LafayetteCollegeLibraries/spot

# frozen_string_literal: true
#
# Adds the ability to index dates in various English forms.
#
# Currently adds:
#   - full month (ex. 'February 2019')
#   - abbreviated month (ex. 'Feb 2019')
#   - season (ex. 'Winter 2019')
#
# By default, it uses the +:date_issued+ property of the object
# and stores the values under +'english_language_date_teim'+, but
# these are configurable by class attributes.
#
# @example configuring the mixin
#   class ImageIndexer < Hyrax::WorkIndexer
#     include IndexesEnglishLanguageDates
#
#     self.english_language_date_field = 'english_readable_date_tesim'
#     self.date_property_for_english_language_indexing = :date_created
#   end
#
module IndexesEnglishLanguageDates
  extend ActiveSupport::Concern

  included do
    class_attribute :english_language_date_field
    self.english_language_date_field = 'english_language_date_teim'

    class_attribute :date_property_for_english_language_indexing
    self.date_property_for_english_language_indexing = :date_issued
  end

  # @return [Hash]
  def generate_solr_document
    super.tap do |solr_doc|
      add_english_language_dates(solr_doc)
    end
  end

  private

  # @param solr_doc [Hash]
  # @return [void]
  def add_english_language_dates(solr_doc)
    solr_doc[english_language_date_field] = dates.map do |date|
      begin
        parsed = Date.parse(date)
      rescue ArgumentError
        next unless date.match?(/^\d{4}-\d{2}/)
        parsed = Date.new(*date.split('-').map(&:to_i))
      end

      season_names_for_date(parsed) + spelled_out_for_date(parsed)
    end.flatten.reject(&:blank?)
  end

  # Determines the season based on the month:#
  #   Spring => March, April, May
  #   Summer => June, July, August
  #   Autumn/Fall => September, October, November
  #   Winter => December, January, February
  #
  # @param date [#strftime, #year]
  # @return [Array<String>]
  def season_names_for_date(date)
    seasons = case date.strftime('%-m').to_i
              when 3..5 then  %w[Spring]
              when 6..8 then  %w[Summer]
              when 9..11 then %w[Autumn Fall]
              else %w[Winter]
              end
    year = date.year
    seasons.map { |season| "#{season} #{year}" }
  end

  # Transforms our date into English-language dates.
  #
  # @example
  #   spelled_out_dates_for_date(Date.parse('2019-02-08'))
  #   => ['February 8 2019', 'Feb 8 2019']
  #
  # @param date [#strftime]
  # @return [Array<String>]
  def spelled_out_for_date(date)
    %w[%B %b].map { |month| date.strftime("#{month} %Y") }
  end

  # Saves us the hassle of having to type out that long attribute
  #
  # @return [Array<String>]
  def dates
    object.send(date_property_for_english_language_indexing)
  end
end