class PgSearch::Configuration::Association

def initialize(model, name, column_names)
  @model = model
  @name = name
  @columns = Array(column_names).map do |column_name, weight|
    Column.new(column_name, weight, @model, self)
  end
end

def join(primary_key)
  selects = columns.map do |column|
    case @model.connection.send(:postgresql_version)
    when 0..90000
      "array_to_string(array_agg(#{column.full_name}), ' ') AS #{column.alias}"
    else
      "string_agg(#{column.full_name}, ' ') AS #{column.alias}"
    end
  end.join(", ")
  relation = @model.joins(@name).select("#{primary_key} AS id, #{selects}").group(primary_key)
  "LEFT OUTER JOIN (#{relation.to_sql}) #{subselect_alias} ON #{subselect_alias}.id = #{primary_key}"
end

def subselect_alias
  Configuration.alias(table_name, @name, "subselect")
end

def table_name
  @model.reflect_on_association(@name).table_name
end