defmodule ToweropsWeb.ChangelogParser do
  @moduledoc """
  Reads and parses priv/static/changelog.txt into structured entries.

  File I/O and Date conversion happen here; pure parsing logic is in Gleam.
  """

  @doc "Returns a list of %{date: Date.t(), title: String.t() | nil, items: [String.t()]}"
  def parse do
    path = Application.app_dir(:towerops, "priv/static/changelog.txt")

    case File.read(path) do
      {:ok, content} ->
        content
        |> :towerops_web@changelog_parser.parse_content()
        |> Enum.map(&convert_entry/1)

      {:error, _} ->
        []
    end
  end

  defp convert_entry({:changelog_entry, date_str, title_opt, items}) do
    %{
      date: Date.from_iso8601!(date_str),
      title: unwrap_option(title_opt),
      items: items
    }
  end

  defp unwrap_option({:some, value}), do: value
  defp unwrap_option(:none), do: nil
end