Write my own Custom OAuth External Login Provider
<p>I am developing a login interface for my work.  I need to implement a 3rd party login to one of our apps, and then save a token in the local storage so users are authorized.</p>

<p>The third party application would be equivalent to Facebook, Twitter, LinkedIn, etc.  I have some interal API methods and endpoints I can call and pass in username/password to authenticate with our DB.</p>

<p><strong>Question:</strong> 
Can someone direct me to a walkthrough about how to implement a custom External Login Provider?  I see tons of documentation on how to implement facebook, twitter, etc.  But none for a custom app (Such as an app you have made previously.).</p>

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<p>Currently I am working with this demo: <a href="http://bitoftech.net/2014/07/16/enable-oauth-refresh-tokens-angularjs-app-using-asp-net-web-api-2-owin/" rel="nofollow">http://bitoftech.net/2014/07/16/enable-oauth-refresh-tokens-angularjs-app-using-asp-net-web-api-2-owin/</a> + <a href="https://github.com/tjoudeh/AngularJSAuthentication" rel="nofollow">https://github.com/tjoudeh/AngularJSAuthentication</a> (Source). I plan to 'rip' out Google/FB and insert in my own custom 3rd party login.</p>

<p>Any suggestions on how one can implement this?</p>