Refactor SearchHelper

[eoinkelly]

SearchHelper makes extensive use of instance variables. This is a bit messy and Rubocp doesn't like it so it would be great to refactor these helpers to not depend on instance variables by turning them into pure functions which are passed all the args they need and don't mutate any of their args (i.e. they return copies).

List of disabled cops in app/helpers/search_helper.rb

[17:05:27] ❯ ag "rubocop:disable"
app/helpers/search_helper.rb
3:module SearchHelper # rubocop:disable Metrics/ModuleLength
44:    return if @query[:hs].blank? # rubocop:disable Rails/HelperInstanceVariable
46:    query_hs = @query[:hs] # rubocop:disable Rails/HelperInstanceVariable
49:    query_hs = @query[:hs].map { |q| "#{q}.1" } if shape.split('.').last == '1' # rubocop:disable Rails/HelperInstanceVariable
55:    'selected' if @query[:l].present? && @query[:l].include?(location.split('.')[1]) # rubocop:disable Rails/HelperInstanceVariable
59:    'selected' if @query[:lg].present? && @query[:lg].include?(location_group.split('.')[0]) # rubocop:disable Rails/HelperInstanceVariable
85:    keys = @query.select { |_key, value| value.present? }.keys # rubocop:disable Rails/HelperInstanceVariable
102:    return if @query[:l].blank? # rubocop:disable Rails/HelperInstanceVariable
120:    return if @query[:hs].blank? # rubocop:disable Rails/HelperInstanceVariable
137:    return if @query[:lg].blank? # rubocop:disable Rails/HelperInstanceVariable
153:    h SignMenu.usage_tags.select { |u| @query[:usage].include?(u.last.to_s) }.map(&:first).join(' ') if @query[:usage].present? # rubocop:disable Rails/HelperInstanceVariable
157:    h SignMenu.topic_tags.select { |u| @query[:tag].include?(u.last.to_s) }.map(&:first).join(' ') if @query[:tag].present? # rubocop:disable Rails/HelperInstanceVariable
161:    return if @query[key].blank? || (@query[key].is_a?(Array) && @query[key].reject(&:blank?).blank?) # rubocop:disable Rails/HelperInstanceVariable
163:    h @query[key].join(' ') # rubocop:disable Rails/HelperInstanceVariable
176:    @display_search_term ||= safe_join(search_term_elements, ' ') # rubocop:disable Rails/HelperInstanceVariable

app/helpers/application_helper.rb
5:    "#{@title}#{' -' if @title} #{t('layout.title')}" # rubocop:disable Rails/HelperInstanceVariable

app/helpers/vocab_sheet_helper.rb
5:    return nil if @sheet.blank? # rubocop:disable Rails/HelperInstanceVariable
6:    return nil if @sheet.items.length.zero? # rubocop:disable Rails/HelperInstanceVariable
13:    return offsets[:"size_#{@size}"] if @size.present? # rubocop:disable Rails/HelperInstanceVariable