Notification for time between state changes

Configuration
1

I now have automations working that monitor the power draw of my washing machine power outlet and sets a input_select to either: Idle or Running

I currently have a notification sent when the washing machine switches back from Running to Idle so that I know it has finished, but ideally I would also like to include the time the washing machine ran for. In my case this would be the difference between when the input_select was changed from Idle to Running and the time it was changed back again. Does anyone have some code I could steal that does this already please?

I use automations to update the status input_select, so I imagine I could base things off the last_triggered times for these automations, but happy for any solution to be honest.

2

I eventually figure out how to do this myself. It may not be perfect, but it seems to work. Code snippet of what I am using is below in case it’s of use to anyone else:

- alias: Laundry - Set washing machine finished when power drops
  trigger:
  - platform: numeric_state
    entity_id: sensor.washing_machine_power
    below: '2'
    for:
      minutes: 1
  condition:
    condition: and
    conditions:
    - condition: state
      entity_id: input_select.washing_machine_status
      state: Running
  action:
  - service: notify.all_ios_devices
    data:
      message: The washing cycle has finished! It took {{ (now().timestamp() - (as_timestamp(states.input_select.washing_machine_status.last_updated))
        | float) | timestamp_custom('%-H hours and %-M minutes', 0) }}
  - service: input_select.select_option
    data:
      entity_id: input_select.washing_machine_status
      option: Finished