this is calendar view sample app originated to: https://github.com/ahmed-alamir/CalendarView?fbclid=IwAR0o3aK4uPFVSFpQLYHAH2dqkwxGbFc23oaZH5ActhX-NFRU1Qc7A1epOZI https://www.toptal.com/android/android-customization-how-to-build-a-ui-component-that-does-what-you-want?fbclid=IwAR1-4K3CDOKamR6tT22xdK1-vvjF7ojX-CV3N9HOckvc3QkY0d-SNHIUDnE