/*!
 * express
 * Copyright(c) 2009-2013 TJ Holowaychuk
 * Copyright(c) 2014-2015 Douglas Christopher Wilson
 * MIT Licensed
 */

'use strict';

/**
 * Module dependencies.
 * @private
 */

import contentDisposition from 'content-disposition';
import escapeHtml from 'escape-html';
import http from 'http';
import onFinished from 'on-finished';
import path from 'path';
import merge from 'utils-merge';
import {sign} from 'cookie-signature';
import {isAbsolute} from './utils';
import {normalizeType} from './utils';
import {normalizeTypes} from './utils';
import {setCharset} from './utils';
import cookie from 'cookie';
import send from 'send';
import vary from 'vary';

const resolve = path.resolve;
const mime = send.mime;
const extname = path.extname;
const statusCodes = http.STATUS_CODES;
const charsetRegExp = /;\s*charset\s*=/;

/**
 * Response class
 */
class Response extends http.ServerResponse{
    constructor() {
        super({});
    }

    /**
     * Set status `code`.
     *
     * @param {Number} code
     * @return {ServerResponse}
     * @public
     */
    status(code) {
      this.statusCode = code;
      return this;
    }

    /**
     * Set Link header field with the given `links`.
     *
     * Examples:
     *
     *    res.links({
     *      next: 'http://api.example.com/users?page=2',
     *      last: 'http://api.example.com/users?page=5'
     *    });
     *
     * @param {Object} links
     * @return {ServerResponse}
     * @public
     */
    links(links){
      let link = this.get('Link') || '';
      if (link) {
          link += ', ';
      }
      let additional = Object.keys(links).map((rel)=> '<' + links[rel] + '>; rel="' + rel + '"').join(', ');
      return this.set('Link', link + additional);
    }

    /**
     * Send a response.
     *
     * Examples:
     *
     *     res.send(new Buffer('wahoo'));
     *     res.send({ some: 'json' });
     *     res.send('<p>some html</p>');
     *
     * @param {string|number|boolean|object|Buffer} body
     * @public
     */
    send(body) {
      let chunk = body;
      let encoding;
      let len;
      let type;

      // settings
      let req = this.req;
      let app = this.app;

      // disambiguate res.send(status) and res.send(status, num)
      if (typeof chunk === 'number') {
        // res.send(status) will set status message as text string
        if (!this.get('Content-Type')) {
          this.type('txt');
        }

        this.statusCode = chunk;
        chunk = statusCodes[chunk];
      }

      switch (typeof chunk) {
        // string defaulting to html
        case 'string':
          if (!this.get('Content-Type')) {
            this.type('html');
          }
          break;
        case 'boolean':
        case 'object':
          if (chunk === null) {
            chunk = '';
          } else if (Buffer.isBuffer(chunk)) {
            if (!this.get('Content-Type')) {
              this.type('bin');
            }
          } else {
            return this.json(chunk);
          }
          break;
      }

      // write strings in utf-8
      if (typeof chunk === 'string') {
        encoding = 'utf8';
        type = this.get('Content-Type');

        // reflect this in content-type
        if (typeof type === 'string') {
          this.set('Content-Type', setCharset(type, 'utf-8'));
        }
      }

      // populate Content-Length
      if (chunk !== undefined) {
        if (!Buffer.isBuffer(chunk)) {
          // convert chunk to Buffer; saves later double conversions
          chunk = new Buffer(chunk, encoding);
          encoding = undefined;
        }

        len = chunk.length;
        this.set('Content-Length', len);
      }

      // populate ETag
      let etag;
      let generateETag = len !== undefined && app.get('etag fn');
      if (typeof generateETag === 'function' && !this.get('ETag')) {
        if ((etag = generateETag(chunk, encoding))) {
          this.set('ETag', etag);
        }
      }

      // freshness
      if (req.fresh) this.statusCode = 304;

      // strip irrelevant headers
      if (204 == this.statusCode || 304 == this.statusCode) {
        this.removeHeader('Content-Type');
        this.removeHeader('Content-Length');
        this.removeHeader('Transfer-Encoding');
        chunk = '';
      }

      if (req.method === 'HEAD') {
        // skip body for HEAD
        this.end();
      } else {
        // respond
        this.end(chunk, encoding);
      }
      return this;
    }

