class Rack::Protection::Base

def self.default_options(options)
  define_method(:default_options) { super().merge(options) }
end

def self.default_reaction(reaction)
  alias_method(:default_reaction, reaction)
end

def accepts?(env)
  raise NotImplementedError, "#{self.class} implementation pending"
end

def call(env)
  unless accepts? env
    instrument env
    result = react env
  end
  result or app.call(env)
end

def default_options
  DEFAULT_OPTIONS
end

def deny(env)
  warn env, "attack prevented by #{self.class}"
  [options[:status], { 'Content-Type' => 'text/plain' }, [options[:message]]]
end

def drop_session(env)
  session(env).clear if session? env
end

def encrypt(value)
  options[:encryptor].hexdigest value.to_s
end

def html?(headers)
  return false unless (header = headers.detect { |k, _v| k.downcase == 'content-type' })
  options[:html_types].include? header.last[%r{^\w+/\w+}]
end

def initialize(app, options = {})
  @app = app
  @options = default_options.merge(options)
end

def instrument(env)
  return unless (i = options[:instrumenter])
  env['rack.protection.attack'] = self.class.name.split('::').last.downcase
  i.instrument('rack.protection', env)
end

def origin(env)
  env['HTTP_ORIGIN'] || env['HTTP_X_ORIGIN']
end

def random_string(secure = defined? SecureRandom)
  secure ? SecureRandom.hex(16) : '%032x' % rand((2**128) - 1)
rescue NotImplementedError
  random_string false
end

def react(env)
  result = send(options[:reaction], env)
  result if (Array === result) && (result.size == 3)
end

def referrer(env)
  ref = env['HTTP_REFERER'].to_s
  return if !options[:allow_empty_referrer] && ref.empty?
  URI.parse(ref).host || Request.new(env).host
rescue URI::InvalidURIError
end

def report(env)
  warn env, "attack reported by #{self.class}"
  env[options[:report_key]] = true
end

def safe?(env)
  %w[GET HEAD OPTIONS TRACE].include? env['REQUEST_METHOD']
end

def secure_compare(a, b)
  Rack::Utils.secure_compare(a.to_s, b.to_s)
end

def session(env)
  return env[options[:session_key]] if session? env
  raise "you need to set up a session middleware *before* #{self.class}"
end

def session?(env)
  env.include? options[:session_key]
end

def warn(env, message)
  return unless options[:logging]
  l = options[:logger] || env['rack.logger'] || ::Logger.new(env['rack.errors'])
  l.warn(message)
end