Coursera Lectures (and Subtitles) Download

fetch_links.rb

# AUTHOR:
# deepak.jois@gmail.com
# (w/ credit to: http://www.brownfort.com/2014/09/scrap-websites-ruby/)
#
# DESCRIPTION:
# Dumps a list of direct, unprotected CDN links to Coursera
# lecture videos, and downloads English subtitles (.txt,.srt) for them.
#
# USAGE:
# ruby fetchlinks.rb <username> <password> <coursename> <section>
#
# <coursename> is the name of the course, as it shows up in the URL.
# For e.g. ‘configuringworld-002’, ‘cryptography-002’, ‘humanlanguage-001’
# etc.
# 
# <section> The section number is a 0-based integer obtained by counting the 
# number of sections from top, on the Video Lectures download page.
# For e.g. if you wish to download videos in the first section, which is 
# usually (but not always) a Welcome or Getting Started section,
# you should use 0.
# 
# 
require 'uri'
require 'nokogiri'
require 'typhoeus'
 
def login(email, password)
  login_url = "https://accounts.coursera.org/api/v1/login"
  method = "post"
  params = { email: email,
             password: password,
             webrequest: true }
  headers = { "Host" => "accounts.coursera.org",
              "Connection"=> "keep-alive",
              "Origin"=> "https://accounts.coursera.org",
              "User-Agent"=> "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.94 Safari/537.36",
              "Content-Type"=> "application/x-www-form-urlencoded",
              "Accept"=> "*/*",
              "X-Requested-With"=> "XMLHttpRequest",
              "Referer"=> "https://accounts.coursera.org/signin?post_redirect=https://www.coursera.org/",
              "X-CSRF2-Token"=> "3dNSKBZddpG2w5RTNLYB9grd",
              "X-CSRF2-Cookie"=> "csrf2_token_iKSpqIdU",
              "X-CSRFToken"=> "hH7MfdwlVA1UGBEjqM2MWC3K",
              "Cookie"=> "csrftoken=hH7MfdwlVA1UGBEjqM2MWC3K; csrf2_token_iKSpqIdU=3dNSKBZddpG2w5RTNLYB9grd"
            }
  request = Typhoeus::Request.new(
      login_url,
      method: :post,
      params: params, headers: headers
  )
  response = request.run
  if response.response_code == 200
    res_headers = response.response_headers.split("\n")
    res_headers.each do |res_head|
      res = res_head.split(":")
      if res[0].eql? "Set-Cookie"
        headers["Cookie"] = "#{headers["Cookie"]};#{res[1].split(";")[0]}"
      end
    end
  end
  return response, headers
end
 
def fetch_links(course, week, headers)
  url = "https://class.coursera.org/#{course}/lecture"
  headers["Referer"] = "https://class.coursera.org/#{course}"
  headers["Host"] = "class.coursera.org"
  request = Typhoeus::Request.new(
      url,
      method: :get,
      headers: headers
  )
  response = request.run
  if response.response_code == 200
    page = Nokogiri::HTML(response.response_body)
    return response, page.css(".course-item-list-section-list")[week].css("a")
  else
    return response, nil
  end
end
 
def resolve_link(link, headers)
  if !link['href'].index('/lecture/download.mp4').nil?
    response =Typhoeus::Request.get("#{link['href']}", followlocation: false, headers: headers, ssl_verifypeer: false)
    puts response.headers_hash["Location"]
  elsif !link['href'].index('/lecture/subtitles').nil?
    response =Typhoeus::Request.get("#{link['href']}", followlocation: true, headers: headers, ssl_verifypeer: false)
    if response.response_code == 200
      cd = response.headers_hash["Content-Disposition"]
      filename = URI.unescape(cd.match(/filename=(\"?)(.+)\1/)[2]).gsub("/", "-")
      File.open(filename, 'w') { |file| file.write(response.response_body) }
      STDERR.puts "Done saving #{filename}"
    else
      STDERR.puts "Problem saving #{filename}"
      STDERR.puts link['href']
      STDERR.puts response.response_code
      STDERR.puts response.response_body
    end
  end
end
 
if ARGV.size > 3
  email = ARGV[0]
  password = ARGV[1]
  course = ARGV[2]
  week = ARGV[3].to_i
  STDERR.puts "Logging in."
  response, headers = login(email, password)
  if response.response_code == 200
    STDERR.puts "Login done."
    STDERR.puts "Fetching links."
    response, links = fetch_links(course, week, headers)
    if response.response_code == 200
      STDERR.puts "Fetching links done."
      links.each do |link|
        resolve_link(link, headers)
      end
    else
      STDERR.puts "Problem fetching links."
    end
  else
    STDERR.puts "Problem Logging in."
  end
else
  STDERR.puts "Please provide email, password, course name and week as first, second, third and fourth argument respectively."
end