add json_rpc method

apps/ethereum_jsonrpc/lib/ethereum_jsonrpc/ipc.ex

@@ -1,7 +1,9 @@
-defmodule EthereumJSONRPC.HTTP.IPCCLient do
+defmodule EthereumJSONRPC.IPC do
   use GenServer
   @moduledoc false
 
+  # Server
+
   def start_link(state \\ []) do
     GenServer.start_link(__MODULE__, Keyword.merge(state, socket: nil))
   end
@@ -55,4 +57,31 @@ defmodule EthereumJSONRPC.HTTP.IPCCLient do
 
     {:reply, response, state}
   end
+
+  # Client
+
+  def json_rpc(pid, payload, _opts) do
+    with {:ok, response} <- post(pid, payload),
+         {:ok, decoded_body} <- Jason.decode(response) do
+      case decoded_body do
+        %{"error" => error} -> {:error, error}
+        result = [%{} | _] -> {:ok, format_batch(result)}
+        result -> {:ok, Map.get(result, "result")}
+      end
+    else
+      {:error, %Jason.DecodeError{data: ""}} -> {:error, :empty_response}
+      {:error, error} -> {:error, {:invalid_json, error}}
+      {:error, error} -> {:error, error}
+    end
+  end
+
+  defp format_batch(list) do
+    list
+    |> Enum.sort(fn %{"id" => id1}, %{"id" => id2} ->
+      id1 <= id2
+    end)
+    |> Enum.map(fn %{"result" => result} ->
+      result
+    end)
+  end
 end