defmodule Outlook.InternalTree.Basic do

  alias Ecto.UUID
  alias Outlook.InternalTree.InternalNode
  alias Outlook.InternalTree.TranslationUnit
  alias Outlook.InternalTree.Html

  @splitmarker "@@translationunit@@"

  def set_split_markers([ %InternalNode{type: :text} = textnode | rest ]) do
    [ %InternalNode{textnode |
        content: String.replace(textnode.content, ~r|([.?!]["'”]?\s*)|u, "\\1#{@splitmarker}")
        } | set_split_markers(rest) ]
  end

  def set_split_markers([ %InternalNode{type: :element} = node | rest ]) do
    [ %InternalNode{node | content: set_split_markers(node.content)}
      | set_split_markers(rest) ]
  end

  def set_split_markers([ node | rest ]) do
    [ node | set_split_markers(rest) ]
  end

  def set_split_markers([]), do: []

  def partition_textnodes([ %InternalNode{type: :element} = node | rest ]) do
    [ %InternalNode{node | content: case get_sibling_collocation(node.content) do
        :block -> partition_textnodes(node.content)
        :inline -> inline_to_translation_units(node.content)
        _ -> [ node ]
      end
    } | partition_textnodes(rest) ]
  end

  def partition_textnodes([ node | rest ]) do
    [ node | partition_textnodes(rest) ]
  end

  def partition_textnodes([]), do: []


  defp inline_to_translation_units(contents) do
    contents
      # |> Html.strip_attributes  # to be implemented
      |> Html.to_html()
      |> String.split(@splitmarker, trim: true)
      |> Enum.map(fn sentence ->
        %TranslationUnit{
          content: sentence,
          status: :untranslated,
          uuid: UUID.generate()
        }
        end
      )
  end

  defp contains_elements?(content) do

  end

  @doc "Returns just either :block or :inline. Assumes that it doesn't contain both."
  def get_sibling_collocation(content) do
    content
    |> Enum.map(fn node -> node.sibling_with end)
    |> Enum.uniq()
    |> List.delete(:both)
    |> List.first
  end
end