From 41560a6a6e543f34c516c89080e39e13f3c16be6 Mon Sep 17 00:00:00 2001
From: Fredrik Simonsson <fredrik@nodle.com>
Date: Thu, 9 Nov 2023 17:56:56 +0900
Subject: [PATCH] Implement legacy RPC system_account_next_index

RPC system_account_next_index compensates for
extrinsics in transaction pool as opposed to
get_account_nonce which does not.
---
 subxt/src/backend/legacy/rpc_methods.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/subxt/src/backend/legacy/rpc_methods.rs b/subxt/src/backend/legacy/rpc_methods.rs
index b4f619f4f4..4dde85ee98 100644
--- a/subxt/src/backend/legacy/rpc_methods.rs
+++ b/subxt/src/backend/legacy/rpc_methods.rs
@@ -138,6 +138,18 @@ impl<T: Config> LegacyRpcMethods<T> {
             .await
     }
 
+    /// Fetch next nonce for an Account
+    ///
+    /// Return account nonce adjusted for extrinsics currently in transaction pool
+    pub async fn system_account_next_index(&self, account_id: &T::AccountId) -> Result<u64, Error>
+    where
+        T::AccountId: Serialize,
+    {
+        self.client
+            .request("system_accountNextIndex", rpc_params![&account_id])
+            .await
+    }
+
     /// Get a header
     pub async fn chain_get_header(
         &self,