index.js

/*
 * http-rewrite-middleware
 * https://github.com/viart/http-rewrite-middleware
 *
 * Copyright (c) 2013 Artem Vitiuk
 * Licensed under the MIT license.
 */
'use strict';

function Rewriter( rules, options ) {
  options = options || {};

  var nop = function() {
  };
  if( options.silent ) {
    this.log = {
      ok     : nop,
      error  : nop,
      verbose: nop
    };
  } else {
    this.log = {
      ok     : console.log,
      error  : console.error,
      verbose: options.verbose ? console.log : nop
    };
  }

  this.rules = [];
  (rules || []).forEach( this.registerRule, this );
}

Rewriter.prototype = {
  registerRule: function( rule ) {
    var type = 'rewrite';

    rule = rule || {};

    if( this.isRuleValid( rule ) ) {
      if( rule.redirect ) {
        rule.redirect = rule.redirect === 'permanent' ? 301 : 302;
        type = 'redirect ' + rule.redirect;
      }

      this.rules.push( {
        from    : new RegExp( rule.from ),
        to      : rule.to,
        redirect: rule.redirect,
        delay   : rule.delay || 0
      } );

      this.log.ok( 'Rewrite rule created for: [' + type.toUpperCase() + ': ' + rule.from + ' -> ' + rule.to + '].' );
      return true;
    } else {
      this.log.error( 'Wrong rule given.' );
      return false;
    }
  },

  isRuleValid: function( rule ) {
    return rule.from && rule.to && typeof rule.from === 'string' && typeof rule.to === 'string';
  },

  resetRules: function() {
    this.rules = [];
  },

  getRules: function() {
    return this.rules;
  },

  dispatcher: function( req, res, next ) {
    var logger = this.log.verbose;
    return function( rule ) {
      var toUrl, delay;
      if( rule.from.test( req.url ) ) {
        toUrl = req.url.replace( rule.from, rule.to );
        delay = rule.delay ? rule.delay instanceof Function ? rule.delay( req ) : rule.delay : 0;
        if( !rule.redirect ) {
          req.url = toUrl;
          if( delay ) {
            setTimeout( function() {
              next();
            }, delay );
          } else {
            next();
          }
        } else {
          res.statusCode = rule.redirect;
          res.setHeader( 'Location', toUrl );
          if( delay ) {
            setTimeout( function() {
              res.end();
            }, delay );
          } else {
            res.end();
          }
        }
        logger(
          (rule.redirect ? 'redirect ' + rule.redirect : 'rewrite').toUpperCase() + ' > ' +
          req.url + ' : ' + rule.from + ' -> ' + toUrl + ( rule.delay ? ', delayed : ' + rule.delay + 'ms' : '' )
        );
        return true;
      }
    };
  },

  getMiddleware: function() {
    return function( req, res, next ) {
      if( !this.rules.length || !this.rules.some( this.dispatcher( req, res, next ) ) ) {
        next();
      }
    }.bind( this );
  }
};

module.exports.getMiddleware = function( rules, options ) {
  return (new Rewriter( rules, options )).getMiddleware();
};

module.exports.Rewriter = Rewriter;