generators.js

/* jshint node: true */
'use strict';

var debug = require('cog/logger')('generators');
var detect = require('./detect');
var defaults = require('cog/defaults');

var mappings = {
  create: {
    dtls: function(c) {
      if (! detect.moz) {
        c.optional = (c.optional || []).concat({ DtlsSrtpKeyAgreement: true });
      }
    }
  }
};

/**
  ### rtc-tools/generators

  The generators package provides some utility methods for generating
  constraint objects and similar constructs.

  ```js
  var generators = require('rtc/generators');
  ```

**/

/**
  #### generators.config(config)

  Generate a configuration object suitable for passing into an W3C
  RTCPeerConnection constructor first argument, based on our custom config.

  In the event that you use short term authentication for TURN, and you want
  to generate new `iceServers` regularly, you can specify an iceServerGenerator
  that will be used prior to coupling. This generator should return a fully
  compliant W3C (RTCIceServer dictionary)[http://www.w3.org/TR/webrtc/#idl-def-RTCIceServer].

  If you pass in both a generator and iceServers, the iceServers _will be
  ignored and the generator used instead.
**/

exports.config = function(config) {
  var iceServerGenerator = (config || {}).iceServerGenerator;

  return defaults({}, config, {
    iceServers: typeof iceServerGenerator == 'function' ? iceServerGenerator() : []
  });
};

/**
  #### generators.connectionConstraints(flags, constraints)

  This is a helper function that will generate appropriate connection
  constraints for a new `RTCPeerConnection` object which is constructed
  in the following way:

  ```js
  var conn = new RTCPeerConnection(flags, constraints);
  ```

  In most cases the constraints object can be left empty, but when creating
  data channels some additional options are required.  This function
  can generate those additional options and intelligently combine any
  user defined constraints (in `constraints`) with shorthand flags that
  might be passed while using the `rtc.createConnection` helper.
**/
exports.connectionConstraints = function(flags, constraints) {
  var generated = {};
  var m = mappings.create;
  var out;

  // iterate through the flags and apply the create mappings
  Object.keys(flags || {}).forEach(function(key) {
    if (m[key]) {
      m[key](generated);
    }
  });

  // generate the connection constraints
  out = defaults({}, constraints, generated);
  debug('generated connection constraints: ', out);

  return out;
};