fade_volume:
  alias: Fade the volume of a media player
  mode: restart
  fields:
    target_player:
      name: Target media player
      description: Target media player of volume fade.
      required: true
      example: media_player.lounge_sonos
      selector:
        entity:
          domain: media_player
    target_volume:
      name: Target volume
      description: Volume the media play will be at the end of the fade duration.
      required: true
      default: 0.5
      example: '0.5'
      selector:
        number:
          max: 1
          min: 0
          step: 0.01
          mode: slider
    duration:
      name: Fade duration
      description: Length of time in seconds the fade should take.
      required: true
      default: 5
      example: '5'
      selector:
        number:
          mode: box
          min: 0
          max: 100000
          unit_of_measurement: s
    curve:
      name: Fade curve algorithm
      description: Shape of the fade curve to apply.
      required: true
      default: logarithmic
      example: logarithmic
      selector:
        select:
          options:
          - logarithmic
          - bezier
          - linear
  variables:
    steps_per_second: 10
    total_steps: '{{ (steps_per_second * duration) | int(0) }}'
    start_volume: '{{ state_attr(target_player, ''volume_level'') | float(0) }}'
    start_diff: '{{ (target_volume - start_volume) | float(0) }}'
  sequence:
  - repeat:
      while:
      - condition: template
        value_template: '{{ repeat.index < total_steps }}'
      - condition: template
        value_template: '{{ ((state_attr(target_player, "volume_level") - target_volume)
          | abs) > 0.001 }}'
      sequence:
      - service: media_player.volume_set
        data_template:
          entity_id: '{{ target_player }}'
          volume_level: "{% set t = repeat.index / total_steps %} {% if curve == 'logarithmic'\
            \ %}\n  {{ (start_volume + (t / (1 + (1 - t))) * start_diff) | float(0)\
            \ }}\n{% elif curve == 'bezier' %}\n  {{ (start_volume + (t * t * (3 -\
            \ 2 * t)) * start_diff) | float(0) }}\n{% else %}\n  {{ (start_volume\
            \ + t * start_diff) | float(0) }}\n{% endif %}\n"
      - delay: '00:00:00.1'
  - service: media_player.volume_set
    data_template:
      entity_id: '{{ target_player }}'
      volume_level: '{{ target_volume }}'
  icon: mdi:tune-vertical