identification_strategy.rb

class IdentificationStrategy
  def initialize origin, priorities
    @origin = origin
    @priorities = [priorities].flatten
  end

  def branch candidates
    case candidates.length
      when 0
        zero
      when 1
        return candidates.first
      when 2...Float::INFINITY
        many candidates
    end
  end

  def search company
    database_results = query(:PAYINDEX, extract_attributes(company).collect(&extract_from(company)))
    candidates = database_results.select(&confidently_identified(company))
    branch candidates
  end

  def extract_attributes company
    @origin.attributes.select(&by_priority_from(company))
  end

  def classify weight
    case weight
      when 0...@origin.suspicious_threshold
        NegativeIdentification
      when @origin.suspicious_threshold...@origin.identification_threshold
        SuspiciousIdentification
      when @origin.identification_threshold...Float::INFINITY
        ConfidentIdentification
    end
  end

  private

  def extract_from company
    ->(attribute) {
      [attribute.name, company.send(attribute.name)]
    }
  end

  def matching candidate, company
    ->(attribute) {
      company.send(attribute.name) == candidate.send(attribute.name)
    }
  end

  def by_priority_from candidate
    ->(attribute) {
      @priorities.include?(attribute.priority) && candidate.send(attribute.name)
    }
  end

  def confidently_identified company
    -> (candidate) {
      equal_attributes = extract_attributes(candidate).select(&matching(candidate, company))
      ConfidentIdentification == classify(equal_attributes.sum(&:weight))
    }
  end
end