middlemanでカレンダーを生成するヘルパ

calendar_helper.rb

require "date"

#
# <%= calendar year: 2015, month: 4 do |date, is_this_month|
#   <td>
#     <%- if is_this_month %>
#       <%= date.day %>
#     <%- else %>
#       <span class="text-muted"><%= date.day %></span>
#     <%- end %>
#   </td>
#

module CalendarHelper
  def calendar(year:, month:, &block)
    Calendar.new(year, month).render(self, &block)
  end

  class Calendar
    attr_reader :year, :month

    def initialize(year, month)
      @year = year
      @month = month
    end

    def render(template, &block)
      @template = template
      @buffer = ""

      render_table do
        render_header
        render_weeks(&block)
      end

      @buffer
    end

    def render_table
      @buffer += %Q{<table class="table table-bordered">}
      yield
      @buffer += %Q{</table>}
    end

    def render_header
      @buffer += %Q{<thead><tr>}

      %w(日 月 火 水 木 金 土).each do |wday|
        @buffer += %Q{<th>#{wday}</th>}
      end

      @buffer += %Q{</tr></thead>}
    end

    def render_weeks(&block)
      @buffer += %Q{<tbody>}

      weeks.each do |week|
        render_week(week, &block)
      end

      @buffer += %Q{</tbody>}
    end

    def render_week(week, &block)
      @buffer += %Q{<tr>}

      week.each do |(date, is_this_month)|
        @buffer += capture_html(date, is_this_month, &block)
      end

      @buffer += %Q{</tr>}
    end

    def weeks
      first_date = Date.new(year, month, 1)
      last_date  = Date.new(year, month, -1)

      result = []
      last_week = []

      first_date.wday.downto(1) do |n|
        date = first_date - n
        last_week << [date, false]
      end

      first_date.upto(last_date) do |date|
        if date.sunday? && last_week.any?
          result << last_week
          last_week = []
        end

        last_week << [date, true]
      end

      1.upto(6 - last_date.wday) do |n|
        date = last_date + n
        last_week << [date, false]
      end

      result << last_week

      result
    end

    def capture_html(*args, &block)
      engine = File.extname(block.source_location[0])[1..-1].to_sym
      handler = ::Padrino::Helpers::OutputHelpers.handlers[engine].new(@template)
      result = handler.capture_from_template(*args, &block)
      ActiveSupport::SafeBuffer.new.safe_concat(result)
    end
  end
end