Allow inverting the state of a cover entity

[emontnemery]

Proposal

Add an entity option to invert the state of a cover; an open cover will be closed and a closed cover will be open. Also, the cover's position should be inverted.

Complications

Covers have two properties corresponding to their open/closed state:

• is_closed - Returns a bool
• current_cover_position - Returns an integer 0..100 where where 0 means closed and 1..100 means open

Just inverting is_closed won't work because position 0 will then mean open and 1..100 will mean closed.

Possible way forward could be to:

• Let the base class calculate is_closed based on the current_cover_position
• Deprecate is_closed, covers with a binary state would instead implement current_cover_position to return either 0 or 100

[thecode]

I am just noting here that in Shelly Gen2 (Gen1 is based on closed=0) we report the state from the device, not based on position:
https://github.com/home-assistant/core/blob/dev/homeassistant/components/shelly/cover.py#L163
This is aligned with the device docs https://shelly-api-docs.shelly.cloud/gen2/ComponentsAndServices/Cover#status because the device can still know it is closed or open while it can't report its position.

While this is not common and may happen due to a problem, I have already seen that, the device lost position, reported that the position is unknown but the cover is closed (since the last direction moved until consumption was 0), you can claim that the device also knows that the position is 0, I don't know the reasons to report closed without a percentage but they may be logic behind that.

I think that a default is_closed method can calculate the position based on percentage, but an integration should be allowed to override it.
I understand that this conflicts with a future idea to invert the cover, but this discussion is about the is_closed and if a future idea is needed it would be better to create a discussion for it and discuss how to handle it.

[rrooggiieerr]

I think this would be a neat addition to the cover entity. My use case would be a projector screen, which is closed when retracted while open when pulled out. Totally opposite the behaviour of the cover entity.

[TimonTrukker]

Slightly related, I have an awning which has correct states (closed means not deployed, open means deployed) and correct positions (0 means not deployed and 100 means fully deployed), but the slider to set a specific condition shows what I interpret as a deployed cover when the position is 0 and what I interpret as a closed cover when the position is 100. So a method to invert that behavior would be awesome.