    /**
     * Send JSON response.
     *
     * Examples:
     *
     *     res.json(null);
     *     res.json({ user: 'tj' });
     *
     * @param {string|number|boolean|object} obj
     * @public
     */
    json(obj) {
      let val = obj;

      // settings
      let app = this.app;
      let replacer = app.get('json replacer');
      let spaces = app.get('json spaces');
      let body = JSON.stringify(val, replacer, spaces);

      // content-type
      if (!this.get('Content-Type')) {
        this.set('Content-Type', 'application/json');
      }

      return this.send(body);
    }

    /**
     * Send JSON response with JSONP callback support.
     *
     * Examples:
     *
     *     res.jsonp(null);
     *     res.jsonp({ user: 'tj' });
     *
     * @param {string|number|boolean|object} obj
     * @public
     */
    jsonp(obj) {
      let val = obj;

      // settings
      let app = this.app;
      let replacer = app.get('json replacer');
      let spaces = app.get('json spaces');
      let body = JSON.stringify(val, replacer, spaces);
      let callback = this.req.query[app.get('jsonp callback name')];

      // content-type
      if (!this.get('Content-Type')) {
        this.set('X-Content-Type-Options', 'nosniff');
        this.set('Content-Type', 'application/json');
      }

      // fixup callback
      if (Array.isArray(callback)) {
        callback = callback[0];
      }

      // jsonp
      if (typeof callback === 'string' && callback.length !== 0) {
        this.charset = 'utf-8';
        this.set('X-Content-Type-Options', 'nosniff');
        this.set('Content-Type', 'text/javascript');

        // restrict callback charset
        callback = callback.replace(/[^\[\]\w$.]/g, '');

        // replace chars not allowed in JavaScript that are in JSON
        body = body
          .replace(/\u2028/g, '\\u2028')
          .replace(/\u2029/g, '\\u2029');

        // the /**/ is a specific security mitigation for "Rosetta Flash JSONP abuse"
        // the typeof check is just to reduce client error noise
        body = '/**/ typeof ' + callback + ' === \'function\' && ' + callback + '(' + body + ');';
      }

      return this.send(body);
    }

    /**
     * Send given HTTP status code.
     *
     * Sets the response status to `statusCode` and the body of the
     * response to the standard description from node's http.STATUS_CODES
     * or the statusCode number if no description.
     *
     * Examples:
     *
     *     res.sendStatus(200);
     *
     * @param {number} statusCode
     * @public
     */

    sendStatus(statusCode) {
      let body = statusCodes[statusCode] || String(statusCode);

      this.statusCode = statusCode;
      this.type('txt');

      return this.send(body);
    }

    /**
     * Transfer the file at the given `path`.
     *
     * Automatically sets the _Content-Type_ response header field.
     * The callback `callback(err)` is invoked when the transfer is complete
     * or when an error occurs. Be sure to check `res.sentHeader`
     * if you wish to attempt responding, as the header and some data
     * may have already been transferred.
     *
     * Options:
     *
     *   - `maxAge`   defaulting to 0 (can be string converted by `ms`)
     *   - `root`     root directory for relative filenames
     *   - `headers`  object of headers to serve with file
     *   - `dotfiles` serve dotfiles, defaulting to false; can be `"allow"` to send them
     *
     * Other options are passed along to `send`.
     *
     * Examples:
     *
     *  The following example illustrates how `res.sendFile()` may
     *  be used as an alternative for the `static()` middleware for
     *  dynamic situations. The code backing `res.sendFile()` is actually
     *  the same code, so HTTP cache support etc is identical.
     *
     *     app.get('/user/:uid/photos/:file', function(req, res){
     *       let uid = req.params.uid
     *         , file = req.params.file;
     *
     *       req.user.mayViewFilesFrom(uid, function(yes){
     *         if (yes) {
     *           res.sendFile('/uploads/' + uid + '/' + file);
     *         } else {
     *           res.send(403, 'Sorry! you cant see that.');
     *         }
     *       });
     *     });
     *
     * @public
     */
    sendFile(path, options, callback) {
      let done = callback;
      let req = this.req;
      let res = this;
      let next = req.next;
      let opts = options || {};

      if (!path) {
        throw new TypeError('path argument is required to res.sendFile');
      }

