require 'open-uri'
module Uricp
  class OrbitAuth
    AuthenticationFailure = Class.new(ArgumentError)

    def initialize(auth_uri, auth_id, auth_key)
      @auth_uri = auth_uri
      @auth_id = auth_id
      @auth_key = auth_key
    end

    def storage_url
      @storage_url ||
        begin
          authenticate
          @storage_url
        end
    end

    def token
      authenticate
      @token
    end

    def self.validate_options(options)
      if options['auth-token'] && (options['auth-key'] || options['auth-user'])
        raise ::OptionParser::NeedlessArgument,
              'use either key based or token based authentication'
      end
      if options['auth-key'].nil? ^ options['auth-user'].nil?
        raise ::OptionParser::MissingArgument,
              "'auth-user' requires 'auth-key'"
      end
      if (options['auth-token'] || options['auth-user']) && options['auth_uri'].nil?
        raise ::OptionParser::NeedlessArgument,
              'authentication is for http uris only'
      end
    end

    def self.add_auth_token(options)
      if options['auth-user']
        orbit_credentials = new(options['auth_uri'],
                                options['auth-user'], options['auth-key'])
        options['authenticator'] = orbit_credentials.method(:token)
      elsif options['auth-token']
        orbit_token = options['auth-token']
        options['authenticator'] = -> { orbit_token }
      end
      options.delete('auth-key')
      options.delete('auth-user')
      options.delete('auth-token')
    end

    def self.add_auth_to_optionparser(app)
      app.on('--auth-token AUTH_TOKEN',
             'Use AUTH_TOKEN for non-local requests')
      app.on('--auth-user AUTH_USER',
             'Use AUTH_USER for authentication')
      app.on('--auth-key AUTH_KEY',
             'Use AUTH_KEY for authentication')
    end

    private

    def authenticate
      @auth_uri.open(
        'X-Auth-User' => @auth_id,
        'X-Auth-Key' => @auth_key,
        'Range' => 'bytes=0-0'
      ) do |uri|
        @storage_url = uri.meta['x-storage-url']
        @token = uri.meta['x-auth-token']
      end
    rescue OpenURI::HTTPError => e
      raise AuthenticationFailure, "Cannot authenticate against #{@auth_uri}"
    end
  end
end