parser.rb

require 'curb'
require 'nokogiri'
require 'csv'

$image_path = "//img[@id='bigpic']/@src"
$item_attributes = "//ul[contains(@class, 'attribute_radio_list')]//li//span"
$item_name  = "//h1[contains(@class, 'product_main_name')]"


class Parser 
    @@easy_options = {:follow_location => true}
    @@multi_options = {:pipeline => Curl::CURLPIPE_HTTP1}
    attr_accessor :url

    def initialize()
        @url = nil
    end
    
    def get_url 
        @url
    end
    
    def url=(url)
        @url = url
    end

    def http_request
        http = Curl::Easy.perform(@url) do |http|
            http.headers["User-Agent"] = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36"
        end  
    end

    def multi_request(*urls)
        htmls = Array.new
        Curl::Multi.get(*urls, @@easy_options, @@multi_options) do |url|
            htmls.push(Nokogiri::HTML(url.body_str))
        end
        return htmls
    end

    def get_html
        Nokogiri::HTML(http_request.body_str)
    end

    def get_item (item)
        get_html.xpath(item).text.strip
    end
end

def get_category_urls url
    parser = Parser.new
    parser.url = url 
    category_urls = Array.new 
    while parser.url != "" 
        category_urls.push(parser.url)
        parser.url = parser.get_item("//link[@rel='next']/@href")
    end
    puts "Сollecting category pages ...."
    return category_urls
end


def get_items_urls url
    parser = Parser.new
    items_urls = Array.new
    category_urls = parser.multi_request(get_category_urls(url))
    category_urls.each do |html|
        html.xpath("//div[contains(@class, 'pro_first_box')]/a/@href").each do |url|
            items_urls.push(url.text)
        end
    end
    puts "Сollecting all the products ...."
    return items_urls
end    


def parse_item url
    data = Array.new
    parser = Parser.new
    items_urls = parser.multi_request(get_items_urls(url))
    items_urls.each do |html|
        product = Hash.new
        items = html.xpath($item_attributes).map { |item| item.content }
        options = items.each_slice(2).to_a
        html.xpath($item_name).each { |name| product[:name] = name.text.strip } 
        html.xpath($image_path).each { |img| product[:img] = img.text }
        product[:options] = options
        data.push(product)
    end 
    puts "We collect data from each product ...."
    return data
end  


def write_to_csv(*data, file_name)
    data.each do |product|
        CSV.open("#{file_name}.csv", "wb", {:col_sep => "\t"}) do |csv|
            csv << ["Name", "Price", "Image"]
            product.each do |h| 
                h[:options].each do |option|
                    item = Array.new
                    item.push("#{h[:name]} - #{option[0]}")
                    item.push(option[1])
                    item.push(h[:img])
                    csv << item
                end
            end
        end
    end
end


while true
    puts "Enter category link: "
    url = gets.chomp
    puts "Enter file name: "
    file_name = gets.chomp
    if url.empty? || file_name.empty?
        puts "You must fill in all fields!"
        redo
    end
    t1 = Time.now
    puts "Connecting to #{url} ...."
    data = parse_item(url)
    write_to_csv(data, file_name)
    puts "Writing to csv ..."
    t2 = Time.now
    delta = t2 - t1
    puts "Load time: #{delta}, Amount of products: #{data.length}"
    break
end