      // support function as second arg
      if (typeof options === 'function') {
        done = options;
        opts = {};
      }

      if (!opts.root && !isAbsolute(path)) {
        throw new TypeError('path must be absolute or specify root to res.sendFile');
      }

      // create file stream
      let pathname = encodeURI(path);
      let file = send(req, pathname, opts);

      // transfer
      sendfile(res, file, opts, function (err) {
        if (done) return done(err);
        if (err && err.code === 'EISDIR') return next();

        // next() all but write errors
        if (err && err.code !== 'ECONNABORTED' && err.syscall !== 'write') {
          next(err);
        }
      });
    }

    /**
     * Transfer the file at the given `path` as an attachment.
     *
     * Optionally providing an alternate attachment `filename`,
     * and optional callback `callback(err)`. The callback is invoked
     * when the data transfer is complete, or when an error has
     * ocurred. Be sure to check `res.headersSent` if you plan to respond.
     *
     * This method uses `res.sendfile()`.
     *
     * @public
     */
    download(path, filename, callback) {
      let done = callback;
      let name = filename;

      // support function as second arg
      if (typeof filename === 'function') {
        done = filename;
        name = null;
      }

      // set Content-Disposition when file is sent
      let headers = {
        'Content-Disposition': contentDisposition(name || path)
      };

      // Resolve the full path for sendFile
      let fullPath = resolve(path);

      return this.sendFile(fullPath, { headers: headers }, done);
    }

    /**
     * Set _Content-Type_ response header with `type` through `mime.lookup()`
     * when it does not contain "/", or set the Content-Type to `type` otherwise.
     *
     * Examples:
     *
     *     res.type('.html');
     *     res.type('html');
     *     res.type('json');
     *     res.type('application/json');
     *     res.type('png');
     *
     * @param {String} type
     * @return {ServerResponse} for chaining
     * @public
     */

    contentType(type) {
      let ct = type.indexOf('/') === -1
        ? mime.lookup(type)
        : type;

      return this.set('Content-Type', ct);
    }

    type(type){
        return this.contentType(type);
    }

    /**
     * Respond to the Acceptable formats using an `obj`
     * of mime-type callbacks.
     *
     * This method uses `req.accepted`, an array of
     * acceptable types ordered by their quality values.
     * When "Accept" is not present the _first_ callback
     * is invoked, otherwise the first match is used. When
     * no match is performed the server responds with
     * 406 "Not Acceptable".
     *
     * Content-Type is set for you, however if you choose
     * you may alter this within the callback using `res.type()`
     * or `res.set('Content-Type', ...)`.
     *
     *    res.format({
     *      'text/plain': function(){
     *        res.send('hey');
     *      },
     *
     *      'text/html': function(){
     *        res.send('<p>hey</p>');
     *      },
     *
     *      'appliation/json': function(){
     *        res.send({ message: 'hey' });
     *      }
     *    });
     *
     * In addition to canonicalized MIME types you may
     * also use extnames mapped to these types:
     *
     *    res.format({
     *      text: function(){
     *        res.send('hey');
     *      },
     *
     *      html: function(){
     *        res.send('<p>hey</p>');
     *      },
     *
     *      json: function(){
     *        res.send({ message: 'hey' });
     *      }
     *    });
     *
     * By default Express passes an `Error`
     * with a `.status` of 406 to `next(err)`
     * if a match is not made. If you provide
     * a `.default` callback it will be invoked
     * instead.
     *
     * @param {Object} obj
     * @return {ServerResponse} for chaining
     * @public
     */
    format(obj){
      let req = this.req;
      let next = req.next;

      let fn = obj.default;
      if (fn) delete obj.default;
      let keys = Object.keys(obj);

      let key = keys.length > 0
        ? req.accepts(keys)
        : false;

      this.vary("Accept");

      if (key) {
        this.set('Content-Type', normalizeType(key).value);
        obj[key](req, this, next);
      } else if (fn) {
        fn();
      } else {
        let err = new Error('Not Acceptable');
        err.status = err.statusCode = 406;
        err.types = normalizeTypes(keys).map(function(o){ return o.value });
        next(err);
      }

      return this;
    }

    /**
     * Set _Content-Disposition_ header to _attachment_ with optional `filename`.
     *
     * @param {String} filename
     * @return {ServerResponse}
     * @public
     */
    attachment(filename) {
      if (filename) {
        this.type(extname(filename));
      }

