Change error handling to always have a copy of response headers

added some methods related to parsing rate limit headers

lib/faraday/raise_http_4xx.rb

@@ -8,17 +8,17 @@ def self.register_on_complete(env)
       env[:response].on_complete do |response|
         case response[:status].to_i
         when 400
-          raise Twitter::BadRequest, error_message(response)
+          raise Twitter::BadRequest.new(error_message(response), response[:response_headers])
         when 401
-          raise Twitter::Unauthorized, error_message(response)
+          raise Twitter::Unauthorized.new(error_message(response), response[:response_headers])
         when 403
-          raise Twitter::Forbidden, error_message(response)
+          raise Twitter::Forbidden.new(error_message(response), response[:response_headers])
         when 404
-          raise Twitter::NotFound, error_message(response)
+          raise Twitter::NotFound.new(error_message(response), response[:response_headers])
         when 406
-          raise Twitter::NotAcceptable, error_message(response)
+          raise Twitter::NotAcceptable.new(error_message(response), response[:response_headers])
         when 420
-          raise Twitter::EnhanceYourCalm.new error_message(response), response[:response_headers]
+          raise Twitter::EnhanceYourCalm.new(error_message(response), response[:response_headers])
         end
       end
     end

lib/faraday/raise_http_5xx.rb

@@ -8,11 +8,11 @@ def self.register_on_complete(env)
       env[:response].on_complete do |response|
         case response[:status].to_i
         when 500
-          raise Twitter::InternalServerError, error_message(response, "Something is technically wrong.")
+          raise Twitter::InternalServerError.new(error_message(response, "Something is technically wrong."), response[:response_headers])
         when 502
-          raise Twitter::BadGateway, error_message(response, "Twitter is down or being upgraded.")
+          raise Twitter::BadGateway.new(error_message(response, "Twitter is down or being upgraded."), response[:response_headers])
         when 503
-          raise Twitter::ServiceUnavailable, error_message(response, "(__-){ Twitter is over capacity.")
+          raise Twitter::ServiceUnavailable.new(error_message(response, "(__-){ Twitter is over capacity."), response[:response_headers])
         end
       end
     end

lib/twitter/error.rb

@@ -1,6 +1,29 @@
 module Twitter
   # Custom error class for rescuing from all Twitter errors
-  class Error < StandardError; end
+  class Error < StandardError
+    attr_reader :http_headers
+
+    def initialize(message, http_headers)
+      @http_headers = Hash[http_headers]
+      super message
+    end
+
+    def ratelimit_reset
+      Time.at(@http_headers.values_at('x-ratelimit-reset', 'X-RateLimit-Reset').detect {|value| value }.to_i)
+    end
+
+    def ratelimit_limit
+      @http_headers.values_at('x-ratelimit-limit', 'X-RateLimit-Limit').detect {|value| value }.to_i
+    end
+
+    def ratelimit_remaining
+      @http_headers.values_at('x-ratelimit-limit', 'X-RateLimit-Limit').detect {|value| value }.to_i
+    end
+
+    def retry_after
+      [(ratelimit_reset - Time.now).ceil, 0].max
+    end
+  end
 
   # Raised when Twitter returns the HTTP status code 400
   class BadRequest < Error; end
@@ -19,12 +42,6 @@ class NotAcceptable < Error; end
 
   # Raised when Twitter returns the HTTP status code 420
   class EnhanceYourCalm < Error
-    # Creates a new EnhanceYourCalm error
-    def initialize(message, http_headers)
-      @http_headers = Hash[http_headers]
-      super message
-    end
-
     # The number of seconds your application should wait before requesting date from the Search API again
     #
     # @see http://dev.twitter.com/pages/rate-limiting