One Piece Downloader

one_piece_downloader.rb

require 'open-uri'
require 'tty-progressbar'

CONCURRENCY = 8
FIRST_EPISODE_NUMBER = 1
LAST_EPISODE_NUMBER = 628

def get_bounds(episode_number)
  episode_number = 1 if episode_number < 1
  lower_bound = ((episode_number - 1) / 100) * 100 + 1
  upper_bound = lower_bound + 100 - 1
  return "#{lower_bound.to_s.rjust(3, '0')}_#{upper_bound.to_s.rjust(3, '0')}"
end

def new_bar(multibar, *arguments)
  return multibar.register(*arguments) if multibar

  return TTY::ProgressBar.new(*arguments)
end

def download(url, title, multibar: nil)
  bar = nil
  content_length_proc = ->(total) { bar = new_bar(multibar, "#{title} [:bar] :percent", total: total) if total && total >= 0 }
  progress_proc = ->(progress) { bar.current = progress if bar }
  URI.open(url, content_length_proc: content_length_proc, progress_proc: progress_proc) do |file|
    yield(file)
  end
end

def download_episode(episode_number, multibar: nil)
  bounds = get_bounds(episode_number)
  episode_str = episode_number.to_s.rjust(3, '0')
  filename = "#{episode_str}.mp4"
  url = "https://serverfile.club/anime/onepiece/ita/#{bounds}/#{filename}"
  download(url, "Download episode #{episode_str}", multibar: multibar) do |file|
    IO.copy_stream(file, filename)
  end
rescue OpenURI::HTTPError => e
  puts "#{url}: #{e.message}"
end

def run_download(queue, multibar: nil)
  episode_number = queue.pop
  if episode_number
    download_episode(episode_number, multibar: multibar)
    run_download(queue, multibar: multibar)
  end
end

# Start here

multibar = TTY::ProgressBar::Multi.new
queue = Queue.new((FIRST_EPISODE_NUMBER..LAST_EPISODE_NUMBER).to_a)
threads = []
CONCURRENCY.times do
  threads << Thread.new { run_download(queue, multibar: multibar) }
end
threads.each(&:join)