/**
 * Module dependencies.
 */

var accepts = require('accepts');
var deprecate = require('depd')('express');
var typeis = require('type-is');
var http = require('http');
var fresh = require('fresh');
var parseRange = require('range-parser');
var parse = require('parseurl');
var proxyaddr = require('proxy-addr');

/**
 * Request prototype.
 */

var req = exports = module.exports = {
  __proto__: http.IncomingMessage.prototype
};

/**
 * Return request header.
 *
 * The `Referrer` header field is special-cased,
 * both `Referrer` and `Referer` are interchangeable.
 *
 * Examples:
 *
 *     req.get('Content-Type');
 *     // => "text/plain"
 *
 *     req.get('content-type');
 *     // => "text/plain"
 *
 *     req.get('Something');
 *     // => undefined
 *
 * Aliased as `req.header()`.
 *
 * @param {String} name
 * @return {String}
 * @api public
 */

req.get =
req.header = function(name){
  switch (name = name.toLowerCase()) {
    case 'referer':
    case 'referrer':
      return this.headers.referrer
        || this.headers.referer;
    default:
      return this.headers[name];
  }
};

/**
 * To do: update docs.
 *
 * Check if the given `type(s)` is acceptable, returning
 * the best match when true, otherwise `undefined`, in which
 * case you should respond with 406 "Not Acceptable".
 *
 * The `type` value may be a single mime type string
 * such as "application/json", the extension name
 * such as "json", a comma-delimted list such as "json, html, text/plain",
 * an argument list such as `"json", "html", "text/plain"`,
 * or an array `["json", "html", "text/plain"]`. When a list
 * or array is given the _best_ match, if any is returned.
 *
 * Examples:
 *
 *     // Accept: text/html
 *     req.accepts('html');
 *     // => "html"
 *
 *     // Accept: text/*, application/json
 *     req.accepts('html');
 *     // => "html"
 *     req.accepts('text/html');
 *     // => "text/html"
 *     req.accepts('json, text');
 *     // => "json"
 *     req.accepts('application/json');
 *     // => "application/json"
 *
 *     // Accept: text/*, application/json
 *     req.accepts('image/png');
 *     req.accepts('png');
 *     // => undefined
 *
 *     // Accept: text/*;q=.5, application/json
 *     req.accepts(['html', 'json']);
 *     req.accepts('html', 'json');
 *     req.accepts('html, json');
 *     // => "json"
 *
 * @param {String|Array} type(s)
 * @return {String}
 * @api public
 */

req.accepts = function(){
  var accept = accepts(this);
  return accept.types.apply(accept, arguments);
};

/**
 * Check if the given `encoding`s are accepted.
 *
 * @param {String} ...encoding
 * @return {Boolean}
 * @api public
 */

req.acceptsEncodings = function(){
  var accept = accepts(this);
  return accept.encodings.apply(accept, arguments);
};

req.acceptsEncoding = deprecate.function(req.acceptsEncodings,
  'req.acceptsEncoding: Use acceptsEncodings instead');

/**
 * Check if the given `charset`s are acceptable,
 * otherwise you should respond with 406 "Not Acceptable".
 *
 * @param {String} ...charset
 * @return {Boolean}
 * @api public
 */

req.acceptsCharsets = function(){
  var accept = accepts(this);
  return accept.charsets.apply(accept, arguments);
};

req.acceptsCharset = deprecate.function(req.acceptsCharsets,
  'req.acceptsCharset: Use acceptsCharsets instead');

/**
 * Check if the given `lang`s are acceptable,
 * otherwise you should respond with 406 "Not Acceptable".
 *
 * @param {String} ...lang
 * @return {Boolean}
 * @api public
 */

req.acceptsLanguages = function(){
  var accept = accepts(this);
  return accept.languages.apply(accept, arguments);
};

req.acceptsLanguage = deprecate.function(req.acceptsLanguages,
  'req.acceptsLanguage: Use acceptsLanguages instead');

/**
 * Parse Range header field,
 * capping to the given `size`.
 *
 * Unspecified ranges such as "0-" require
 * knowledge of your resource length. In
 * the case of a byte range this is of course
 * the total number of bytes. If the Range
 * header field is not given `null` is returned,
 * `-1` when unsatisfiable, `-2` when syntactically invalid.
 *
 * NOTE: remember that ranges are inclusive, so
 * for example "Range: users=0-3" should respond
 * with 4 users when available, not 3.
 *
 * @param {Number} size
 * @return {Array}
 * @api public
 */

req.range = function(size){
  var range = this.get('Range');
  if (!range) return;
  return parseRange(size, range);
};

/**
 * Return the value of param `name` when present or `defaultValue`.
 *
 *  - Checks route placeholders, ex: _/user/:id_
 *  - Checks body params, ex: id=12, {"id":12}
 *  - Checks query string params, ex: ?id=12
 *
 * To utilize request bodies, `req.body`
 * should be an object. This can be done by using
 * the `bodyParser()` middleware.
 *
 * @param {String} name
 * @param {Mixed} [defaultValue]
 * @return {String}
 * @api public
 */

req.param = function(name, defaultValue){
  var params = this.params || {};
  var body = this.body || {};
  var query = this.query || {};
  if (null != params[name] && params.hasOwnProperty(name)) return params[name];
  if (null != body[name]) return body[name];
  if (null != query[name]) return query[name];
  return defaultValue;
};

