T-timers refactor

[rjmunro]

About the Contributor

Type of Contribution

This is a Code improvement

Current Behavior

T-Timers have complexity depending on mode. startTimes that change etc.

New Behavior

T-Timer's state is now represented by a type:

export type TimerState = { paused: false, zeroTime: number }
	| { paused: true, duration: number }

When paused, there is a remaining duration (which may be negative if we are counting upwards). When running there is a time at which the timer reads 0, (which may be in the past if we are counting upwards).

This contains everything you need to calculate the time to display, regardless of mode.

currentDuration = state.paused ? state.duration : state.zeroTime - now
endTime =  state.paused ? state.duration + now : state.zeroTime

Testing

• I have added one or more unit tests for this PR
• I have updated the relevant unit tests
• No unit test changes are needed for this PR

Affected areas

This affects the new T-Timers work.

Time Frame

Other Information

Status

• PR is ready to be reviewed.
• The functionality has been tested by the author.
• Relevant unit tests has been added / updated.
• Relevant documentation (code comments, system documentation) has been added / updated.