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leesharmaleesharma
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Add Amazon Product API "ItemLookup" endpoint (#173)
* Refactor AmazonProductAPI In preparation for #62, this commit pulls the endpoint-specific information out of the HTTPClient class and into and endpoint-specific class. Now HTTPClient is responsible only for managing the environment information and directing the user to the relevant endpoint. Adding a new endpoint is as simple as adding a method (ex. `item_search`) and corresponding class (ex. `ItemSearchEndpoint). The interface is *not* in its final form yet. This is just a good breaking point for a commit. * Add ItemSearch endpoint Building on the last commit, this adds a new ItemLookup endpoint. Now we can pull details on an individual item based on the ASIN. The endpoints and responses include a lot of duplication. Some refactoring will probably be needed. * Extract spec for ItemSearchEndpoint When the item search endpoint was extracted, the specs weren't extracted with it; this means that the HTTPClientSpec was testing everything relating to the item search endpoint. This commit extracts all specs relating to the endpoint into a new file. This can now be refactored and copied over for the `ItemLookupEndpointSpec`. * Add spec for ItemLookupEndpoint * Fix CodeClimate issue This is a bit of a hack solution, but I don't feel comfortable doing any major abstraction here yet; I don't think we have enough information. Hopefully this'll clear up the CodeClimate complaints about duplicated code! * Fix easy PR-related rubocop issues Two big points: 1. This only fixes easy rubocop issues related to this PR. This doesn't touch any of the new capistrano code; I want the diff for this PR to be fairly contained. 2. This includes two rubocop config changes: i. Exclude the vendor directory from linting ii. Allow multiline braces in tests (for exception checks, let, etc.) There are a few more risky/controversial rubocop changes I omitted from this commit. Those are coming next. * Fix all Lint/UriEscapeUnescape violations Fixes #56 This commit changes all the `URI.escape` calls to `CGI.escape`. All tests pass and the app still works. As a bonus, this seems to resolve issue #56 too-apostrophes are now properly escaped. This resolves all rubocop issues relating to this PR. * Give better name to AWS test credentials in specs Following the review suggestions. This renames `env` to `aws_credentials`. The latter is a better name because it represents a credentials object (built from env vars), not the ENV object itself. Hopefully this will be clearer! * Fix item lookup hash When I fixed the code style for Code Climate in #173, I used the wrong hash leading to no update attributes being found. This fixes the bug, adds a test, and renames some of the variables.
1 parent fdd92e4 commit d50f959

14 files changed

Lines changed: 416 additions & 142 deletions

‎.rubocop.yml‎

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@@ -5,6 +5,7 @@ AllCops:
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# directories or files.
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Exclude:
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- db/**/*
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- vendor/**/*
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TargetRubyVersion: 2.4.1
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# Cop names are not displayed in offense messages by default. Change behavior
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# by overriding DisplayCopNames, or by giving the `-D/--display-cop-names`
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DisplayStyleGuide: true
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Style/NumericLiterals:
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Enabled: false
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Enabled: false
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Style/BlockDelimiters:
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Exclude:
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- spec/**/*

‎app/controllers/amazon_search_controller.rb‎

Lines changed: 6 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@ class AmazonSearchController < ApplicationController
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def show
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authorize :amazon_search, :show?
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@response = amazon_client.search_response
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@response = amazon_search_response
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end
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def new
@@ -18,9 +18,11 @@ def new
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private
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def amazon_client
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AmazonProductAPI::HTTPClient.new(query: params[:query],
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page_num: params[:page_num] || 1)
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def amazon_search_response
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client = AmazonProductAPI::HTTPClient.new
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query = client.item_search(query: params[:query],
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page: params[:page_num] || 1)
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query.response
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end
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def set_wishlist