      this.set('Content-Disposition', contentDisposition(filename));

      return this;
    }

    /**
     * Append additional header `field` with value `val`.
     *
     * Example:
     *
     *    res.append('Link', ['<http://localhost/>', '<http://localhost:3000/>']);
     *    res.append('Set-Cookie', 'foo=bar; Path=/; HttpOnly');
     *    res.append('Warning', '199 Miscellaneous warning');
     *
     * @param {String} field
     * @param {String|Array} val
     * @return {ServerResponse} for chaining
     * @public
     */
    append(field, val) {
      let prev = this.get(field);
      let value = val;

      if (prev) {
        // concat the new and prev vals
        let _prev = Array.isArray(prev)?prev:[prev];
        let _val = Array.isArray(val)?val:[val];

        value = _prev.concat(_val);
      }

      return this.set(field, value);
    }

    /**
     * Set header `field` to `val`, or pass
     * an object of header fields.
     *
     * Examples:
     *
     *    res.set('Foo', ['bar', 'baz']);
     *    res.set('Accept', 'application/json');
     *    res.set({ Accept: 'text/plain', 'X-API-Key': 'tobi' });
     *
     * Aliased as `res.header()`.
     *
     * @param {String|Object} field
     * @param {String|Array} val
     * @return {ServerResponse} for chaining
     * @public
     */
    set(field, val) {
      if (arguments.length === 2) {
        let value = Array.isArray(val)
          ? val.map(String)
          : String(val);

        // add charset to content-type
        if (field.toLowerCase() === 'content-type' && !charsetRegExp.test(value)) {
          let charset = mime.charsets.lookup(value.split(';')[0]);
          if (charset) value += '; charset=' + charset.toLowerCase();
        }

        this.setHeader(field, value);
      } else {
        for (let key in field) {
          this.set(key, field[key]);
        }
      }
      return this;
    }
    header(field, val){
        return this.set(field, val);
    }

    /**
     * Get value for header `field`.
     *
     * @param {String} field
     * @return {String}
     * @public
     */
    get(field){
      return this.getHeader(field);
    }

    /**
     * Clear cookie `name`.
     *
     * @param {String} name
     * @param {Object} options
     * @return {ServerResponse} for chaining
     * @public
     */
    clearCookie(name, options) {
      let opts = merge({ expires: new Date(1), path: '/' }, options);

      return this.cookie(name, '', opts);
    }

    /**
     * Set cookie `name` to `value`, with the given `options`.
     *
     * Options:
     *
     *    - `maxAge`   max-age in milliseconds, converted to `expires`
     *    - `signed`   sign the cookie
     *    - `path`     defaults to "/"
     *
     * Examples:
     *
     *    // "Remember Me" for 15 minutes
     *    res.cookie('rememberme', '1', { expires: new Date(Date.now() + 900000), httpOnly: true });
     *
     *    // save as above
     *    res.cookie('rememberme', '1', { maxAge: 900000, httpOnly: true })
     *
     * @param {String} name
     * @param {String|Object} value
     * @param {Options} options
     * @return {ServerResponse} for chaining
     * @public
     */
    cookie(name, value, options) {
      let opts = merge({}, options);
      let secret = this.req.secret;
      let signed = opts.signed;

      if (signed && !secret) {
        throw new Error('cookieParser("secret") required for signed cookies');
      }

      let val = typeof value === 'object'
        ? 'j:' + JSON.stringify(value)
        : String(value);

      if (signed) {
        val = 's:' + sign(val, secret);
      }

      if ('maxAge' in opts) {
        opts.expires = new Date(Date.now() + opts.maxAge);
        opts.maxAge /= 1000;
      }

      if (opts.path == null) {
        opts.path = '/';
      }

      this.append('Set-Cookie', cookie.serialize(name, String(val), opts));

      return this;
    }

    /**
     * Set the location header to `url`.
     *
     * The given `url` can also be "back", which redirects
     * to the _Referrer_ or _Referer_ headers or "/".
     *
     * Examples:
     *
     *    res.location('/foo/bar').;
     *    res.location('http://example.com');
     *    res.location('../login');
     *
     * @param {String} url
     * @return {ServerResponse} for chaining
     * @public
     */
     location(url) {
      let loc = url;

