Openlayers 3 Select Interaction style function

I have a style function for LineStrings which will place a circle at each vertex of a feature.

When I select the feature it reverts to using the default style even though I have replicated my style function with a minor (colour) change. The other minor bug is that the function has two params (start, end) but I would like to place the circle on every vertex. Is there a way to achieve this?

Specifically though, is there a reason why it might be unable to display a selected feature using a style function? I am replicating the code below:

var selectedStyle = function (feature, resolution) {
var geometry = feature.getGeometry();
var styles = [
  // linestring
  new ol.style.Style({

      stroke: new ol.style.Stroke({
          color: '#ffcc33',
          width: 6
      })
  })
];

geometry.forEachSegment(function (start, end) {
    var dx = end[0] - start[0];
    var dy = end[1] - start[1];

    var rotation = Math.atan2(dy, dx);
    // circles
    styles.push(new ol.style.Style({
        geometry: new ol.geom.Point(end),
        image: new ol.style.Circle({
            radius: 5,
            fill: new ol.style.Fill({
                color: 'rgb(0, 0, 255)'
            }),
            stroke: new ol.style.Stroke({ color: 'blue', width: 2 })

        })
    }));
});

return styles;
};

Answer

UPDATE:

When a function is used on ol.Feature#setStyle your feature is referenced with the this keyword. Like:

var selectedStyle = function () {

    console.info(this);
    var feature = this;
    var geometry = feature.getGeometry();
};

The reason that your features don't keep style is because they are (when selected) on a temporary ol.layer.Vector. So, to achieve what you want you can do:

select.on('select', function(evt){
    var selected = evt.selected;
    var deselected = evt.deselected;


    if (selected.length) {
        selected.forEach(function(feature){
            console.info(feature);
            feature.setStyle(style_modify);
        });
    } else {
        deselected.forEach(function(feature){
            console.info(feature);
            feature.setStyle(null);
        });

    }
});

http://jsfiddle.net/jonataswalker/eogk4r4b/