From 483e2aadf13461f12fd9b14d8521d00430b5e400 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Tue, 15 Feb 2022 11:57:55 +0100
Subject: [PATCH] Begin updating the way updates are built

---
 telethon/_client/updates.py            | 104 ++++++++------
 telethon/_events/album.py              |   8 +-
 telethon/_events/base.py               |   9 +-
 telethon/_events/callbackquery.py      |  37 ++---
 telethon/_events/chataction.py         | 186 +++++++++++++------------
 telethon/_events/inlinequery.py        |  24 ++--
 telethon/_events/messagedeleted.py     |  26 ++--
 telethon/_events/messageedited.py      |   2 +-
 telethon/_events/messageread.py        |  39 ++++--
 telethon/_events/newmessage.py         |  10 +-
 telethon/_events/raw.py                |   2 +-
 telethon/_events/userupdate.py         |  50 +++----
 telethon/_misc/utils.py                |  36 +----
 telethon/types/_custom/chat.py         |  46 ++++--
 telethon/types/_custom/chatgetter.py   |   8 +-
 telethon/types/_custom/message.py      |   6 +-
 telethon/types/_custom/sendergetter.py |   8 +-
 telethon/types/_custom/user.py         |  20 ++-
 18 files changed, 337 insertions(+), 284 deletions(-)

diff --git a/telethon/_client/updates.py b/telethon/_client/updates.py
index 16c20266..32375dd6 100644
--- a/telethon/_client/updates.py
+++ b/telethon/_client/updates.py
@@ -170,7 +170,7 @@ async def _update_loop(self: 'TelegramClient'):
         updates_to_dispatch = deque()
         while self.is_connected():
             if updates_to_dispatch:
-                await _dispatch(self, updates_to_dispatch.popleft())
+                await _dispatch(self, *updates_to_dispatch.popleft())
                 continue
 
             get_diff = self._message_box.get_difference()
@@ -178,8 +178,7 @@ async def _update_loop(self: 'TelegramClient'):
                 self._log[__name__].info('Getting difference for account updates')
                 diff = await self(get_diff)
                 updates, users, chats = self._message_box.apply_difference(diff, self._entity_cache)
-                self._entity_cache.extend(users, chats)
-                updates_to_dispatch.extend(updates)
+                updates_to_dispatch.extend(_preprocess_updates(self, updates, users, chats))
                 continue
 
             get_diff = self._message_box.get_channel_difference(self._entity_cache)
@@ -187,8 +186,7 @@ async def _update_loop(self: 'TelegramClient'):
                 self._log[__name__].info('Getting difference for channel updates')
                 diff = await self(get_diff)
                 updates, users, chats = self._message_box.apply_channel_difference(get_diff, diff, self._entity_cache)
-                self._entity_cache.extend(users, chats)
-                updates_to_dispatch.extend(updates)
+                updates_to_dispatch.extend(_preprocess_updates(self, updates, users, chats))
                 continue
 
             deadline = self._message_box.check_deadlines()
@@ -203,46 +201,74 @@ async def _update_loop(self: 'TelegramClient'):
 
             processed = []
             users, chats = self._message_box.process_updates(updates, self._entity_cache, processed)
-            self._entity_cache.extend(users, chats)
-            updates_to_dispatch.extend(processed)
+            updates_to_dispatch.extend(_preprocess_updates(self, processed, users, chats))
     except Exception:
         self._log[__name__].exception('Fatal error handling updates (this is a bug in Telethon, please report it)')
 
 
-async def _dispatch(self, update):
+def _preprocess_updates(self, updates, users, chats):
+    self._entity_cache.extend(users, chats)
+    entities = Entities(self, users, chats)
+    return ((u, entities) for u in updates)
+
+
+class Entities:
+    def __init__(self, client, users, chats):
+        self.self_id = client._session_state.user_id
+        self._entities = {e.id: e for e in itertools.chain(
+            (User(client, u) for u in users),
+            (Chat(client, c) for u in chats),
+        )}
+
+    def get(self, client, peer):
+        if not peer:
+            return None
+
+        id = utils.get_peer_id(peer)
+        try:
+            return self._entities[id]
+        except KeyError:
+            entity = client._entity_cache.get(query.user_id)
+            if not entity:
+                raise RuntimeError('Update is missing a hash but did not trigger a gap')
+
+            self._entities[entity.id] = User(client, entity) if entity.is_user else Chat(client, entity)
+            return self._entities[entity.id]
+
+
+async def _dispatch(self, update, entities):
     self._dispatching_update_handlers = True
+    try:
+        event_cache = {}
+        for handler in self._update_handlers:
+            event, entities = event_cache.get(handler._event)
+            if not event:
+                # build can fail if we're missing an access hash; we want this to crash
+                event_cache[handler._event] = event = handler._event._build(self, update, entities)
 
