Allow for disconnecting from WhatsApp with command

This commit introduces a new ad-hoc command, `logout`, which disconnects
from WhatsApp without unlinking our authentication credentials (i.e.
what is generally understood to be meant when saying "log out").

slidge_whatsapp/command.py

@@ -3,6 +3,7 @@ from typing import TYPE_CHECKING, Optional
 from slidge.command import Command, CommandAccess, Form, FormField
 from slidge.util import is_valid_phone_number
 from slixmpp import JID
+from slixmpp.exceptions import XMPPError
 
 from .generated import whatsapp
 
@@ -10,6 +11,37 @@ if TYPE_CHECKING:
     from .session import Session
 
 
+class Logout(Command):
+    NAME = "Disconnect from WhatsApp"
+    HELP = (
+        "Disconnects active WhatsApp session without removing any linked device credentials. "
+        "To re-connect, use the 're-login' command."
+    )
+    NODE = "wa_logout"
+    CHAT_COMMAND = "logout"
+    ACCESS = CommandAccess.USER_LOGGED
+
+    async def run(
+        self,
+        session: Optional["Session"],  # type:ignore
+        ifrom: JID,
+        *args,
+    ) -> Form:
+        assert session is not None
+        try:
+            msg = session.shutdown()
+        except Exception as e:
+            session.send_gateway_status(f"Logout failed: {e}", show="dnd")
+            raise XMPPError(
+                "internal-server-error",
+                etype="wait",
+                text=f"Could not logout WhatsApp session: {e}",
+            )
+        session.send_gateway_message(msg or "Logged out successfully")
+        session.send_gateway_status(msg or "Logged out", show="away")
+        return msg
+
+
 class PairPhone(Command):
     NAME = "Complete registration via phone number"
     HELP = (
@@ -88,24 +120,3 @@ class ChangePresence(Command):
         else:
             raise ValueError("Not a valid presence kind.", p)
         return f"Presence succesfully set to {p}"
-
-
-class SubscribeToPresences(Command):
-    NAME = "Subscribe to contacts' presences"
-    HELP = (
-        "This command is here for tests about "
-        "https://todo.sr.ht/~nicoco/slidge-whatsapp/7 ."
-    )
-    NODE = "wa_subscribe"
-    CHAT_COMMAND = "subscribe"
-    ACCESS = CommandAccess.USER_LOGGED
-
-    async def run(
-        self,
-        session: Optional["Session"],  # type:ignore
-        ifrom: JID,
-        *args,
-    ) -> str:
-        assert session is not None
-        session.whatsapp.GetContacts(False)
-        return "Looks like no exception was raised. Success, I guess?"

slidge_whatsapp/session.py

@@ -93,6 +93,7 @@ class Session(BaseSession[str, Recipient]):
         will thus allow previously authenticated sessions to re-authenticate without needing to pair.
         """
         self.whatsapp.Disconnect()
+        self.logged = False
 
     @ignore_contact_is_user
     async def handle_event(self, event, ptr):