#script to query amazon for album information
#author: Dan Pickett ( dpickett@enlightsolutions.com )

require 'amazon/search'
require 'time'
require 'date'
require 'optparse'
require 'ostruct'

include Amazon::Search  # don't want to have to fully qualify identifiers

class Connector
	ASSOCIATES_ID = "webservices-20" # if you don't have one of these, don't
	                                 # pass the second argument to Request.new

	DEV_TOKEN     = "1ZVJEA6D3VH000PJTM02" # your development token
	DEBUG = false
	
	def self.search(query, sort_by_field, sort_order)
		
		begin
			#perform search off of amazon
			request  = Request.new(DEV_TOKEN)  # second argument optional
			response = request.keyword_search(query, 'music', HEAVY, 1)
		rescue Amazon::Search::Request::SearchError => e
			return nil
		end
		
		if DEBUG
			#prints out complete product information
			for product in response.products
		  	printf("Found a product:\n%s---\n", product)
		  end
		end
		
		#add track quantity as an attribute so that we can use it for sorting
		products = Array.new
		for product in response.products
			product = product.to_h
			if product['tracks'].nil?
				product['track_qty'] = 0
			else
				product['track_qty'] = (product['tracks'].size || 0)
			end
			
			if !product['release_date'].nil?
				product['date_released'] = Date.parse(product['release_date'])
			end
			products << product
		end
		
		if sort_by_field == 'date_released'
			sort_minimum = Date.parse('11/11/1900')
			sort_maximum = Date.parse('11/11/3050')
		else
			sort_minimum = -1
			sort_maximum = 2^32
		end
		
		if sort_order == 'D'
			products = products.sort_by {|x| x[sort_by_field] || sort_minimum}
			products.reverse!
		else
			products = products.sort_by {|x| x[sort_by_field] || sort_maximum}
		end
		
		return products;
	end
	
end

class AmazonXmlTranslator
	def self.to_xml(amazon_result, image_only = false)
		
		xml_result = REXML::Element.new('results')
		if !amazon_result.nil?
			for album in amazon_result
				xml_album = REXML::Element.new('album')
				xml_album.add_attribute('title', album['product_name'])
				xml_album.add_attribute('artist', album['artists'])
				xml_album.add_attribute('sales_rank', album['sales_rank'])
				
				xml_album.add_attribute('image_url', album['image_url_large'])
				xml_album.add_attribute('release_date', album['release_date'])
				xml_album.add_attribute('user_rating', album['average_customer_rating'])
				if !image_only
					i = 0
			
					#clean up and get rid of nil entries
					tracks = (album['tracks'] || []).reject{|x| x.nil?}
			
					#iterate through tracks and put into xml
					for track in tracks
						i += 1
					
						xml_track = REXML::Element.new('track')
						xml_track.add_attribute('id', i.to_s)
						xml_track.add_text(track)
						xml_album.add_element(xml_track)
					end
				end
				if(!album['tracks'].nil?)
					xml_album.add_attribute("tracks", album['tracks'].size || 0)
				end
				xml_result.add_element(xml_album)
			end
		end
		return xml_result
	end
end

require 'optparse'

options = OpenStruct.new
options.sort_by_field = 'sales_rank'
options.sort_order = 'A'
options.image_only = false

OptionParser.new do |opts|
  opts.banner = "Usage: amazon.rb 'search query' [options]"

  opts.on("-a", "--album_only", "Only retrieve album information (no tracks)") do |i|
    options.image_only = true
	end
	opts.on("-s", "--sort_by FIELD",
		"Sort by field (Acceptable options: average_user_rating, date_released, sales_rank, track_qty)") do |sort|
			#TODO validate sort fields
			options.sort_by_field = sort
	end
	opts.on("-d", "--descending", "Sort in descending order") do |a|
		options.sort_order = 'D'
  end
end.parse!


if ARGV[0].nil?
	puts "Improper Usage: please supply a quoted search argument"
else
	results = Connector.search(ARGV[0], options.sort_by_field, options.sort_order)
	AmazonXmlTranslator.to_xml(results, options.image_only).write($stdout, 0)
end