-    event_cache = {}
-    for handler in self._update_handlers:
-        event = event_cache.get(handler._event)
-        if not event:
-            event_cache[handler._event] = event = handler._event._build(
-                update, [], self._session_state.user_id, {}, self)
-
-        while True:
-            # filters can be modified at any time, and there can be any amount of them which are not yet resolved
-            try:
-                if handler._filter(event):
-                    try:
-                        await handler._callback(event)
-                    except StopPropagation:
-                        self._dispatching_update_handlers = False
-                        return
-                    except Exception:
-                        name = getattr(handler._callback, '__name__', repr(handler._callback))
-                        self._log[__name__].exception('Unhandled exception on %s (this is likely a bug in your code)', name)
-            except NotResolved as nr:
+            while True:
+                # filters can be modified at any time, and there can be any amount of them which are not yet resolved
                 try:
-                    await nr.unresolved.resolve()
-                    continue
+                    if handler._filter(event):
+                        try:
+                            await handler._callback(event)
+                        except StopPropagation:
+                            return
+                        except Exception:
+                            name = getattr(handler._callback, '__name__', repr(handler._callback))
+                            self._log[__name__].exception('Unhandled exception on %s (this is likely a bug in your code)', name)
+                except NotResolved as nr:
+                    try:
+                        await nr.unresolved.resolve()
+                        continue
+                    except Exception as e:
+                        # we cannot really do much about this; it might be a temporary network issue
+                        warnings.warn(f'failed to resolve filter, handler will be skipped: {e}: {nr.unresolved!r}')
                 except Exception as e:
-                    # we cannot really do much about this; it might be a temporary network issue
-                    warnings.warn(f'failed to resolve filter, handler will be skipped: {e}: {nr.unresolved!r}')
-            except Exception as e:
-                # invalid filter (e.g. types when types were not used as input)
-                warnings.warn(f'invalid filter applied, handler will be skipped: {e}: {e.filter!r}')
+                    # invalid filter (e.g. types when types were not used as input)
+                    warnings.warn(f'invalid filter applied, handler will be skipped: {e}: {e.filter!r}')
 
-            # we only want to continue on unresolved filter (to check if there are more unresolved)
-            break
-
-    self._dispatching_update_handlers = False
+                # we only want to continue on unresolved filter (to check if there are more unresolved)
+                break
+    finally:
+        self._dispatching_update_handlers = False
diff --git a/telethon/_events/album.py b/telethon/_events/album.py
index 41646acf..d57968f0 100644
--- a/telethon/_events/album.py
+++ b/telethon/_events/album.py
@@ -107,7 +107,7 @@ class Album(EventBuilder, _custom.chatgetter.ChatGetter, _custom.sendergetter.Se
         _custom.sendergetter.SenderGetter.__init__(self, message.sender_id)
         self.messages = messages
 
-    def _build(cls, update, others=None, self_id=None, *todo, **todo2):
+    def _build(cls, client, update, entities):
         if not others:
             return  # We only care about albums which come inside the same Updates
 
@@ -146,6 +146,12 @@ class Album(EventBuilder, _custom.chatgetter.ChatGetter, _custom.sendergetter.Se
                     and u.message.grouped_id == group)
             ])
 
+        self = cls.__new__(cls)
+        self._client = client
+        self._sender = entities.get(_tl.PeerUser(update.user_id))
+        self._chat = entities.get(_tl.PeerUser(update.user_id))
+        return self
+
     def _set_client(self, client):
         super()._set_client(client)
         self._sender, self._input_sender = utils._get_entity_pair(self.sender_id, self._entities)
diff --git a/telethon/_events/base.py b/telethon/_events/base.py
index f0af195f..404ff7b6 100644
--- a/telethon/_events/base.py
+++ b/telethon/_events/base.py
@@ -34,15 +34,12 @@ class StopPropagation(Exception):
 class EventBuilder(abc.ABC):
     @classmethod
     @abc.abstractmethod
-    def _build(cls, update, others, self_id, entities, client):
+    def _build(cls, client, update, entities):
         """
         Builds an event for the given update if possible, or returns None.
 
-        `others` are the rest of updates that came in the same container
-        as the current `update`.
-
-        `self_id` should be the current user's ID, since it is required
-        for some events which lack this information but still need it.
+        `entities` must have `get(Peer) -> User|Chat` and `self_id`,
+        which must be the current user's ID.
         """
 
