ex(abillix@raznix.vnix)2> defmodule Z do defstruct c: 0 end
{:module, Z, …}
iex(abillix@raznix.vnix)3> %Z{c: 3}                         
%Z{c: 3}
iex(abillix@raznix.vnix)4> v |> (update_in [:c], &(&1-1))   
** (UndefinedFunctionError) function Z.get_and_update/3 is undefined (Z does not implement the Access behaviour)
…
iex(abillix@raznix.vnix)4> v |> (cond_do value.c > 0, do: update_in value.c, &(&1-1))
%Z{c: 2}
iex(abillix@raznix.vnix)5> v |> (cond_do value.c > 0, do: update_in value.c, &(&1-1))
%Z{c: 1}
iex(abillix@raznix.vnix)6> v |> (cond_do value.c > 0, do: update_in value.c, &(&1-1))
%Z{c: 0}
iex(abillix@raznix.vnix)7> v |> (cond_do value.c > 0, do: update_in value.c, &(&1-1))
%Z{c: 0}

def run([url, report_id]) do
    :ssl.start()
    :ibrowse.start()
    HPDF.Application.start([], [])

    my_url = url
    d = DateTime.utc_now
    file_name = "#{d.year}_#{d.month}_#{d.day}"
    {:ok, file} = File.open("printing/#{file_name}_report_graph.pdf", [:write])
    case HPDF.print_pdf!(my_url, timeout: 60_000, print_options: %{landscape: true}, after_load_delay: 10000) do
      {:ok, pdf_data} -> IO.binwrite(file, pdf_data)
    end
end

def print_pdf!(url, opts \\ []) do
    {:ok, pid} = HPDF.Controller.Supervisor.start_child([])
    timeout = Keyword.get(opts, :timeout, :infinity)
    result = GenServer.call(pid, {:print_pdf, url, opts}, timeout)
    GenServer.stop(pid, :normal)
    result
  end

** (exit) exited in: GenServer.call(#PID<0.189.0>, {:print_pdf, "http://localhost/DC%207/overview/10?layout=report", [timeout: 60000, print_options: %{landscape: true}, after_load_delay: 10000]}, 60000)
    ** (EXIT) time out
    (elixir) lib/gen_server.ex:1009: GenServer.call/3
    lib/hpdf/controller.ex:22: HPDF.Controller.print_pdf!/2
    lib/tasks/meminfo.ex:18: Mix.Tasks.Meminfo.run/1
    (mix) lib/mix/task.ex:331: Mix.Task.run_task/3
    (mix) lib/mix/cli.ex:79: Mix.CLI.run_task/2

def handle_call({:print_pdf, url, opts}, from, state) do

def handle_call({:print_pdf, url, opts}, _from, state) do
    :timer.sleep(5000)
    case HPDF.Browser.new_session() do
      {:ok, session} ->
        result = HPDF.Printer.print_page!(session.page_ws_uri, url, opts)
        HPDF.Browser.close_session(session)
        {:reply, result, state}
      {:error, _reason} = err -> err
    end
  end

15:15:43.864 [error] GenServer #PID<0.180.0> terminating
** (stop) bad return value: {:error, :not_connected}
Last message (from #PID<0.92.0>): {:print_pdf, "http://localhost/DC%207/overview/10?layout=report", [timeout: 60000, print_options: %{landscape: true}, after_load_delay: 10000]}
State: %{}
Client #PID<0.92.0> is alive

    (stdlib) gen.erl:167: :gen.do_call/4
    (elixir) lib/gen_server.ex:1006: GenServer.call/3
    lib/hpdf/controller.ex:22: HPDF.Controller.print_pdf!/2
    lib/tasks/meminfo.ex:18: Mix.Tasks.Meminfo.run/1
    (mix) lib/mix/task.ex:331: Mix.Task.run_task/3
    (mix) lib/mix/cli.ex:79: Mix.CLI.run_task/2
    (elixir) src/elixir_compiler.erl:81: :elixir_compiler.dispatch/4
    (elixir) src/elixir_compiler.erl:65: :elixir_compiler.compile/3

def print_page!(ws_address, url, opts \\ []) do
    ws_uri = URI.parse(ws_address)

    args = Keyword.merge(
      [
        socket_args: [{ws_uri.host, ws_uri.port}, [path: ws_uri.path]],
      ],
      opts
    )

    {:ok, printer} = __MODULE__.start_link(args)
    print_page(printer, url, opts)
  end

  defp print_page(printer, url, opts) do
    timeout = Keyword.get(opts, :timeout, @default_timeout)
    GenServer.call(printer, {:print_pdf, url, opts}, timeout)
  end