From 8b8ea1b5704d1d0fca74216a1956e3702bcdb4d0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adrien=20Coye=20de=20Brune=CC=81lis?=
 <adrien.coye@infomaniak.com>
Date: Thu, 8 Jun 2023 09:20:08 +0200
Subject: [PATCH] feat: observe unread count to disable filtering when reaching
 zero

---
 .../ThreadListViewModel+Observation.swift     | 44 +++++++++++++++----
 .../Thread List/ThreadListViewModel.swift     | 10 +++++
 2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/Mail/Views/Thread List/ThreadListViewModel+Observation.swift b/Mail/Views/Thread List/ThreadListViewModel+Observation.swift
index e914b816a3..1f036b8e88 100644
--- a/Mail/Views/Thread List/ThreadListViewModel+Observation.swift	
+++ b/Mail/Views/Thread List/ThreadListViewModel+Observation.swift	
@@ -22,14 +22,11 @@ import RealmSwift
 import SwiftUI
 
 extension ThreadListViewModel {
-    // MARK: - Observe global changes
-
-    func observeChanges(animateInitialThreadChanges: Bool = false) {
-        stopObserveChanges()
-
+    
+    private func threadResults() -> Results<Thread>? {
         guard let folder = folder.thaw() else {
             sections = []
-            return
+            return nil
         }
 
         let threadResults: Results<Thread>
@@ -39,8 +36,16 @@ extension ThreadListViewModel {
         } else {
             threadResults = folder.threads.sorted(by: \.date, ascending: false)
         }
+        
+        return threadResults
+    }
+    
+    // MARK: - Observe global changes
 
-        observationThreadToken = threadResults.observe(on: observeQueue) { [weak self] changes in
+    func observeChanges(animateInitialThreadChanges: Bool = false) {
+        stopObserveChanges()
+
+        observationThreadToken = threadResults()?.observe(on: observeQueue) { [weak self] changes in
             guard let self = self else {
                 return
             }
@@ -99,7 +104,30 @@ extension ThreadListViewModel {
 
     // MARK: - Observe unread count
 
+    /// Observe the unread count to disable filtering when it reaches 0
     func observeUnreadCount() {
-        // TODO observe the unread count to disable filtering when it reaches 0
+        stopObserveUnread()
+
+        observationUnreadToken = threadResults()?.observe(on: observeQueue) { [weak self] changes in
+            guard let self = self else {
+                return
+            }
+            
+            switch changes {
+            case .initial(let changes), .update(let changes, _, _, _):
+                let count = changes.where { $0.unseenMessages > 0 }.count
+                Task {
+                    await MainActor.run {
+                        self.unreadCount = count
+                    }
+                }
+            case .error:
+                break
+            }
+        }
+    }
+    
+    func stopObserveUnread() {
+        observationUnreadToken?.invalidate()
     }
 }
diff --git a/Mail/Views/Thread List/ThreadListViewModel.swift b/Mail/Views/Thread List/ThreadListViewModel.swift
index c6580b3c06..72f94b1cd2 100644
--- a/Mail/Views/Thread List/ThreadListViewModel.swift	
+++ b/Mail/Views/Thread List/ThreadListViewModel.swift	
@@ -129,6 +129,15 @@ final class DateSection: Identifiable {
     var observationLastUpdateToken: NotificationToken?
     let observeQueue = DispatchQueue(label: "com.infomaniak.thread-results", qos: .userInteractive)
 
+    @Published var unreadCount: Int = 0 {
+        didSet {
+            // Disable filter if we have no unread emails left
+            if unreadCount == 0 && filterUnreadOn {
+                filterUnreadOn = false
+            }
+        }
+    }
+    
     @Published var filter = Filter.all {
         didSet {
             Task {
@@ -165,6 +174,7 @@ final class DateSection: Identifiable {
         lastUpdate = folder.lastUpdate
         self.isCompact = isCompact
         observeChanges()
+        observeUnreadCount()
     }
 
     func fetchThreads() async {