Homeassistant blueprint for storing an alarm time in a date helper

alarmhelper.yaml

blueprint:
  name: Alarmhelper
  description: Stores alarm time in helper
  domain: automation
  source_url: https://gist.github.com/Ultrawipf/39399ed7aea20e060e448d3649c12766
  input:
    alarm:
      name: Alarm timestamp sensor
      description: 'Sensor with timestamp of next alarm with device_class: timestamp'
      selector:
        entity:
          device_class: timestamp
    helper:
      name: Helper date
      selector:
        entity:
          domain: input_datetime
    offset:
      name: Alarm offset
      description: Offset from alarm
      default: 0
      selector:
        number:
          min: -600
          max: 600
          unit_of_measurement: seconds
          
variables:
  offset: !input 'offset'
  sensor: !input 'alarm'
  
trigger:
  platform: state
  entity_id: !input alarm
action:
  service: input_datetime.set_datetime
  data:
    timestamp: '{{as_timestamp(states(sensor)) + offset}}'
  target:
    entity_id: !input helper