utils.js

const logger = require("@root/logger").getLogger("utils");


class HTTPError extends Error {
	constructor (status, message, error) {
		super(message);
		this.status = status;
		this.error = error;
	}
}


function error(status, message) {
	if (message instanceof HTTPError) {
		message.status = status;
		return message;
	}
	if (message instanceof Error) {
		return new HTTPError(status, message.message, message);
	}
	return new HTTPError(status, message);
}


function result(status, content, resource_id) {
	return { status, content, resource_id };
}


function promisify(f, ...args) {
	return new Promise((resolve, reject) => {
		try {
			resolve(f(...args));
		} catch(err) {
			reject(err);
		}
	});
}


function mwrap(req, res, next, handler) {
	var promise;
	if (typeof(handler) === "function") {
		promise = promisify(handler);
	}
	else if (handler instanceof Promise) {
		promise = handler;
	}
	else {
		promise = Promise.resolve(handler);
	}

	promise.then(response => {
		if (response === undefined) {
			next();
		}
		else if (response == null) {
			res.status(204).end();
		}
		else if (response instanceof Buffer) {
			logger.debug(`response=Buffer, length=${response.length}`);
			res.status(200).send(response);
		}
		else if (typeof(response) === "number") {
			res.status(response).end();
		}
		else {
			//logger.debug(`response=${JSON.stringify(response)}`);
			res.status(200).json(response);
		}
	}).catch(err => {
		if (err instanceof HTTPError) {
			logger.debug(`error ${err.status}: ${err.message}`);
			res.status(err.status || 500);
			if (err.message) {
				res.statusMessage = err.message;
			}
			res.end();
		}
		else {
			next(err);
		}
	});
}


// autovivify a'la perl
// https://dev.to/a2triple/autovivification-in-javascript-3c5p
function av(obj = {}) {
	return new Proxy(obj, {
		get: (target, name) => {
			if (name === "toJSON") {
				return () => target;
			}
			else if (name === "toBSON") {
				return () => target;
			}
			else {
				return name in target ?  target[name] : target[name] = av();
			}
		},
	});
}


// string to bool
function s2bool(s) {
	if (s === undefined)
		return false;
	// in case of "...&is_whatever&..." the empty value also means true
	return (s === "") || (s === "true") || (s === true);
}


function add_cors_response_headers(res, origin) {
	res.header("Access-Control-Allow-Origin", origin || "*");
	res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization");
	res.header("Access-Control-Allow-Credentials", true);
	res.header("Access-Control-Allow-Methods", "GET,PUT,POST,DELETE,PATCH,OPTIONS");
}


function dump_request(req) {
	// https://expressjs.com/en/guide/routing.html
	// req is-a IncomingMessage
	//
	// req.headers
	// req.rawHeaders
	// req.url
	// req.method
	// req.statusCode
	// req.statusMessage
	// req.query = {}
	// req.body = {}

	logger.debug(`Request; hostname='${req.hostname}', ip='${req.ip}', method='${req.method}', url='${req.url}'`);
	for (let name in req.headers) {
		logger.debug(`Request header; name='${name}', value='${req.headers[name]}'`);
	}
	for (let name in req.params) {
		logger.debug(`Request param; name='${name}', value='${req.params[name]}'`);
	}
	for (let name in req.query) {
		logger.debug(`Request query; name='${name}', value='${req.query[name]}'`);
	}
	for (let name in req.body) {
		logger.debug(`Request body; name='${name}', value='${req.body[name]}'`);
	}
	for (let name in req.cookies) {
		logger.debug(`Request cookie; name='${name}', value='${req.cookies[name]}'`);
	}
}


function require_client(req, client_email) {
	if (!req.session || !req.session.email) {
		throw error(401, "Authentication needed");
	}
	if (client_email && (req.session.email != client_email)) {
		throw error(403, "Not owner of data");
	}
}


function require_admin(req) {
	require_client(req);
	if (!req.session.is_admin) {
		throw error(403, "Must be admin");
	}
}


function require_body(req, attrs) {
	for (let attr of attrs) {
		if (req.body[attr] === undefined) {
			throw error(400, `Missing ${attr}`);
		}
	}
}


module.exports = {
	HTTPError,
	error,
	result,
	promisify,
	mwrap,
	av,
	s2bool,
	add_cors_response_headers,
	dump_request,
	require_client,
	require_admin,
	require_body,
}

// vim: set ts=4 sw=4 noet list: