Fix setting minutes in time pickers

[nilsreichardt]

Description

#568 introduced a new bug: When adding a new event (e.g. an exam) it's only allowed to enter 0 or 30 as value for the minute at the time picker.

Screen.Recording.2023-04-06.at.14.11.58.mov

The problem was the minute interval for the Material time picker was hard-coded.

Solution demo

Screen.Recording.2023-04-07.at.00.44.02.mov

Related Tickets

Closes #584

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[Jonas-Sander]

LGTM, see comment

[Jonas-Sander]

If we're basically hard coding the logic here that it's either 30 or 5 minute intervals then shouldn't we also also add an assert that minutesInteval is one or the other?

[nilsreichardt]

I'm using an extension now on int to get the VisibleStep and throw an exception if it's an unknown minute value:

extension on int {
  VisibleStep toVisibleStep() {
    switch (this) {
      case 1:
      case 5:
        return VisibleStep.fifths;
      case 6:
        return VisibleStep.sixths;
      case 10:
        return VisibleStep.tenths;
      case 20:
        return VisibleStep.twentieths;
      case 30:
        return VisibleStep.thirtieths;
      case 60:
        return VisibleStep.sixtieth;
      default:
        // At the moment, only these intervals are supported. If you need
        // another one, please add it and handle it in the switch statement.
        throw Exception(
          "Unsupported minutes interval: $this. Please handle the other cases yourself.",
        );
    }
  }
}