+
+/*!
+ * Connect - utils
+ * Copyright(c) 2010 Sencha Inc.
+ * Copyright(c) 2011 TJ Holowaychuk
+ * MIT Licensed
+ */
+
+/**
+ * Module dependencies.
+ */
+
+var crypto = require('crypto')
+ , Path = require('path')
+ , fs = require('fs');
+
+/**
+ * Flatten the given `arr`.
+ *
+ * @param {Array} arr
+ * @return {Array}
+ * @api private
+ */
+
+exports.flatten = function(arr, ret){
+ var ret = ret || []
+ , len = arr.length;
+ for (var i = 0; i < len; ++i) {
+ if (Array.isArray(arr[i])) {
+ exports.flatten(arr[i], ret);
+ } else {
+ ret.push(arr[i]);
+ }
+ }
+ return ret;
+};
+
+/**
+ * Return md5 hash of the given string and optional encoding,
+ * defaulting to hex.
+ *
+ * utils.md5('wahoo');
+ * // => "e493298061761236c96b02ea6aa8a2ad"
+ *
+ * @param {String} str
+ * @param {String} encoding
+ * @return {String}
+ * @api public
+ */
+
+exports.md5 = function(str, encoding){
+ return crypto
+ .createHash('md5')
+ .update(str)
+ .digest(encoding || 'hex');
+};
+
+/**
+ * Merge object b with object a.
+ *
+ * var a = { foo: 'bar' }
+ * , b = { bar: 'baz' };
+ *
+ * utils.merge(a, b);
+ * // => { foo: 'bar', bar: 'baz' }
+ *
+ * @param {Object} a
+ * @param {Object} b
+ * @return {Object}
+ * @api public
+ */
+
+exports.merge = function(a, b){
+ if (a && b) {
+ for (var key in b) {
+ a[key] = b[key];
+ }
+ }
+ return a;
+};
+
+/**
+ * Escape the given string of `html`.
+ *
+ * @param {String} html
+ * @return {String}
+ * @api public
+ */
+
+exports.escape = function(html){
+ return String(html)
+ .replace(/&(?!\w+;)/g, '&')
+ .replace(/</g, '<')
+ .replace(/>/g, '>')
+ .replace(/"/g, '"');
+};
+
+
+/**
+ * Return a unique identifier with the given `len`.
+ *
+ * utils.uid(10);
+ * // => "FDaS435D2z"
+ *
+ * @param {Number} len
+ * @return {String}
+ * @api public
+ */
+
+exports.uid = function(len) {
+ var buf = []
+ , chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
+ , charlen = chars.length;
+
+ for (var i = 0; i < len; ++i) {
+ buf.push(chars[getRandomInt(0, charlen - 1)]);
+ }
+
+ return buf.join('');
+};
+
+/**
+ * Parse the given cookie string into an object.
+ *
+ * @param {String} str
+ * @return {Object}
+ * @api public
+ */
+
+exports.parseCookie = function(str){
+ var obj = {}
+ , pairs = str.split(/[;,] */);
+ for (var i = 0, len = pairs.length; i < len; ++i) {
+ var pair = pairs[i]
+ , eqlIndex = pair.indexOf('=')
+ , key = pair.substr(0, eqlIndex).trim().toLowerCase()
+ , val = pair.substr(++eqlIndex, pair.length).trim();
+
+ // Quoted values
+ if (val[0] === '"') {
+ val = val.slice(1, -1);
+ }
+
+ // Only assign once
+ if (obj[key] === undefined) {
+ obj[key] = decodeURIComponent(val.replace(/\+/g, ' '));
+ }
+ }
+ return obj;
+};
+
+/**
+ * Serialize the given object into a cookie string.
+ *
+ * utils.serializeCookie('name', 'tj', { httpOnly: true })
+ * // => "name=tj; httpOnly"
+ *
+ * @param {String} name
+ * @param {String} val
+ * @param {Object} obj
+ * @return {String}
+ * @api public
+ */
+
+exports.serializeCookie = function(name, val, obj){
+ var pairs = [name + '=' + encodeURIComponent(val)]
+ , obj = obj || {};
+
+ if (obj.domain) pairs.push('domain=' + obj.domain);
+ if (obj.path) pairs.push('path=' + obj.path);
+ if (obj.expires) pairs.push('expires=' + obj.expires.toUTCString());
+ if (obj.httpOnly) pairs.push('httpOnly');
+ if (obj.secure) pairs.push('secure');
+
+ return pairs.join('; ');
+};
+
+/**
+ * Pause `data` and `end` events on the given `obj`.
+ * Middleware performing async tasks _should_ utilize
+ * this utility (or similar), to re-emit data once
+ * the async operation has completed, otherwise these
+ * events may be lost.
