const fs = require("fs");
const path = require("path");
const types = require("./types.js");
const log = require("./log.js");
const { version } = require("./modules/03-cache.js");
const mustache = require("mustache");
const LRU = require("lru-cache");

const cache = new LRU({ max: 100 });
const time = Date.now().toString(32).toString(36);
const template404 = fs.readFileSync("assets/404.html", "utf8");

module.exports = generate;

const handlers = {
	directory: require("./handlers/directory.js"),
	markdown: require("./handlers/markdown.js"),
	gemini: require("./handlers/gemini.js"),
	file: require("./handlers/file.js"),
};

function generate(file, raw = false) {
	const where = path.resolve(__dirname + "/overlay/" + file);

	if(!fs.existsSync(where)) {
		return send("text/html", mustache.render(template404, { file, time, cache: { style: version("/assets/style.css") } }), 404);
	}

	try {
		const stat = fs.statSync(where);

		if(stat.isDirectory()) {
			if(!file.endsWith("/")) return (req, res) => res.redirect(file + "/");
			return send("text/html", run(handlers.directory));
		} else if(path.extname(where) === ".md" && !raw) {
			return send("text/html", run(handlers.markdown));
		} else if(path.extname(where) === ".gmi" && !raw) {
			return send("text/html", run(handlers.gemini));
		} else {
			const type = types.get(path.extname(where).slice(1));
			if(stat.size < 1024 * 32) {
				return send(type, run(handlers.file));
			} else {
				return (req, res) => {
					const range = req.range(stat.size);
					if(range === -2) return res.sendStatus(400);
					if(range === -1) return res.sendStatus(416);
					const headers = {
						"Content-Type": type || "application/octet-stream",
						"Content-Length": stat.size,
						"Accept-Ranges": "bytes",
					};
					if(range) {
						if(range.type !== "bytes") return res.sendStatus(400);
						headers["Content-Range"] = `bytes ${range[0].start}-${range[0].end}/${stat.size}`;
						headers["Content-Length"] = Math.abs(range[0].end - range[0].start) + 1;
						res.writeHead(206, headers);
						fs.createReadStream(where, range[0]).pipe(res);
					} else {
						res.writeHead(200, headers);
						fs.createReadStream(where).pipe(res);
					}
				};
			}
		}
	} catch {
		return send("text/html", mustache.render(template404, { file, time, cache: { style: version("/assets/style.css") } }), 404);
	}

	function send(type, content, status = 200) {
		if(typeof content === "function") return content;
		content = Buffer.from(content);
		const headers = { "Content-Type": type || "text/plain", "Content-Length": content.length };
		return (req, res) => res.writeHead(status, headers).end(content);
	}

	function run(mod) {
		const hash = mod.hash(where, file);
		if(cache.has(where)) {
			const [rendered, oldhash] = cache.get(where);
			if(hash === oldhash) return rendered;
		}
		const rendered = mod.render(where, file);
		cache.set(where, [rendered, hash]);
		return rendered;
	}
};

module.exports.handle = (req, res) => {
	// stop sneaky people
	if(req.path.includes("..")) return res.writeHead(403).end("nice try bud, but we don't do that here.");

	generate(path.normalize(decodeURIComponent(req.path)), "raw" in req.query)(req, res);
};