var crypto = require('crypto');
var utils = require('./utils');
var UError = require('./error').UserError;
var Logger = require('./logger');

module.exports.validate_name = function validate_name(req, res, next, value, name) {
	if (utils.validate_name(req.params.package)) {
		req.params.package = String(req.params.package);
		next();
	} else {
		next(new UError({
			status: 403,
			msg: 'invalid package name',
		}));
	}
};

module.exports.media = function media(expect) {
	return function(req, res, next) {
		if (req.headers['content-type'] !== expect) {
			next(new UError({
				status: 415,
				msg: 'wrong content-type, expect: '+expect+', got: '+req.headers['content-type'],
			}));
		} else {
			next();
		}
	}
}

module.exports.expect_json = function expect_json(req, res, next) {
	if (!utils.is_object(req.body)) {
		return next({
			status: 400,
			msg: 'can\'t parse incoming json',
		});
	}
	next();
}

module.exports.basic_auth = function basic_auth(callback) {
	return function(req, res, next) {
		var authorization = req.headers.authorization;

		if (req.user) return next();
		if (authorization == null) {
			req.user = req.remoteUser = undefined;
			return next();
		}

		var parts = authorization.split(' ');

		if (parts.length !== 2) return next({
			status: 400,
			msg: 'bad authorization header',
		});

		var scheme = parts[0]
		, credentials = new Buffer(parts[1], 'base64').toString()
		, index = credentials.indexOf(':');

		if ('Basic' != scheme || index < 0) return next({
			status: 400,
			msg: 'bad authorization header',
		});
    
		var user = credentials.slice(0, index)
		, pass = credentials.slice(index + 1);

		if (callback(user, pass)) {
			req.user = req.remoteUser = user;
			next();
		} else {
			next({
				status: 403,
				msg: 'bad username/password, access denied',
			});
		}
	}
};

// express doesn't do etags with requests <= 1024b
// we use md5 here, it works well on 1k+ bytes, but sucks with fewer data
// could improve performance using crc32 after benchmarks
function md5sum(data) {
	return crypto.createHash('md5').update(data).digest('hex');
}

module.exports.log_and_etagify = function(req, res, next) {
	// logger
	req.log = Logger.logger.child({sub: 'in'});

	var _auth = req.headers.authorization
	if (_auth) req.headers.authorization = '<Classified>'
	req.log.info({req: req, ip: req.ip}, '@{ip} requested \'@{req.method} @{req.url}\'')
	if (_auth) req.headers.authorization = _auth

	var bytesin = 0;
	req.on('data', function(chunk){ bytesin += chunk.length });

	var _send = res.send;
	res.send = function(body) {
		if (typeof(body) === 'string' || typeof(body) === 'object') {
			res.header('Content-type', 'application/json');

			if (typeof(body) === 'object' && body != null) {
				if (body.error) {
					res._sinopia_error = body.error;
				}
				body = JSON.stringify(body, undefined, '\t');
			}
			
			res.header('ETag', '"' + md5sum(body) + '"');
		} else {
			// send(null), send(204), etc.
		}

		res.send = _send;
		res.send(body);
	}

	var bytesout = 0
	var _write = res.write
	res.write = function(buf) {
		bytesout += buf.length
		_write.apply(res, arguments)
	}

	var _end = res.end;
	res.end = function(buf) {
		if (buf) bytesout += buf.length
		_end.apply(res, arguments)

		var msg = '@{status}, user: @{user}, req: \'@{request.method} @{request.url}\'';
		if (res._sinopia_error) {
			msg += ', error: @{!error}';
		} else {
			msg += ', bytes: @{bytes.in}/@{bytes.out}';
		}
		req.log.warn({
			request: {method: req.method, url: req.url},
			level: 35, // http
			user: req.user,
			status: res.statusCode,
			error: res._sinopia_error,
			bytes: {
				in: bytesin,
				out: bytesout,
			}
		}, msg);
	};
	next();
}