Calendar - Must Have Functionalities

In order to have a functional Calendar, that can be used, the following functionalities are a must. 

• Stack events by time of day (have time of day)
• Show duration of an event on the calendar (i.e 8-10 AM Shooting video)
• Sort/filter based on any custom field(s)
• Create custom views based on filters and sorts
• See calendar entries in grid view, kanban or gallery
• Create custom automations to add data to calendar
• Automatically sync data between multiple calendars
• Create reporting dashboards using calendar data, or from multiple calendars
• Sync calendar data/fields with project data (one update will appear in both places)
• Have personal and collaborator views with ability to change permissions and access levels
• Formula fields to calculate data (numerical, text operators, arrays, etc.)
• Ability to create form to input calendar entries (for non-paid users)
• Ability to add approval process to calendar items
• Change time/date from calendar view
• Select what info is showing in the calendar
• Calendar block /show calendar block first
• Save different views
• Notifications if something is added, deleted or scheduled over blocked time
• Share calendar view with internal / external users
• View printer-friendly version of any view and print to PDF