/**
 * Check if the incoming request contains the "Content-Type"
 * header field, and it contains the give mime `type`.
 *
 * Examples:
 *
 *      // With Content-Type: text/html; charset=utf-8
 *      req.is('html');
 *      req.is('text/html');
 *      req.is('text/*');
 *      // => true
 *
 *      // When Content-Type is application/json
 *      req.is('json');
 *      req.is('application/json');
 *      req.is('application/*');
 *      // => true
 *
 *      req.is('html');
 *      // => false
 *
 * @param {String} type
 * @return {Boolean}
 * @api public
 */

req.is = function(types){
  if (!Array.isArray(types)) types = [].slice.call(arguments);
  return typeis(this, types);
};

/**
 * Return the protocol string "http" or "https"
 * when requested with TLS. When the "trust proxy"
 * setting trusts the socket address, the
 * "X-Forwarded-Proto" header field will be trusted
 * and used if present.
 *
 * If you're running behind a reverse proxy that
 * supplies https for you this may be enabled.
 *
 * @return {String}
 * @api public
 */

defineGetter(req, 'protocol', function protocol(){
  var proto = this.connection.encrypted
    ? 'https'
    : 'http';
  var trust = this.app.get('trust proxy fn');

  if (!trust(this.connection.remoteAddress)) {
    return proto;
  }

  // Note: X-Forwarded-Proto is normally only ever a
  //       single value, but this is to be safe.
  proto = this.get('X-Forwarded-Proto') || proto;
  return proto.split(/\s*,\s*/)[0];
});

/**
 * Short-hand for:
 *
 *    req.protocol == 'https'
 *
 * @return {Boolean}
 * @api public
 */

defineGetter(req, 'secure', function secure(){
  return 'https' == this.protocol;
});

/**
 * Return the remote address from the trusted proxy.
 *
 * The is the remote address on the socket unless
 * "trust proxy" is set.
 *
 * @return {String}
 * @api public
 */

defineGetter(req, 'ip', function ip(){
  var trust = this.app.get('trust proxy fn');
  return proxyaddr(this, trust);
});

/**
 * When "trust proxy" is set, trusted proxy addresses + client.
 *
 * For example if the value were "client, proxy1, proxy2"
 * you would receive the array `["client", "proxy1", "proxy2"]`
 * where "proxy2" is the furthest down-stream and "proxy1" and
 * "proxy2" were trusted.
 *
 * @return {Array}
 * @api public
 */

defineGetter(req, 'ips', function ips() {
  var trust = this.app.get('trust proxy fn');
  var addrs = proxyaddr.all(this, trust);
  return addrs.slice(1).reverse();
});

/**
 * Return subdomains as an array.
 *
 * Subdomains are the dot-separated parts of the host before the main domain of
 * the app. By default, the domain of the app is assumed to be the last two
 * parts of the host. This can be changed by setting "subdomain offset".
 *
 * For example, if the domain is "tobi.ferrets.example.com":
 * If "subdomain offset" is not set, req.subdomains is `["ferrets", "tobi"]`.
 * If "subdomain offset" is 3, req.subdomains is `["tobi"]`.
 *
 * @return {Array}
 * @api public
 */

defineGetter(req, 'subdomains', function subdomains() {
  var offset = this.app.get('subdomain offset');
  return (this.hostname || '')
    .split('.')
    .reverse()
    .slice(offset);
});

/**
 * Short-hand for `url.parse(req.url).pathname`.
 *
 * @return {String}
 * @api public
 */

defineGetter(req, 'path', function path() {
  return parse(this).pathname;
});

/**
 * Parse the "Host" header field to a hostname.
 *
 * When the "trust proxy" setting trusts the socket
 * address, the "X-Forwarded-Host" header field will
 * be trusted.
 *
 * @return {String}
 * @api public
 */

defineGetter(req, 'hostname', function hostname(){
  var trust = this.app.get('trust proxy fn');
  var host = this.get('X-Forwarded-Host');

  if (!host || !trust(this.connection.remoteAddress)) {
    host = this.get('Host');
  }

  if (!host) return;

  // IPv6 literal support
  var offset = host[0] === '['
    ? host.indexOf(']') + 1
    : 0;
  var index = host.indexOf(':', offset);

  return ~index
    ? host.substring(0, index)
    : host;
});

// TODO: change req.host to return host in next major

defineGetter(req, 'host', deprecate.function(function host(){
  return this.hostname;
}, 'req.host: Use req.hostname instead'));

/**
 * Check if the request is fresh, aka
 * Last-Modified and/or the ETag
 * still match.
 *
 * @return {Boolean}
 * @api public
 */

defineGetter(req, 'fresh', function(){
  var method = this.method;
  var s = this.res.statusCode;

  // GET or HEAD for weak freshness validation only
  if ('GET' != method && 'HEAD' != method) return false;

  // 2xx or 304 as per rfc2616 14.26
  if ((s >= 200 && s < 300) || 304 == s) {
    return fresh(this.headers, this.res._headers);
  }

  return false;
});

/**
 * Check if the request is stale, aka
 * "Last-Modified" and / or the "ETag" for the
 * resource has changed.
 *
 * @return {Boolean}
 * @api public
 */

defineGetter(req, 'stale', function stale(){
  return !this.fresh;
});

/**
 * Check if the request was an _XMLHttpRequest_.
 *
 * @return {Boolean}
 * @api public
 */

defineGetter(req, 'xhr', function xhr(){
  var val = this.get('X-Requested-With') || '';
  return 'xmlhttprequest' == val.toLowerCase();
});

/**
 * Helper function for creating a getter on an object.
 *
 * @param {Object} obj
 * @param {String} name
 * @param {Function} getter
 * @api private
 */
function defineGetter(obj, name, getter) {
  Object.defineProperty(obj, name, {
    configurable: true,
    enumerable: true,
    get: getter
  });
};
