add rails initializer configuration style

lib/asin.rb

@@ -6,6 +6,7 @@
 
 require 'asin/item'
 require 'asin/version'
+require 'asin/configuration'
 
 # ASIN (Amazon Simple INterface) is a gem for easy access of the Amazon E-Commerce-API.
 # It is simple to configure and use. Since it's very small and flexible, it is easy to extend it to your needs.
@@ -73,13 +74,7 @@ module ASIN
   # [logger] a different logger than logging to STDERR
   # 
   def configure(options={})
-    @options = {
-      :secret => '',
-      :key => '',
-      :host => 'webservices.amazon.com',
-      :logger => Logger.new(STDERR),
-    } if @options.nil?
-    @options.merge! options
+    Configuration.configure(options)
   end
 
   # Performs an +ItemLookup+ REST call against the Amazon API.
@@ -124,14 +119,18 @@ def search(search_string, params={:SearchIndex => :Books})
 
   private
 
+  def credentials_valid?
+    !Configuration.secret.nil? && !Configuration.key.nil?
+  end
+
   def call(params)
-    raise "you have to configure ASIN: 'configure :secret => 'your-secret', :key => 'your-key''" if @options.nil?
+    raise "you have to configure ASIN: 'configure :secret => 'your-secret', :key => 'your-key''" unless credentials_valid?
 
     log(:debug, "calling with params=#{params}")
     signed = create_signed_query_string(params)
 
-    url = "http://#{@options[:host]}#{PATH}?#{signed}"
-    log(:info, "performing rest call to url='#{url}' with client='#{@options[:client]}'")
+    url = "http://#{Configuration.host}#{PATH}?#{signed}"
+    log(:info, "performing rest call to url='#{url}'")
 
     response = HTTPI.get(url)
     if response.code == 200
@@ -149,24 +148,24 @@ def call(params)
   def create_signed_query_string(params)
     # nice tutorial http://cloudcarpenters.com/blog/amazon_products_api_request_signing/
     params[:Service] = :AWSECommerceService
-    params[:AWSAccessKeyId] = @options[:key]
+    params[:AWSAccessKeyId] = Configuration.key
     # utc timestamp needed for signing
     params[:Timestamp] = Time.now.utc.strftime('%Y-%m-%dT%H:%M:%SZ') 
 
     # signing needs to order the query alphabetically
     query = params.map{|key, value| "#{key}=#{CGI.escape(value.to_s)}" }.sort.join('&').gsub('+','%20')
 
     # yeah, you really need to sign the get-request not the query
-    request_to_sign = "GET\n#{@options[:host]}\n#{PATH}\n#{query}"
-    hmac = OpenSSL::HMAC.digest(DIGEST, @options[:secret], request_to_sign)
+    request_to_sign = "GET\n#{Configuration.host}\n#{PATH}\n#{query}"
+    hmac = OpenSSL::HMAC.digest(DIGEST, Configuration.secret, request_to_sign)
 
     # don't forget to remove the newline from base64
     signature = CGI.escape(Base64.encode64(hmac).chomp)
     "#{query}&Signature=#{signature}"
   end
 
   def log(severity, message)
-    @options[:logger].send severity, message if @options[:logger]
+    Configuration.logger.send severity, message if Configuration.logger
   end
 
-end
+end

lib/asin/configuration.rb

@@ -0,0 +1,48 @@
+module ASIN
+  class Configuration
+    class << self
+
+      attr_accessor :secret, :key, :host, :logger
+
+      # Rails initializer configuration.
+      # 
+      # Expects at least +secret+ and +key+ for the API call:
+      # 
+      #   ASIN::Configuration.configure do |config|
+      #     config.secret = 'your-secret'
+      #     config.key = 'your-key'
+      #   end
+      # 
+      # ==== Options:
+      # 
+      # [secret] the API secret key
+      # [key] the API access key
+      # [host] the host, which defaults to 'webservices.amazon.com'
+      # [logger] a different logger than logging to STDERR
+      # 
+      def configure(options={})
+        init_config
+        if block_given?
+          yield self
+        else
+          options.each do |key, value|
+            send(:"#{key}=", value)
+          end
+        end
+        self
+      end
+
+      private
+
+      def init_config(force=false)
+        return if @init && !force
+        @init   = true
+        @secret = ''
+        @key    = ''
+        @host   = 'webservices.amazon.com'
+        @logger = Logger.new(STDERR)
+      end
+    end
+  end
+end
+

spec/asin_spec.rb

@@ -16,14 +16,25 @@
     it "should fail without secret and key" do
       lambda { @helper.lookup ANY_ASIN }.should raise_error(RuntimeError)
     end
+
+    it "should fail with wrong configuration key" do
+      lambda { @helper.configure :wrong => 'key' }.should raise_error(NoMethodError)
+    end
 
     it "should not override the configuration" do
-      config = @helper.configure :something => 'wont get overridden'
-      config[:something].should_not be_nil
+      config = @helper.configure :key => 'wont get overridden'
+      config.key.should_not be_nil
+
+      config = @helper.configure :secret => 'is also set'
+      config.key.should_not be_nil
+      config.secret.should_not be_nil
+    end
 
-      config = @helper.configure :different => 'is also set'
-      config[:something].should_not be_nil
-      config[:different].should_not be_nil
+    it "should work with a configuration block" do
+      config = ASIN::Configuration.configure do |config|
+        config.key = 'bla'
+      end
+      config.key.should eql('bla')
     end
   end