From 8a9f1d2a789074ce5fc1118df3438eb9e63ff00c Mon Sep 17 00:00:00 2001
From: Gil Eluard <gile@element.io>
Date: Mon, 19 Dec 2022 14:56:06 +0100
Subject: [PATCH] Load the thread list using server-side sorting and pagination

---
 .../ThreadList/ThreadListViewController.swift |  6 +++++-
 .../ThreadList/ThreadListViewModel.swift      | 19 ++++++++++++++-----
 changelog.d/6059.feature                      |  1 +
 3 files changed, 20 insertions(+), 6 deletions(-)
 create mode 100644 changelog.d/6059.feature

diff --git a/Riot/Modules/Threads/ThreadList/ThreadListViewController.swift b/Riot/Modules/Threads/ThreadList/ThreadListViewController.swift
index f4075a0cf9..7c532be5ad 100644
--- a/Riot/Modules/Threads/ThreadList/ThreadListViewController.swift
+++ b/Riot/Modules/Threads/ThreadList/ThreadListViewController.swift
@@ -162,7 +162,7 @@ final class ThreadListViewController: UIViewController {
     
     private func renderLoading() {
         emptyView.isHidden = true
-        threadsTableView.isHidden = true
+        threadsTableView.isHidden = viewModel.numberOfThreads == 0
         self.activityPresenter.presentActivityIndicator(on: self.view, animated: true)
     }
     
@@ -352,6 +352,10 @@ extension ThreadListViewController: UITableViewDelegate {
         cell.backgroundColor = theme.backgroundColor
         cell.selectedBackgroundView = UIView()
         cell.selectedBackgroundView?.backgroundColor = theme.selectedBackgroundColor
+        
+        if indexPath.row == viewModel.numberOfThreads - 1 {
+            viewModel.process(viewAction: .loadData)
+        }
     }
     
     func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
diff --git a/Riot/Modules/Threads/ThreadList/ThreadListViewModel.swift b/Riot/Modules/Threads/ThreadList/ThreadListViewModel.swift
index 29ae93b020..16620a6214 100644
--- a/Riot/Modules/Threads/ThreadList/ThreadListViewModel.swift
+++ b/Riot/Modules/Threads/ThreadList/ThreadListViewModel.swift
@@ -29,7 +29,7 @@ final class ThreadListViewModel: ThreadListViewModelProtocol {
     private var threads: [MXThreadProtocol] = []
     private var eventFormatter: MXKEventFormatter?
     private var roomState: MXRoomState?
-    
+    private var nextBatch: String?
     private var currentOperation: MXHTTPOperation?
     private var longPressedThread: MXThreadProtocol?
     
@@ -71,6 +71,7 @@ final class ThreadListViewModel: ThreadListViewModelProtocol {
             viewState = .showingFilterTypes
         case .selectFilterType(let type):
             selectedFilterType = type
+            resetData()
             loadData()
         case .selectThread(let index):
             selectThread(index)
@@ -230,7 +231,15 @@ final class ThreadListViewModel: ThreadListViewModelProtocol {
         )
     }
     
+    private func resetData() {
+        nextBatch = nil
+        threads = []
+    }
+    
     private func loadData(showLoading: Bool = true) {
+        guard threads.isEmpty || nextBatch != nil else {
+            return
+        }
 
         if showLoading {
             viewState = .loading
@@ -245,12 +254,12 @@ final class ThreadListViewModel: ThreadListViewModelProtocol {
             onlyParticipated = true
         }
         
-        session.threadingService.allThreads(inRoom: roomId,
-                                            onlyParticipated: onlyParticipated) { [weak self] response in
+        session.threadingService.allThreads(inRoom: roomId, from: nextBatch, onlyParticipated: onlyParticipated) { [weak self] response in
             guard let self = self else { return }
             switch response {
-            case .success(let threads):
-                self.threads = threads
+            case .success(let value):
+                self.threads = self.threads + value.threads
+                self.nextBatch = value.nextBatch
                 self.threadsLoaded()
             case .failure(let error):
                 MXLog.error("[ThreadListViewModel] loadData", context: error)
diff --git a/changelog.d/6059.feature b/changelog.d/6059.feature
new file mode 100644
index 0000000000..c4a9e72215
--- /dev/null
+++ b/changelog.d/6059.feature
@@ -0,0 +1 @@
+Threads: Load the thread list using server-side sorting and pagination
\ No newline at end of file