‎lib/amazon_product_api/http_client.rb‎

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# frozen_string_literal: true
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3-
require 'amazon_product_api/search_response'
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require 'amazon_product_api/item_search_endpoint'
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require 'amazon_product_api/item_lookup_endpoint'
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module AmazonProductAPI
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# Responsible for building and executing the query to the Amazon Product API.
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# Responsible for managing all Amazon Product API queries.
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#
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# Any logic relating to endpoints, building the query string, authentication
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# signatures, etc. should live in this class.
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# All endpoints (returning query objects) should live in this class.
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class HTTPClient
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require 'httparty'
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require 'time'
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require 'uri'
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require 'openssl'
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require 'base64'
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attr_reader :env # injectable credentials
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# The region you are interested in
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ENDPOINT = 'webservices.amazon.com'
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REQUEST_URI = '/onca/xml'
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attr_reader :env
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attr_writer :query, :page_num
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def initialize(query:, page_num: 1, env: ENV)
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@query = query
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@page_num = page_num
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def initialize(env: ENV)
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@env = env
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assign_env_vars
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end
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# Generate the signed URL
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def url
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raise InvalidQueryError unless query && page_num
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"http://#{ENDPOINT}#{REQUEST_URI}" + # base
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"?#{canonical_query_string}" + # query
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"&Signature=#{uri_escape(signature)}" # signature
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end
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# Performs the search query and returns the resulting SearchResponse
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def search_response(http: HTTParty)
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response = get(http: http)
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SearchResponse.new parse_response(response)
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def item_search(query:, page: 1)
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ItemSearchEndpoint.new(query, page, aws_credentials)
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end
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# Send the HTTP request
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def get(http: HTTParty)
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http.get(url)
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def item_lookup(asin)
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ItemLookupEndpoint.new(asin, aws_credentials)
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end
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private
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attr_reader :query, :page_num, :aws_credentials
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attr_reader :aws_credentials
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def assign_env_vars
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@aws_credentials = AWSCredentials.new(env['AWS_ACCESS_KEY'],
@@ -61,54 +36,6 @@ def assign_env_vars
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"they're set."
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raise InvalidQueryError, msg unless @aws_credentials.present?
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end
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def parse_response(response)
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Hash.from_xml(response.body)
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end
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def uri_escape(phrase)
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URI.encode_www_form_component(phrase.to_s)
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end
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def params
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params = {
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'Service' => 'AWSECommerceService',
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'Operation' => 'ItemSearch',
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'AWSAccessKeyId' => aws_credentials.access_key,
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'AssociateTag' => aws_credentials.associate_tag,
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'SearchIndex' => 'All',
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'Keywords' => query.to_s,
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'ResponseGroup' => 'ItemAttributes,Offers,Images',
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'ItemPage' => page_num.to_s
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}
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# Set current timestamp if not set
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params['Timestamp'] ||= Time.now.gmtime.iso8601
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params
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end
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90-
# Generate the canonical query
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def canonical_query_string
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params.sort
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.map { |key, value| "#{uri_escape(key)}=#{uri_escape(value)}" }
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.join('&')
95-
end
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# Generate the string to be signed
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def string_to_sign
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"GET\n#{ENDPOINT}\n#{REQUEST_URI}\n#{canonical_query_string}"
100-
end
101-
102-
# Generate the signature required by the Product Advertising API
103-
def signature
104-
Base64.encode64(digest_with_key(string_to_sign)).strip
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end
106-
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def digest_with_key(string)
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OpenSSL::HMAC.digest(OpenSSL::Digest.new('sha256'),
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aws_credentials.secret_key,
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string)
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end
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end
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# Wrapper object to store/verify AWS credentials

‎lib/amazon_product_api/item_lookup_endpoint.rb‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,98 @@
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# frozen_string_literal: true
2+
3+
require 'amazon_product_api/lookup_response'
4+
5+
module AmazonProductAPI
6+
# Responsible for looking up an item listing on Amazon
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#
8+
# http://docs.aws.amazon.com/AWSECommerceService/latest/DG/ItemLookup.html
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#
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# Any logic relating to lookup, building the query string, authentication
11+
# signatures, etc. should live in this class.
12+
class ItemLookupEndpoint
13+
require 'httparty'
14+
require 'time'
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require 'uri'
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require 'openssl'
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require 'base64'
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# The region you are interested in
20+
ENDPOINT = 'webservices.amazon.com'
21+
REQUEST_URI = '/onca/xml'
22+
23+
attr_accessor :asin, :aws_credentials
24+
25+
def initialize(asin, aws_credentials)
26+
@asin = asin
27+
@aws_credentials = aws_credentials
28+
end
29+
30+
# Generate the signed URL
31+
def url
32+
"http://#{ENDPOINT}#{REQUEST_URI}" + # base
33+
"?#{canonical_query_string}" + # query
34+
"&Signature=#{uri_escape(signature)}" # signature
35+
end
36+
37+
# Send the HTTP request
38+
def get(http: HTTParty)
39+
http.get(url)
40+
end
41+
42+
# Performs the search query and returns the resulting SearchResponse
43+
def response(http: HTTParty, logger: Rails.logger)
44+
response = parse_response get(http: http)
45+
logger.debug(response)
46+
LookupResponse.new(response).item
47+
end
48+
49+
private
50+
51+
def parse_response(response)
52+
Hash.from_xml(response.body)
53+
end
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55+
# Generate the signature required by the Product Advertising API
56+
def signature
57+
Base64.encode64(digest_with_key(string_to_sign)).strip
58+
end
59+
60+
# Generate the string to be signed
61+
def string_to_sign
62+
"GET\n#{ENDPOINT}\n#{REQUEST_URI}\n#{canonical_query_string}"
63+
end
64+
65+
# Generate the canonical query
66+
def canonical_query_string
67+
params.sort
68+
.map { |key, value| "#{uri_escape(key)}=#{uri_escape(value)}" }
69+
.join('&')
70+
end
71+
72+
def params
73+
params = {
74+
'Service' => 'AWSECommerceService',
75+
'AWSAccessKeyId' => aws_credentials.access_key,
76+
'AssociateTag' => aws_credentials.associate_tag,
77+
# endpoint-specific
78+
'Operation' => 'ItemLookup',
79+
'ResponseGroup' => 'ItemAttributes,Offers,Images',
80+
'ItemId' => asin.to_s
81+
}
82+
83+
# Set current timestamp if not set
84+
params['Timestamp'] ||= Time.now.gmtime.iso8601
85+
params
86+
end
87+
88+
def digest_with_key(string)
89+
OpenSSL::HMAC.digest(OpenSSL::Digest.new('sha256'),
90+
aws_credentials.secret_key,
91+
string)
92+
end
93+
94+
def uri_escape(phrase)
95+
CGI.escape(phrase.to_s)
96+
end
97+
end
98+
end

