Add support for Amazon short links (#79)

Adds support for the following short links and introduces a new setting for a tracking code to use with amzn.eu.

* a.co
* amzn.eu
* amzn.to

config/locales/server.en.yml

@@ -5,7 +5,7 @@ en:
     affiliate_amazon_cn: "Your amazon.cn (China) Associates ID."
     affiliate_amazon_co_jp: "Your amazon.co.jp (Japan) Associates ID."
     affiliate_amazon_co_uk: "Your amazon.co.uk (United Kingdom) Associates ID."
-    affiliate_amazon_com: "Your amazon.com/amzn.com (United States) Associates ID."
+    affiliate_amazon_com: "Your amazon.com/amzn.com/amzn.to (United States) Associates ID."
     affiliate_amazon_com_au: "Your amazon.com.au (Australia) Associates ID."
     affiliate_amazon_com_br: "Your amazon.com.br (Brazil) Associates ID."
     affiliate_amazon_com_mx: "Your amazon.com.mx (Mexico) Associates ID."
@@ -15,4 +15,5 @@ en:
     affiliate_amazon_in: "Your amazon.in (India) Associates ID."
     affiliate_amazon_it: "Your amazon.it (Italy) Associates ID."
     affiliate_amazon_nl: "Your amazon.nl (Netherlands) Associates ID."
+    affiliate_amazon_eu: "Your amzn.eu (Europe) Associates ID."
     affiliate_ldlc_com: "Your ldlc.com Affiliate ID (without the #)."

config/settings.yml

@@ -44,6 +44,9 @@ discourse_affiliate:
   affiliate_amazon_nl:
     default: ""
     client: true
+  affiliate_amazon_eu:
+    default: ""
+    client: true
   affiliate_ldlc_com:
     default: ""
     client: true

lib/affiliate_processor.rb

@@ -24,14 +24,17 @@ def self.create_amazon_rule(domain)
 
   def self.rules
     return @rules if @rules
-    postfixes = %w[com com.au com.br com.mx ca cn co.jp co.uk de es fr in it nl]
+    postfixes = %w[com com.au com.br com.mx ca cn co.jp co.uk de es fr in it nl to co eu]
 
     rules = {}
 
     postfixes.map do |postfix|
       rule = create_amazon_rule(postfix)
 
       rules["amzn.com"] = rule if postfix == "com"
+      rules["amzn.to"] = create_amazon_rule("com") if postfix == "to"
+      rules["amzn.eu"] = rule if postfix == "eu"
+      rules["a.co"] = create_amazon_rule("com") if postfix == "co"
       rules["www.amazon.#{postfix}"] = rule
       rules["smile.amazon.#{postfix}"] = rule
       rules["amazon.#{postfix}"] = rule

spec/lib/affiliate_processor_spec.rb

@@ -20,6 +20,7 @@ def r(url)
     SiteSetting.affiliate_amazon_com = "sams-shop"
     SiteSetting.affiliate_amazon_ca = "ca-sams-shop"
     SiteSetting.affiliate_amazon_com_au = "au-sams-shop"
+    SiteSetting.affiliate_amazon_eu = "eu-sams-shop"
 
     expect(r("https://www.amazon.com")).to eq("https://www.amazon.com?tag=sams-shop")
     expect(r("http://www.amazon.com/some_product?xyz=1")).to eq(
@@ -47,6 +48,13 @@ def r(url)
     ).to eq(
       "https://www.amazon.ca/Dragon-Quest-Echoes-Elusive-Age-PlayStation/dp/B07BP3J6RG/ref=br_asw_pdt-5?tag=ca-sams-shop",
     )
+    expect(r("https://amzn.to/d/some_short_link")).to eq(
+      "https://amzn.to/d/some_short_link?tag=sams-shop",
+    )
+    expect(r("https://amzn.eu/d/some_short_link")).to eq(
+      "https://amzn.eu/d/some_short_link?tag=eu-sams-shop",
+    )
+    expect(r("https://a.co/some_short_link")).to eq("https://a.co/some_short_link?tag=sams-shop")
 
     # keep node (BrowseNodeSearch) query parameter
     expect(r("https://www.amazon.com/b?ie=UTF8&node=13548845011")).to eq(