 
diff --git a/telethon/_events/callbackquery.py b/telethon/_events/callbackquery.py
index 585fba51..5d36856b 100644
--- a/telethon/_events/callbackquery.py
+++ b/telethon/_events/callbackquery.py
@@ -69,29 +69,32 @@ class CallbackQuery(EventBuilder, _custom.chatgetter.ChatGetter, _custom.senderg
                     Button.inline('Nope', b'no')
                 ])
     """
-    def __init__(self, query, peer, msg_id):
-        _custom.chatgetter.ChatGetter.__init__(self, peer)
-        _custom.sendergetter.SenderGetter.__init__(self, query.user_id)
+    @classmethod
+    def _build(cls, client, update, entities):
+        query = update
+        if isinstance(update, _tl.UpdateBotCallbackQuery):
+            peer = update.peer
+            msg_id = update.msg_id
+        elif isinstance(update, _tl.UpdateInlineBotCallbackQuery):
+            # See https://github.com/LonamiWebs/Telethon/pull/1005
+            # The long message ID is actually just msg_id + peer_id
+            msg_id, pid = struct.unpack('<ii', struct.pack('<q', update.msg_id.id))
+            peer = _tl.PeerChannel(-pid) if pid < 0 else _tl.PeerUser(pid)
+        else:
+            return None
+
+        self = cls.__new__(cls)
+        self._client = client
+        self._sender = entities.get(_tl.PeerUser(query.user_id))
+        self._chat = entities.get(peer)
+
         self.query = query
         self.data_match = None
         self.pattern_match = None
         self._message = None
         self._answered = False
 
-    @classmethod
-    def _build(cls, update, others=None, self_id=None, *todo, **todo2):
-        if isinstance(update, _tl.UpdateBotCallbackQuery):
-            return cls.Event(update, update.peer, update.msg_id)
-        elif isinstance(update, _tl.UpdateInlineBotCallbackQuery):
-            # See https://github.com/LonamiWebs/Telethon/pull/1005
-            # The long message ID is actually just msg_id + peer_id
-            mid, pid = struct.unpack('<ii', struct.pack('<q', update.msg_id.id))
-            peer = _tl.PeerChannel(-pid) if pid < 0 else _tl.PeerUser(pid)
-            return cls.Event(update, peer, mid)
-
-    def _set_client(self, client):
-        super()._set_client(client)
-        self._sender, self._input_sender = utils._get_entity_pair(self.sender_id, self._entities)
+        return self
 
     @property
     def id(self):
diff --git a/telethon/_events/chataction.py b/telethon/_events/chataction.py
index 1e9b7271..6b4d21e9 100644
--- a/telethon/_events/chataction.py
+++ b/telethon/_events/chataction.py
@@ -72,18 +72,110 @@ class ChatAction(EventBuilder):
                     await event.reply('Welcome to the group!')
     """
 
-    def __init__(self, where, new_photo=None,
-                    added_by=None, kicked_by=None, created=None, from_approval=None,
-                    users=None, new_title=None, pin_ids=None, pin=None, new_score=None):
+    @classmethod
+    def _build(cls, client, update, entities):
+        where = None
+        new_photo = None
+        added_by = None
+        kicked_by = None
+        created = None
+        from_approval = None
+        users = None
+        new_title = None
+        pin_ids = None
+        pin = None
+        new_score = None
+
+        # Rely on specific pin updates for unpins, but otherwise ignore them
+        # for new pins (we'd rather handle the new service message with pin,
+        # so that we can act on that message').
+        if isinstance(update, _tl.UpdatePinnedChannelMessages) and not update.pinned:
+            where = _tl.PeerChannel(update.channel_id)
+            pin_ids = update.messages
+            pin = update.pinned
+
+        elif isinstance(update, _tl.UpdatePinnedMessages) and not update.pinned:
+            where = update.peer
+            pin_ids = update.messages
+            pin = update.pinned
+
+        elif isinstance(update, _tl.UpdateChatParticipantAdd):
+            where = _tl.PeerChat(update.chat_id)
+            added_by = update.inviter_id or True
+            users = update.user_id
+
+        elif isinstance(update, _tl.UpdateChatParticipantDelete):
+            where = _tl.PeerChat(update.chat_id)
+            kicked_by = True
+            users = update.user_id
+
+        # UpdateChannel is sent if we leave a channel, and the update._entities
+        # set by _process_update would let us make some guesses. However it's
+        # better not to rely on this. Rely only in MessageActionChatDeleteUser.
+
+        elif (isinstance(update, (
+                _tl.UpdateNewMessage, _tl.UpdateNewChannelMessage))
+              and isinstance(update.message, _tl.MessageService)):
+            msg = update.message
+            action = update.message.action
+            if isinstance(action, _tl.MessageActionChatJoinedByLink):
+                where = msg
+                added_by = True
+                users = msg.from_id
+            elif isinstance(action, _tl.MessageActionChatAddUser):
+                # If a user adds itself, it means they joined via the public chat username
+                added_by = ([msg.sender_id] == action.users) or msg.from_id
+                where = msg
+                added_by = added_by
+                users = action.users
+            elif isinstance(action, _tl.MessageActionChatJoinedByRequest):
+                # user joined from join request (after getting admin approval)
+                where = msg
+                from_approval = True
+                users = msg.from_id
+            elif isinstance(action, _tl.MessageActionChatDeleteUser):
+                where = msg
+                kicked_by = utils.get_peer_id(msg.from_id) if msg.from_id else True
+                users = action.user_id
+            elif isinstance(action, _tl.MessageActionChatCreate):
+                where = msg
+                users = action.users
+                created = True
+                new_title = action.title
+            elif isinstance(action, _tl.MessageActionChannelCreate):
+                where = msg
+                created = True
+                users = msg.from_id
+                new_title = action.title
+            elif isinstance(action, _tl.MessageActionChatEditTitle):
+                where = msg
+                users = msg.from_id
+                new_title = action.title
+            elif isinstance(action, _tl.MessageActionChatEditPhoto):
+                where = msg
+                users = msg.from_id
+                new_photo = action.photo
+            elif isinstance(action, _tl.MessageActionChatDeletePhoto):
+                where = msg
+                users = msg.from_id
+                new_photo = True
+            elif isinstance(action, _tl.MessageActionPinMessage) and msg.reply_to:
+                where = msg
+                pin_ids=[msg.reply_to_msg_id]
+            elif isinstance(action, _tl.MessageActionGameScore):
+                where = msg
+                new_score = action.score
+
+        self = cls.__new__(cls)
+        self._client = client
+
         if isinstance(where, _tl.MessageService):
             self.action_message = where
             where = where.peer_id
         else:
             self.action_message = None
 
