class Dry::Types::Enum

def call(input = Undefined)
  type[map_value(input)]
end

def default(*)
  raise '.enum(*values).default(value) is not supported. Call '\
        '.default(value).enum(*values) instead'
end

def initialize(type, options)
  super
  @mapping = options.fetch(:mapping).freeze
  @values = @mapping.keys.freeze
  @inverted_mapping = @mapping.invert.freeze
  freeze
end

def map_value(input)
  if input.equal?(Undefined)
    type.call
  elsif mapping.key?(input)
    input
  else
    inverted_mapping.fetch(input, input)
  end
end

def to_ast(meta: true)
  [:enum, [type.to_ast(meta: meta),
           mapping,
           meta ? self.meta : EMPTY_HASH]]
end

def try(input)
  super(map_value(input))
end