var shimConstraints_ = function()

in release/connect-rtc.js [6762:6826]
50 lines of code
24 McCabe index (conditional complexity)

  var shimConstraints_ = function(constraints, func) {
    if (browserDetails.version >= 61) {
      return func(constraints);
    }
    constraints = JSON.parse(JSON.stringify(constraints));
    if (constraints && typeof constraints.audio === 'object') {
      var remap = function(obj, a, b) {
        if (a in obj && !(b in obj)) {
          obj[b] = obj[a];
          delete obj[a];
        }
      };
      constraints = JSON.parse(JSON.stringify(constraints));
      remap(constraints.audio, 'autoGainControl', 'googAutoGainControl');
      remap(constraints.audio, 'noiseSuppression', 'googNoiseSuppression');
      constraints.audio = constraintsToChrome_(constraints.audio);
    }
    if (constraints && typeof constraints.video === 'object') {
      // Shim facingMode for mobile & surface pro.
      var face = constraints.video.facingMode;
      face = face && ((typeof face === 'object') ? face : {ideal: face});
      var getSupportedFacingModeLies = browserDetails.version < 66;

      if ((face && (face.exact === 'user' || face.exact === 'environment' ||
                    face.ideal === 'user' || face.ideal === 'environment')) &&
          !(navigator.mediaDevices.getSupportedConstraints &&
            navigator.mediaDevices.getSupportedConstraints().facingMode &&
            !getSupportedFacingModeLies)) {
        delete constraints.video.facingMode;
        var matches;
        if (face.exact === 'environment' || face.ideal === 'environment') {
          matches = ['back', 'rear'];
        } else if (face.exact === 'user' || face.ideal === 'user') {
          matches = ['front'];
        }
        if (matches) {
          // Look for matches in label, or use last cam for back (typical).
          return navigator.mediaDevices.enumerateDevices()
          .then(function(devices) {
            devices = devices.filter(function(d) {
              return d.kind === 'videoinput';
            });
            var dev = devices.find(function(d) {
              return matches.some(function(match) {
                return d.label.toLowerCase().indexOf(match) !== -1;
              });
            });
            if (!dev && devices.length && matches.indexOf('back') !== -1) {
              dev = devices[devices.length - 1]; // more likely the back cam
            }
            if (dev) {
              constraints.video.deviceId = face.exact ? {exact: dev.deviceId} :
                                                        {ideal: dev.deviceId};
            }
            constraints.video = constraintsToChrome_(constraints.video);
            logging('chrome: ' + JSON.stringify(constraints));
            return func(constraints);
          });
        }
      }
      constraints.video = constraintsToChrome_(constraints.video);
    }
    logging('chrome: ' + JSON.stringify(constraints));
    return func(constraints);
  };