For stackoverflow Q#4955355

.gitignore

db

README.rb

# This presumes that each day is seperate, and you don't actually want to expose 
# the durations to the user, ie, for "take this week off" 
# (thus the goofy name HoliDay which emphasizes the day-nature,)
# and also that the HTML-interface you want is checkboxes for :am_pm and :all_day, 
# and :date as a normal rails-style date select list.

holi_day.rb

#app/models/holi_day.rb 
# The actual model logic that extends the general concept of a 
# holiday into one which only handles single-day requests.
require 'holiday'
class HoliDay < Holiday 
  # This is ever so slightly a hack.
  # We're going to use AR::Base's STI facility to transparently 
  # decorate these objects. There's no actual :type field in the db.
  # The same functionality could be done with normal decorators as well.
  # or even down in the Presenter class, as private methods.
  
  #This is all model-db-level info, the view shouldn't know about this stuff:
  ALL_DAY = [0.hours, 24.hours]
  MORNING_EVENING = {
    false => [9.hours,12.hours], #:pm? #=> false
    true => [12.hours,17.hours]  #:pm? #=> true
    }
  #Just building a queryable data structure here for our args mapping the booleans 
  # from the view to ranges of time in the db
  ALL_DAY_MORNING_EVENING = {
    true => {true => ALL_DAY, false => ALL_DAY},
    false => MORNING_EVENING
  }
  
  #Little bridge for the view-attributes
  def pm?
    start_time && (start_time.hour >= 12) #This should be equal to at least EVENING start, if not MORNING end, above.
  end
  def date
    start_time && start_time.to_date
  end
  
  
  def normalize_holi_day_attrs(unchecked_args)
    args = {:date => self.date || Date.today, :am_pm => true, :all_day => true}.merge(unchecked_args) 
    #am_pm and all_day need to be boolean, and we assume they're true by default
    #date must be present
    args
  end
  #Knows how to change the view-style data into the db-style range type
  #Wat up MTV: Dis my data representation bridge, dis where da magic happen
  def holi_day_attrs_to_duration(args={:date=>Date.today, :am_pm => true, :all_day => true})
    args = normalize_holi_day_attrs(args)
    days = [args[:date].to_time,args[:date].to_time] #=>[Date.today, Date.today]
    times = ALL_DAY_MORNING_EVENING[args[:all_day]][args[:am_pm]] #=>[9.hours, 12.hours]
    a_duration = days.zip(times).map{|day,time| day+time} #=> [[Date.today, 9.hours],[Date.today, 12.hours]] #=> [today at 9, today at noon] 
    Range.new(*a_duration)
  end
  def duration=(arg)
    if arg.is_a?(Hash)
      self.duration = holi_day_attrs_to_duration(arg)
    else
      super(arg)
    end
  end
  
end

holi_day_presenter.rb

#app/helpers/holi_day_presenter.rb
require 'forwardable'
require 'holi_day'
class HoliDayPresenter
  # A small proxy for the view that mediates between the view-tag-helpers and the model.
  # You can use it like so in the controller: 
  #    @holi_day = HoliDayPresenter.new() #quacks like a HoliDay as far as active_model goes.
  # Or:
  #    @holi_day = HoliDayPresenter.new(HoliDay.find(params[:id])) #Though, it would be easy to make 
  #                                                                #HoliDayPresenter implement a #find
  #                                                                #class_method, if you care.
  #    @holi_day.update_attributes(params[:holi_day])
  #    @holi_day.valid? && @holi_day.save
  # And the view _only_ knows the HoliDay via the presenter:
  # <% semantic_form_for :holi_day, :object => @holi_day do |f| %>
  #   <%= f.input :am_pm %> <%#because these act like t/f attributes to the view %>
  #   <%= f.input :all_day %>
  #   <%= f.input :date %>
  #   <%= f.commit_button %>
  # <% end %>
  
  extend Forwardable
  
  def initialize(atts={})
    @model= case atts
      when HoliDay then
        atts
      when Hash then
        HoliDay.new(self.durationize_atts(atts))
      else
        HoliDay.new
      end
  end
  
  
  #view-facing methods
  def_delegator :@model, :pm?, :am_pm #makes :am_pm act like a t/f attribute
  def_delegator :@model, :date 
  def_delegator :@model, :all_day?, :all_day #makes :all_day act like a t/f attribute
  
