#### audio_manager.lua ####

local mgr = {}

mgr.queue = {}
mgr.state = "paused"

local function next(event)
   local fun = table.remove(mgr.queue, 1)
   if fun then
      fun()
   else
      mgr.state = "paused"
   end
end

local function resume ()
   if mgr.state == "paused" then
      mgr.state = "running"
      next()
   else
      -- assert(false, "audio playback queue already running")
   end
end

function mgr:add (handle, delay, onStart, onEnd)
   delay = delay or 0

   local options = {
      onComplete = function (event)
	 if onEnd then onEnd() end
	 next(event)
      end
   }

   local fun = function ()
      audio.play(handle, options)
      if onStart then onStart() end
   end

   local player = function ()
      timer.performWithDelay(delay, fun)
   end

   table.insert(self.queue, player)
   resume()
end

return mgr

#### sample usage ####


local function onSpeakEnd()
   --if(event.completed == true) then
      --print("completed")
      girlmouth:pause()
      girlmouth:setFrame(1)
   --end
end

local function onSpeakStart()
   girlmouth:play()
end

local function lucySpeaks(handle, delay, callback)
   local onend = onSpeakEnd
   if callback then
      onend = function ()
	 onSpeakEnd()
	 callback()
      end
   end
   audio_mgr:add(handle, delay, onSpeakStart, onend)
end

function issueRequest (delay)
....
	 local request = audio.loadSound("assets/sound/specific-requests/"..foo.."-"..math.random(3)..".mp3")
	 local callback = function ()
	    fsm.state = "request-issued"
	 end
	 lucySpeaks(request, delay, callback)
	 --audio.dispose(request)
....
end

   -- say greetings and issue first request
   local intro = audio.loadSound("assets/sound/intro/hi-i-m-lucy-"..math.random(4)..".mp3")
   lucySpeaks(intro)
   issueRequest(700)