The Home Assistant command line sensor has a 255 character limitation. For many people this causes an issue where the sensor only imports part of the list. To overcome this limitation, @stu1811 came up with this brilliant solution.

Create a script that shows next 20 dates from the current day forward.

#!/bin/bash
new_dates=$(for x in $(cat /share/import_dates.txt); do
                if [[ $(date -d $x +"%y%m%d") -ge $(date +"%y%m%d") ]]; then
                    echo $x
                fi
            done)
echo "$new_dates" | head -n20

Then, create the command line sensor taking the output of this script.

sensor:
  - platform: command_line
    name: Import dates
    command: "sh /share/import_dates.sh"

The following services are used within automations, triggered by the garbage_collection_loaded event. Don't use them anywhere else, it won't work. For the examples of their use, see the examples

flowchart TD
    A[HA updates entity] -->B[triggered garbage_collection_loaded event]
    B --> C[calling services]
    C --> D[garbage_collection.add_date] & E[garbage_collection.remove_date] & F[garbage_collection.offset_date] --> C
    D & E & F --> G[manual update finished -> garbage_collection.update_state]

Add a date to the list of dates calculated automatically. To add multiple dates, call this service multiple-times with different dates. Note that this date will be removed on the next sensor update, when the data is re-calculated and loaded. This is why, this service should be called from the automation triggered by the event garbage_collection_loaded. This event is called each time the sensor is updated. And at the end of this automation, you need to call the garbage_collection.update_state service to update the sensor state based on automatically collected dates, and the dates added, removed, or offset by the automation.

Remove a date to the list of dates calculated automatically. To remove multiple dates, call this service multiple-times with different dates. Note that this date will be removed on the next sensor update, when the data is re-calculated and loaded. This is why, this service should be called from the automation triggered by the event garbage_collection_loaded. This event is called each time the sensor is updated. And at the end of this automation, you need to call the garbage_collection.update_state service to update the sensor state based on automatically collected dates, and the dates added, removed, or offset by the automation.

Offset the calculated collection day by the offset number of days. Note that this date will be removed on the next sensor update, when the data is re-calculated and loaded. This is why, this service should be called from the automation triggered by the event garbage_collection_loaded. This event is called each time the sensor is updated. And at the end of this automation, you need to call the garbage_collection.update_state service to update the sensor state based on automatically collected dates, and the dates added, removed, or offset by the automation.

Choose the next collection date from the list of dates calculated automatically, added by service calls (and not removed), and update the entity state and attributes.

This event is triggered each time a garbage_collection entity is being updated. You can create an automation to modify the collection schedule before the entity state update.

Event data:

For the example below, the entity should be configured with manual_update set to true. Then, when the garbage_collection entity is updated (normally once a day at midnight, or restart, or when triggering entity update by script), it will calculate the collection schedule for previous, current and next year. But it will NOT UPDATE the entity state. Instead, it will trigger an event garbage_collection_loaded with a list of automatically calculated dates as a parameter. You will have to create an automation triggered by this event. In this automation, you will need to call the service garbage_collection.update_state to update the state. Before that, you can call the services garbage_collection.add_date and/or garbage_collection.remove_date and/or garbage_collection.offset_date to programmatically tweak the dates in whatever way you need (e.g. based on values from external API sensor, comparing the dates with the list of holidays, calculating custom offsets based on the day of the week etc.). This is complicated but gives you the ultimate flexibility.

Adding an extra collection date (a fixed date in this case) - for the entity sensor.test.

alias: garbage_collection event
description: "Manually add a collection date, then trigger entity state update."
trigger:
  - platform: event
    event_type: garbage_collection_loaded
    event_data:
      entity_id: sensor.test
action:
  - service: garbage_collection.add_date
    data:
      entity_id: "{{ trigger.event.data.entity_id }}"
      date: "2022-01-07"
  - service: garbage_collection.update_state
    data:
      entity_id: sensor.test
mode: single

This will loop through the calculated dates, and add an extra collection to a day after each calculated one. So if this is set for a collection every first Wednesday each month, it will result in a collection on the first Wednesday, and the following day (kind of first Thursday, except if the week is starting on Thursday - just a random weird example :).

This example is for an entity sensor.test. If you want to use it for yours, replace it with the real entity name in the trigger.

alias: test garbage_collection event
description: "Loop through all calculated dates, add extra collection a day after the calculate one"
trigger:
  - platform: event
    event_type: garbage_collection_loaded
    event_data:
      entity_id: sensor.test
action:
  - repeat:
      for_each: "{{ trigger.event.data.collection_dates }}"
      sequence:
        - service: garbage_collection.add_date
          data:
            entity_id: "{{ trigger.event.data.entity_id }}"
            date: >-
              {{( as_datetime(repeat.item) + timedelta( days = 1)) | as_timestamp | timestamp_custom("%Y-%m-%d") }}
  - service: garbage_collection.update_state
    data:
      entity_id: "{{ trigger.event.data.entity_id }}"
mode: single

This is an equivalent of "holiday in week" move - checking if there is a public holiday on the calculated collection day, or earlier in the week. And if yes, moving the collection by one day. This is fully custom logic, so it could be further complicated by whatever rules anyone wants.

This example is for an entity sensor.test. If you want to use it for yours, replace it with a real entity name in the trigger.

alias: test garbage_collection event
description: >-
  Loop through all calculated dates, move the collection by 1 day if a public holiday was in the week before or on the calculated collection date calculate one
trigger:
  - platform: event
    event_type: garbage_collection_loaded
    event_data:
      entity_id: sensor.test
action:
  - repeat:
      for_each: "{{ trigger.event.data.collection_dates }}"
      sequence:
        - condition: template
          value_template: >-
            {%- set collection_date = as_datetime(repeat.item) %}
            {%- set ns = namespace(found=false) %}
            {%- for i in range(collection_date.weekday()+1) %}
              {%- set d = ( collection_date + timedelta( days=-i) ) | as_timestamp | timestamp_custom("%Y-%m-%d") %}
              {%- if d in state_attr(trigger.event.data.entity_id,'holidays') %}
                {%- set ns.found = true %}
              {%- endif %}
            {%- endfor %}  
            {{ ns.found }}
        - service: garbage_collection.offset_date
          data:
            entity_id: "{{ trigger.event.data.entity_id }}"
            date: "{{ repeat.item }}"
            offset: 1
  - service: garbage_collection.update_state
    data:
      entity_id: "{{ trigger.event.data.entity_id }}"
mode: single

Or you can use the blueprints I made for you. And you are welcome to create your own and share with others.

You can use the custom garbage collection card developed by @amaximus.

This is what I use (I like images). I use a horizontal stack of picture-entities, with card-templater plugin (Lovelace Card Templater) to show the number of days:

(The state is designed to be used as traffic lights. That's why it has 3 values. You obviously cannot use this with verbose_state)

This is the configuration

- type: "custom:card-templater"
  card:
    type: picture-entity
    name_template: >-
      {{ state_attr('sensor.bio','days') }} days
    show_name: True
    show_state: False
    entity: sensor.bio
    state_image:
      "0": "/local/containers/bio_today.png"
      "1": "/local/containers/bio_tomorrow.png"
      "2": "/local/containers/bio_off.png"
  entities:
    - sensor.bio

The simplest visualization is to use entities. In this case, I use verbose_state to show state as text.

Lovelace configuration

- type: entities
  entities:
    - sensor.general_waste
    - sensor.bio
    - sensor.paper
    - sensor.plastic

Lovelace Configuration

- type: glance
  entities:
    - sensor.general_waste