template:
  - trigger:
      - platform: event
        event_type: set_variable
      - platform: event
        event_type: remove_variable
      - platform: event
        event_type: clear_variables
    condition:
      - condition: template
        value_template: >
          {{
              (
                trigger.event.event_type == 'set_variable'
                and trigger.event.data is defined
                and trigger.event.data.key is defined
                and trigger.event.data.value is defined
              )
              or
              (
                trigger.event.event_type == 'remove_variable'
                and trigger.event.data is defined
                and trigger.event.data.key is defined
              )
              or 
              trigger.event.event_type == 'clear_variables'
          }}
    action:
      - if: "{{ trigger.event.data.get('log', state_attr('sensor.variables', 'log_events')) }}"
        then:
          - service: logbook.log
            data:
              name: "{{ trigger.event.event_type }}:"
              message: >
                {{ trigger.event.data.key | default('All variables removed') }}
                {%- if trigger.event.event_type == 'set_variable' -%}
                  : {{ trigger.event.data.value }}.
                {%- endif -%}
    sensor:
      - unique_id: 4a4c8e53-9e68-4198-9cc5-b336e228ea4d
        name: Variables
        state: Variables
        attributes:
          default_timestamp: false
          log_events: false
          variables: >
            {% set others = dict(this.attributes.get('variables', {}).items() | rejectattr('0', 'eq', trigger.event.data.key)) %}
            {% if trigger.event.event_type == 'set_variable'
                and trigger.event.data.get('set_timestamp', this.attributes.get('default_timestamp', false))
            %}
              {% set value  = trigger.event.data.value %}
              {% set value = value.isoformat() if value is datetime else value %}
              {% set new = {trigger.event.data.key: {'value': value, 'timestamp': now().isoformat()}} %}
              {{ dict(others, **new) }}
            {% elif trigger.event.event_type == 'set_variable' %}
              {% set new = {trigger.event.data.key: trigger.event.data.value} %}
              {{ dict(others, **new) }}
            {% elif trigger.event.event_type == 'remove_variable' %}
              {{ others }}
            {% elif trigger.event.event_type == 'clear_variables' %}
              {}
            {% endif %}