      // "back" is an alias for the referrer
      if (url === 'back') {
        loc = this.req.get('Referrer') || '/';
      }

      // set location
      this.set('Location', loc);
      return this;
    }

    /**
     * Redirect to the given `url` with optional response `status`
     * defaulting to 302.
     *
     * The resulting `url` is determined by `res.location()`, so
     * it will play nicely with mounted apps, relative paths,
     * `"back"` etc.
     *
     * Examples:
     *
     *    res.redirect('/foo/bar');
     *    res.redirect('http://example.com');
     *    res.redirect(301, 'http://example.com');
     *    res.redirect('../login'); // /blog/post/1 -> /blog/login
     *
     * @public
     */
    redirect(url) {
      let address = url;
      let body;
      let status=302;

      // allow status / url
      if (arguments.length === 2) {
        if (typeof arguments[0] === 'number') {
          status = arguments[0];
          address = arguments[1];
        }
      }

      // Set location header
      this.location(address);
      address = this.get('Location');

      // Support text/{plain,html} by default
      this.format({
        text: function(){
          body = statusCodes[status] + '. Redirecting to ' + encodeURI(address);
        },

        html: function(){
          let u = escapeHtml(address);
          body = '<p>' + statusCodes[status] + '. Redirecting to <a href="' + u + '">' + u + '</a></p>';
        },

        default: function(){
          body = '';
        }
      });

      // Respond
      this.statusCode = status;
      this.set('Content-Length', Buffer.byteLength(body));

      if (this.req.method === 'HEAD') {
        this.end();
      } else {
        this.end(body);
      }
    }

    /**
     * Add `field` to Vary. If already present in the Vary set, then
     * this call is simply ignored.
     *
     * @param {Array|String} field
     * @return {ServerResponse} for chaining
     * @public
     */
    vary(field){
      vary(this, field);

      return this;
    }

    /**
     * Render `view` with the given `options` and optional callback `fn`.
     * When a callback function is given a response will _not_ be made
     * automatically, otherwise a response of _200_ and _text/html_ is given.
     *
     * Options:
     *
     *  - `cache`     boolean hinting to the engine it should cache
     *  - `filename`  filename of the view being rendered
     *
     * @public
     */
    render(view, options, callback) {
      let app = this.req.app;
      let done = callback;
      let opts = options || {};
      let req = this.req;
      let self = this;

      // support callback function as second arg
      if (typeof options === 'function') {
        done = options;
        opts = {};
      }

      // merge res.locals
      opts._locals = self.locals;

      // default callback to respond
      done = done || function (err, str) {
        if (err) return req.next(err);
        self.send(str);
      };

      // render
      app.render(view, opts, done);
    };
}


// pipe the send file stream
function sendfile(res, file, options, callback) {
  let done = false;
  let streaming;

  file.on('directory', ondirectory);
  file.on('end', onend);
  file.on('error', onerror);
  file.on('file', onfile);
  file.on('stream', onstream);
  onFinished(res, onfinish);

  if (options.headers) {
    // set headers on successful transfer
    file.on('headers', function headers(res) {
      let obj = options.headers;
      let keys = Object.keys(obj);

      for (let i = 0; i < keys.length; i++) {
        let k = keys[i];
        res.setHeader(k, obj[k]);
      }
    });
  }

  // pipe
  file.pipe(res);

  // request aborted
  function onaborted() {
    if (done) return;
    done = true;

    let err = new Error('Request aborted');
    err.code = 'ECONNABORTED';
    callback(err);
  }

  // directory
  function ondirectory() {
    if (done) return;
    done = true;

    let err = new Error('EISDIR, read');
    err.code = 'EISDIR';
    callback(err);
  }

  // errors
  function onerror(err) {
    if (done) return;
    done = true;
    callback(err);
  }

  // ended
  function onend() {
    if (done) return;
    done = true;
    callback();
  }

  // file
  function onfile() {
    streaming = false;
  }

  // finished
  function onfinish(err) {
    if (err && err.code === 'ECONNRESET') return onaborted();
    if (err) return onerror(err);
    if (done) return;

    setImmediate(function () {
      if (streaming !== false && !done) {
        onaborted();
        return;
      }

      if (done) return;
      done = true;
      callback();
    });
  }

  // streaming
  function onstream() {
    streaming = true;
  }
}


const res = new Response();
export default res;
