defmodule Next do
  import Phoenix.HTML
  import Phoenix.HTML.Tag

  def rev(tag, rev_opts, tag_opts, do: block) do
    content_tag(tag, merge_opts(rev_opts, tag_opts), do: block)
  end

  def rev(rev_opts, tag_opts, do: block) do
    {tag, rev_opts} = Keyword.pop_first(rev_opts, :tag, :div)
    rev(tag, rev_opts, tag_opts, do: block)
  end

  defp merge_opts(rev_opts, tag_opts) do
    {rev_class, rev_opts} = Keyword.pop_first(rev_opts, :class)
    {tag_class, tag_opts} = Keyword.pop_first(tag_opts, :class)

    class =
      rev_class || (tag_class && [rev_class, tag_class]
      |> Enum.filter(& &1)
      |> Enum.join(" "))

    rev_opts
    |> Keyword.merge(tag_opts)
    |> Keyword.put(:class, class)
  end

  def suit(base_class, modifiers \\ []) do
    modifiers
    |> Enum.reduce("#{base_class}", fn {modifier, value}, class ->
      case modifier do
        :class ->
          "#{class} #{value}"

        _ ->
          case value do
            false -> class
            true -> "#{class} #{base_class}--#{modifier}"
            other -> "#{class} #{base_class}--#{modifier}#{other}"
          end
      end
    end)
  end

  def row(mods, x), do: rev(class: suit("rev-Row", mods), x)
  def row(x), do: row([], x)

  def col(mods, x), do: rev(class: suit("rev-Col", mods), x)
  def col(x), do: col([], x)

  def menu(mods, x), do: rev(tag: :ul, class: suit("rev-Menu", mods), x) do
  def menu(x), do: menu([], x)

  def menu_item(mods, x), do: rev(tag: :li, class: suit("rev-Menu-item", mods), x)
  def menu_item(x), do: menu([], x)
end

defmodule Next.Example do
  def example() do
    ~E"""
    <%= rev row() do %>
      <%= rev col(medium: 4), class: "extra classes" do %>
        <%= rev menu() do %>
          <%= rev menu_item() do %>
            Menu Item 1
          <% end %>
        <% end %>
      <% end %>
    <% end %>
    """
  end
end