let timerInterval = null;
let startTime = null;
let secondsToSubtract = 0;
let micLevel = 0;

navigator.mediaDevices.getUserMedia({
	audio: true
}).then((stream) => {
	const audioContext = new AudioContext();
	const analyser = audioContext.createAnalyser();
	const microphone = audioContext.createMediaStreamSource(stream);
	const scriptProcessor = audioContext.createScriptProcessor(2048, 1, 1);

	analyser.smoothingTimeConstant = 0.8;
	analyser.fftSize = 1024;

	microphone.connect(analyser);
	analyser.connect(scriptProcessor);
	scriptProcessor.connect(audioContext.destination);
	setInterval(() => {
		const array = new Uint8Array(analyser.frequencyBinCount);
		analyser.getByteFrequencyData(array);
		const arraySum = array.reduce((a, value) => a + value, 0);
		micLevel = arraySum / array.length;
		document.querySelector('#mic').innerHTML = Math.round(micLevel);
	}, 1000)
})
.catch((err) => {
	console.error(err);
});

const updateTimerDisplay = ()=>{
	if(micLevel < 15){
		secondsToSubtract++;
	}
	const secondsSinceTimerStart = Math.floor((Date.now() - startTime)/1000);
	document.querySelector('#seconds').innerHTML = secondsSinceTimerStart;
	document.querySelector('#subtracted').innerHTML = secondsToSubtract;
	document.querySelector('#total').innerHTML = secondsSinceTimerStart - secondsToSubtract;
}

document.querySelector('#start').addEventListener('click', ()=>{
	startTime = Date.now();
	timerInterval = window.setInterval(updateTimerDisplay,1000);
})

document.querySelector('#stop').addEventListener('click', ()=>{
	window.clearInterval(timerInterval);
})