var volume = 0.5; //not too loud by default or you'll drown out screen readers
var YMPParams = 
	{
		volume:volume,
		displaystate:3
	} 
var ympObjectId = 'swfproxy'; //the id Yahoo assigns to the YMP <object>
var playlistId = 'playlist';
var nowPlayingId = 'nowPlaying';
var controllerId = 'controls';
var thisMediaObj;
var controller;
var playerState;
var numSongs; 
var songTitle;
var playpause;
var seekForward;
var seekBack;
var stop;
var timer;
var currentTimeContainer;
var durationContainer;
var duration;
var elapsedTime;
var mute;
var volumeUp;
var volumeDown;
var playlist;
var nowPlayingDiv;
var statusSpan;
var seekInterval = 15; //number of seconds to seek forward or back (for HTML5)

// Once API ready handler is invoked, YAHOO.MediaPlayer class can be accessed safely
var apiReadyHandler = function () {
 
	nowPlayingDiv = document.getElementById(nowPlayingId);
	playlist = document.getElementById(playlistId);
	controller = document.getElementById(controllerId);
 
	playpause = document.createElement('input');
	playpause.setAttribute('type','button');
	playpause.setAttribute('id','playpause');
	playpause.setAttribute('value','');
	playpause.setAttribute('title','Play');
	playpause.setAttribute('accesskey','P');
	controller.appendChild(playpause);
 
	stop = document.createElement('input');
	stop.setAttribute('type','button');
	stop.setAttribute('id','stop');
	stop.setAttribute('value','');
	stop.setAttribute('title','Stop');		
	stop.setAttribute('accesskey','S');
	controller.appendChild(stop);
	
	seekBack = document.createElement('input');
	seekBack.setAttribute('type','button');
	seekBack.setAttribute('id','seekBack');
	seekBack.setAttribute('value','');
	seekBack.setAttribute('title','Rewind ' + seekInterval + ' seconds');
	seekBack.setAttribute('accesskey','R');
	seekBack.disabled=true; //will be enabled after track begins to play
	seekBack.setAttribute('class','disabled');
	controller.appendChild(seekBack);
 
	seekForward = document.createElement('input');
	seekForward.setAttribute('type','button');
	seekForward.setAttribute('id','seekForward');
	seekForward.setAttribute('value','');
	seekForward.setAttribute('title','Forward ' + seekInterval + ' seconds');
	seekForward.setAttribute('accesskey','F');
	seekForward.disabled=true; //will be enabled after track begins to play
	seekForward.setAttribute('class','disabled');
	controller.appendChild(seekForward);
	
	timer = document.createElement('span');
	timer.setAttribute('id','timer');		
	currentTimeContainer = document.createElement('span');
	currentTimeContainer.setAttribute('id','currentTime');
	var startTime = document.createTextNode('0:00');
	currentTimeContainer.appendChild(startTime);
	
	durationContainer = document.createElement('span');
	durationContainer.setAttribute('id','duration');
	timer.appendChild(currentTimeContainer);
	timer.appendChild(durationContainer);
	controller.appendChild(timer);
 
	mute = document.createElement('input');
	mute.setAttribute('type','button');
	mute.setAttribute('id','mute');
	mute.setAttribute('value','');
	mute.setAttribute('title','Mute');		
	mute.setAttribute('accesskey','M');
	controller.appendChild(mute);

	volumeUp = document.createElement('input');		
	volumeUp.setAttribute('type','button');
	volumeUp.setAttribute('id','volumeUp');
	volumeUp.setAttribute('value','');
	volumeUp.setAttribute('title','Volume Up');		
	volumeUp.setAttribute('accesskey','U');
	controller.appendChild(volumeUp);
 
	volumeDown = document.createElement('input');
	volumeDown.setAttribute('type','button');
	volumeDown.setAttribute('id','volumeDown');
	volumeDown.setAttribute('value','');
	volumeDown.setAttribute('title','Volume Down');		
	volumeDown.setAttribute('accesskey','D');
	controller.appendChild(volumeDown);
		
	//get and set default values 
	YAHOO.MediaPlayer.setVolume(volume);
 
