Get Duplicated EPin

def get_duplicated_epin() do
    Temp.track!()
    {:ok, _pd, file} = Temp.open(%{prefix: "Getrecharge_duplicate_stock", suffix: "sales.csv"})
    key = ["buying_price", "csv_id", "inserted_at", "order_id","pin", "product_name","provider", "provider_order_id","sale_type", "serial_number", "sold_date"]
    query = from(
            s in Sales,
            where: s.salestype == "epin" and s.status == "success",
            select: s.epinstock_id
            )

    list =
    Repo.all(query)
    |> Enum.group_by(&(&1))
    |> Enum.filter(fn {_, [_,_|_]} -> true; _ -> false end)
    |> Enum.map(fn {x, _} -> x end)
    |> Enum.map(fn x ->

        query = from(
                  s in Sales,
                  where: s.salestype == "epin" and s.status == "success" and s.epinstock_id == ^x,
                  join: e in Epinstocks,
                  where: s.epinstock_id == e.id,
                  join: p in Products,
                  where: s.product_id == p.id,
                  select: %{
                              :buying_price => s.buying_price,
                              :csv_id       => e.csvfile,
                              :inserted_at  => s.inserted_at,
                              :order_id     => s.merchant_order_id,
                              :pin          => e.pin,
                              :product_name => p.name,
                              :provider     => s.provider,
                              :provider_order_id => e.batch,
                              :sale_type    => s.salestype,
                              :serial_number     => s.epin_serial,
                              :sold_date    => s.updated_at,
                           }
                )
        Repo.all(query)
      end )

      list
      |> List.flatten()
      |> Enum.map(fn x -> Map.values(QueryHelpers.get_purchase_date(x)) end)
      |> List.insert_at(0, key)
      |> CSV.encode()
      |> Enum.each(&File.write(file, &1, [:append]))

  end