"use strict";

const got = require("got");
const log = require("../log");
const pkg = require("../../package.json");

const TIME_TO_LIVE = 15 * 60 * 1000; // 15 minutes, in milliseconds

module.exports = {
	fetch,
};

const versions = {
	current: {
		version: `v${pkg.version}`,
	},
};

async function fetch() {
	// Serving information from cache
	if (versions.current.changelog) {
		return versions;
	}

	try {
		const response = await got("https://api.github.com/repos/thelounge/thelounge/releases", {
			headers: {
				"Accept": "application/vnd.github.v3.html", // Request rendered markdown
				"User-Agent": pkg.name + "; +" + pkg.repository.git, // Identify the client
			},
		});

		if (response.statusCode !== 200) {
			return versions;
		}

		updateVersions(response);

		// Emptying cached information after reaching said expiration date
		setTimeout(() => {
			delete versions.current.changelog;
			delete versions.latest;
		}, TIME_TO_LIVE);
	} catch (error) {
		log.error(`Failed to fetch changelog: ${error}`);
	}

	return versions;
}

function updateVersions(response) {
	let i;
	let release;
	let prerelease = false;

	const body = JSON.parse(response.body);

	// Find the current release among releases on GitHub
	for (i = 0; i < body.length; i++) {
		release = body[i];

		if (release.tag_name === versions.current.version) {
			versions.current.changelog = release.body_html;
			prerelease = release.prerelease;

			break;
		}
	}

	// Find the latest release made after the current one if there is one
	if (i > 0) {
		for (let j = 0; j < i; j++) {
			release = body[j];

			// Find latest release or pre-release if current version is also a pre-release
			if (!release.prerelease || release.prerelease === prerelease) {
				versions.latest = {
					prerelease: release.prerelease,
					version: release.tag_name,
					url: release.html_url,
				};

				break;
			}
		}
	}

	// Add expiration date to the data to send to the client for later refresh
	versions.expiresAt = Date.now() + TIME_TO_LIVE;
}