-        # TODO needs some testing (can there be more than one id, and do they follow pin order?)
-        #      same in get_pinned_message
-        super().__init__(chat_peer=where, msg_id=pin_ids[0] if pin_ids else None)
+        self._chat = entities.get(where)
 
         self.new_pin = pin_ids is not None
         self._pin_ids = pin_ids
@@ -128,87 +220,7 @@ class ChatAction(EventBuilder):
         self.new_score = new_score
         self.unpin = not pin
 
-    @classmethod
-    def _build(cls, update, others=None, self_id=None, *todo, **todo2):
-        # Rely on specific pin updates for unpins, but otherwise ignore them
-        # for new pins (we'd rather handle the new service message with pin,
-        # so that we can act on that message').
-        if isinstance(update, _tl.UpdatePinnedChannelMessages) and not update.pinned:
-            return cls.Event(_tl.PeerChannel(update.channel_id),
-                             pin_ids=update.messages,
-                             pin=update.pinned)
-
-        elif isinstance(update, _tl.UpdatePinnedMessages) and not update.pinned:
-            return cls.Event(update.peer,
-                             pin_ids=update.messages,
-                             pin=update.pinned)
-
-        elif isinstance(update, _tl.UpdateChatParticipantAdd):
-            return cls.Event(_tl.PeerChat(update.chat_id),
-                             added_by=update.inviter_id or True,
-                             users=update.user_id)
-
-        elif isinstance(update, _tl.UpdateChatParticipantDelete):
-            return cls.Event(_tl.PeerChat(update.chat_id),
-                             kicked_by=True,
-                             users=update.user_id)
-
-        # UpdateChannel is sent if we leave a channel, and the update._entities
-        # set by _process_update would let us make some guesses. However it's
-        # better not to rely on this. Rely only in MessageActionChatDeleteUser.
-
-        elif (isinstance(update, (
-                _tl.UpdateNewMessage, _tl.UpdateNewChannelMessage))
-              and isinstance(update.message, _tl.MessageService)):
-            msg = update.message
-            action = update.message.action
-            if isinstance(action, _tl.MessageActionChatJoinedByLink):
-                return cls.Event(msg,
-                                 added_by=True,
-                                 users=msg.from_id)
-            elif isinstance(action, _tl.MessageActionChatAddUser):
-                # If a user adds itself, it means they joined via the public chat username
-                added_by = ([msg.sender_id] == action.users) or msg.from_id
-                return cls.Event(msg,
-                                 added_by=added_by,
-                                 users=action.users)
-            elif isinstance(action, _tl.MessageActionChatJoinedByRequest):
-                # user joined from join request (after getting admin approval)
-                return cls.Event(msg,
-                                 from_approval=True,
-                                 users=msg.from_id)
-            elif isinstance(action, _tl.MessageActionChatDeleteUser):
-                return cls.Event(msg,
-                                 kicked_by=utils.get_peer_id(msg.from_id) if msg.from_id else True,
-                                 users=action.user_id)
-            elif isinstance(action, _tl.MessageActionChatCreate):
-                return cls.Event(msg,
-                                 users=action.users,
-                                 created=True,
-                                 new_title=action.title)
-            elif isinstance(action, _tl.MessageActionChannelCreate):
-                return cls.Event(msg,
-                                 created=True,
-                                 users=msg.from_id,
-                                 new_title=action.title)
-            elif isinstance(action, _tl.MessageActionChatEditTitle):
-                return cls.Event(msg,
-                                 users=msg.from_id,
-                                 new_title=action.title)
-            elif isinstance(action, _tl.MessageActionChatEditPhoto):
-                return cls.Event(msg,
-                                 users=msg.from_id,
-                                 new_photo=action.photo)
-            elif isinstance(action, _tl.MessageActionChatDeletePhoto):
-                return cls.Event(msg,
-                                 users=msg.from_id,
-                                 new_photo=True)
-            elif isinstance(action, _tl.MessageActionPinMessage) and msg.reply_to:
-                return cls.Event(msg,
-                                 pin_ids=[msg.reply_to_msg_id])
-            elif isinstance(action, _tl.MessageActionGameScore):
-                return cls.Event(msg,
-                                 new_score=action.score)
+        return self
 
