SameSite=None user agent sniffing for incompatible browsers (Ruby)

application_controller.rb

class ApplicationController < ActionController::Base
  ...
  # Use when setting 3rd party cookies and make sure to tack .compact on the
  #   end to make sure that the :same_site key is not included when the value is missing
  #
  def set_cookie(key, value)
    cookies.encrypted[key] = {
      :value => value.to_s,
      :expires => 1.year, :domain => :all,
      :same_site => SameSite.value(request.headers['User-Agent']),
      :secure => Rails.env.production?
    }.compact
  end
  
  ...

end

same_site.rb

class SameSite
  def self.value(agent)
    send_same_site_none?(agent) ? :none : nil
  end

  private

  ##
  # Based on https://www.chromium.org/updates/same-site/incompatible-clients
  #
  #  Don’t send `SameSite=None` to known incompatible clients.
  #
  def self.send_same_site_none?(useragent)
    return true if useragent.blank?

    !same_site_none_incompatible?(useragent)
  end

  #  Classes of browsers known to be incompatible.
  #
  def self.same_site_none_incompatible?(useragent)
    web_kit_same_site_bug?(useragent) ||
      drops_unrecognized_cookies?(useragent)
  end

  def self.web_kit_same_site_bug?(useragent)
    ios_version?(useragent, major: 12) ||
      (macosx_version?(useragent, major: 10, minor: 14) &&
        (safari?(useragent) || mac_embedded_browser?(useragent)))
  end

  def self.drops_unrecognized_cookies?(useragent)
    return !uc_browser_version_at_least?(useragent, major: 12, minor: 13, build: 2) if uc_browser?(useragent)

    chromium_based?(useragent) &&
      chromium_version_at_least?(useragent, major: 51) &&
      !chromium_version_at_least?(useragent, major: 67)
  end

  def self.ios_version?(useragent, major: nil)
    /\(iP.+; CPU .*OS (\d+)[_\d]*.*\) AppleWebKit\// =~ useragent

    $1 == major.to_s
  end

  def self.macosx_version?(useragent, major:nil, minor:nil)
    /\(Macintosh;.*Mac OS X (\d+)_(\d+)[_\d]*.*\) AppleWebKit\// =~ useragent

    $1 == major.to_s && $2 == minor.to_s
  end

  def self.safari?(useragent)
    /Version\/.* Safari\// === useragent && !chromium_based?(useragent)
  end

  def self.mac_embedded_browser?(useragent)
    /^Mozilla\/[.\d]+ \(Macintosh;.*Mac OS X [_\d]+\) AppleWebKit\/[.\d]+ \(KHTML, like Gecko\)$/ === useragent
  end

  def self.chromium_based?(useragent)
    /Chrom(e|ium)/ === useragent
  end

  def self.chromium_version_at_least?(useragent, major: nil)
    /Chrom[^ \/]+\/(\d+)[.\d]* / =~ useragent

    $1.to_i >= major
  end

  def self.uc_browser?(useragent)
    /UCBrowser\// =~ useragent
  end

  def self.uc_browser_version_at_least?(useragent, major: nil, minor: nil, build: nil)
    /UCBrowser\/(\d+)\.(\d+)\.(\d+)[.\d]* / =~ useragent

    major_version = $1.to_i
    minor_version = $2.to_i

    if major_version != major
      return major_version > major
    elsif minor_version != minor
      return minor_version > minor
    end

    $3.to_i >= build
  end
end