YouTube -> Markdown using BrettTerpstra.com/yt-md/api

yt-md.rb

#!/usr/bin/env ruby
# Simple CLI wrapper that queries https://brettterpstra.com/yt-md/api
# Usage: yt-md.rb [--title "Custom Title"] <YouTube URL or ID>

require 'optparse'
require 'net/http'
require 'uri'
require 'cgi'

options = {}
opt = OptionParser.new do |o|
  o.banner = "Usage: #{File.basename($0)} [options] URL_or_ID"
  o.on('-t', '--title TITLE', 'Override the scraped title') { |v| options[:title] = v }
  o.on('--thumb SIZE', 'Thumbnail thumb: 0,1,2,3,hq,sd,max,maxres, or filename') { |v| options[:thumb] = v }
  o.on('-h', '--help', 'Show this help') { puts o; exit }
  o.on('-o', '--output TYPE', 'Output type: markdown (default), json, html') { |v| options[:output] = v }
  # caption flag: true by default; provide --no-caption to omit caption
  options[:caption] = true
  o.on('--no-caption', 'Omit caption from HTML output') { options[:caption] = false }
end

begin
  opt.parse!(ARGV)
rescue StandardError => e
  $stderr.puts "Error parsing options: #{e.message}"
  $stderr.puts opt
  exit 1
end

arg = ARGV.shift
if arg.nil? || arg.strip.empty?
  $stderr.puts opt
  exit 1
end

base = 'https://brettterpstra.com/yt-md/api'
params = {}
# If it looks like a URL (contains a slash or youtube host), send as url; otherwise use id
if arg.include?('/') || arg =~ /youtu(?:\.be|be\.com)/i
  params['url'] = arg
else
  params['id'] = arg
end
params['title'] = options[:title] if options[:title]
params['caption'] = options.key?(:caption) ? (options[:caption] ? '1' : '0') : '1'
params['thumb'] = options[:thumb] if options[:thumb]

# Decide which output to request. Default to markdown when no --output is provided.
desired = (options[:output] || 'markdown').to_s.downcase
desired = 'markdown' if desired == 'md'
params['output'] = desired

query = URI.encode_www_form(params)
uri = URI.parse("#{base}?#{query}")

begin
  res = Net::HTTP.get_response(uri)
  if res.is_a?(Net::HTTPSuccess)
    body = res.body
    # If JSON requested, pretty-print; otherwise print the body directly (API returns the requested format)
    if params['output'] == 'json'
      begin
        parsed = JSON.parse(body)
        puts JSON.pretty_generate(parsed)
      rescue StandardError
        puts body
      end
    else
      # markdown or html returned directly by the API; just print
      puts body
    end
    exit 0
  else
    $stderr.puts "Request failed: #{res.code} #{res.message}"
    $stderr.puts res.body unless res.body.nil? || res.body.empty?
    exit 2
  end
rescue StandardError => e
  $stderr.puts "Network error: #{e.class}: #{e.message}"
  exit 3
end