I need help in Calendar integration into site using .net

I'm demanding to create a web-based proof of concept for the following scenario.

I'd like to permit a user to select a specific calendar feed type (Google, Apple, Yahoo, Microsoft Exchange/Outlook) from a webpage, provide their credentials and then sync & display the feed on a web-based (html/js/css) calendar view. A user can have 0 or numerous calendar feeds.

The web-based calendar to be utilized

The integration code to-be-written must return JSON which will be loaded into the actual calendar.

The user wants to be able to read and write (create) events. When creating an event, the user must select which calendar feed to create the event - default selection will be "all".

When creating the solution please parameterize main variables and settings to allow for flexibility if later modifications need to be made.

I require following Skills .NET, Microsoft SQL Server Administration, MongoDB, Node.js