMagazine/Features/FeedLibrary/Sources/FeedLibrary/ViewModel/FeedViewModel.swift

@@ -47,10 +47,17 @@ public class FeedViewModel {
                 async let reviews = self.fetch(category: .reviews, page: page)
                 async let tutoriais = self.fetch(category: .tutorials, page: page)
                 async let rumors = self.fetch(category: .rumors, page: page)
-                let feed = try await [highlights, appletv, reviews, tutoriais, rumors]
-                self.storage.save(feed: Array(feed.joined()).toFeedDB)
-                let posts = try await self.fetch(category: .news, page: page)
-                self.storage.save(feed: posts.toFeedDB)
+                async let news = self.fetch(category: .news, page: page)
+
+                let groups: [(category: NewsCategory, posts: [FeedDB])] = [
+                    (.highlights, try await highlights.toFeedDB),
+                    (.appletv, try await appletv.toFeedDB),
+                    (.reviews, try await reviews.toFeedDB),
+                    (.tutorials, try await tutoriais.toFeedDB),
+                    (.rumors, try await rumors.toFeedDB),
+                    (.news, try await news.toFeedDB)
+                ]
+                self.storage.save(feed: groups)
             }.value
             status = .done
         } catch {

MacMagazine/Features/FeedLibrary/Tests/FeedLibraryTests/StorageServiceTests.swift

@@ -1,5 +1,6 @@
 @testable import FeedLibrary
 import Foundation
+import MacMagazineLibrary
 import StorageLibrary
 import Testing
 
@@ -379,6 +380,126 @@ struct StorageServiceTests {
         #expect(cats.contains("Reviews"))
     }
 
