class ActiveRecord::Base
  alias_method :orig_extract_callstack_for_multiparameter_attributes, :extract_callstack_for_multiparameter_attributes

  def extract_callstack_for_multiparameter_attributes(pairs)
    attributes = orig_extract_callstack_for_multiparameter_attributes(pairs)
    attributes.each do |name, values|
      klass = (self.class.reflect_on_aggregation(name) || column_for_attribute(name)).klass
      if klass == Time && values.length == 6
        if values[5] == "AM" && values[3] == 12
          values[3] = 0
        elsif values[5] == "PM" && values[3] != 12
          values[3] += 12
        end
      end
    end
  end
end

module ActionView::Helpers::DateHelper
  def select_hour(datetime, options = {}) 
    hour_options = []

    1.upto(12) do |hour|
      time = Time.local(0, 1, 1, ((datetime.kind_of?(Fixnum)) ? datetime : datetime.hour))
      selected = (time.strftime("%I").to_i == hour) ? ' selected="selected"' : ''
      hour_options << %(<option value="#{leading_zero_on_single_digits(hour)}"#{selected}>#{leading_zero_on_single_digits(hour)}</option>\n)
    end

    select_html(options[:field_name] || 'hour', hour_options, options[:prefix], options[:include_blank], options[:discard_type], options[:disabled])
  end

  def select_ampm(datetime, options = {})
    ampm_options = []

    ["AM", "PM"].each do |value|
      time = Time.local(0, 1, 1, ((datetime.kind_of?(Fixnum)) ? datetime : datetime.hour))
      selected = (time.strftime("%p") == value) ? ' selected="selected"' : ''
      ampm_options << %(<option value="#{value}"#{selected}>#{value}</option>\n)
    end

    select_html(options[:field_name] || "ampm", ampm_options, options[:prefix], options[:include_blank], options[:discard_type], options[:disabled])
  end
end

class ActionView::Helpers::InstanceTag
  alias_method :orig_to_datetime_select_tag, :to_datetime_select_tag

  def to_datetime_select_tag(options = {})
    defaults = { :discard_type => true }
    options  = defaults.merge(options)
    options_with_prefix = Proc.new { |position| options.merge(:prefix => "#{@object_name}[#{@method_name}(#{position}s)]") }
    datetime = options[:include_blank] ? (value || nil) : (value || Time.now)

    orig_to_datetime_select_tag(options) + ' ' + select_ampm(datetime, options_with_prefix.call(6)) unless options[:discard_hour]
  end
end