Add encryption history banner and update session verification banner strings. (#1250)

* Add a hard wall on back-pagination in encrypted rooms.
Until the app supports key backup, the history will never be decryptable.

* Fix initial display of the timeline table view.

* Update session verification banner strings.

ElementX/Sources/Screens/RoomScreen/View/Timeline/EncryptedHistoryRoomTimelineView.swift

@@ -0,0 +1,61 @@
+//
+// Copyright 2023 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import SwiftUI
+
+/// The item shown when all previous items are un-decryptable due to
+/// key backup not yet being supported in the app.
+struct EncryptedHistoryRoomTimelineView: View {
+    let timelineItem: EncryptedHistoryRoomTimelineItem
+    
+    var body: some View {
+        Label {
+            Text(L10n.screenRoomEncryptedHistoryBanner)
+                .font(.compound.bodyMDSemibold)
+                .foregroundColor(.compound.textInfoPrimary)
+        } icon: {
+            Image(systemName: "info.circle.fill")
+                .foregroundColor(.compound.iconInfoPrimary)
+        }
+        .labelStyle(EncryptedHistoryLabelStyle())
+        .padding(16)
+        .background {
+            RoundedRectangle(cornerRadius: 8)
+                .fill(Color.compound.bgInfoSubtle)
+            RoundedRectangle(cornerRadius: 8)
+                .stroke(Color.compound.borderInfoSubtle)
+        }
+        .frame(maxWidth: .infinity)
+        .padding(.horizontal, 8)
+        .padding(.vertical, 16)
+    }
+}
+
+private struct EncryptedHistoryLabelStyle: LabelStyle {
+    func makeBody(configuration: Configuration) -> some View {
+        HStack(alignment: .firstTextBaseline, spacing: 16) {
+            configuration.icon
+            configuration.title
+        }
+    }
+}
+
+struct EncryptedHistoryRoomTimelineView_Previews: PreviewProvider {
+    static var previews: some View {
+        let item = EncryptedHistoryRoomTimelineItem(id: UUID().uuidString)
+        EncryptedHistoryRoomTimelineView(timelineItem: item)
+    }
+}

ElementX/Sources/Screens/RoomScreen/View/TimelineTableViewController.swift

@@ -119,6 +119,13 @@ class TimelineTableViewController: UIViewController {
         // for each possible cell, causing layout issues
         tableView.accessibilityElementsHidden = Tests.shouldDisableTimelineAccessibility
         
+        tableView.publisher(for: \.contentSize)
+            .removeDuplicates()
+            .sink { [weak self] _ in
+                self?.updateTopPadding()
+            }
+            .store(in: &cancellables)
+        
         scrollToBottomPublisher
             .sink { [weak self] _ in
                 self?.scrollToBottom(animated: true)
@@ -242,9 +249,11 @@ class TimelineTableViewController: UIViewController {
         snapshot.appendSections([.main])
         snapshot.appendItems(timelineItemsIDs)
         dataSource.apply(snapshot, animatingDifferences: false)
-
+        
+        // Probably redundant now we observe content size changes…
+        // Leaving in place for the release and will reassess after.
         updateTopPadding()
-
+        
         if previousLayout.isBottomVisible {
             scrollToBottom(animated: false)
         } else if let pinnedItem = previousLayout.pinnedItem {
@@ -283,7 +292,8 @@ class TimelineTableViewController: UIViewController {
         let contentHeight = tableView.contentSize.height - headerHeight
         let newHeight = max(0, tableView.visibleSize.height - contentHeight)
         
-        guard newHeight != headerHeight else { return }
+        // Round the check to account floating point accuracy during keyboard appearance.
+        guard newHeight.rounded() != headerHeight.rounded() else { return }
         
         if newHeight > 0 {
             let frame = CGRect(origin: .zero, size: CGSize(width: tableView.contentSize.width, height: newHeight))