Untitled

require 'cgi'
require 'openssl'
require 'net/https'
require 'rubygems'
require 'activesupport'

module AWS
  class API
    def initialize(access_key, secret_key, uri='/')
      prefix = self.class.name.split('::').last.downcase!
      @host = "#{prefix}.amazonaws.com"
      @access_key = access_key
      @secret_key = secret_key
      @uri = uri
      @signature_version = '2'
      @signature_method = 'HmacSHA256'
    end

    def method_missing(symbol, args={})
      send_request(format_method(symbol.to_s), args)
    end

    private
      def format_method(string)
        string.gsub!(/^[a-z]|_+[a-z]/) { |a| a.upcase }
        string.gsub!(/_/, '')
      end

      def format_params(params)
        param_array = Array.new
        params.sort_by { |k, v| k}.each do |param|
          param_array << "#{CGI.escape(param[0]).gsub('+', '%20')}=#{CGI.escape(param[1]).gsub('+', '%20')}"
        end

        flat_params = "#{param_array.join('&')}"

        # make the proper string to sign
        string_to_sign = "#{@request_method}\n#{@host}\n#{@uri}\n#{flat_params}"
        digest = OpenSSL::Digest::Digest.new('sha256')
        b64_hmac = [OpenSSL::HMAC.digest(digest, @secret_key, string_to_sign)].pack("m").strip
        signature = CGI.escape(b64_hmac)
        "#{flat_params}&Signature=#{signature}"
      end

      def add_default_params
        {
          'Timestamp'         => Time.now.utc.strftime("%Y-%m-%dT%H:%M:%SZ"),
          'AWSAccessKeyId'    => @access_key,
          'Version'           => @api_version,
          'SignatureVersion'  => @signature_version,
          'SignatureMethod'   => @signature_method
        }
      end

      def send_request(method, params={}, request_method=:get)
        @request_method = 'GET' if request_method == :get # TODO: add POST support
        params.merge! add_default_params
        params['Action'] = method
        canonical_string = format_params(params)

        http = Net::HTTP.new(@host, 443)
        http.use_ssl = true
        http.verify_mode = OpenSSL::SSL::VERIFY_NONE
        response, xml_data = http.get("#{@uri}?#{canonical_string}")
        data = Hash.from_xml(xml_data)
        case response
        when Net::HTTPOK
          data
        else
          raise Error.new(data)
        end
      end

  end

  class Error < Exception
    attr_reader :message
    def initialize(data)
      @message = "#{data['Response']['Errors']['Error']['Code']}: #{data['Response']['Errors']['Error']['Message']}"
    end
  end

  class EC2 < AWS::API
    def initialize(access_key, secret_key)
      @api_version = '2010-11-15'
      super
    end
  end
  class IAM < AWS::API
    def initalize(access_key, secret_key)
      @api_version = '2010-05-08'
      super
    end
  end
end