module Searchable
  extend ActiveSupport::Concern

  included do
    include PgSearch::Model
    class_attribute :searchable_attributes, default: []
    class_attribute :searchable_internal_attributes, default: []
    multisearchable against: [
      :searchable_attributes_text,
      :custom_searchable_text
    ],
    # See `internal_content` method below
    additional_attributes: -> (doc) { { internal_content: doc.internal_content } },
    internal_against: [
      :searchable_internal_attributes_text,
      :custom_internal_searchable_text
    ]
  end

  # Helper method so that Models can search just themselves from within the
  # multisearch index
  class_methods do
    def search_scope(q)
      PgSearch::Document.search(q).where(searchable_type: self.base_class.name)
    end

    def search(q)
      # use select here instead of pluck because it will make it a single query
      # instead of 2 queries
      self.where(id: search_scope(q).select(:searchable_id))
    end

    def internal_search_scope(q)
      PgSearch::Document.internal_search(q).where(searchable_type: self.base_class.name)
    end

    def internal_search(q)
      self.where(id: internal_search_scope(q).select(:searchable_id))
    end
  end

  # Meta programming so that modles can just set an class attribute of all the 
  # attributes that are searchable
  #
  def searchable_attributes_text
    Array.new.tap do |a|
      searchable_attributes.each do |f|
        a << self.send(f)
      end
    end.compact.join(" ")
  end

  def related_searchable_objects
    []
  end

  def custom_searchable_text
    Array.new.tap do |a|
      related_searchable_objects.each do |related|
        a << related_object_searchable_text(related)
      end
    end.compact.join(" ")
  end

  def related_object_searchable_text(related)
    return nil unless related.present?
    return nil unless related.kind_of?(Searchable)
    return related.searchable_attributes_text
  end

  # Basically equivalent to PgSearch::Mutisearchable#searchable_text
  def internal_content
    pg_search_multisearchable_options[:internal_against].map do |symbol|
      send(symbol)
    end.compact.join(" ")
  end

  def searchable_internal_attributes_text
    Array.new.tap do |a|
      searchable_internal_attributes.each do |f|
        a << self.send(f)
      end
    end.compact.join(" ")
  end

  def custom_internal_searchable_text
    Array.new.tap do |a|
      related_searchable_objects.each do |related|
        a << related_object_searchable_internal_text(related)
      end
    end.compact.join(" ")
  end

  def related_object_searchable_internal_text(related)
    return nil unless related.present?
    return nil unless related.kind_of?(Searchable)
    return related.searchable_internal_attributes_text
  end
end