Mark unread messages in the room as read when all messages are visible

This is an alternative to network/neochat!467. When discussing in the matrix channel this option seemed more popular so I implemented it.

Mark the unread messages in the room as read when all messages are visible to the user after a short timer. This happens on entry and when new messages come in as long as Neochat is active. If neochat isn't active, the room hasn't loaded or the read marker hasn't loaded the timer is for this is reset until all 3 conditions are false.

imports/NeoChat/Page/RoomPage.qml

@@ -23,6 +23,7 @@ Kirigami.ScrollablePage {
 
     /// It's not readonly because of the seperate window view.
     property var currentRoom: RoomManager.currentRoom
+    property bool loading: page.currentRoom === null || (messageListView.count === 0 && !page.currentRoom.allHistoryLoaded && !page.currentRoom.isInvite)
     /// Used to determine if scrolling to the bottom should mark the message as unread
     property bool hasScrolledUpBefore: false;
 
@@ -55,6 +56,25 @@ Kirigami.ScrollablePage {
         ChatBoxHelper.clearEditReply()
     }
 
+    Connections {
+        target: messageEventModel
+        function onRowsInserted() {
+            markReadIfVisibleTimer.restart()
+        }
+    }
+
+    Timer {
+        id: markReadIfVisibleTimer
+        interval: 1000
+        onTriggered: {
+            if (loading || !currentRoom.readMarkerLoaded || !applicationWindow().active) {
+                restart()
+            } else {
+                markReadIfVisible()
+            }
+        }
+    }
+
     ActionsHandler {
         id: actionsHandler
         room: page.currentRoom
@@ -123,7 +143,7 @@ Kirigami.ScrollablePage {
     Kirigami.PlaceholderMessage {
         id: loadingIndicator
         anchors.centerIn: parent
-        visible: page.currentRoom === null || (messageListView.count === 0 && !page.currentRoom.allHistoryLoaded && !page.currentRoom.isInvite)
+        visible: loading
         text: i18n("Loading…")
         QQC2.BusyIndicator {
             running: loadingIndicator.visible
@@ -592,6 +612,14 @@ Kirigami.ScrollablePage {
         return index;
     }
 
+    // Mark all messages as read if all unread messages are visible to the user
+    function markReadIfVisible() {
+        let readMarkerRow = eventToIndex(currentRoom.readMarkerEventId)
+        if (readMarkerRow > 0 && readMarkerRow < firstVisibleIndex()) {
+            currentRoom.markAllMessagesAsRead()
+        }
+    }
+
     /// Open message context dialog for file and videos
     function openFileContext(event, file) {
         const contextMenu = fileDelegateContextMenu.createObject(page, {