defmodule WebAssembly.Tools do
  @moduledoc """
  Tools manipulating assembly input & output.

  See `WebAssembly.Tools.Input` & `WebAssembly.Tools.Output`.
  """

  alias WebAssembly.Types, as: T


  defmodule Input do

    @doc ~S"""
    Turn a keyword list of attributes to an list of attribute framgents
    in a format used by html.

    Underscores in key names are turned into dash signs.

    ## Examples
        iex> WebAssembly.Tools.Input.htmlize_attrs(class: "light", id: :myid)
        ["class=\"light\"", " ", "id=\"myid\""]

        iex> WebAssembly.Tools.Input.htmlize_attrs(http_equiv: "Content-Type")
        ["http-equiv=\"Content-Type\""]
    """

    @spec htmlize_attrs(T.attrs) :: [String.t]

    def htmlize_attrs(attrs) do
      Enum.map(attrs, fn {k,v} ->
      k = k |> to_string |> String.replace("_", "-")
        ~s/#{k}="#{v}"/
      end)
      |> Enum.intersperse(" ")
    end
  end


  defmodule Output do

    @doc ~S"""
    Flush nested list of tag fragments into a flat string.

    Flushing is not needed when you pass tag fragments
    directly to Plug. Still it may come handy when testing,
    prototyping or using WebAssembly output together with
    web views based on templates.

    ## Examples
        iex(1)> use WebAssembly
        nil
        iex(2)> doc = builder do: div do: (span "hey!")
        ["\n<div>", ["\n<span>", "hey!", "</span>"], "</div>"]
        iex(3)> WebAssembly.Tools.Output.flush doc
        "\n<div>\n<span>hey!</span></div>"
    """

    @spec flush(T.out_tag) :: String.t

    def flush(chunks) when is_list(chunks) do
      chunks |> List.flatten |> Enum.join
    end
  end
end