AngularJS dropdown multiselect not working

I wanted to create a simple multi-select dropdown which displays days (mon,tue...sun), select all, unselect all...using angular JS, bootstrap,JS.

I wanted to write controller in a way that if i select monday twice, it de-selects and remove it from the selected items....instead it is keep on adding the elements again and again...and unselect all is not working.

I tried every other way and couldn't succeed. Plz help me or share any similar code that can give me a idea.

PS: I don't want to use jQuery for this.