function populateServerSelectionList() {
	const servers = localstorage_credentials.getServers();

	let nodes = [];
	for (let server of servers) {
		const li = document.createElement("li");
		const endpoint = humanReadableEndpoint(server.endpoint);
		li.innerText = `${server.login_id}@${endpoint} `;

		const logoutButton = document.createElement("button");
		logoutButton.className = "logout";
		logoutButton.innerText = "Log out";
		logoutButton.addEventListener("click", e => logOut(server.endpoint, e.currentTarget));

		li.appendChild(logoutButton);
		nodes.push(li);
	}
	byId("server_selection_list").innerHTML = "";
	byId("server_selection_list").append(...nodes);
}

function populateChannelList() {
	async function addChannelItems(client) {
		const teams = await client.myTeams();

		for (let team of teams) {
			let nodes = [];
			const channels = await client.myChannels(team.id);
			for (let channel of channels) {
				const li = document.createElement("li");
				const a = document.createElement("a");
				a.href = "javascript:void(0)";
				const titleAndElements = channelNameElements(team, channel);
				if (!titleAndElements) continue;
				a.title = titleAndElements[0];
				a.append(...titleAndElements[1]);

				a.addEventListener("click", () => switchToChannel(client, team, channel));

				li.appendChild(a);
				li.dataset["id"] = channel.id;
				nodes.push(li);
			}
			byId("channel_list").append(...nodes);
		}
	}

	byId("channel_list").innerHTML = "";
	const endpoints = localstorage_credentials.getServers().map(server => server.endpoint);
	for (let client of mm_client.getMultiple(endpoints)) {
		addChannelItems(client);
	}
}


function transformMessageText(message) {
	return message
		.split(/(?<=:|\W|^)(:[a-z0-9_-]+:)(?=:|\W|$)/)
		.map((x, i) => i % 2
			?  emoji[x.slice(1, -1)] || x
			: x)
		.join("");
}


async function createMessageElement(client, post, lastTime, lastAuthor) {
	const users = await client.getUsers();
	const isThreadReply = !!post.parent_id;

	const messageDiv = document.createElement("div");
	messageDiv.className = "message";
	messageDiv.innerText = transformMessageText(post.message);

	const createAt = new Date(post.create_at);
	const createAtDiv = document.createElement("time");
	createAtDiv.className = "create_at";
	const sim = dateSimilarity(lastTime, createAt);
	lastTime = createAt;
	let createAtText = "";
	if (sim < DATE_SIMILARITY.date) createAtText += formatDdddMmYy(createAt);
	if (sim < DATE_SIMILARITY.minutes) createAtText += " " + formatHhMm(createAt);
	createAtDiv.title = createAt.toString();
	createAtDiv.innerText = createAtText;
	createAtDiv.dateTime = createAt.toISOString();

	const authorName = users[post.user_id] ? users[post.user_id].username : post.user_id;
	const authorDiv = document.createElement("div");
	authorDiv.className = "author";
	authorDiv.innerText = authorName;

	const postDiv = document.createElement("div");
	postDiv.className = "post";
	if (lastAuthor === post.user_id) {
		postDiv.className += " same_author";
	}
	lastAuthor = post.user_id;

	postDiv.dataset["id"] = post.id;
	postDiv.appendChild(authorDiv);
	postDiv.appendChild(createAtDiv);
	postDiv.appendChild(messageDiv);

	if (post.metadata && (post.metadata.files || []).length > 0) {
		const attachmentsUl = document.createElement("ul");
		attachmentsUl.className = "attachments";
		for (let file of post.metadata.files || []) {
			const attachmentLi = document.createElement("li");
			attachmentLi.dataset["id"] = file.id;

			const attachmentA = document.createElement("a");
			client.filePublicLink(file.id).then(link => attachmentA.href = link);
			attachmentA.target = "_blank";
			attachmentA.innerText = file.name;

			if (file.mini_preview) {
				const attachmentImg = document.createElement("img");
				attachmentImg.src = `data:image/jpeg;base64,${file.mini_preview}`;
				attachmentA.appendChild(attachmentImg);
			}

			attachmentLi.appendChild(attachmentA);
			attachmentsUl.appendChild(attachmentLi);
		}
		postDiv.appendChild(attachmentsUl);
	}

	return {postDiv, lastTime, lastAuthor};
}


async function populateChannelContents(client, channel, contents) {
	byId("channel_contents").innerHTML = "";

	let result = {lastAuthor: null, lastTime: null, postDiv: null};

	let nodes = [];
	for (let id of contents.order) {
		result = await createMessageElement(client, contents.posts[id], result.lastTime, result.lastAuthor);
		nodes.push(result.postDiv);
	}

	byId("channel_contents").dataset["server"] = client.endpoint;
	byId("channel_contents").dataset["id"] = channel.id;
	byId("channel_contents").dataset["lastTime"] = result.lastTime.getTime();
	byId("channel_contents").dataset["lastAuthor"] = result.lastAuthor;
	byId("channel_contents").append(...nodes);
	scrollToBottom();
}


async function addMessage(client, post) {
	const shouldScroll = isScrolledToBottom();

	const result = await createMessageElement(
		client, post,
		new Date(1 * (byId("channel_contents").dataset["lastTime"])),
		byId("channel_contents").dataset["lastAuthor"]
	);
	console.log(result);
	byId("channel_contents").dataset["lastTime"] = result.lastTime.getTime();
	byId("channel_contents").dataset["lastAuthor"] = result.lastAuthor;
	byId("channel_contents").appendChild(result.postDiv);

	if (shouldScroll) {
		scrollToBottom();
	}
}


function scrollToBottom() {
	const el = byId("channel_contents_wrapper");
	el.scrollTop = el.scrollHeight;
	el.className = "";
}


function updateComposeHeight() {
	byId("compose").style.height = "";
	byId("compose").style.height = (byId("compose").scrollHeight + 1) + "px";
}
byId("compose").addEventListener("input", updateComposeHeight);

function isScrolledToBottom() {
	const el = byId("channel_contents_wrapper");

	const scrolledTo = el.clientHeight + el.scrollTop;
	return scrolledTo >= el.scrollHeight;
}
function checkScrolledToBottom() {
	byId("channel_contents_wrapper").className = isScrolledToBottom() ? "" : "not-at-bottom";
}
byId("channel_contents_wrapper").addEventListener("scroll", checkScrolledToBottom);


pubsub.subscribe("MESSAGES_NEW", post => {
	if (
		post.endpoint === byId("channel_contents").dataset["server"] &&
		post.channel_id === byId("channel_contents").dataset["id"]
	) {
		addMessage(mm_client.get(post.endpoint), post);
	}
});