+ *
+ * var pause = utils.pause(req);
+ * fs.readFile(path, function(){
+ * next();
+ * pause.resume();
+ * });
+ *
+ * @param {Object} obj
+ * @return {Object}
+ * @api public
+ */
+
+exports.pause = function(obj){
+ var onData
+ , onEnd
+ , events = [];
+
+ // buffer data
+ obj.on('data', onData = function(data, encoding){
+ events.push(['data', data, encoding]);
+ });
+
+ // buffer end
+ obj.on('end', onEnd = function(data, encoding){
+ events.push(['end', data, encoding]);
+ });
+
+ return {
+ end: function(){
+ obj.removeListener('data', onData);
+ obj.removeListener('end', onEnd);
+ },
+ resume: function(){
+ this.end();
+ for (var i = 0, len = events.length; i < len; ++i) {
+ obj.emit.apply(obj, events[i]);
+ }
+ }
+ };
+};
+
+/**
+ * Check `req` and `res` to see if it has been modified.
+ *
+ * @param {IncomingMessage} req
+ * @param {ServerResponse} res
+ * @return {Boolean}
+ * @api public
+ */
+
+exports.modified = function(req, res, headers) {
+ var headers = headers || res._headers || {}
+ , modifiedSince = req.headers['if-modified-since']
+ , lastModified = headers['last-modified']
+ , noneMatch = req.headers['if-none-match']
+ , etag = headers['etag'];
+
+ if (noneMatch) noneMatch = noneMatch.split(/ *, */);
+
+ // check If-None-Match
+ if (noneMatch && etag && ~noneMatch.indexOf(etag)) {
+ return false;
+ }
+
+ // check If-Modified-Since
+ if (modifiedSince && lastModified) {
+ modifiedSince = new Date(modifiedSince);
+ lastModified = new Date(lastModified);
+ // Ignore invalid dates
+ if (!isNaN(modifiedSince.getTime())) {
+ if (lastModified <= modifiedSince) return false;
+ }
+ }
+
+ return true;
+};
+
+/**
+ * Strip `Content-*` headers from `res`.
+ *
+ * @param {ServerResponse} res
+ * @api public
+ */
+
+exports.removeContentHeaders = function(res){
+ Object.keys(res._headers).forEach(function(field){
+ if (0 == field.indexOf('content')) {
+ res.removeHeader(field);
+ }
+ });
+};
+
+/**
+ * Check if `req` is a conditional GET request.
+ *
+ * @param {IncomingMessage} req
+ * @return {Boolean}
+ * @api public
+ */
+
+exports.conditionalGET = function(req) {
+ return req.headers['if-modified-since']
+ || req.headers['if-none-match'];
+};
+
+/**
+ * Respond with 412 "Unauthorized".
+ *
+ * @param {ServerResponse} res
+ * @param {String} realm
+ * @api public
+ */
+
+exports.unauthorized = function(res, realm) {
+ res.statusCode = 401;
+ res.setHeader('WWW-Authenticate', 'Basic realm="' + realm + '"');
+ res.end('Unauthorized');
+};
+
+/**
+ * Respond with 400 "Bad Request".
+ *
+ * @param {ServerResponse} res
+ * @api public
+ */
+
+exports.badRequest = function(res) {
+ res.statusCode = 400;
+ res.end('Bad Request');
+};
+
+/**
+ * Respond with 304 "Not Modified".
+ *
+ * @param {ServerResponse} res
+ * @param {Object} headers
+ * @api public
+ */
+
+exports.notModified = function(res) {
+ exports.removeContentHeaders(res);
+ res.statusCode = 304;
+ res.end();
+};
+
+/**
+ * Return an ETag in the form of `"<size>-<mtime>"`
+ * from the given `stat`.
+ *
+ * @param {Object} stat
+ * @return {String}
+ * @api public
+ */
+
+exports.etag = function(stat) {
+ return '"' + stat.size + '-' + Number(stat.mtime) + '"';
+};
+
+/**
+ * Parse "Range" header `str` relative to the given file `size`.
+ *
+ * @param {Number} size
+ * @param {String} str
+ * @return {Array}
+ * @api public
+ */
+
+exports.parseRange = function(size, str){
+ var valid = true;
+ var arr = str.substr(6).split(',').map(function(range){
+ var range = range.split('-')
+ , start = parseInt(range[0], 10)
+ , end = parseInt(range[1], 10);
+
+ // -500
+ if (isNaN(start)) {
+ start = size - end;
+ end = size - 1;
+ // 500-
+ } else if (isNaN(end)) {
+ end = size - 1;
+ }
+
+ // Invalid
+ if (isNaN(start) || isNaN(end) || start > end) valid = false;
+
+ return { start: start, end: end };
+ });
+ return valid ? arr : undefined;
+};
+
+/**
+ * Convert array-like object to an `Array`.
+ *
+ * node-bench measured "16.5 times faster than Array.prototype.slice.call()"
+ *
+ * @param {Object} obj
+ * @return {Array}
+ * @api public
+ */
+
+var toArray = exports.toArray = function(obj){
+ var len = obj.length
+ , arr = new Array(len);
+ for (var i = 0; i < len; ++i) {
+ arr[i] = obj[i];
+ }
+ return arr;
+};
+
+/**
+ * Retrun a random int, used by `utils.uid()`
+ *
+ * @param {Number} min
+ * @param {Number} max
+ * @return {Number}
+ * @api private
+ */
+
+function getRandomInt(min, max) {
+ return Math.floor(Math.random() * (max - min + 1)) + min;
+}