     async def respond(self, *args, **kwargs):
         """
diff --git a/telethon/_events/inlinequery.py b/telethon/_events/inlinequery.py
index c6c3bba6..716a9c98 100644
--- a/telethon/_events/inlinequery.py
+++ b/telethon/_events/inlinequery.py
@@ -40,21 +40,19 @@ class InlineQuery(EventBuilder, _custom.chatgetter.ChatGetter, _custom.senderget
                     builder.article('lowercase', text=event.text.lower()),
                 ])
     """
-    def __init__(self, query):
-        _custom.chatgetter.ChatGetter.__init__(self, _tl.PeerUser(query.user_id))
-        _custom.sendergetter.SenderGetter.__init__(self, query.user_id)
-        self.query = query
+    @classmethod
+    def _build(cls, client, update, entities):
+        if not isinstance(update, _tl.UpdateBotInlineQuery):
+            return None
+
+        self = cls.__new__(cls)
+        self._client = client
+        self._sender = entities.get(_tl.PeerUser(update.user_id))
+        self._chat = entities.get(_tl.PeerUser(update.user_id))
+        self.query = update
         self.pattern_match = None
         self._answered = False
-
-    @classmethod
-    def _build(cls, update, others=None, self_id=None, *todo, **todo2):
-        if isinstance(update, _tl.UpdateBotInlineQuery):
-            return cls.Event(update)
-
-    def _set_client(self, client):
-        super()._set_client(client)
-        self._sender, self._input_sender = utils._get_entity_pair(self.sender_id, self._entities)
+        return self
 
     @property
     def id(self):
diff --git a/telethon/_events/messagedeleted.py b/telethon/_events/messagedeleted.py
index 6e7603b3..f83bd7dd 100644
--- a/telethon/_events/messagedeleted.py
+++ b/telethon/_events/messagedeleted.py
@@ -35,20 +35,18 @@ class MessageDeleted(EventBuilder, _custom.chatgetter.ChatGetter):
                 for msg_id in event.deleted_ids:
                     print('Message', msg_id, 'was deleted in', event.chat_id)
     """
-    def __init__(self, deleted_ids, peer):
-        _custom.chatgetter.ChatGetter.__init__(self, chat_peer=peer)
-        self.deleted_id = None if not deleted_ids else deleted_ids[0]
-        self.deleted_ids = deleted_ids
-
     @classmethod
-    def _build(cls, update, others=None, self_id=None, *todo, **todo2):
+    def _build(cls, client, update, entities):
         if isinstance(update, _tl.UpdateDeleteMessages):
-            return cls.Event(
-                deleted_ids=update.messages,
-                peer=None
-            )
+            peer = None
         elif isinstance(update, _tl.UpdateDeleteChannelMessages):
-            return cls.Event(
-                deleted_ids=update.messages,
-                peer=_tl.PeerChannel(update.channel_id)
-            )
+            peer = _tl.PeerChannel(update.channel_id)
+        else:
+            return None
+
+        self = cls.__new__(cls)
+        self._client = client
+        self._chat = entities.get(peer)
+        self.deleted_id = None if not update.messages else update.messages[0]
+        self.deleted_ids = update.messages
+        return self
diff --git a/telethon/_events/messageedited.py b/telethon/_events/messageedited.py
index 373f5fee..9ce9f1ed 100644
--- a/telethon/_events/messageedited.py
+++ b/telethon/_events/messageedited.py
@@ -41,7 +41,7 @@ class MessageEdited(EventBuilder):
                 print('Message', event.id, 'changed at', event.date)
     """
     @classmethod
-    def _build(cls, update, others, self_id, entities, client):
+    def _build(cls, client, update, entities):
         if isinstance(update, (_tl.UpdateEditMessage,
                                _tl.UpdateEditChannelMessage)):
             return cls._new(client, update.message, entities, None)
diff --git a/telethon/_events/messageread.py b/telethon/_events/messageread.py
index 08f145dc..7708ae75 100644
--- a/telethon/_events/messageread.py
+++ b/telethon/_events/messageread.py
@@ -45,24 +45,39 @@ class MessageRead(EventBuilder):
         super().__init__(peer, self.max_id)
 
