feat: cleanup-wallets cli command (#2176)

* feat: `cleanup-wallet` cli command
`lnbits-cli db cleanup-wallets` removes all wallets that never had an transaction.
this helps against spammers creating random wallets, eventually slowing down the db.
* add commands
* add to example env
* db_versions was used in app
* add delta as cli argument
* use days unit
* simplify cli argument name (cleanup_wallet_days -> days)!

---------

Co-authored-by: Vlad Stan <stan.v.vlad@gmail.com>
Co-authored-by: Pavol Rusnak <pavol@rusnak.io>

lnbits/core/crud.py

@@ -164,6 +164,21 @@ async def get_account(
     return user
 
 
+async def delete_accounts_no_wallets(
+    time_delta: int,
+    conn: Optional[Connection] = None,
+) -> None:
+    await (conn or db).execute(
+        f"""
+        DELETE FROM accounts
+        WHERE NOT EXISTS (
+            SELECT wallets.id FROM wallets WHERE wallets.user = accounts.id
+        ) AND updated_at < {db.timestamp_placeholder}
+        """,
+        (int(time()) - time_delta,),
+    )
+
+
 async def get_user_password(user_id: str) -> Optional[str]:
     row = await db.fetchone(
         "SELECT pass FROM accounts WHERE id = ?",
@@ -497,6 +512,25 @@ async def delete_wallet(
     )
 
 
+async def remove_deleted_wallets(conn: Optional[Connection] = None) -> None:
+    await (conn or db).execute("DELETE FROM wallets WHERE deleted = true")
+
+
+async def delete_unused_wallets(
+    time_delta: int,
+    conn: Optional[Connection] = None,
+) -> None:
+    await (conn or db).execute(
+        f"""
+        DELETE FROM wallets
+        WHERE (
+            SELECT COUNT(*) FROM apipayments WHERE wallet = wallets.id
+        ) = 0 AND updated_at < {db.timestamp_placeholder}
+        """,
+        (int(time()) - time_delta,),
+    )
+
+
 async def get_wallet(
     wallet_id: str, conn: Optional[Connection] = None
 ) -> Optional[Wallet]: