module HackerOne
  module Client
    class Weakness
      class << self
        def validate_cwe!(cwe)
          fail NotAnOwaspWeaknessError if cwe.upcase.start_with?('CAPEC-')
          fail StandardError::ArgumentError unless cwe.upcase.start_with?('CWE-')
        end

        def extract_cwe_number(cwe)
          return if cwe.nil?
          validate_cwe!(cwe)

          cwe.split('CWE-').last.to_i
        end
      end

      class NotAnOwaspWeaknessError < StandardError
        def message
          "CAPEC labels do not describe OWASP weaknesses"
        end
      end

      CLASSIFICATION_MAPPING = {
        "None Applicable" => "A0-Other",
        "Denial of Service" => "A0-Other",
        "Memory Corruption" => "A0-Other",
        "Cryptographic Issue" => "A0-Other",
        "Privilege Escalation" => "A0-Other",
        "UI Redressing (Clickjacking)" => "A0-Other",
        "Command Injection" => "A1-Injection",
        "Remote Code Execution" => "A1-Injection",
        "SQL Injection" => "A1-Injection",
        "Authentication" => "A2-AuthSession",
        "Cross-Site Scripting (XSS)" => "A3-XSS",
        "Information Disclosure" => "A6-DataExposure",
        "Cross-Site Request Forgery (CSRF)" => "A8-CSRF",
        "Unvalidated / Open Redirect" => "A10-Redirects"
      }

      OWASP_TOP_10_2013_TO_CWE = {
        'A1-Injection' => [77, 78, 88, 89, 90, 91, 564],
        'A2-AuthSession' =>
          [287, 613, 522, 256, 384, 472, 346, 441, 523, 620, 640, 319, 311],
        'A3-XSS' => [79],
        'A4-DirectObjRef' => [639, 99, 22],
        'A5-Misconfig' => [16, 2, 215, 548, 209],
        'A6-DataExposure' => [312, 319, 310, 326, 320, 311, 325, 328, 327],
        'A7-MissingACL' => [285, 287],
        'A8-CSRF' => [352, 642, 613, 346, 441],
        'A9-KnownVuln' => [],
        'A10-Redirects' => [601],
      }.freeze

      OWASP_DEFAULT = 'A0-Other'.freeze

      def initialize(weakness)
        @attributes = weakness
      end

      def to_owasp
        from_cwe = OWASP_TOP_10_2013_TO_CWE.map do |owasp, cwes|
          owasp if cwes.include?(self.class.extract_cwe_number(to_cwe))
        end.compact.first

        from_cwe || CLASSIFICATION_MAPPING[@attributes[:name]] || OWASP_DEFAULT
      end

      def to_cwe
        @attributes[:external_id]
      end
    end
  end
end