     @classmethod
-    def _build(cls, update, others=None, self_id=None, *todo, **todo2):
+    def _build(cls, client, update, entities):
+        out = False
+        contents = False
+        message_ids = None
         if isinstance(update, _tl.UpdateReadHistoryInbox):
-            return cls.Event(update.peer, update.max_id, False)
+            peer = update.peer
+            max_id = update.max_id
+            out = False
         elif isinstance(update, _tl.UpdateReadHistoryOutbox):
-            return cls.Event(update.peer, update.max_id, True)
+            peer = update.peer
+            max_id = update.max_id
+            out = True
         elif isinstance(update, _tl.UpdateReadChannelInbox):
-            return cls.Event(_tl.PeerChannel(update.channel_id),
-                             update.max_id, False)
+            peer = _tl.PeerChannel(update.channel_id)
+            max_id = update.max_id
+            out = False
         elif isinstance(update, _tl.UpdateReadChannelOutbox):
-            return cls.Event(_tl.PeerChannel(update.channel_id),
-                             update.max_id, True)
+            peer = _tl.PeerChannel(update.channel_id)
+            max_id = update.max_id
+            out = True
         elif isinstance(update, _tl.UpdateReadMessagesContents):
-            return cls.Event(message_ids=update.messages,
-                             contents=True)
+            peer = None
+            message_ids = update.messages
+            contents = True
         elif isinstance(update, _tl.UpdateChannelReadMessagesContents):
-            return cls.Event(_tl.PeerChannel(update.channel_id),
-                             message_ids=update.messages,
-                             contents=True)
+            peer = _tl.PeerChannel(update.channel_id)
+            message_ids = update.messages
+            contents = True
+
+        self = cls.__new__(cls)
+        self._client = client
+        self._chat = entities.get(peer)
+        return self
 
     @property
     def inbox(self):
diff --git a/telethon/_events/newmessage.py b/telethon/_events/newmessage.py
index 38b3d8f7..d659a8ef 100644
--- a/telethon/_events/newmessage.py
+++ b/telethon/_events/newmessage.py
@@ -57,16 +57,8 @@ class NewMessage(EventBuilder, _custom.Message):
                 await asyncio.sleep(5)
                 await client.delete_messages(event.chat_id, [event.id, m.id])
     """
-    def __init__(self, message):
-        self.__dict__['_init'] = False
-        super().__init__(chat_peer=message.peer_id,
-                            msg_id=message.id, broadcast=bool(message.post))
-
-        self.pattern_match = None
-        self.message = message
-
     @classmethod
-    def _build(cls, update, others, self_id, entities, client):
+    def _build(cls, client, update, entities):
         if isinstance(update,
                       (_tl.UpdateNewMessage, _tl.UpdateNewChannelMessage)):
             if not isinstance(update.message, _tl.Message):
diff --git a/telethon/_events/raw.py b/telethon/_events/raw.py
index 75b32de6..7faf8e0b 100644
--- a/telethon/_events/raw.py
+++ b/telethon/_events/raw.py
@@ -19,5 +19,5 @@ class Raw(EventBuilder):
                 print(update.stringify())
     """
     @classmethod
-    def _build(cls, update, others=None, self_id=None, *todo, **todo2):
+    def _build(cls, client, update, entities):
         return update
diff --git a/telethon/_events/userupdate.py b/telethon/_events/userupdate.py
index 24d87708..2ea622bb 100644
--- a/telethon/_events/userupdate.py
+++ b/telethon/_events/userupdate.py
@@ -62,33 +62,35 @@ class UserUpdate(EventBuilder, _custom.chatgetter.ChatGetter, _custom.sendergett
                 if event.uploading:
                     await client.send_message(event.user_id, 'What are you sending?')
     """
-    def __init__(self, peer, *, status=None, chat_peer=None, typing=None):
-        _custom.chatgetter.ChatGetter.__init__(self, chat_peer or peer)
-        _custom.sendergetter.SenderGetter.__init__(self, utils.get_peer_id(peer))
+    @classmethod
+    def _build(cls, client, update, entities):
+        chat_peer = None
+        status = None
+        if isinstance(update, _tl.UpdateUserStatus):
+            peer = _tl.PeerUser(update.user_id)
+            status = update.status
+            typing = None
+        elif isinstance(update, _tl.UpdateChannelUserTyping):
+            peer = update.from_id
+            chat_peer = _tl.PeerChannel(update.channel_id)
+            typing = update.action
+        elif isinstance(update, _tl.UpdateChatUserTyping):
+            peer = update.from_id
+            chat_peer = _tl.PeerChat(update.chat_id)
+            typing = update.action
+        elif isinstance(update, _tl.UpdateUserTyping):
+            peer = update.user_id
+            typing = update.action
+        else:
+            return None
 
+        self = cls.__new__(cls)
+        self._client = client
+        self._sender = entities.get(peer)
+        self._chat = entities.get(chat_peer or peer)
         self.status = status
         self.action = typing
-
-    @classmethod
-    def _build(cls, update, others=None, self_id=None, *todo, **todo2):
-        if isinstance(update, _tl.UpdateUserStatus):
-            return UserUpdateEvent(_tl.PeerUser(update.user_id),
-                             status=update.status)
-        elif isinstance(update, _tl.UpdateChannelUserTyping):
-            return UserUpdateEvent(update.from_id,
-                             chat_peer=_tl.PeerChannel(update.channel_id),
-                             typing=update.action)
-        elif isinstance(update, _tl.UpdateChatUserTyping):
-            return UserUpdateEvent(update.from_id,
-                             chat_peer=_tl.PeerChat(update.chat_id),
-                             typing=update.action)
-        elif isinstance(update, _tl.UpdateUserTyping):
-            return UserUpdateEvent(update.user_id,
-                             typing=update.action)
-
-    def _set_client(self, client):
-        super()._set_client(client)
-        self._sender, self._input_sender = utils._get_entity_pair(self.sender_id, self._entities)
+        return self
 
