function AudioForm(el) {
	const interval = el.elements['interval']
	const play = el.elements['play']
	const output = el.querySelector('output')
	const audioPool = []
	let intervalHandle = null
	let audioIndex = 0
	const items = 50

	for (let i = 0; i < items; i += 1) {
		const newAudio = new Audio('./sfx/weapons/guns/smg-hkmp7/1_unload_var0.wav')
		newAudio.volume = 0.2;
		newAudio.addEventListener('canplaythrough', () => {
			audioPool[i].ready = true
		})
		newAudio.addEventListener('ended', () => {
			newAudio.pause()
			newAudio.currentTime = 0
		})

		audioPool[i] = {
			audio: newAudio,
			ended: true,
			ready: false,
		}
		newAudio.load()
	}

	const playSound = () => {
		for (let i = 0; i < items; i += 1) {
			if (!audioPool[i].ready) {
				return;
			}
		}

		audioPool[audioIndex].audio.play();
		audioIndex = (audioIndex + 1) % items;
	}

	el.addEventListener('submit', (e) => {
		e.preventDefault()

		const ms = 60000 / Number(interval.value);
		output.innerText = `${ms} ms`
		if (play.checked) {
			intervalHandle = window.setInterval(() => {
				playSound()
			}, ms)
		} else {
			window.clearInterval(intervalHandle);
		}

		play.checked = !play.checked
	})
}

const audioForm = new AudioForm(window.document.getElementById('formAudio'))