From 93ef6980d1103a2d4efbb7839d266fb555621ced Mon Sep 17 00:00:00 2001
From: Satindar Dhillon <satindar@gmail.com>
Date: Tue, 19 Apr 2022 12:08:19 -0700
Subject: [PATCH] fetch items from core data if network request fails

---
 .../App/Views/Home/HomeFeedViewModel.swift    |  3 +++
 .../Sources/Models/DataModels/FeedItem.swift  | 23 +++++++++++++++++++
 .../Queries/LibraryItemsQuery.swift           |  8 +++++++
 3 files changed, 34 insertions(+)

diff --git a/apple/OmnivoreKit/Sources/App/Views/Home/HomeFeedViewModel.swift b/apple/OmnivoreKit/Sources/App/Views/Home/HomeFeedViewModel.swift
index b20389a81..8da3422cb 100644
--- a/apple/OmnivoreKit/Sources/App/Views/Home/HomeFeedViewModel.swift
+++ b/apple/OmnivoreKit/Sources/App/Views/Home/HomeFeedViewModel.swift
@@ -76,6 +76,9 @@ import Views
       receiveCompletion: { [weak self] completion in
         guard case .failure = completion else { return }
         self?.isLoading = false
+        // return cachedItems found in CoreData when request fails
+        self?.items = dataService.cachedFeedItems()
+        self?.cursor = nil
       },
       receiveValue: { [weak self] result in
         // Search results aren't guaranteed to return in order so this
diff --git a/apple/OmnivoreKit/Sources/Models/DataModels/FeedItem.swift b/apple/OmnivoreKit/Sources/Models/DataModels/FeedItem.swift
index 9c162178f..c84bf93ca 100644
--- a/apple/OmnivoreKit/Sources/Models/DataModels/FeedItem.swift
+++ b/apple/OmnivoreKit/Sources/Models/DataModels/FeedItem.swift
@@ -166,6 +166,29 @@ public extension FeedItemDep {
 
     return linkedItem
   }
+
+  static func make(from item: LinkedItem) -> FeedItemDep {
+    FeedItemDep(
+      id: item.id ?? "",
+      title: item.title ?? "",
+      createdAt: item.createdAt ?? Date(),
+      savedAt: item.savedAt ?? Date(),
+      readingProgress: item.readingProgress,
+      readingProgressAnchor: Int(item.readingProgressAnchor),
+      imageURLString: item.imageURLString,
+      onDeviceImageURLString: item.onDeviceImageURLString,
+      documentDirectoryPath: nil,
+      pageURLString: item.pageURLString ?? "",
+      descriptionText: item.title,
+      publisherURLString: item.publisherURLString,
+      author: item.author,
+      publishDate: item.publishDate,
+      slug: item.slug ?? "",
+      isArchived: item.isArchived,
+      contentReader: item.contentReader,
+      labels: []
+    )
+  }
 }
 
 public extension Sequence where Element == FeedItemDep {
diff --git a/apple/OmnivoreKit/Sources/Services/DataService/Queries/LibraryItemsQuery.swift b/apple/OmnivoreKit/Sources/Services/DataService/Queries/LibraryItemsQuery.swift
index 5ec018a76..f00dc9466 100644
--- a/apple/OmnivoreKit/Sources/Services/DataService/Queries/LibraryItemsQuery.swift
+++ b/apple/OmnivoreKit/Sources/Services/DataService/Queries/LibraryItemsQuery.swift
@@ -1,4 +1,5 @@
 import Combine
+import CoreData
 import Foundation
 import Models
 import SwiftGraphQL
@@ -74,6 +75,13 @@ public extension DataService {
     .receive(on: DispatchQueue.main)
     .eraseToAnyPublisher()
   }
+
+  func cachedFeedItems() -> [FeedItemDep] {
+    let fetchRequest: NSFetchRequest<Models.LinkedItem> = LinkedItem.fetchRequest()
+    // TODO: set sort order?
+    let items = (try? persistentContainer.viewContext.fetch(fetchRequest)) ?? []
+    return items.map { FeedItemDep.make(from: $0) }
+  }
 }
 
 let homeFeedItemSelection = Selection.Article {