	// Add other listeners for Yahoo events
	YAHOO.MediaPlayer.onPlaylistUpdate.subscribe(onPlaylistUpateHandler);
	YAHOO.MediaPlayer.onTrackStart.subscribe(onTrackStartHandler);
	YAHOO.MediaPlayer.onTrackPause.subscribe(onTrackPauseHandler);
	YAHOO.MediaPlayer.onProgress.subscribe(onProgressHandler);
	
	//handle playpause click
	if (document.addEventListener) { 
		playpause.addEventListener('click',function() { 
			playAudio();
		}, false);
	}
	else if (document.attachEvent) { //IE 8 and below
		playpause.attachEvent('onclick',function () { 
			playAudio();
		});
	}
 
	//handle stop click
	if (document.addEventListener) { 
		stop.addEventListener('click',function() { 
			YAHOO.MediaPlayer.stop();
			playpause.setAttribute('title','Play');
			playpause.style.backgroundImage="url('images/audio_play.gif')";
			showTime(0,currentTimeContainer);
		}, false);
	}
	else if (document.attachEvent) { //IE 8 and below
		stop.attachEvent('onclick',function () { 
			YAHOO.MediaPlayer.stop();
			playpause.setAttribute('title','Play');
			playpause.style.backgroundImage="url('images/audio_play.gif')";
			showTime(0,currentTimeContainer);
		});
	}
	
	//handle seekForward click
	if (document.addEventListener) { 
		seekForward.addEventListener('click',function() { 
			seekAudio('forward');
		}, false);
	}
	else if (document.attachEvent) { //IE 8 and below
		seekForward.attachEvent('onclick',function () { 
			seekAudio('forward');
		});
	}
 
	//handle seekBack click
	if (document.addEventListener) { 
		seekBack.addEventListener('click',function() { 
			seekAudio('back');
		}, false);
	}
	else if (document.attachEvent) { //IE 8 and below
		seekBack.attachEvent('onclick',function () { 
			seekAudio('back');
		});
	}
 
	//handle mute click
	if (document.addEventListener) { 
		mute.addEventListener('click',function() { 
			toggleMute();
		}, false);
	}
	else if (document.attachEvent) { //IE 8 and below
		mute.attachEvent('onclick',function () { 
			toggleMute();
		});
	}
	
	//handle volumeUp click
	if (document.addEventListener) { 
		volumeUp.addEventListener('click',function() { 
			updateVolume('up');
		}, false);
	}
	else if (document.attachEvent) { //IE 8 and below
		volumeUp.attachEvent('onclick',function () { 
			updateVolume('up');
		});
	}
 
