From a6d29b203c60266b45241972d6cbce4ea8c1dd93 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Wed, 26 Jan 2022 23:07:35 -0500
Subject: [PATCH] Use batch update endpoint for marking items (un)read

---
 Fervor/FervorClient.swift     | 14 +++++++++++
 Reader/FervorController.swift | 44 ++++++++++++++++++-----------------
 Reader/SceneDelegate.swift    |  6 +----
 3 files changed, 38 insertions(+), 26 deletions(-)

diff --git a/Fervor/FervorClient.swift b/Fervor/FervorClient.swift
index a8c42bd..aec7e2d 100644
--- a/Fervor/FervorClient.swift
+++ b/Fervor/FervorClient.swift
@@ -131,6 +131,20 @@ public class FervorClient {
         return try await performRequest(request)
     }
     
+    public func read(ids: [FervorID]) async throws -> [FervorID] {
+        var request = URLRequest(url: buildURL(path: "/api/v1/items/read"))
+        request.httpMethod = "POST"
+        request.setURLEncodedBody(params: ["ids": ids.joined(separator: ",")])
+        return try await performRequest(request)
+    }
+    
+    public func unread(ids: [FervorID]) async throws -> [FervorID] {
+        var request = URLRequest(url: buildURL(path: "/api/v1/items/unread"))
+        request.httpMethod = "POST"
+        request.setURLEncodedBody(params: ["ids": ids.joined(separator: ",")])
+        return try await performRequest(request)
+    }
+    
     public struct Auth {
         public let accessToken: String
         public let refreshToken: String?
diff --git a/Reader/FervorController.swift b/Reader/FervorController.swift
index 823e67d..c5dfb8d 100644
--- a/Reader/FervorController.swift
+++ b/Reader/FervorController.swift
@@ -87,36 +87,38 @@ class FervorController {
     }
     
     @MainActor
-    func syncReadToServer() async throws {
+    func syncReadToServer() async {
         var count = 0
-        // todo: there should be a batch update api endpoint
-        for case let item as Item in persistentContainer.viewContext.updatedObjects {
-            let f = item.read ? client.read(item:) : client.unread(item:)
-            do {
-                let _ = try await f(item.id!)
-                count += 1
-            } catch {
-                logger.error("Failed to sync read state: \(String(describing: error), privacy: .public)")
-                item.needsReadStateSync = true
-            }
-        }
         
         // try to sync items which failed last time
         let req = Item.fetchRequest()
         req.predicate = NSPredicate(format: "needsReadStateSync = YES")
-        if let needsSync = try? persistentContainer.viewContext.fetch(req) {
-            for item in needsSync {
-                let f = item.read ? client.read(item:) : client.unread(item:)
+        if var needsSync = try? persistentContainer.viewContext.fetch(req) {
+            let firstReadIndex = needsSync.partition(by: \.read)
+            let unreadIDs = needsSync[..<firstReadIndex].map(\.id.unsafelyUnwrapped)
+            let readIDs = needsSync[firstReadIndex...].map(\.id.unsafelyUnwrapped)
+            var updatedIDs = Set<FervorID>()
+            if !unreadIDs.isEmpty {
                 do {
-                    let _ = try await f(item.id!)
-                    count += 1
-                    item.needsReadStateSync = false
+                    let ids = try await client.unread(ids: unreadIDs)
+                    updatedIDs.formUnion(ids)
                 } catch {
-                    logger.error("Failed to sync read state again: \(String(describing: error), privacy: .public)")
-                    item.needsReadStateSync = true
-                    // todo: this should probably fail after a certain number of attempts
+                    logger.error("Failed to sync unread state: \(String(describing: error), privacy: .public)")
                 }
             }
+            if !readIDs.isEmpty {
+                do {
+                    let ids = try await client.read(ids: readIDs)
+                    updatedIDs.formUnion(ids)
+                } catch {
+                    logger.error("Failed to sync read state: \(String(describing: error), privacy: .public)")
+                }
+            }
+            
+            count += updatedIDs.count
+            for item in needsSync where updatedIDs.contains(item.id!) {
+                item.needsReadStateSync = false
+            }
         }
         
         logger.info("Synced \(count, privacy: .public) read/unread to server")
diff --git a/Reader/SceneDelegate.swift b/Reader/SceneDelegate.swift
index 18abaa5..3ad2ac8 100644
--- a/Reader/SceneDelegate.swift
+++ b/Reader/SceneDelegate.swift
@@ -81,11 +81,7 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         
         if let fervorController = fervorController {
             Task(priority: .userInitiated) {
-                do {
-                    try await fervorController.syncReadToServer()
-                } catch {
-                    logger.error("Unable to sync read state to server: \(String(describing: error), privacy: .public)")
-                }
+                await fervorController.syncReadToServer()
             }
         }
     }