class PgSearch::ScopeOptions

def apply(scope)
  scope = include_table_aliasing_for_rank(scope)
  rank_table_alias = scope.pg_search_rank_table_alias(:include_counter)
  scope
    .joins(rank_join(rank_table_alias))
    .order(Arel.sql("#{rank_table_alias}.rank DESC, #{order_within_rank}"))
    .extend(DisableEagerLoading)
    .extend(WithPgSearchRank)
    .extend(WithPgSearchHighlight[feature_for(:tsearch)])
end

def conditions
  config.features
        .reject { |_feature_name, feature_options| feature_options && feature_options[:sort_only] }
        .map { |feature_name, _feature_options| feature_for(feature_name).conditions }
        .inject { |accumulator, expression| Arel::Nodes::Or.new(accumulator, expression) }
end

def feature_for(feature_name)
  feature_name = feature_name.to_sym
  feature_class = FEATURE_CLASSES[feature_name]
  raise ArgumentError, "Unknown feature: #{feature_name}" unless feature_class
  normalizer = Normalizer.new(config)
  feature_class.new(
    config.query,
    feature_options[feature_name],
    config.columns,
    config.model,
    normalizer
  )
end

def include_table_aliasing_for_rank(scope)
  return scope if scope.included_modules.include?(PgSearchRankTableAliasing)
  scope.all.spawn.tap do |new_scope|
    new_scope.class_eval { include PgSearchRankTableAliasing }
  end
end

def initialize(config)
  @config = config
  @model = config.model
  @feature_options = config.feature_options
end

def order_within_rank
  config.order_within_rank || "#{primary_key} ASC"
end

def primary_key
  "#{quoted_table_name}.#{connection.quote_column_name(model.primary_key)}"
end

def rank
  (config.ranking_sql || ":tsearch").gsub(/:(\w*)/) do
    feature_for(Regexp.last_match(1)).rank.to_sql
  end
end

def rank_join(rank_table_alias)
  "INNER JOIN (#{subquery.to_sql}) AS #{rank_table_alias} ON #{primary_key} = #{rank_table_alias}.pg_search_id"
end

def subquery
  model
    .unscoped
    .select("#{primary_key} AS pg_search_id")
    .select("#{rank} AS rank")
    .joins(subquery_join)
    .where(conditions)
    .limit(nil)
    .offset(nil)
end

def subquery_join
  if config.associations.any?
    config.associations.map do |association|
      association.join(primary_key)
    end.join(' ')
  end
end