Ruby script to download all NCERT book PDFs

ncert.rb

# NCERT books are excellent but being altered for political or other reasons
# See: https://twitter.com/SouthAsiaIndex/status/1518062204058103809
# To download the entire current set, run this script with Ruby

require 'httparty'

source = HTTParty.get('https://ncert.nic.in/textbook.php').force_encoding("ISO-8859-1").encode("utf-8", replace: nil)

# book names are like aeen1dd.zip
# First letter tells the class number a to l is class 1 to class 12. m stands for class 11 and 12 combined
# Second letter is the language the book is written in: e for English, h for Hindi, u for Urdu

bookids = source.scan(/textbook.php\?[a-z]{4,4}\d/).uniq

def download_book(book_name)
    puts "Downloading #{book_name}"
    File.open(book_name, "w") do |file|
        file.binmode
        HTTParty.get('https://ncert.nic.in/textbook/pdf/' + book_name, follow_redirects: true, stream_body: true) do |fragment|
          file.write(fragment)
        end
    end
rescue
end

bookids.each do |bid|
    book_name = bid.gsub("textbook.php?", "") + "dd.zip" 
    download_book(book_name)
    sleep(0.2)
end