#!/home/cabo/src/bin/ruby
require 'webrick'
require 'monitor'
include WEBrick
class SyncState < Monitor
  attr_reader :value
  def initialize
    @value = ''
    @cond = new_cond
    super
  end
  def set(value)
    synchronize do
      @value = value
      l = @cond.count_waiters
      @cond.broadcast
      l
    end
  end
  def news(oldvalue)
    synchronize do
      @cond.wait_while {oldvalue == @value};
      @value
    end
  end
end

def no_cache(resp)
  resp['Content-Type'] = "text/plain"
  resp['Pragma'] = "no-cache"
  resp['Cache-Control'] = "no-cache"
  resp['Expires'] = "Thu, 01 Dec 1994 16:00:00 GMT"
end

class MyServlet < HTTPServlet::AbstractServlet
  def initialize(server, state)
    super
    @state = state
  end
  def do_GET(req, resp)
    no_cache(resp)
    url = req.query['url']
    do_it(req, resp, url)
  end

  alias do_POST do_GET
end

class LeadServlet < MyServlet
  def do_it(req, resp, url)
    puts "before set ov=#{@state[url].value} nv=#{req.query['value']} #{Thread.list}"
    l = @state[url].set(req.query['value'])
    puts "after set nw=#{l}"
    resp.body = l.to_s
  end
end

class FollowServlet < MyServlet
  def do_it(req, resp, url)
    puts "before news #{req.query['value']} #{Thread.list}"
    resp.body = @state[url].news(req.query['value'])
    puts "after news #{resp.body}" 
  end
end

state = Hash.new {|hash, key| hash[key] = SyncState.new }

s = HTTPServer.new(
                   :Port => 2000,
                   :DocumentRoot => "/home/cabo/src/sync/site"
                   )
s.mount("/lead", LeadServlet, state)
s.mount("/follow", FollowServlet, state)
trap("INT"){ s.shutdown }
s.start