Call multicall contract with ExAbi in Elixir

ex_abi_multicall.ex

defmodule MyProject.Ethereum.Multicall do
  @multicall_addr "0xeefBa1e63905eF1D7ACbA5a8513c70307C1cE441"

  @doc """
  Takes a list of {address, call} tuples, returns an ok tuple with block number and data in same order as list of calls

  iex> MyProject.Ethereum.Multicall.multicall({"0x000", ABI.encode("tokenURI(uint256)", [token_id])})
  {:ok, 0x000}
  """
  def multicall(list) do
    abi_data =
      list
      |> Enum.map(&encode_call/1)
      |> encode_aggregate_call()

    Ethereumex.HttpClient.eth_call(%{
      data: "0x" <> abi_data,
      to: @multicall_addr
    })
    |> case do
      {:ok, data} ->
        data
        |> String.slice(2..-1)
        |> Base.decode16!(case: :lower)
        |> ABI.TypeDecoder.decode_raw([{:uint, 256}, {:array, :bytes}])
        |> case do
          [block_number, answers] -> {:ok, block_number, answers}
          _ -> {:error, "Incorrectly formatted response from aggregate function"}
        end

      {:error, error} ->
        {:error, error}
    end
  end

  defp encode_call({"0x" <> address, data}) do
    {Base.decode16!(address, case: :mixed), data}
  end

  defp encode_aggregate_call(calls) do
    ABI.encode("aggregate((address,bytes)[])", [calls])
    |> Base.encode16(case: :lower)
  end
end