‎lib/amazon_product_api/item_search_endpoint.rb‎

Lines changed: 103 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,103 @@
1+
# frozen_string_literal: true
2+
3+
require 'amazon_product_api/search_response'
4+
5+
module AmazonProductAPI
6+
# Responsible for building and executing an Amazon Product API search query.
7+
#
8+
# http://docs.aws.amazon.com/AWSECommerceService/latest/DG/ItemSearch.html
9+
#
10+
# Any logic relating to searching, building the query string, authentication
11+
# signatures, etc. should live in this class.
12+
class ItemSearchEndpoint
13+
require 'httparty'
14+
require 'time'
15+
require 'uri'
16+
require 'openssl'
17+
require 'base64'
18+
19+
# The region you are interested in
20+
ENDPOINT = 'webservices.amazon.com'
21+
REQUEST_URI = '/onca/xml'
22+
23+
attr_accessor :query, :page, :aws_credentials
24+
25+
def initialize(query, page, aws_credentials)
26+
@query = query
27+
@page = page
28+
@aws_credentials = aws_credentials
29+
end
30+
31+
# Generate the signed URL
32+
def url
33+
raise InvalidQueryError unless query && page
34+
35+
"http://#{ENDPOINT}#{REQUEST_URI}" + # base
36+
"?#{canonical_query_string}" + # query
37+
"&Signature=#{uri_escape(signature)}" # signature
38+
end
39+
40+
# Send the HTTP request
41+
def get(http: HTTParty)
42+
http.get(url)
43+
end
44+
45+
# Performs the search query and returns the resulting SearchResponse
46+
def response(http: HTTParty, logger: Rails.logger)
47+
response = parse_response get(http: http)
48+
logger.debug response
49+
SearchResponse.new response
50+
end
51+
52+
private
53+
54+
def parse_response(response)
55+
Hash.from_xml(response.body)
56+
end
57+
58+
# Generate the signature required by the Product Advertising API
59+
def signature
60+
Base64.encode64(digest_with_key(string_to_sign)).strip
61+
end
62+
63+
# Generate the string to be signed
64+
def string_to_sign
65+
"GET\n#{ENDPOINT}\n#{REQUEST_URI}\n#{canonical_query_string}"
66+
end
67+
68+
# Generate the canonical query
69+
def canonical_query_string
70+
params.sort
71+
.map { |key, value| "#{uri_escape(key)}=#{uri_escape(value)}" }
72+
.join('&')
73+
end
74+
75+
def params
76+
params = {
77+
'Service' => 'AWSECommerceService',
78+
'AWSAccessKeyId' => aws_credentials.access_key,
79+
'AssociateTag' => aws_credentials.associate_tag,
80+
# endpoint-specific
81+
'Operation' => 'ItemSearch',
82+
'ResponseGroup' => 'ItemAttributes,Offers,Images',
83+
'SearchIndex' => 'All',
84+
'Keywords' => query.to_s,
85+
'ItemPage' => page.to_s
86+
}
87+
88+
# Set current timestamp if not set
89+
params['Timestamp'] ||= Time.now.gmtime.iso8601
90+
params
91+
end
92+
93+
def digest_with_key(string)
94+
OpenSSL::HMAC.digest(OpenSSL::Digest.new('sha256'),
95+
aws_credentials.secret_key,
96+
string)
97+
end
98+
99+
def uri_escape(phrase)
100+
CGI.escape(phrase.to_s)
101+
end
102+
end
103+
end

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