defmodule Gulib.Validations.Length do

  def validate(value, options \\ []) do
    Gulib.Validate.unless_skipping(value, options) do
      size = Gulib.String.length(value, trim: (Keyword.get(options, :trim)))

      case bounds(options) do
        {nil, nil} -> raise "Missing length validation range(is, min, max or range)"
        {same, same} -> 
          if size == same do
            :ok
          else
            {:fail, :wrong_length, Gulib.Translator.dgettext("validate", "must have a length of %{length}", length: same)}
          end
        {nil, max}   -> 
          if size <= max do
            :ok
          else
            {:fail, :too_long, Gulib.Translator.dgettext("validate", "must have a length of no more than %{max}", max: max)}
          end
        {min, nil}   -> 
          if min <= size do
            :ok
          else
            {:fail, :too_short, Gulib.Translator.dgettext("validate", "must have a length of at least %{min}", min: min)}
          end
        {min, max}   -> 
          if min <= size and size <= max do
            :ok
          else
            {:fail, :wrong_length, Gulib.Translator.dgettext("validate", "must have a length between %{min} and %{max}", min: min, max: max)}
          end
      end
    end
  end

  defp bounds(options) do
    is = Keyword.get(options, :is)
    min = Keyword.get(options, :min)
    max = Keyword.get(options, :max)
    range = Keyword.get(options, :in)

    cond do
      is -> {is, is}
      min -> {min, max}
      max -> {min, max}
      range -> {range.first, range.last}
      true -> {nil, nil}
    end
  end
end