const fs = require("fs");
const path = require("path");

const Koa = require("koa");
const koaPug = require("koa-pug");
const koaRouter = require("koa-router");
const koaRange = require("koa-range");
//const koaServe = require("koa-static");
const FileType = require("file-type");

const config = require("./config");
const util = require("./util");
const { type } = require("os");
const { ENOENT, ECONNRESET } = require("constants");

const sizeUnits = [ "B", "KiB", "MiB", "GiB" ];

function makeCurrentPathField(path) {
	let current = "";
	if (path.endsWith("/"))
		path = path.slice(1, path.length-1);
	const path_parts = path.split("/");

	current = `<a href="/">root</a>`;

	for (i = 0; i < path_parts.length; ++i) {
		let lnk = "";
		for (j = 0; j < i+1; ++j) {
			lnk += `/${path_parts[j]}`;
		}
		current += `/<a href="${encodeURI(lnk)}/">${path_parts[i]}</a>`;
	}

	return current;
}

function convertSize(size) {
	let i = 0;
	for (; size > 1024; size /= 1024) { ++i; }
	return [i > 0 ? size.toFixed(2) : size, sizeUnits[i]];
}

function fileType(name) {
	if (name.endsWith("txt") || name.endsWith("md"))
		return "text/plain";
	return "octet-stream";
}

async function getDirectoryList(dir_path, base_url) {
	let dirs = [];
	let files = [];
	let d = await fs.promises.opendir(dir_path);
	for await (const dirent of d) {
		const stat = fs.lstatSync(path.join(dir_path, dirent.name));
		const [s, u] = convertSize(stat.size);
		if (stat.isDirectory())
			dirs.push({
				name: dirent.name,
				link: `${base_url}${encodeURIComponent(dirent.name)}/`,
				datetime: util.datetime(stat.mtime, util.formats.file_date),
				size: "DIR",
				size_unit: '' });
		else
			files.push({
				name: dirent.name,
				link: `${base_url}${encodeURIComponent(dirent.name)}`,
				datetime: util.datetime(stat.mtime, util.formats.file_date),
				size: +s,
				size_unit: u });
	}

	const sort_by_name = (a, b) => {
		if (a.name > b.name)
			return 1;
		else if (a.name < b.name)
			return -1;
		return 0;
	}

	dirs.sort(sort_by_name);
	files.sort(sort_by_name);

	return dirs.concat(files);
}

function setRoutes(router) {
	router.get('/(.*)?', async (ctx, next) => {
		if (ctx.originalUrl.startsWith("/assets") || ctx.originalUrl.startsWith("/shared")) {
			await next();
			return;
		}
		const file_path = path.join(config.files.file_path, decodeURI(ctx.originalUrl));
		let stat = fs.lstatSync(file_path);
		if (stat.isDirectory()) {
			await ctx.render('index', {
				title: "/ Files",
				description: "File share.",
				host: util.getBaseHost(ctx.header.host),
				current_path: makeCurrentPathField(decodeURI(ctx.originalUrl)),
				items: await getDirectoryList(file_path, ctx.originalUrl) });
		} else {
			let f = await FileType.fromStream(fs.createReadStream(file_path));
			if (f === undefined)
				ctx.type = fileType(file_path);
			else
				ctx.type = f.mime;
			ctx.set("Content-Length", stat.size);

			const stream = fs.createReadStream(file_path);
			// let ch = 0;
			// stream.on("end", () => { });
			// stream.on("data", (chunk) => { ch += chunk.length; });
			ctx.body = stream;
		}
	});
}

module.exports = () => {
	const app = new Koa();
	const pug = new koaPug({
		viewPath: path.join(__dirname, "views", "files"),
		locals: {
			moment: date => util.datetime(date, util.formats.file_date) },
		app: app
	});

	const radio_router = koaRouter();
	setRoutes(radio_router);

	app.proxy = true;
	app
		.use(koaRange)
		.use(radio_router.routes())
		// .use(koaServe(path.join("static", "shared")))
		// .use(koaServe(path.join("static", "files")))
		.on("error", err => { if (!err.code == ECONNRESET || !err.code == ENOENT) console.log(err.code); })
		.listen(config.files.port, config.files.host);

	return app;
}