feet/inches utilities

imperial.rb

#  ___                     _      _
# |_ _|_ __  _ __  ___ _ _(_)__ _| |
#  | || '  \| '_ \/ -_) '_| / _` | |
# |___|_|_|_| .__/\___|_| |_\__,_|_|
#           |_|
module Imperial
  extend ActiveSupport::Concern

  included do
    # options for select menu
    FEET_RANGE = (4..6).freeze
    INCHES_RANGE = (0..11).freeze
    MM_PER_INCH = 25.4
  end

  class_methods do
    def feet_inches
      FEET_RANGE.to_a.product(INCHES_RANGE.to_a)
    end

    def height_mm_options
      feet_inches.map { |feet, inch|
        [feet_inches_to_s(feet, inch),
         feet_inches_to_mm(feet, inch)]
      }
    end

    def height_inch_options
      feet_inches.map { |feet, inch|
        [feet_inches_to_s(feet, inch),
         feet * 12 + inch]
      }
    end

    def feet_inches_to_s(feet, inches)
      "#{feet}' #{inches}''"
    end

    def feet_inches_to_mm(feet, inches)
      (feet * 12 + inches) * 25.4
    end

    def mm_to_inches(mm)
      (mm / MM_PER_INCH).round
    end

    def inches_to_mm(inches)
      (inches * MM_PER_INCH).round
    end
  end
end