     @property
     def user(self):
diff --git a/telethon/_misc/utils.py b/telethon/_misc/utils.py
index b2834b93..78677142 100644
--- a/telethon/_misc/utils.py
+++ b/telethon/_misc/utils.py
@@ -578,20 +578,6 @@ def get_input_group_call(call):
         _raise_cast_fail(call, 'InputGroupCall')
 
 
-def _get_entity_pair(entity_id, entities,
-                     get_input_peer=get_input_peer):
-    """
-    Returns ``(entity, input_entity)`` for the given entity ID.
-    """
-    entity = entities.get(entity_id)
-    try:
-        input_entity = get_input_peer(entity)
-    except TypeError:
-        input_entity = None
-
-    return entity, input_entity
-
-
 def get_message_id(message):
     """Similar to :meth:`get_input_peer`, but for message IDs."""
     if message is None:
@@ -977,27 +963,13 @@ def get_peer(peer):
 
 def get_peer_id(peer):
     """
-    Extract the integer ID from the given peer.
+    Extract the integer ID from the given :tl:`Peer`.
     """
-    # First we assert it's a Peer TLObject, or early return for integers
-    if isinstance(peer, int):
-        return peer
-
-    # Tell the user to use their client to resolve InputPeerSelf if we got one
-    if isinstance(peer, _tl.InputPeerSelf):
-        _raise_cast_fail(peer, 'int (you might want to use client.get_peer_id)')
-
-    try:
-        peer = get_peer(peer)
-    except TypeError:
+    pid = getattr(peer, 'user_id', None) or getattr(peer, 'channel_id', None) or getattr(peer, 'chat_id', None)
+    if not isisintance(pid, int):
         _raise_cast_fail(peer, 'int')
 
-    if isinstance(peer, _tl.PeerUser):
-        return peer.user_id
-    elif isinstance(peer, _tl.PeerChat):
-        return peer.chat_id
-    else:  # if isinstance(peer, _tl.PeerChannel):
-        return peer.channel_id
+    return pid
 
 
 def _rle_decode(data):
diff --git a/telethon/types/_custom/chat.py b/telethon/types/_custom/chat.py
index 57593428..a0031bc1 100644
--- a/telethon/types/_custom/chat.py
+++ b/telethon/types/_custom/chat.py
@@ -1,5 +1,6 @@
 from typing import Optional, List, TYPE_CHECKING
 from datetime import datetime
+from dataclasses import dataclass
 import mimetypes
 from .chatgetter import ChatGetter
 from .sendergetter import SenderGetter
@@ -27,17 +28,21 @@ def _fwd(field, doc):
     return property(fget, fset, None, doc)
 
 
-class _InputChat:
-    """
-    Input channels and peer chats use a different name for "id" which breaks the property forwarding.
-
-    This class simply holds the two fields with proper names.
-    """
+@dataclass(frozen=True)
+class _TinyChat:
     __slots__ = ('id', 'access_hash')
 
-    def __init__(self, input):
-        self.id = getattr(input, 'channel_id', None) or input.chat_id
-        self.access_hash = getattr(input, 'access_hash', None)
+    id: int
+    access_hash: int
+
+
+@dataclass(frozen=True)
+class _TinyChannel:
+    __slots__ = ('id', 'access_hash', 'megagroup')
+
+    id: int
+    access_hash: int
+    megagroup: bool  # gigagroup is not present in channelForbidden but megagroup is
 
 
 class Chat:
@@ -159,7 +164,11 @@ class Chat:
         except AttributeError:
             migrated = None
 
-        return Chat(_InputChat(migrated), self._client) if migrated else None
+        if migrated is None:
+            return migrated
+
+        # Small chats don't migrate to other small chats, nor do they migrate to broadcast channels
+        return type(self)._new(self._client, _TinyChannel(migrated.channel_id, migrated.access_hash, True))
 
     def __init__(self):
         raise TypeError('You cannot create Chat instances by hand!')
@@ -168,7 +177,18 @@ class Chat:
     def _new(cls, client, chat):
         self = cls.__new__(cls)
         self._client = client
+
         self._chat = chat
+        if isinstance(cls, Entity):
+            if chat.is_user:
+                raise TypeError('Tried to construct Chat with non-chat Entity')
+            elif chat.ty == EntityType.GROUP:
+                self._chat = _TinyChat(chat.id)
+            else:
+                self._chat = _TinyChannel(chat.id, chat.hash, chat.is_group)
+        else:
+            self._chat = chat
+
         self._full = None
         return self
 
@@ -237,12 +257,12 @@ class Chat:
 
         .. _megagroup: https://telegram.org/blog/supergroups5k
         """
-        return True
+        return isinstance(self._chat, (_tl.Chat, _TinyChat, _tl.ChatForbidden, _tl.ChatEmpty)) or self._chat.megagroup
 
     @property
     def is_broadcast(self):
         """
-        Returns `True` if the chat is a broadcast channel  group chat or `broadcast group`_.
+        Returns `True` if the chat is a broadcast channel group chat or `broadcast group`_.
 
