service/src/get-port.cr

require "file_utils"
require "option_parser"

require "./config.cr"

START_PORT = 49152
PORTS_CACHE_DIRECTORY = "#{CACHE_DIRECTORY}/ports/"

service = ""
wanted_default_port : String? = nil

parser = OptionParser.parse do |parser|
	parser.banner = "usage: get-post <id> [default-port] [options]\n" +
		"options:\n"

	parser.on "-h", "--help", "Prints this help message." do
		puts parser
		exit 0
	end

	parser.unknown_args do |arg|
		if arg.size < 1 || arg.size > 2
			puts parser
			exit 1
		end

		service = arg[0]
		wanted_default_port = arg[1]?
	end
end

service_port_file = "#{PORTS_CACHE_DIRECTORY}/#{service.gsub /\//, ":"}"

begin
	if File.exists? service_port_file
		puts File.read service_port_file
		exit 0
	end

	FileUtils.mkdir_p PORTS_CACHE_DIRECTORY

	used_ports = Dir.children(PORTS_CACHE_DIRECTORY)
		.map { |x| "#{PORTS_CACHE_DIRECTORY}/#{x}" }
		.map { |x| File.read(x).to_i }
		.sort

	port = START_PORT
	if wanted_default_port && ! used_ports.any? &.==(wanted_default_port)
		port = wanted_default_port
	else
		while used_ports.any? &.==(port)
			port = port + 1
		end
	end

	File.write service_port_file, port

	puts port
rescue e
	STDERR.puts "error: #{e.message}"
	exit 1
end