From 4c45959597eb27fb515e1565b6c4d90fbb40bb1a Mon Sep 17 00:00:00 2001
From: Alisina Bahadori <alisina.bm@gmail.com>
Date: Thu, 4 Apr 2024 14:03:20 -0400
Subject: [PATCH] Add `Ethers.get_transaction_count/2` (#110)

---
 CHANGELOG.md              |  6 ++++++
 lib/ethers.ex             | 29 +++++++++++++++++++++++++++--
 lib/ethers/transaction.ex |  6 +++++-
 test/ethers_test.exs      | 20 ++++++++++++++++++++
 4 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b2b3e69..4df3649 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+### Enhancements
+
+- Add `Ethers.get_transaction_count/2`
+
 ## v0.4.2 (2024-04-04)
 
 ### Enhancements
diff --git a/lib/ethers.ex b/lib/ethers.ex
index 3f79d3d..ea2634c 100644
--- a/lib/ethers.ex
+++ b/lib/ethers.ex
@@ -70,10 +70,11 @@ defmodule Ethers do
 
   @option_keys [:rpc_client, :rpc_opts, :signer, :signer_opts, :tx_type]
   @hex_decode_post_process [
-    :current_gas_price,
     :current_block_number,
+    :current_gas_price,
     :estimate_gas,
     :get_balance,
+    :get_transaction_count,
     :max_priority_fee_per_gas
   ]
   @rpc_actions_map %{
@@ -139,6 +140,29 @@ defmodule Ethers do
     end
   end
 
+  @doc """
+  Returns the transaction count of an address.
+
+  ## Parameters
+  - account: Account which the transaction count is queried for.
+  - overrides:
+    - block: The block you want to query the transaction count in (defaults to latest).
+    - rpc_client: The RPC module to use for this request (overrides default).
+    - rpc_opts: Specific RPC options to specify for this request.
+  """
+  @spec get_transaction_count(Types.t_address(), Keyword.t()) ::
+          {:ok, non_neg_integer()} | {:error, term()}
+  def get_transaction_count(account, overrides \\ []) do
+    {opts, overrides} = Keyword.split(overrides, @option_keys)
+
+    {rpc_client, rpc_opts} = get_rpc_client(opts)
+
+    with {:ok, account, block} <- pre_process(account, overrides, :get_transaction_count, opts) do
+      rpc_client.eth_get_transaction_count(account, block, rpc_opts)
+      |> post_process(nil, :get_transaction_count)
+    end
+  end
+
   @doc """
   Returns the native transaction (ETH) by transaction hash.
 
@@ -571,7 +595,8 @@ defmodule Ethers do
     end
   end
 
-  defp pre_process(account, overrides, :get_balance = _action, _opts) do
+  defp pre_process(account, overrides, action, _opts)
+       when action in [:get_balance, :get_transaction_count] do
     block =
       case Keyword.get(overrides, :block, "latest") do
         number when is_integer(number) -> Utils.integer_to_hex(number)
diff --git a/lib/ethers/transaction.ex b/lib/ethers/transaction.ex
index 4225f4c..030cda5 100644
--- a/lib/ethers/transaction.ex
+++ b/lib/ethers/transaction.ex
@@ -229,7 +229,7 @@ defmodule Ethers.Transaction do
   end
 
   defp fill_action(:chain_id, _tx), do: :chain_id
-  defp fill_action(:nonce, tx), do: {:get_transaction_count, [tx.from, "latest"]}
+  defp fill_action(:nonce, tx), do: {:get_transaction_count, tx.from, block: "latest"}
   defp fill_action(:max_fee_per_gas, _tx), do: :gas_price
   defp fill_action(:max_priority_fee_per_gas, _tx), do: :max_priority_fee_per_gas
   defp fill_action(:gas_price, _tx), do: :gas_price
@@ -257,6 +257,10 @@ defmodule Ethers.Transaction do
     {:ok, {:max_priority_fee_per_gas, Utils.integer_to_hex(v_int)}}
   end
 
+  defp do_post_process(:nonce, {:ok, nonce}) when is_integer(nonce) do
+    {:ok, {:nonce, Utils.integer_to_hex(nonce)}}
+  end
+
   defp do_post_process(key, {:ok, v_hex}) do
     {:ok, {key, v_hex}}
   end
diff --git a/test/ethers_test.exs b/test/ethers_test.exs
index 92e04df..3254f3d 100644
--- a/test/ethers_test.exs
+++ b/test/ethers_test.exs
@@ -67,6 +67,26 @@ defmodule EthersTest do
     end
   end
 
+  describe "get_transaction_count" do
+    test "returns the correct transaction count" do
+      assert {:ok, c} =
+               Ethers.get_transaction_count("0xACa94ef8bD5ffEE41947b4585a84BdA5a3d3DA6E")
+
+      assert is_integer(c)
+      assert c >= 0
+
+      {:ok, _} =
+        Ethers.send(%{
+          from: "0xACa94ef8bD5ffEE41947b4585a84BdA5a3d3DA6E",
+          to: "0xaadA6BF26964aF9D7eEd9e03E53415D37aA96045",
+          value: 1000
+        })
+
+      assert {:ok, c + 1} ==
+               Ethers.get_transaction_count("0xACa94ef8bD5ffEE41947b4585a84BdA5a3d3DA6E")
+    end
+  end
+
   describe "get_transaction" do
     test "returns correct transaction by tx_hash" do
       {:ok, tx_hash} =