fairmondo/fairmondo

#   Copyright (c) 2012-2017, Fairmondo eG.  This file is
#   licensed under the GNU Affero General Public License version 3 or later.
#   See the COPYRIGHT file for details.

# What used to be Exhibitions are now Libraries
class FeaturedLibraryQuery
  def initialize exhibition_name = nil
    set exhibition_name if exhibition_name
  end

  def set exhibition_name
    @exhibition_name = exhibition_name
    @library = Library.where(exhibition_name: exhibition_name).first
    @relation = LibraryElement.where(library_id: @library.id).includes(article: :title_image).joins(:article).where("articles.state = 'active'") if @library
    self
  end

  def find count = 2
    return { library: nil, exhibits: [] } unless @library

    exhibits = ordered_active_one_day_exhibited count
    exhibits.each do |exhibit|
      put_exhibition_date_of exhibit unless exhibit.exhibition_date # fills nil
    end
    exhibits = fill_exhibits_randomly(exhibits.to_a, count) unless exhibits.length >= count

    { library: @library, exhibits: exhibits.map { |exhibit| exhibit.article } }
  end

  private

  def ordered_active_one_day_exhibited limit
    @relation.where('library_elements.exhibition_date IS NULL OR library_elements.exhibition_date >= ?', DateTime.now - 1.day).order('library_elements.created_at ASC').limit limit
  end

  def put_exhibition_date_of library_element
    library_element.update_column :exhibition_date, DateTime.now
  end

  # Conditional scope, used when one_day_exhibited doesn't return enough results
  # @return [Array] exhibits plus older ones to fill empty spaces
  def fill_exhibits_randomly exhibits, count
    max_offset = filler_query(exhibits).count - 1
    (count - exhibits.length).times do
      random_offset = rand 0..max_offset
      if filler_library_element = filler_query(exhibits).offset(random_offset).first
        put_exhibition_date_of filler_library_element
        exhibits.push(filler_library_element)
      end
      max_offset -= 1
    end
    exhibits
  end

  def filler_query exhibits
    @relation.where('library_elements.id NOT IN (?)', exhibits.map { |e| e.id } + [0]).where('library_elements.exhibition_date IS NOT NULL AND library_elements.exhibition_date < ?', DateTime.now - 1.day)
  end
end