	//handle volumeDown click
	if (document.addEventListener) { 
		volumeDown.addEventListener('click',function() { 
			updateVolume('down');
		}, false);
	}
	else if (document.attachEvent) { //IE 8 and below
		volumeDown.attachEvent('onclick',function () { 
			updateVolume('down');
		});
	}
}
var onPlaylistUpateHandler = function (playlistArray) {
	numSongs = YAHOO.MediaPlayer.getPlaylistCount();
	//set first track as "Now playing"
	var children = playlist.childNodes;
	var finished = false;
	for (var i=0; i < children.length; i++) { 
		if (children[i].nodeName == 'LI' && finished == false) { 
			songTitle = children[i].childNodes[0].innerHTML;
			finished = true;
		}
	}
	nowPlayingDiv.innerHTML = '<span>Now Playing:</span><br/>' + songTitle;
}
function onTrackStartHandler (mediaObj) {
	//track has started playing, possible via a click in the playlist
	//be sure playpause button is in pause state
	var trackMeta = YAHOO.MediaPlayer.getMetaData();
	songTitle = trackMeta['title'];
	nowPlayingDiv.innerHTML = '<span>Now Playing:</span><br/>' + songTitle;
	playpause.setAttribute('title','Pause');
	playpause.style.backgroundImage="url('images/audio_pause.gif')";
	thisMediaObj = mediaObj;
	//at this point, ok to enable seek buttons
	seekBack.disabled=false;
	seekBack.removeAttribute('class');
	seekForward.disabled=false;
	seekForward.removeAttribute('class');
}
function onTrackPauseHandler (mediaObj) {
	//track has been possed, possible via a click on a pause button in the playlist
	//be sure playpause button is in play state
	playpause.setAttribute('title','Play');
	playpause.style.backgroundImage="url('images/audio_play.gif')";
}
function onProgressHandler (progressArray) {
	//progressArray includes keys 'elapsed' and 'duration', both in ms
	elapsedTime = progressArray['elapsed']; 
	if (elapsedTime > 0) showTime(elapsedTime/1000,currentTimeContainer);
	else showTime(0,currentTimeContainer);
	duration = progressArray['duration'];
	if (duration > 0) showTime(duration/1000,durationContainer);
	else showTime(0,durationContainer);
}
function playAudio() { 
	playerState = YAHOO.MediaPlayer.getPlayerState();
	//values: STOPPED: 0, PAUSED: 1, PLAYING: 2,BUFFERING: 5, ENDED: 7
	if (playerState == 2) { //playing 
		YAHOO.MediaPlayer.pause();
		playpause.setAttribute('title','Play');
		playpause.style.backgroundImage="url('images/audio_play.gif')";
	}
	else { 
		YAHOO.MediaPlayer.play();
		playpause.setAttribute('title','Pause');
		playpause.style.backgroundImage="url('images/audio_pause.gif')";
	}				
}
function seekAudio(direction) {
	//element is either seekForward or seekBack
	//this only works if a track has started playing
	//shouldn't be possible to call this function prior to that because seek buttons are disabled
	//but this if loop is here to prevent an error, just in case
	if (typeof thisMediaObj != 'undefined') { 
		var trackPos = YAHOO.MediaPlayer.getTrackPosition(); 
		if (direction == 'forward') { 
			//NOTE: API docs at http://mediaplayer.yahoo.com/api say getTrackPosition() returns value in ms
			//This is incorrect - it returns the current position in SECONDS!
			//Target time, however, must be passed to play() in ms  
			var targetTime = Math.floor(trackPos + seekInterval) * 1000;			
		}
		else if (direction == 'back') { 
			var targetTime =  Math.floor(trackPos - seekInterval) * 1000;
		}
		YAHOO.MediaPlayer.play(thisMediaObj.track,targetTime);
	}
}
function showTime(time,elem,hasSlider) { 
	if (elem == durationContainer && time == 0) {
		//duration is unknown. Don't display it
		//also, should disable seekBack and and seekForward buttons
	}
	else { 
		var minutes = Math.floor(time/60);  
		var seconds = Math.floor(time % 60); 
		if (seconds < 10) seconds = '0' + seconds;
		var output = minutes + ':' + seconds; 
		if (elem == currentTimeContainer) elem.innerHTML = output;
		else elem.innerHTML = ' / ' + output;
	}
}
 	function updateVolume(direction) {
	//volume is a range between 0 and 1
	volume = YAHOO.MediaPlayer.getVolume();
	if (direction == 'up') { 
		if (volume < 0.9) { 
			if (volume == 0) toggleMute();
			volume = (volume + 0.1);
		}
		else volume = 1;
	}
	else { //direction is down
		if (volume > 0.1) volume = (volume - 0.1);
		else volume = 0; 
	}
	YAHOO.MediaPlayer.setVolume(volume);
}
function toggleMute() { 
	if (YAHOO.MediaPlayer.getVolume() == 0) { //muted, so unmute. 
		mute.setAttribute('title','Mute');
		YAHOO.MediaPlayer.setVolume(volume); //volume should still be at pre-muted value
		mute.style.backgroundImage="url('images/audio_volume.gif')";
	}
	else { //not muted, so mute
		mute.setAttribute('title','UnMute');
		//don't update var volume. Keep it at previous level 
		//so we can return to it on unmute
		YAHOO.MediaPlayer.setVolume(0);
		mute.style.backgroundImage="url('images/audio_mute.gif')";
	}
}
YAHOO.MediaPlayer.onAPIReady.subscribe(apiReadyHandler);