src/derails/passive_model/type/helpers/numeric.rb
# frozen_string_literal: true

module PassiveModel
  module Type
    module Helpers # :nodoc: all
      module Numeric
        def serialize(value)
          cast(value)
        end

        def serialize_cast_value(value)
          value
        end

        def cast(value)
          # Checks whether the value is numeric. Spaceship operator
          # will return nil if value is not numeric.
          value = if value <=> 0
            value
          else
            case value
            when true then 1
            when false then 0
            else value.presence
            end
          end

          super(value)
        end

        def changed?(old_value, _new_value, new_value_before_type_cast) # :nodoc:
          (super || number_to_non_number?(old_value, new_value_before_type_cast)) &&
            !equal_nan?(old_value, new_value_before_type_cast)
        end

        private
          def equal_nan?(old_value, new_value)
            (old_value.is_a?(::Float) || old_value.is_a?(BigDecimal)) &&
              old_value.nan? &&
              old_value.instance_of?(new_value.class) &&
              new_value.nan?
          end

          def number_to_non_number?(old_value, new_value_before_type_cast)
            old_value != nil && !new_value_before_type_cast.is_a?(::Numeric) &&
              non_numeric_string?(new_value_before_type_cast.to_s)
          end

          def non_numeric_string?(value)
            # 'wibble'.to_i will give zero, we want to make sure
            # that we aren't marking int zero to string zero as
            # changed.
            !NUMERIC_REGEX.match?(value)
          end

          NUMERIC_REGEX = /\A\s*[+-]?\d/
          private_constant :NUMERIC_REGEX
      end
    end
  end
end
