Amazon Product Advertising API using Clojure

amazon-test.clj

(ns yswrl.test.swirls.amazon-test
  (:use clojure.test)
  (:require [yswrl.test.scaffolding :refer :all]
            [yswrl.swirls.amazon :as amazon])
  (:use clj-http.fake)
  (:use yswrl.fake.faker))

(deftest amazon-test

  (testing "url Params are in order"
    (let [urlToCall (amazon/search-url "javainterviewbootcamp")]
      (is (.contains urlToCall (str "http://webservices.amazon.com/onca/xml?AWSAccessKeyId=your-access-key&AssociateTag=your-associate-tag&Keywords=javainterviewbootcamp&Operation=ItemSearch&ResponseGroup=Images%2CItemAttributes%2CEditorialReview&SearchIndex=Books&Service=AWSECommerceService&")) urlToCall)))

  (testing "Amazon URL is correctly generated"
    (let [urlToCall (amazon/createEncryptedUrl (sorted-map
                                                 :AWSAccessKeyId "your-access-key"
                                                 :AssociateTag "your-associate-tag"
                                                 :Keywords  "horcrux"
                                                 :Operation "ItemSearch"
                                                 :ResponseGroup "Images,ItemAttributes"
                                                 :SearchIndex "Books"
                                                 :Service "AWSECommerceService"
                                                 :Timestamp "2015-05-14T04:26:12.000Z"
                                                 :Version "2011-08-01"
                                                 ))]
      (is
        (.equals urlToCall
                 (str "http://webservices.amazon.com/onca/xml?AWSAccessKeyId=AKIAIO3J752UN7X4HUWA&AssociateTag=corejavaint0d-20&Keywords=horcrux&Operation=ItemSearch&ResponseGroup=Images%2CItemAttributes&SearchIndex=Books&Service=AWSECommerceService&Timestamp=2015-05-14T04%3A26%3A12.000Z&Version=2011-08-01&Signature=NpX9t1jcz6wR2CCLKfG%2B8Pt2RxQli9QbAZu3dHpifXc%3D")) urlToCall)))


  (testing "Example 1 from http://docs.aws.amazon.com/AWSECommerceService/latest/DG/rest-signature.html"
    (let [urlToCall
            (ring.util.codec/form-encode (amazon/sign "1234567890"
                         "GET\nwebservices.amazon.com\n/onca/xml\nAWSAccessKeyId=AKIAIOSFODNN7EXAMPLE&AssociateTag=mytag-20&ItemId=0679722769&Operation=ItemLookup&ResponseGroup=Images%2CItemAttributes%2COffers%2CReviews&Service=AWSECommerceService&Timestamp=2014-08-18T12%3A00%3A00Z&Version=2013-08-01"))]
      (is
        (.equals urlToCall
                 (str "j7bZM0LXZ9eXeZruTqWm2DIvDYVUU3wxPPpp%2BiXxzQc%3D")) urlToCall)))

  (testing "Real example using my key generated from http://associates-amazon.s3.amazonaws.com/scratchpad/index.html"
    (let [urlToCall
          (ring.util.codec/form-encode (amazon/sign amazon/amazon-key
                                                    (amazon/string-to-sign (sorted-map
                                                                             :AWSAccessKeyId "your-access-key"
                                                                             :AssociateTag "your-associate-tag"
                                                                             :Keywords  "horcrux"
                                                                             :Operation "ItemSearch"
                                                                             :ResponseGroup "Images,ItemAttributes"
                                                                             :SearchIndex "Books"
                                                                             :Service "AWSECommerceService"
                                                                             :Timestamp "2015-05-14T04:26:12.000Z"
                                                                             :Version "2011-08-01"
                                                                             ))))]
      (is
        (.equals urlToCall
                 (str "NpX9t1jcz6wR2CCLKfG%2B8Pt2RxQli9QbAZu3dHpifXc%3D")) urlToCall)))

amazon.clj

(ns yswrl.swirls.amazon
  (:use [clojure.data.zip.xml :only (attr text xml-> xml1->)])
  (:require
    [clj-http.client :as client]
    [clj-time.core :as t]
    [buddy.core.codecs :as codecs]
    [buddy.core.mac.hmac :as hmac]
    [clojure.zip :as zip]
    [clojure.data.xml :as xml-data]))


(def amazon-key "your-key")

(def params (sorted-map
              :AWSAccessKeyId "your-access-key"
              :AssociateTag "your-associate-tag-20"
              :ResponseGroup "Images,ItemAttributes,EditorialReview"
              :Service "AWSECommerceService"
              :Version "2011-08-01"
              ))

(defn timestamp [parameters]
  (assoc parameters :Timestamp (str (t/now))))

(defn string-to-sign [pms]
  (str "GET\nwebservices.amazon.com\n/onca/xml\n"
       (ring.util.codec/form-encode pms)))

(defn sign [key string]
  (-> (hmac/hash string key :sha256)
      (codecs/bytes->base64)))


(defn createEncryptedUrl [paz]
  (let [to-sign (string-to-sign paz)
        encoded (clojure.string/replace to-sign "+" "%20")
        signed (sign amazon-key encoded)
        encodedSignature (ring.util.codec/form-encode signed)]
    (str "http://webservices.amazon.com/onca/xml?" (ring.util.codec/form-encode paz) "&Signature=" encodedSignature)))

(defn search-url [bookname]
  (createEncryptedUrl (assoc (timestamp params) :Keywords bookname :Operation "ItemSearch" :SearchIndex "Books"
                                                )))

(defn handle-amazon [bookname]
  (let [url (search-url bookname)
        raw-data ((client/get url) :body)
        result-data (xml-data/parse-str raw-data)]
    (zip/xml-zip result-data)))

(defn search-books [search-term]
  (if (clojure.string/blank? search-term)
    {:results []}
    (let [result (handle-amazon search-term)] {
                                               :results (map (fn [r] {:url             (apply str (xml-> r :DetailPageURL text))
                                                                      :title           (apply str (xml-> r :ItemAttributes :Title text))
                                                                      :author          (apply str (xml-> r :ItemAttributes :Author text))
                                                                      :book-id         (apply str (xml-> r :ASIN text))
                                                                      :thumbnail-url   (apply str (xml-> r :SmallImage :URL text))
                                                                      :large-image-url (apply str (xml-> r :LargeImage :URL text))}) (xml-> result :Items :Item))
                                               })))


(defn item-url [item-id]
  (createEncryptedUrl (assoc (timestamp params) :idType "ASIN" :ItemId item-id :Operation "ItemLookup")))

(defn get-book [asin]
  (let [url (item-url asin)
        raw-data ((client/get url) :body)
        result-data (xml-data/parse-str raw-data)
        zip-data (zip/xml-zip result-data)
        book (xml1-> zip-data :Items :Item)]
    (println url)
    {:url         (apply str (xml-> book :DetailPageURL text))
     :title       (apply str (xml-> book :ItemAttributes :Title text))
     :author      (apply str (xml-> book :ItemAttributes :Author text))
     :big-img-url (apply str (xml-> book :LargeImage :URL text))
     :blurb       (apply str (xml-> book :EditorialReviews :EditorialReview :Content text))
     }
    )
  )