Simple debug HTTP server in Crystal

server.cr

require "option_parser"
require "http/server"
require "json"

class Settings
  property port = 3000
  property host = "127.0.0.1"
  property? show_headers = false
  property? show_raw_json = false
end

settings = Settings.new


OptionParser.parse! do |p|
  p.banner = "crystal server.cr -- [-p 3000] [-h 127.0.0.1] [--headers] [--rawjson]"

  p.on("-p PORT", "--port=PORT", "The port to bind on (default: 3000).") do |port|
    settings.port = port.to_i? || abort("Invalid port #{port}")
  end

  p.on("-h HOST", "--host=HOST", "The hostname to bind on (default: 127.0.0.1).") do |host|
    settings.host = host
  end

  p.on("--headers", "If set, request headers will be shown.") do
    settings.show_headers = true
  end

  p.on("--rawjson", "If set, JSON payload will not be formatted.") do
    settings.show_raw_json = true
  end

  p.on("--help", "Displays this message.") do
    puts p
    exit
  end
end rescue abort "Invalid arguments, see --help."

server = HTTP::Server.new(settings.host, settings.port) do |context|
  puts "-" * 80
  puts
  puts Time.now
  puts "#{context.request.method} #{context.request.path}"
  if settings.show_headers?
    puts
    puts "Headers:"
    puts context.request.headers.map {|k, v| "  #{k}: #{v.join("; ")}" }.join("\n")
  end

  if body = context.request.body
    puts
    content_type = context.request.headers["Content-Type"]
    if  content_type.includes?("json") && !settings.show_raw_json?
      puts JSON.parse(body).to_pretty_json
    elsif content_type.includes?("text") || content_type.includes?("json")
      puts body
    else
      puts "Got body of #{content_type} with #{context.request.headers["Content-Length"]} bytes."
    end
  end
  puts

  context.response.status_code = 204
end

puts "Listening on #{settings.host}:#{settings.port}"
server.listen