defmodule Exdiff do
  @moduledoc """
    Exdiff is a simple wrapper to make String.myers_difference/2 useful.
  """
  
  def diff_to_html(string1, string2, separator \\ "</p>") do
    s1 = string1 |> String.split(separator, trim: true) |> Enum.map(fn(x) -> x <> separator end)
    s2 = string2 |> String.split(separator, trim: true) |> Enum.map(fn(x) -> x <> separator end)
    List.myers_difference(s1, s2) |> wrap_html()
  end
  
  defp wrap_html(lmd) do
    lmd
    |> Enum.map_join(fn {k, v} ->
      case k do
        :del -> "<div class='exdiff-del'>#{v}</div>"
        :ins -> "<div class='exdiff-ins'>#{v}</div>"
        _    -> "<div class='exdiff-eq'>#{v}</div>"
      end
    end)
  end
end