From 6ab4acdc84eebf9f8733716132f2a8d3c706fcbf Mon Sep 17 00:00:00 2001
From: miruka <miruka@disroot.org>
Date: Wed, 17 Apr 2019 22:34:22 -0400
Subject: [PATCH] Improve room past events loading

- Trigger when room is shown if there's not enough messages to fill the
  list height

- Trigger whenever user is scrolling before a certain point, instead of
  when dragging is released/scrolling stopped and the top edge is hit

- Prevent multiple load requests at same time

- Keep a set of fully loaded rooms, don't request anymore history
  if a room is fully loaded
---
 TODO.md                                    |  4 ++++
 harmonyqml/backend/backend.py              | 17 ++++++++++++-----
 harmonyqml/backend/client.py               | 14 ++++++++++++--
 harmonyqml/backend/signal_manager.py       |  3 +++
 harmonyqml/components/chat/MessageList.qml | 10 ++++++++--
 5 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/TODO.md b/TODO.md
index 6428bfa2..5542e75b 100644
--- a/TODO.md
+++ b/TODO.md
@@ -30,3 +30,7 @@
 - Push instead of replacing in stack view
 
 - QQuickImageProvider, matrix preview API
+
+- Spinner when loading past room events or images
+
+- nio: org.matrix.room.preview\_urls, m.room.aliases
diff --git a/harmonyqml/backend/backend.py b/harmonyqml/backend/backend.py
index 3398f7be..6ff370b0 100644
--- a/harmonyqml/backend/backend.py
+++ b/harmonyqml/backend/backend.py
@@ -2,20 +2,21 @@
 # This file is part of harmonyqml, licensed under GPLv3.
 
 import hashlib
-from typing import Dict
+from typing import Dict, Set
 
 from PyQt5.QtCore import QObject, pyqtProperty, pyqtSlot
 
 from .client_manager import ClientManager
+from .html_filter import HtmlFilter
 from .model.items import User
 from .model.qml_models import QMLModels
-from .html_filter import HtmlFilter
 
 
 class Backend(QObject):
     def __init__(self) -> None:
         super().__init__()
-        self.past_tokens: Dict[str, str] = {}
+        self.past_tokens:        Dict[str, str] = {}
+        self.fully_loaded_rooms: Set[str]       = set()
 
         self._client_manager: ClientManager = ClientManager()
         self._models:         QMLModels     = QMLModels()
@@ -61,13 +62,19 @@ class Backend(QObject):
 
 
     @pyqtSlot(str)
-    def loadPastEvents(self, room_id: str) -> None:
+    @pyqtSlot(str, int)
+    def loadPastEvents(self, room_id: str, limit: int = 100) -> None:
         if not room_id in self.past_tokens:
             return  # Initial sync not done yet
 
+        if room_id in self.fully_loaded_rooms:
+            return
+
         for client in self.clientManager.clients.values():
             if room_id in client.nio.rooms:
-                client.loadPastEvents(room_id, self.past_tokens[room_id])
+                client.loadPastEvents(
+                    room_id, self.past_tokens[room_id], limit
+                )
                 break
         else:
             raise ValueError(f"Room not found in any client: {room_id}")
diff --git a/harmonyqml/backend/client.py b/harmonyqml/backend/client.py
index 6ae81db5..6c71fbb2 100644
--- a/harmonyqml/backend/client.py
+++ b/harmonyqml/backend/client.py
@@ -69,6 +69,8 @@ class Client(QObject):
         self.net      = NetworkManager(self.host, self.port, self.nio)
         self.net_sync = NetworkManager(self.host, self.port, self.nio_sync)
 
+        self._loading: bool = False
+
         self._stop_sync: Event = Event()
 
 
@@ -157,14 +159,22 @@ class Client(QObject):
 
 
     @futurize
-    def loadPastEvents(self, room_id: str, start_token: str) -> None:
+    def loadPastEvents(self, room_id: str, start_token: str, limit: int = 100
+                      ) -> None:
         # From QML, use Backend.loastPastEvents instead
+
+        if self._loading:
+            return
+        self._loading = True
+
+        print("load", limit)
         self._on_past_events(
             room_id,
             self.net.talk(
-                self.nio.room_messages, room_id, start=start_token, limit=100
+                self.nio.room_messages, room_id, start=start_token, limit=limit
             )
         )
+        self._loading = False
 
 
     def _on_past_events(self, room_id: str, response: nr.RoomMessagesResponse
diff --git a/harmonyqml/backend/signal_manager.py b/harmonyqml/backend/signal_manager.py
index c79b7b89..54c44ab6 100644
--- a/harmonyqml/backend/signal_manager.py
+++ b/harmonyqml/backend/signal_manager.py
@@ -93,6 +93,9 @@ class SignalManager(QObject):
             self, _: Client, room_id: str, token: str
         ) -> None:
 
+        if self.backend.past_tokens[room_id] == token:
+            self.backend.fully_loaded_rooms.add(room_id)
+
         self.backend.past_tokens[room_id] = token
 
 
diff --git a/harmonyqml/components/chat/MessageList.qml b/harmonyqml/components/chat/MessageList.qml
index 29081f63..3228da07 100644
--- a/harmonyqml/components/chat/MessageList.qml
+++ b/harmonyqml/components/chat/MessageList.qml
@@ -26,8 +26,14 @@ Rectangle {
         // reloaded from network.
         cacheBuffer: height * 6
 
-        onMovementEnded: if (atYBeginning) {
-            Backend.loadPastEvents(chatPage.room.room_id)
+        // Declaring this "alias" provides the on... signal
+        property real yPos: visibleArea.yPosition
+
+        onYPosChanged: {
+            console.log(yPos)
+            if (yPos <= 0.1) {
+                Backend.loadPastEvents(chatPage.room.room_id)
+            }
         }
     }
 }