finder.rb

 class Finder
  def self.find(query)
    people = []

    conditions = []

    words = query.split(' ')
    case words.count
    when 1
      conditions << ["id = ?", query]
      conditions << ["enp = ?", query]
      conditions << ["n_pol = ?", query]
      conditions << ["fam LIKE %?%", Unicode::upcase(query)]
    when 2
      first, second = words
      conditions << ["fam LIKE %?% AND im LIKE %?%", Unicode::upcase(first), Unicode::upcase(second)]
      conditions << ["s_pol LIKE ? AND n_pol LIKE ?", first, second]
    when 3
      first, second, third = words
      conditions << ["fam LIKE %?% AND im LIKE %?% AND ot LIKE %?%", Unicode::upcase(first), Unicode::upcase(second), Unicode::upcase(third)]
      conditions << ["sn_rasp = ?", query]
    end

    sql = []
    bindings = []
    conditions.each do |condition|
      sql = "(#{condition.first})"
      bindings.concat condition.drop(1)
    end

    Person.where(sql.join(' OR '), *bindings)
  end