var fs = require("fs");
var pathlib = require("path");

var mimes = {
	txt: "text/plain",
	css: "text/css",
	html: "text/html",

	js: "application/javascript",
	json: "application/json",
	xml: "application/xml",
	zip: "application/zip",
	pdf: "application/pdf",

	gif: "image/gif",
	png: "image/png",
	jpeg: "image/jpeg",
	jpg: "image/jpeg",
	svg: "image/svg+xml",
	bmp: "image/bmp",
	webp: "image/webp",

	midi: "audio/midi",
	mp3: "audio/mpeg",
	ogg: "audio/ogg",

	webm: "video/webm",
	mkv: "video/mkv",
	ogv: "video/ogg",
}

function mimetype(path) {
	var unknown = "application/octet-stream";

	var ext = pathlib.extname(path);
	if (ext)
		return mimes[ext.substr(1)] || unknown;
	else
		return unknown;
}

function sendfile(path, app, pathname, req, res) {
	fs.open(path, "r", (err, fd) => {
		if (err) {
			app.notice(err);
			res.writeHead(404);
			res.end(app.template(app.res404,
				{ method: req.method, pathname: pathname }));
			return;
		}

		res.writeHead(200, {
			"Content-Type": mimetype(path)
		});

		var rs = fs.createReadStream(null, { fd: fd });
		rs.on("error", err => {
			app.warning(err);
		});
		rs.on("data", d => res.write(d));
		rs.on("end", () => res.end());
	});
}

var transformCache = {};
function handleTransform(stat, path, req, res, app) {
	var ext = pathlib.extname(path);
	if (ext === "")
		return false;

	var transform = app._transforms[ext];
	if (!transform)
		return false;

	if (transformCache[path]) {
		var c = transformCache[path];
		if (stat.ctime === c.ctime) {
			res.writeHead(c.data.status, c.data.headers);
			res.end(c.data.content);
			return true;
		} else {
			delete transformCache[path];
		}
	}

	var data = { content: "", headers: null, status: null };

	var writeStream = {
		headersSent: false,
		status: 200,
		headers: {
			"content-type": transform.mime
		},

		write: function(d) {
			if (!writeStream.headersSent) {
				res.writeHead(writeStream.status, writeStream.headers);
				writeStream.headersSent = true;
			}
			if (d != null) {
				data.content += d;
				res.write(d);
			}
		},

		end: function(d, nocache) {
			writeStream.write(d);

			res.end();

			if (!nocache) {
				data.status = writeStream.status;
				data.headers = writeStream.headers;
				transformCache[path] = {
					data: data,
					ctime: stat.ctime
				};
			}
		},

		error: function(err) {
			if (writeStream.status === 200)
				writeStream.status = 500;

			app.warning("Transform for "+path+": "+err.toString());
			writeStream.end(null, true);
		}
	}

	transform.func(path, writeStream);
	return true;
}

module.exports = function(root, before) {
	return function(req, res, app) {
		// `req.urlobj.pathname` is too long.
		var pn = req.urlobj.pathname;

		// Join the web root with the request's path name
		var path = pathlib.join(root, pn.replace(before, ""));

		// Send a file
		function send(path) {
			sendfile(path, app, pn, req, res);
		}

		// Prevent leaking information
		if (pn.indexOf("../") !== -1 || pn.indexOf("/..") !== -1 || pn === "..") {
			res.writeHead(403);
			res.end(app.template(app.res403,
				{ method: req.method, pathname: pn }));
			return;
		}

		fs.stat(path, (err, stat) => {

			// If there's an error stat'ing, just error
			if (err) {
				app.notice(err);
				res.writeHead(404);
				res.end(app.template(app.res404,
					{ method: req.method, pathname: pn }));
				return;
			}

			// If it's a directory, we want the index.html file,
			// or redirect to <pathname>/
			if (stat.isDirectory()) {
				if (pn[pn.length - 1] !== "/") {
					res.writeHead(302, { location: pn + "/" });
					res.end();
					return;
				}

				path = pathlib.join(path, "index.html");
			}

			// If there's a transform, let that handle it
			if (handleTransform(stat, path, req, res, app))
				return;

			// Otherwise, send the file
			send(path);
		});
	}
}