From 5be9df0eece36d4f5ea29447edec309991f443c1 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Wed, 4 Oct 2017 13:58:36 +0200
Subject: [PATCH] Add a basic EntityDatabase class

---
 telethon/entity_database.py | 75 +++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 telethon/entity_database.py

diff --git a/telethon/entity_database.py b/telethon/entity_database.py
new file mode 100644
index 00000000..1e96fe51
--- /dev/null
+++ b/telethon/entity_database.py
@@ -0,0 +1,75 @@
+from . import utils
+from .tl import TLObject
+
+
+class EntityDatabase:
+    def __init__(self, enabled=True):
+        self.enabled = enabled
+
+        self._entities = {}  # marked_id: user|chat|channel
+
+        # TODO Allow disabling some extra mappings
+        self._username_id = {}  # username: marked_id
+
+    def add(self, entity):
+        if not self.enabled:
+            return
+
+        # Adds or updates the given entity
+        marked_id = utils.get_peer_id(entity, add_mark=True)
+        try:
+            old_entity = self._entities[marked_id]
+            old_entity.__dict__.update(entity)  # Keep old references
+
+            # Update must delete old username
+            username = getattr(old_entity, 'username', None)
+            if username:
+                del self._username_id[username.lower()]
+        except KeyError:
+            # Add new entity
+            self._entities[marked_id] = entity
+
+        # Always update username if any
+        username = getattr(entity, 'username', None)
+        if username:
+            self._username_id[username.lower()] = marked_id
+
+    def __getitem__(self, key):
+        """Accepts a digit only string as phone number,
+           otherwise it's treated as an username.
+
+           If an integer is given, it's treated as the ID of the desired User.
+           The ID given won't try to be guessed as the ID of a chat or channel,
+           as there may be an user with that ID, and it would be unreliable.
+
+           If a Peer is given (PeerUser, PeerChat, PeerChannel),
+           its specific entity is retrieved as User, Chat or Channel.
+           Note that megagroups are channels with .megagroup = True.
+        """
+        if isinstance(key, str):
+            # TODO Parse phone properly, currently only usernames
+            key = key.lstrip('@').lower()
+            # TODO Use the client to return from username if not found
+            return self._entities[self._username_id[key]]
+
+        if isinstance(key, int):
+            return self._entities[key]  # normal IDs are assumed users
+
+        if isinstance(key, TLObject) and type(key).SUBCLASS_OF_ID == 0x2d45687:
+            return self._entities[utils.get_peer_id(key, add_mark=True)]
+
+        raise KeyError(key)
+
+    def __delitem__(self, key):
+        target = self[key]
+        del self._entities[key]
+        if getattr(target, 'username'):
+            del self._username_id[target.username]
+
+    # TODO Allow search by name by tokenizing the input and return a list
+
+    def clear(self, target=None):
+        if target is None:
+            self._entities.clear()
+        else:
+            del self[target]