+    // MARK: - Category Reconciliation Tests
+
+    @Test("grouped save inserts a post carrying its fetched category key")
+    func groupedSaveAddsCategoryKey() {
+        let storage = Database(models: [FeedDB.self], inMemory: true)
+        let post = FeedDB(postId: "1", title: "Rumor", pubDate: Date(), categories: [NewsCategory.rumors.filterKey])
+
+        storage.save(feed: [(category: NewsCategory.rumors, posts: [post])])
+
+        let fetched = storage.fetch(FeedDB.self).first
+        #expect(fetched?.categories.contains(NewsCategory.rumors.filterKey) == true)
+    }
+
+    @Test("grouped save removes a stale category key for a post that dropped out of its date window")
+    func groupedSaveRemovesStaleCategoryKey() {
+        let storage = Database(models: [FeedDB.self], inMemory: true)
+        let earlier = Date(timeIntervalSince1970: 900_000)
+        let dehighlightedDate = Date(timeIntervalSince1970: 1_000_000)
+        let later = Date(timeIntervalSince1970: 1_100_000)
+
+        let dehighlighted = FeedDB(
+            postId: "1",
+            title: "No Longer Highlighted",
+            pubDate: dehighlightedDate,
+            categories: [NewsCategory.highlights.filterKey]
+        )
+        storage.save(feed: dehighlighted)
+
+        let before = FeedDB(postId: "2", title: "Before", pubDate: earlier, categories: [NewsCategory.highlights.filterKey])
+        let after = FeedDB(postId: "3", title: "After", pubDate: later, categories: [NewsCategory.highlights.filterKey])
+
+        storage.save(feed: [(category: NewsCategory.highlights, posts: [before, after])])
+
+        let predicate = #Predicate<FeedDB> { $0.postId == "1" }
+        let fetched = storage.fetch(FeedDB.self, predicate: predicate).first
+        #expect(fetched?.categories.contains(NewsCategory.highlights.filterKey) == false)
+    }
+
+    @Test("grouped save never touches a sibling category's key while reconciling")
+    func groupedSavePreservesSiblingCategoryKey() {
+        let storage = Database(models: [FeedDB.self], inMemory: true)
+        let date = Date(timeIntervalSince1970: 1_000_000)
+
+        let multiCategory = FeedDB(
+            postId: "1",
+            title: "Review And Rumor",
+            pubDate: date,
+            categories: [NewsCategory.reviews.filterKey, NewsCategory.rumors.filterKey]
+        )
+        storage.save(feed: multiCategory)
+
+        let otherReview = FeedDB(postId: "2", title: "Other Review", pubDate: date, categories: [NewsCategory.reviews.filterKey])
+        storage.save(feed: [(category: NewsCategory.reviews, posts: [otherReview])])
+
+        let predicate = #Predicate<FeedDB> { $0.postId == "1" }
+        let fetched = storage.fetch(FeedDB.self, predicate: predicate).first
+        #expect(fetched?.categories.contains(NewsCategory.reviews.filterKey) == false)
+        #expect(fetched?.categories.contains(NewsCategory.rumors.filterKey) == true)
+    }
+
+    @Test("grouped save skips reconciliation when the fetched category result is empty")
+    func groupedSaveSkipsReconciliationForEmptyResult() {
+        let storage = Database(models: [FeedDB.self], inMemory: true)
+        let highlighted = FeedDB(
+            postId: "1",
+            title: "Highlight",
+            pubDate: Date(),
+            categories: [NewsCategory.highlights.filterKey]
+        )
+        storage.save(feed: highlighted)
+
+        storage.save(feed: [(category: NewsCategory.highlights, posts: [])])
+
+        let fetched = storage.fetch(FeedDB.self).first
+        #expect(fetched?.categories.contains(NewsCategory.highlights.filterKey) == true)
+    }
+
+    @Test("grouped save leaves a category key untouched when the post falls outside the fetched date window")
+    func groupedSavePreservesKeyOutsideDateWindow() {
+        let storage = Database(models: [FeedDB.self], inMemory: true)
+        let farInThePast = Date(timeIntervalSince1970: 0)
+        let recent = Date(timeIntervalSince1970: 2_000_000)
+
+        let oldHighlight = FeedDB(
+            postId: "1",
+            title: "Old Highlight",
+            pubDate: farInThePast,
+            categories: [NewsCategory.highlights.filterKey]
+        )
+        storage.save(feed: oldHighlight)
+
+        let recentHighlight = FeedDB(postId: "2", title: "Recent Highlight", pubDate: recent, categories: [NewsCategory.highlights.filterKey])
+        storage.save(feed: [(category: NewsCategory.highlights, posts: [recentHighlight])])
+
+        let predicate = #Predicate<FeedDB> { $0.postId == "1" }
+        let fetched = storage.fetch(FeedDB.self, predicate: predicate).first
+        #expect(fetched?.categories.contains(NewsCategory.highlights.filterKey) == true)
+    }
+
+    @Test("grouped save does not reconcile the news category")
+    func groupedSaveDoesNotReconcileNewsCategory() {
+        let storage = Database(models: [FeedDB.self], inMemory: true)
+        let date = Date(timeIntervalSince1970: 1_000_000)
+
+        let post = FeedDB(
+            postId: "1",
+            title: "Old News Marker",
+            pubDate: date,
+            categories: [NewsCategory.news.filterKey]
+        )
+        storage.save(feed: post)
+
+        let otherPost = FeedDB(postId: "2", title: "Other Post", pubDate: date, categories: [NewsCategory.news.filterKey])
+        storage.save(feed: [(category: NewsCategory.news, posts: [otherPost])])
+
+        let predicate = #Predicate<FeedDB> { $0.postId == "1" }
+        let fetched = storage.fetch(FeedDB.self, predicate: predicate).first
+        #expect(fetched?.categories.contains(NewsCategory.news.filterKey) == true)
+    }
+
     @Test("save should preserve favorite status on update for podcast")
     func savePreservesFavoriteStatusForPodcast() {
         let storage = Database(models: [PodcastDB.self], inMemory: true)