class NumericInputValue < ActiveRecord::Base

  include InputValueBehaviour

  DEFAULT_PRECISION = 2

  NUMBER_PARSER = NumbersParser.new

  # avoid default error message
  # schema_validations :except => :value

  validates_numericality_of :value,
    :message => "Nur Zahlen sind erlaubt",
    :only_integer => true


  def precision
    has_value_specification? ? value_specification.precision : DEFAULT_PRECISION
  end

  def numeric_input_ranges
    value_specification.numeric_input_ranges if has_value_specification?
  end

  def has_numeric_input_ranges?
    not numeric_input_ranges.nil?
  end

  def allowed?(value)
    if has_numeric_input_ranges?
      numeric_input_ranges.all? {|r| r.allows_value?(value) }
    else
      true
    end
  end


  def value=(v)
    write_attribute(:value, internal_value(v))
  end

  def value
    precision == 0 ? external_value.to_i : external_value
  end


  def validate
    errors.add(:value, "#{error_message}") unless allowed?(value)
  end



  private

  # if the original value can't be parsed, return it and rely on
  # default exception and error message handling
  def internal_value(v)
    ast = NUMBER_PARSER.parse(v.to_s)
    ast ? (format("%0.#{precision}f", ast.eval).to_f * 10**precision).to_i : v
  end

  def external_value
    read_attribute(:value).to_f / (10**precision)
  end

  def error_message
    numeric_input_ranges.inject("") { |memo, range| memo << range.to_error_message }
  end

end