perseus

require Logger

defmodule Perseus.Boxes.Edts do
  defstruct(
    name: :edts,
    elst: nil
  )
end

alias Perseus.Boxes.Edts

defimpl Perseus.Box, for: Edts do
  def loop(<<length::integer-32, atom_type::binary-4>>, file, cnt, size, edts)
      when cnt < size do
    Logger.debug("cnt: #{cnt}, size: #{size}, length: #{length}")

    box =
      case atom_type do
        "elst" ->
          %Perseus.Boxes.Elst{}

        type ->
          %Perseus.Boxes.Unknown{name: String.to_atom(type)}

      end

    box = Perseus.Box.parse(box, file, length - 8)
    Logger.debug(inspect(box))

    loop(IO.binread(file, 8), file, cnt + length, size, edts |> Map.put(box.name, box))
  end

  def loop(:eof, _, _, _, edts) do
    edts
  end

  def loop(<<_::integer-32, _::binary-4>>, file, _, _, edts) do
    # because the current pos is past next atom's length and name

    :file.position(file, {:cur, -8})
    edts
  end

  def loop({:error, reason}, _, _, _, _) do
    Logger.debug("Error occurred while reading file #{reason}")
  end

  def parse(edts, file, size) do
    loop(IO.binread(file, 8), file, 8, size, edts)
  end
end