Ruby Module to Generate Amazon Affiliate URLs for Products and Searches

amazon-affiliate_url.rb

require "uri"

#  
# Generate Amazon Affiliate URLs for products and searches
# 
# Amazon::AffiliateURL.config do |cfg|
#   cfg.id = "your-id"       # required
#   cfg.domain = :us         # optional, defaults to :us, can be a domain name
#   cfg.category = "grocery" # optional, default category for search(), 
#   cfg.secure = true        # optional, use https scheme or not, defaults to false
# end
#
# puts Amazon::AffiliateURL.search("salt sugar")
# puts Amazon::AffiliateURL.search("ipad","computers")
# puts Amazon::AffiliateURL.product("B009W8YQ6K")
#
# By Skye Shaw (https://gist.github.com/sshaw/88372931a538cb3bfd28)
# 

module Amazon
  module AffiliateURL
    DOMAINS = {
      :ca => "amazon.ca",
      :cn => "amazon.cn",
      :de => "amazon.de",
      :fr => "amazon.fr",
      :jp => "amazon.co.jp",
      :uk => "amazon.co.uk",
      :us => "amazon.com"
    }

    class << self
      def config
        yield settings
      end

      alias :configure :config

      def product(id)
        URI.join(host, "gp/product/", id, query).to_s
      end

      def search(terms, category = settings.category)
        params = { "field-keywords" => terms }
        params["url"] = "search-alias=#{category}" if category

        URI.join(host, "s", query(params)).to_s
      end

      private
      def host
        name = %(http#{"s" if settings.secure}://)
        name << domain
      end

      def domain
        option = settings.domain

        domain = if option.is_a?(Symbol)
          DOMAINS[option]
        elsif option.is_a?(String)
          option
        end

        raise ArgumentError, "missing or invalid domain: '#{option}'" unless domain
        domain
      end

      def query(q = {})
        "?" << URI.encode_www_form(q.merge(:tag => settings.id)).gsub("+", "%20")
      end

      def settings
        @settings ||= Struct.new(:domain, :secure, :category, :id).new(:us, false)
      end
    end
  end
end