#!/usr/bin/env ruby

require 'gtk2'
require 'dbus'
require 'digest/sha1'

module RandomServer

	class SessionEntry
		attr_accessor :h, :r1, :r2, :b1, :b2, :b
		def initialize(h, r1, b2)
			@h, @r1, @b2 = h, r1, b2
		end
		def check
			h == Digest::SHA1.hexdigest(sprintf("%d-%d-%d", r1, r2, b1))
		end
		def to_s
			"SessionEntry(h=#{h}, r1=#{r1}, r2=#{r2}, b1=#{b1}, b2=#{b2}, b=#{b})\n"
		end
	end

	class RandomObj < DBus::Object
		def initialize(path, max)
			super(path)
			@max = max
			@records = {}
		end

		dbus_interface "org.muadda.random" do
			dbus_method :suggest_random, "in h:s, in r1:u, out b2:u" do |h, r1|
				puts "suggest_random h=#{h}, r1=#{r1}"
				if @records.has_key?(h)
					puts "Detect replay attempt!"
					return [0]
				end
				b2 = rand(@max)
				puts "choose b2=#{b2}"
				@records[h] = SessionEntry.new(h, r1, b2)
				[b2]
			end
			dbus_method :confirm_random, "in h:s, in r2:u, in b1:u" do |h, r2, b1|
				puts "confirm_random h=#{h}, r2=#{r2} b1=#{b1}"
				if ! @records.has_key?(h)
					puts "Cannot confirm: missing key!"
					return
				end
				@records[h].r2 = r2
				@records[h].b1 = b1
				if !@records[h].check
					puts "Cannot confirm: cheat detected!"
					return
				end
				@records[h].b = (b1 + @records[h].b2).modulo(@max)
				puts "b = " + @records[h].b.to_s
			end
		end
	end

	srand
	DBus::SessionBus.instance.glibize

	bus = DBus.session_bus
	service = bus.request_service("org.muadda.random")

	r = RandomObj.new("/org/muadda/random256", 256)
	service.export(r)
	r = RandomObj.new("/org/muadda/random16", 16)
	service.export(r)
	r = RandomObj.new("/org/muadda/random2", 2)
	service.export(r)

	Gtk.main

end