function normalizeUrl(url) {
	if (url.indexOf("http://") == -1 && url.indexOf("https://") == -1) {
		url = "https://" + url;
	}
	if (url.charAt(url.length - 1) !== '/'){
		url = url + "/";
	}
	return url;
}

const instance = document.getElementById('instance');
const instances_list = document.getElementById('instances_list');

var prefillInstance = window.localStorage.getItem('mastodon_instance');

var paramPairs = window.location.search.substr(1).split('&');
var paramPairsLength = paramPairs.length;
for (var i = 0; i < paramPairsLength; i++) {
	var paramPair = paramPairs[i].split('=');
	if (paramPair[0] === 'text') {
		document.getElementById('text').value = decodeURIComponent(paramPair[1]);
	} else if (paramPair[0] === 'instance') {
		prefillInstance = decodeURIComponent(paramPair[1]);
	}
}
delete i
delete paramPair

function instances_loading_error() {
	console.error('Failed to fetch servers list from joinmastodon.');
}

function instances_loaded() {
	if (this.status !== 200) {
		instances_loading_error();
		return;
	}

	const servers = JSON.parse(this.responseText);

	const chosen_instance = instance.value;
	const domains = servers.map(obj => obj.domain);
	if (chosen_instance && domains.indexOf(chosen_instance) === -1) {
		domains.push(chosen_instance);
	}
	domains.sort();

	for (const domain of domains) {
		const opt = document.createElement('option');
		opt.value = normalizeUrl(domain);
		instances_list.appendChild(opt);
	}
}

if (prefillInstance != null) {
	instance.value = normalizeUrl(prefillInstance);
}

instance.addEventListener('focus', function (e) {
	if (instances_list.children.length === 0) {
		const req = new XMLHttpRequest();
		req.addEventListener('load', instances_loaded);
		req.addEventListener('error', instances_loading_error);
		req.open('GET', 'https://api.joinmastodon.org/servers');
		req.send();
	}
})

document
  .getElementById('form')
  .addEventListener('submit', function (e) {
		e.preventDefault();
		var text = e.target.elements['text'].value;
		var instance = normalizeUrl(e.target.elements['instance'].value);
		var remember = e.target.elements['remember'].checked;

		if (remember) {
			window.localStorage.setItem('mastodon_instance', instance);
		}

		var shareUrl = instance + "share?text=" + encodeURIComponent(text);
		window.location.href = shareUrl;
  })