Travelhelper is an unfininished schenghen area visa calculator

There is a restriction that visitors are not permitted to spend more than 90 days within 180 days in the territory of the Schengen Area even using a long-term (e.g. 1 year) travel visa. There are different online calculators that let you input previous visits' dates and tell you how many more you have left. However it's tedious to have to input the dates every time. This project was supposed to store the user's visits to the database so it'd be possible to add them just once and check how many days are left using an endpoint that can be called from some UI.

The goal of the project was to help me track my own visits but then I relocated to EU and didn't have motivation to continue it anymore. It still helped me to learn more about Spring security with the help of another github user who's kindly reviewed my code and explained tons of stuff about OAuth. This was also my first experience with Kotlin.