         This property also exists in `User`, where it returns `False`.
 
@@ -253,7 +273,7 @@ class Chat:
 
         .. _broadcast group: https://telegram.org/blog/autodelete-inv2#groups-with-unlimited-members
         """
-        return True
+        return not self.is_group
 
     @property
     def full_name(self):
diff --git a/telethon/types/_custom/chatgetter.py b/telethon/types/_custom/chatgetter.py
index 3f991d7f..ff06d642 100644
--- a/telethon/types/_custom/chatgetter.py
+++ b/telethon/types/_custom/chatgetter.py
@@ -7,11 +7,9 @@ from ... import errors, _tl
 class ChatGetter(abc.ABC):
     """
     Helper base class that introduces the chat-related properties and methods.
-    """
-    def __init__(self, chat, client):
-        self._chat = chat
-        self._client = client
 
+    The parent class must set both ``_chat`` and ``_client``.
+    """
     @property
     def chat(self):
         """
@@ -60,7 +58,7 @@ class ChatGetter(abc.ABC):
                 # Here there's no need to fetch the chat - get_messages already did
                 print(message.chat.stringify())
         """
-        raise RuntimeError('TODO')
+        raise RuntimeError('TODO fetch if it is tiny')
 
     @property
     def chat_id(self):
diff --git a/telethon/types/_custom/message.py b/telethon/types/_custom/message.py
index f87142ee..8a8460fa 100644
--- a/telethon/types/_custom/message.py
+++ b/telethon/types/_custom/message.py
@@ -428,10 +428,10 @@ class Message(ChatGetter, SenderGetter):
             if message.from_id is not None:
                 sender_id = utils.get_peer_id(message.from_id)
 
-        # Note that these calls would reset the client
-        ChatGetter.__init__(self, message.peer_id, broadcast=message.post)
-        SenderGetter.__init__(self, sender_id)
+        self = cls.__new__(cls)
         self._client = client
+        self._sender = entities.get(_tl.PeerUser(update.user_id))
+        self._chat = entities.get(_tl.PeerUser(update.user_id))
         self._message = message
 
         # Convenient storage for custom functions
diff --git a/telethon/types/_custom/sendergetter.py b/telethon/types/_custom/sendergetter.py
index 9f264cc0..71f39580 100644
--- a/telethon/types/_custom/sendergetter.py
+++ b/telethon/types/_custom/sendergetter.py
@@ -4,11 +4,9 @@ import abc
 class SenderGetter(abc.ABC):
     """
     Helper base class that introduces the sender-related properties and methods.
-    """
-    def __init__(self, sender, client):
-        self._sender = sender
-        self._client = client
 
+    The parent class must set both ``_sender`` and ``_client``.
+    """
     @property
     def sender(self):
         """
@@ -57,7 +55,7 @@ class SenderGetter(abc.ABC):
                 # Here there's no need to fetch the sender - get_messages already did
                 print(message.sender.stringify())
         """
-        raise RuntimeError('TODO')
+        raise RuntimeError('TODO fetch if it is tiny')
 
     @property
     def sender_id(self):
diff --git a/telethon/types/_custom/user.py b/telethon/types/_custom/user.py
index 63b3fccb..79e7c21e 100644
--- a/telethon/types/_custom/user.py
+++ b/telethon/types/_custom/user.py
@@ -1,5 +1,6 @@
 from typing import Optional, List, TYPE_CHECKING
 from datetime import datetime
+from dataclasses import dataclass
 import mimetypes
 from .chatgetter import ChatGetter
 from .sendergetter import SenderGetter
@@ -67,6 +68,14 @@ class BotInfo:
         self._user = user
 
 
+@dataclass(frozen=True)
+class _TinyUser:
+    __slots__ = ('id', 'access_hash')
+
+    id: int
+    access_hash: int
+
+
 class User:
     """
     Represents a :tl:`User` (or :tl:`UserEmpty`, or :tl:`UserFull`) from the API.
@@ -161,9 +170,16 @@ class User:
     @classmethod
     def _new(cls, client, user):
         self = cls.__new__(cls)
-
         self._client = client
-        self._user = user
+
+        if isinstance(user, Entity):
+            if not user.is_user:
+                raise TypeError('Tried to construct User with non-user Entity')
+
+            self._user = _TinyUser(user.id, user.hash)
+        else:
+            self._user = user
+
         self._full = None
         raise RuntimeError('self._i_need_to_include_participant_info')