enh: add lazy loading of texts and make them scrollable.

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ### Added
 
-
+1. Add lazy loading of texts and make them scrollable.
 
 ### Changed
 

src/memorytext/models/message_list.py

@@ -1,15 +1,29 @@
 from __future__ import annotations
-from PySide6.QtCore import QAbstractListModel, Qt, QModelIndex
+from typing import TYPE_CHECKING
+
+from PySide6.QtCore import QAbstractListModel, QPersistentModelIndex, Qt, QModelIndex
+
+if TYPE_CHECKING:
+    from collections.abc import Callable
+    from memorytext.models.core import Message
 
 
 class MessageList(QAbstractListModel):
     IsSameSenderRole = Qt.ItemDataRole.UserRole + 1
     SenderRole = Qt.ItemDataRole.UserRole + 2
     TimestampRole = Qt.ItemDataRole.UserRole + 3
 
-    def __init__(self, message_list, parent=None):
+    def __init__(
+        self,
+        conversation_id: int | None,
+        message_service: Callable[[int | None, int, int], tuple[list[Message], int]],
+        limit: int = 10,
+        parent=None,
+    ):
         super().__init__(parent)
-        self._items = message_list
+        self._conversation_id = conversation_id
+        self._message_service = message_service
+        self._items, self._total = self._message_service(conversation_id, limit, 0)
 
     def rowCount(self, parent=QModelIndex()):  # pyright: ignore[reportIncompatibleMethodOverride]
         return len(self._items)
@@ -47,7 +61,35 @@ def data(self, index, role=Qt.ItemDataRole.DisplayRole):  # pyright: ignore[repo
     def flags(self, index):
         return Qt.ItemFlag.ItemIsEnabled
 
-    def set_messages(self, message_list):
+    def set_messages(
+        self,
+        conversation_id: int | None,
+        message_service: Callable[[int | None, int, int], tuple[list, int]],
+        limit: int = 10,
+        offset: int = 0,
+    ):
         self.beginResetModel()
-        self._items = message_list
+        self._conversation_id = conversation_id
+        self._message_service = message_service
+        self._items, self._total = self._message_service(conversation_id, limit, offset)
         self.endResetModel()
+
+    def canFetchMore(self, parent: QModelIndex | QPersistentModelIndex) -> bool:
+        return self.rowCount() < self._total
+
+    def fetchMore(
+        self,
+        parent: QModelIndex | QPersistentModelIndex = QModelIndex(),
+    ) -> None:
+        offset = self.rowCount()
+        remaining = self._total - offset
+        limit = 10
+        to_fetch = min(limit, remaining)
+        if to_fetch > 0:
+            new_messages, count = self._message_service(
+                self._conversation_id, to_fetch, offset
+            )
+            if count > 0:
+                self.beginInsertRows(QModelIndex(), offset, offset + count - 1)
+                self._items.extend(new_messages)
+                self.endInsertRows()

src/memorytext/services/message_service.py

@@ -6,9 +6,27 @@
 from memorytext.db import get_db
 
 
-def get_messages(conversation_id, count: int = 10):
+def get_messages(
+    conversation_id: int | None, limit: int = 10, offset: int = 0
+) -> tuple[list, int]:
     engine = get_db()
+    count = limit + offset
     with Session(engine) as session:
-        stmt = select(Message).where(Message.conversation_id == conversation_id)
-        message_list = session.scalars(stmt).fetchmany(count)
-    return message_list
+        stmt = (
+            select(Message)
+            .where(Message.conversation_id == conversation_id)
+            .order_by(Message.timestamp.asc())
+        )
+        message_list = list(session.scalars(stmt).fetchall())
+    if message_list is not None:
+        total = len(message_list)
+    else:
+        total = 0
+    if message_list is not None and offset >= total:
+        return [], total
+    elif message_list is not None and count >= total:
+        return message_list[offset:], total
+    elif message_list is not None:
+        return message_list[offset:count], total
+    else:
+        return [], total

src/memorytext/views/chat_view.py

@@ -1,11 +1,18 @@
+from __future__ import annotations
+from typing import TYPE_CHECKING
 from PySide6.QtWidgets import QListView
 from PySide6.QtCore import Qt
 from PySide6.QtGui import QFont
 
 from memorytext.models.message_list import MessageList
+from memorytext.services import message_service
 from memorytext.delegates.message_list import MessageDelegate
 
 
+if TYPE_CHECKING:
+    from collections.abc import Callable
+
+
 class ChatView(QListView):
     def __init__(self):
         super().__init__()
@@ -14,15 +21,23 @@ def __init__(self):
         font.setPointSize(14)
         self.setFont(font)
         self.setSpacing(10)
-        self.message_model = MessageList([])
+        self.message_model = MessageList(None, message_service.get_messages)
         self.setModel(self.message_model)
         self.setItemDelegate(MessageDelegate())
         self.setWordWrap(True)
         self.setUniformItemSizes(False)
         self.setFocusPolicy(Qt.NoFocus)  # pyright: ignore[reportAttributeAccessIssue]
 
-    def set_messages(self, message_list):
-        self.message_model.set_messages(message_list)
+    def set_messages(
+        self,
+        conversation_id: int | None,
+        message_service: Callable[[int | None, int, int], tuple[list, int]],
+        limit: int = 10,
+        offset: int = 0,
+    ):
+        self.message_model.set_messages(
+            conversation_id, message_service, limit=limit, offset=offset
+        )
 
     def resizeEvent(self, event):
         super().resizeEvent(event)

src/memorytext/windows/main_window.py

@@ -8,8 +8,8 @@
 from PySide6.QtCore import QModelIndex
 from memorytext.views.chat_view import ChatView
 from memorytext.views.chat_list_view import ChatListView
-import memorytext.services.message_service as msg_service
 from memorytext.windows.import_window import ImportWindow
+from memorytext.services import message_service
 
 
 class MainWindow(QMainWindow):
@@ -41,9 +41,7 @@ def __init__(self):
 
     def load_messages(self, index: QModelIndex):
         convo_id = self.sidebar.model().get_id(index)  # pyright: ignore[reportAttributeAccessIssue]
-
-        message_list = msg_service.get_messages(convo_id, count=20)
-        self.chat_area.set_messages(message_list)
+        self.chat_area.set_messages(convo_id, message_service.get_messages)
 
     def import_new_chat(self):
         if self.import_window is None: