defmodule NLdoc.Validation.Rules.PAsHeading do
  @moduledoc """
  Ensures paragraph elements are not used to style headings.
  """

  alias NLdoc.Spec.Paragraph
  alias NLdoc.Validation.Severity

  use NLdoc.Validation.Rule,
    severity: Severity.warning(),
    rule: "p-as-heading",
    ruleset: "https://dequeuniversity.com/rules/axe/html",
    ruleset_version: "4.10",
    validates: [Paragraph]

  @impl true
  def valid?(paragraph = %Paragraph{children: children}, _) do
    !Enum.all?(children, &bold?/1) || !NLdoc.Spec.Content.discernible_text?(paragraph)
  end

  @spec bold?(term()) :: boolean()
  defp bold?(%{styling: styling, text: text}),
    do: Enum.member?(styling, :bold) || !NLdoc.Spec.Content.discernible_text?(text)

  defp bold?(_),
    do: false
end