madrugao_suplementos_whey_crawler.rb

# encoding: utf-8

# Copyright (C) 2011 by Murilo Pereira <murilo@murilopereira.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

%w[getoptlong open-uri nokogiri].each { |gem| require gem }

module MadrugaoSuplementos
  extend self

  USAGE = <<-USAGE.gsub(/^    /, '')
    Usage: ruby madrugao_suplementos_whey_crawler.rb [-h|--help] [options]
      -s, --show-links     Show the URL for each whey
      -n, --no-colorize    Show non-colorized output
  USAGE

  BASE_URL = 'http://www.madrugaosuplementos.com.br'
  NUMBER_OF_WHEY_PAGES = 5

  def whey_protein_page_url(options)
    "#{BASE_URL}/produtos/Massa+Muscular/319_Whey+Protein.html/#{options[:page]}"
  end

  module Util
    def to_decimal(string)
      string.sub(',', '.').to_f
    end
  end

  module Extractor
    include Util

    DECIMAL_REGEXP = '\d+(?:[,\.]\d+)?'
    KILOGRAM_UNITS = %w[kg k KG K]
    GRAM_UNITS = %w[g G]
    POUND_UNITS = %w[lb lbs LB LBS]
    UNITS = [KILOGRAM_UNITS, GRAM_UNITS, POUND_UNITS].flatten
    # Captures a decimal number and its unit.
    WEIGHT_REGEXP = /\((#{DECIMAL_REGEXP})\s*(#{UNITS.join('|')})\)/
    # Captures a decimal number.
    PRICE_REGEXP = /(?:R\$)?\s*(#{DECIMAL_REGEXP})/

    def extract_name(node)
      node.at_css('span.nome a').content
    end

    def extract_weight(node)
      if match = node.at_css('span.nome a').content.match(WEIGHT_REGEXP)
        weight, unit = match.captures
        if KILOGRAM_UNITS.include?(unit)
          to_decimal(weight) * 1000
        elsif GRAM_UNITS.include?(unit)
          normalize_weight(weight, unit)
        elsif POUND_UNITS.include?(unit)
          to_decimal(weight) * 453.59
        end
      else
        STDERR.puts("error: '#{node.at_css('span.nome a').content}' didn't " <<
                    "have a valid weight unit. (grams, kilograms or pounds)")
      end
    end

    def extract_price(node)
      to_decimal(node.at_css('p.preco-com-desconto').content.match(PRICE_REGEXP)[1])
    end

    def extract_link(node)
      BASE_URL + node.at_css('span.nome a')['href']
    end

    private

    # Treat dumb weights strings like '1.500g', which when called #to_f on
    # are converted to 1.5.
    def normalize_weight(weight, unit)
      if weight.include?('.') && GRAM_UNITS.include?(unit)
        to_decimal(weight.delete('.'))
      else
        to_decimal(weight)
      end
    end
  end

  module WheyCrawler
    extend self, Extractor

    def crawl(options)
      (1..NUMBER_OF_WHEY_PAGES).map do |page|
        html = Nokogiri::HTML(open(MadrugaoSuplementos.whey_protein_page_url(:page => page)))
        html.css('div.quadro_produto_index').map do |node|
          whey_hash = { :name => extract_name(node),
                        :weight => extract_weight(node),
                        :price => extract_price(node) }
          options[:show_links] ? whey_hash.merge(:link => extract_link(node)) : whey_hash
        end
      end.flatten
    end
  end

  class Whey
    attr_reader :name, :weight, :price, :link

    def initialize(params)
      @name = params[:name].to_s
      @weight = params[:weight].to_f
      @price = params[:price].to_f
      @link = params[:link].to_s
    end

    def valid?
      !name.nil? && !name.empty? && weight > 0 && price > 0
    end

    def grams_per_real
      weight / price
    end

    def to_hash
      whey_hash = { :name => name,
                    :weight => weight,
                    :price => price,
                    :grams_per_real => grams_per_real }
      (!link.nil? && !link.empty?) ? whey_hash.merge(:link => link) : whey_hash
    end

    def to_s
      to_hash.to_s
    end
  end

  module Output
    extend self

    def puts_whey(whey, options = {})
      puts(options[:colorize] ? colorize_whey(whey) : whey)
    end

    private

    def colorize(text, color_code); "#{color_code}#{text}\033[0;0m"; end
    def cyan(text); colorize(text, "\033[0;36m"); end
    def purple(text); colorize(text, "\033[0;35m"); end
    def green(text); colorize(text, "\033[0;32m"); end
    def dark_gray(text); colorize(text, "\033[1;30m"); end
    def white(text); colorize(text, "\033[1;37m"); end

    def colorize_whey(whey)
      whey.to_s.
        gsub(/(:link)(=>)"(.*)"/) { purple($1) << dark_gray($2) << '"' << $3 << '"' }.
        gsub(/:(name|weight|price|grams_per_real)(=>)(?:"(.*?)"|(.*?))(,|})/) do
          purple(':' + $1) << dark_gray($2) << '"' << white($3 || $4) << '"' << $5
        end.
        gsub(/(^\{|\}$)/) { green($1) }.
        gsub(',', dark_gray(',')).
        gsub('"', dark_gray('"'))
    end
  end

  module CLI
    def self.run(options)
      if options[:help]
        abort(USAGE)
      else
        MadrugaoSuplementos::WheyCrawler.
          crawl(:show_links => options[:show_links]).
          map { |whey_params| MadrugaoSuplementos::Whey.new(whey_params) }.
          select(&:valid?).
          sort_by { |whey| whey.price/whey.weight }.
          each { |whey| MadrugaoSuplementos::Output.puts_whey(whey, options) }
      end
    end
  end
end

opts = GetoptLong.new(['--help',        '-h', GetoptLong::NO_ARGUMENT],
                      ['--show-links',  '-s', GetoptLong::NO_ARGUMENT],
                      ['--no-colorize', '-n', GetoptLong::NO_ARGUMENT])

options = { :colorize => true,
            :show_links => false }

opts.each do |opt, arg|
  case opt
  when '--help'
    options[:help] = true
  when '--show-links'
    options[:show_links] = true
  when '--no-colorize'
    options[:colorize] = false
  end
end

MadrugaoSuplementos::CLI.run(options) if $0 == __FILE__