  #Standard AR::Model bits here for error messages
  def_delegator :@model, :valid?
  def_delegator :@model, :save
  def durationize_atts(att)
    att = att.clone
    others = att.slice!(:date, :all_day, :am_pm)
    others.merge!({:duration => att}) #subtle: needs to exist so records initialize properly.
    others
  end
  def update_attributes(att={})
    @model.update_attributes(self.durationize_atts(att))
  end

end

holi_day_test.rb

gem 'activerecord', '> 2.3.8','< 3.1'
gem 'activesupport', '> 2.3.8', '< 3.1'
require 'test/unit'
require 'active_record'
require 'active_support'
require 'forwardable'

ActiveRecord::Base.establish_connection({
  'adapter' => 'sqlite3',
  'database' => 'db/holidays',
  'timeout' => 5000
})

ActiveRecord::Migration.create_table 'holidays', :force => true  do |h| #drops on create
  h.datetime :start_time
  h.datetime :finish_time
  h.timestamps
end

$LOAD_PATH.push(File.dirname(__FILE__)) unless RUBY_VERSION < '1.9'

#test/unit/holi_day_test.rb
require 'active_support/core_ext/kernel/requires'
require 'active_support/test_case'
require 'active_record/test_case'
class HoliDayTest < Test::Unit::TestCase
  extend ActiveSupport::Testing::Declarative
  require 'holiday'
  #Holiday
  test "a holiday has a start_time and finish_time duration" do
    t = Time.current
    h=Holiday.new(:start_time => t, :finish_time => 4.days.from_now(t))
    assert_equal 4.days, h.duration.last - h.duration.first
  end
  test "updating a holiday duration" do
    h=Holiday.new
    t=Time.current
    h.duration = Range.new(t, 4.days.from_now(t))
    assert_equal 4.days, h.finish_time - h.start_time
  end
  
  require 'holi_day'
  #HoliDay
  test "an all_day holi_day from the db's pov" do
    h=HoliDay.new(:start_time => Date.today, :finish_time => 24.hours.from_now(Date.today))
    assert_equal [true], [h.all_day?]
  end
  test "a morning holi_day from the db's pov" do
    h=HoliDay.new(:start_time => 9.hours.from_now(Date.today), :finish_time => 12.hours.from_now(Date.today))
    assert_equal [false,false, Date.today], [h.all_day?, h.pm?, h.date]
  end 
  test "an evening holi_day from the db's pov" do
    h=HoliDay.new(:start_time => 12.hours.from_now(Date.today), :finish_time => 24.hours.from_now(Date.today))
    assert_equal [false,true, Date.today], [h.all_day?, h.pm?, h.date]
  end
  test "handles presenter attr hash for duration" do
    h=HoliDay.new(:start_time => Date.today, :finish_time => 24.hours.from_now(Date.today))
    yr = 1.year.from_now(Date.today)
    h.duration = {:date => yr, :am_pm => true, :all_day => true}
    assert_equal [true,false, yr.to_time - Date.today.to_time ], [h.all_day?, h.pm?, (h.date.to_time - Date.today.to_time) ]
  end


  require 'holi_day_presenter'
  #HoliDayPresenter
  #db hit
  test "the presenter passes on relevant methods" do
      h=HoliDay.new(:start_time => 12.hours.from_now(Date.today), :finish_time => 24.hours.from_now(Date.today))
      h_p = HoliDayPresenter.new(h)
      assert_equal [false,true, Date.today, true, true], [h_p.all_day, h_p.am_pm, h_p.date, h_p.valid?, h_p.save]
  end
  #db hit
  test "update_attributes handles other args as well as duration" do #This might need the other attrs' getters implemented as well.
    h=HoliDay.new
    h_p = HoliDayPresenter.new(h)
    h_p.update_attributes(:am_pm => false, :all_day => false, 
      :created_at => 2.minutes.ago(Time.current))
    assert_equal [2, false,false, Date.today, true, true ], [Time.current.min - h.created_at.min, h_p.all_day, h_p.am_pm, h_p.date, h_p.valid?, h_p.save]
  end 
  test "on today and all_day, is the default" do
    h_p = HoliDayPresenter.new
    assert_equal [true,false, Date.today], [h_p.all_day, h_p.am_pm, h_p.date]
  end
  
end

holiday.rb

#app/models/holiday.rb
class Holiday < ActiveRecord::Base
  composed_of :duration, :mapping =>[[:start_time, :first],[:finish_time,:last]], :class_name => 'Range'
  #note that this will work for days-long durations, db-wise.
  def all_day?
    finish_time && start_time && ((finish_time.to_time - start_time.to_time ).to_i % 1.day.to_i == 0)
  end
end

init.rb