Module: ProjectEulerCli::Scraper

Included in:
ArchiveController, ArchiveSearcher, ArchiveViewer
Defined in:
lib/project_euler_cli/concerns/scraper.rb

Overview

Holds all of the methods related to accessing the site.

Instance Method Summary collapse

Instance Method Details

#load_page(page, problems) ⇒ Object

Loads the problem numbers and titles for an individual page of the archive.



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# File 'lib/project_euler_cli/concerns/scraper.rb', line 51

def load_page(page, problems)
  return if Page.visited.include?(page)

  html = open("https://projecteuler.net/archives;page=#{page}")
  fragment = Nokogiri::HTML(html)

  problem_links = fragment.css('#problems_table td a')

  i = (page - 1) * Page::LENGTH + 1
  problem_links.each do |link|
    problems[i].title = link.text
    i += 1
  end

  Page.visited << page
end

#load_problem_details(id, problems) ⇒ Object

Loads the details of an individual problem.



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# File 'lib/project_euler_cli/concerns/scraper.rb', line 69

def load_problem_details(id, problems)
  return unless problems[id].published.nil?

  html = open("https://projecteuler.net/problem=#{id}")
  fragment = Nokogiri::HTML(html)

  problem_info = fragment.css('div#problem_info span span')

  details = problem_info.text.split(';')
  problems[id].published = details[0].strip
  problems[id].solved_by = details[1].strip

  # recent problems do not have a difficult rating
  problems[id].difficulty = details[2].strip if id < Problem.total - 9
end

#load_recent(problems) ⇒ Object

Loads in all of the problem numbers and titles from the recent page.



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# File 'lib/project_euler_cli/concerns/scraper.rb', line 33

def load_recent(problems)
  return if Page.visited.include?(0)

  html = open("https://projecteuler.net/recent")
  fragment = Nokogiri::HTML(html)

  problem_links = fragment.css('#problems_table td a')

  i = Problem.total
  problem_links.each do |link|
    problems[i].title = link.text
    i -= 1
  end

  Page.visited << 0
end

#lookup_totals ⇒ Object

Pulls information from the recent page to determine the total number of problems and pages.



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# File 'lib/project_euler_cli/concerns/scraper.rb', line 8

def lookup_totals
  begin
    Timeout.timeout(4) do
      html = open("https://projecteuler.net/recent")
      fragment = Nokogiri::HTML(html)

      id_col = fragment.css('#problems_table td.id_column')

      # The newest problem is the first one listed on the recent page. The ID 
      # of this problem will always equal the total number of problems.
      Problem.total = id_col.first.text.to_i
      # There are ten problems on the recent page, so the last archive problem 
      # can be found by subtracting 10 from the total number of problems. This 
      # is used to calculate the total number of pages.
      last_archive_id = Problem.total - 10
      Page.total = (last_archive_id - 1) / Page::LENGTH + 1
    end
  rescue Timeout::Error
    puts "Project Euler is not responding."

    exit(true)
  end
end