require_relative '../cvss_property'
require_relative '../cvss_metric'

##
# This class represents a CVSS Base metric in version 2.

class Cvss2Base < CvssMetric

  ##
  # Property of this metric

  attr_reader :access_vector, :access_complexity, :authentication,
              :confidentiality_impact, :integrity_impact, :availability_impact

  ##
  # Returns the base score of the CVSS vector. The calculation is based on formula version 2.10 .
  # See CVSS documentation for further information https://www.first.org/cvss/v2/guide#i3.2.1 .
  #
  # Takes +Security+ +Requirement+ +Impacts+ for calculating environmental score.

  def score(sr_cr_score = 1, sr_ir_score = 1, sr_ar_score = 1)

    impact = calc_impact sr_cr_score, sr_ir_score, sr_ar_score

    exploitability = calc_exploitability

    additional_impact = (impact == 0 ? 0 : 1.176)

    ((0.6 * impact) + (0.4 * exploitability) - 1.5) * additional_impact

  end

  private

  def init_properties
    @properties.push(@access_vector =
                      CvssProperty.new(name: 'Access Vector', abbreviation: 'AV', position: [0],
                                       choices: [{ name: 'Network', abbreviation: 'N', weight: 1.0 },
                                                 { name: 'Adjacent Network', abbreviation: 'A', weight: 0.646 },
                                                 { name: 'Local', abbreviation: 'L', weight: 0.395 }]))
    @properties.push(@access_complexity =
                      CvssProperty.new(name: 'Access Complexity', abbreviation: 'AC', position: [1],
                                       choices: [{ name: 'Low', abbreviation: 'L', weight: 0.71 },
                                                 { name: 'Medium', abbreviation: 'M', weight: 0.61 },
                                                 { name: 'High', abbreviation: 'H', weight: 0.35 }]))
    @properties.push(@authentication =
                      CvssProperty.new(name: 'Authentication', abbreviation: 'Au', position: [2],
                                       choices: [{ name: 'None', abbreviation: 'N', weight: 0.704 },
                                                 { name: 'Single', abbreviation: 'S', weight: 0.56 },
                                                 { name: 'Multiple', abbreviation: 'M', weight: 0.45 }]))
    @properties.push(@confidentiality_impact =
                      CvssProperty.new(name: 'Confidentiality Impact', abbreviation: 'C', position: [3],
                                       choices: [{ name: 'None', abbreviation: 'N', weight: 0.0 },
                                                 { name: 'Partial', abbreviation: 'P', weight: 0.275 },
                                                 { name: 'Complete', abbreviation: 'C', weight: 0.66 }]))
    @properties.push(@integrity_impact =
                      CvssProperty.new(name: 'Integrity Impact', abbreviation: 'I', position: [4],
                                       choices: [{ name: 'None', abbreviation: 'N', weight: 0.0 },
                                                 { name: 'Partial', abbreviation: 'P', weight: 0.275 },
                                                 { name: 'Complete', abbreviation: 'C', weight: 0.66 }]))
    @properties.push(@availability_impact =
                      CvssProperty.new(name: 'Availability Impact', abbreviation: 'A', position: [5],
                                       choices: [{ name: 'None', abbreviation: 'N', weight: 0.0},
                                                 { name: 'Partial', abbreviation: 'P', weight: 0.275},
                                                 { name: 'Complete', abbreviation: 'C', weight: 0.66}]))
  end

  def calc_impact(sr_cr_score, sr_ir_score, sr_ar_score)
    confidentiality_score = 1 - @confidentiality_impact.score * sr_cr_score
    integrity_score = 1 - @integrity_impact.score * sr_ir_score
    availability_score = 1 - @availability_impact.score * sr_ar_score

    [10, 10.41 * (1-confidentiality_score*integrity_score*availability_score)].min
  end

  def calc_exploitability
    20 * @access_vector.score * @access_complexity.score * @authentication.score
  end

end