support locking quests (changes made using StreetComplete sometimes should remove active quests)

[matkoniecz]

Currently SC handles situation where solving a quest may unlock new ones ( https://github.com/westnordost/StreetComplete/blob/3f327ca1a70d2663c9363e4022bdfdad6d9ad5bc/app/src/main/java/de/westnordost/streetcomplete/data/osm/OsmQuestUnlocker.java )

Cases where solving one quests disables others are unhandled.

Such situation never happens with current quests but I noticed problem with my custom ones (I created boolean quest that asks whatever there is any bicycle infrastructure, after adding cycleway:both=no standard StreetComplete quest asking about cycleways still appears).

I am not sure is functionality supporting this is considered as desirable in StreetComplete (and that is assuming that somebody will make a PR) as currently it is not affecting any SC quests.

[westnordost]

This would probably be problematic to implement because not all quests can determine whether an element now appliesTo it just by looking at that element - some more complex ones also need to look at other elements (with Overpass query) . The QuestUnlocker however works offline, not with Overpass. If a quest cannot determine whether it applies to an element (i.e. by the way, the cycleway quest), it returns false in appliesTo.
If that would lead to the quest being disabled, the cycleway quests wouldn't be displayed at all.

[matkoniecz]

If that would lead to the quest being disabled, the cycleway quests wouldn't be displayed at all.

Yes, without some additional changes bikeway quest would be listed only if at time of quest download it was quest with the highest priority for a given element.

This probably may be solved by splitting querries into "tag filter" and "geometry filter". So in case of quest that always return false in appliesTo disable quest if tag filter started to fail as result of applying other quests.

But it is additional logic that currently would not be used.

It still would not be feasible to check offline whatever geometry filter started to fail.

[westnordost]

It still would not be feasible to check offline whatever geometry filter started to fail.

The geometry is also not saved offline. I.e. the "use sidepath" cycleways are not saved for offline, only used once to filter out streets that have cycleways drawn on a separate path.

[westnordost]

So, I do neither have a solution for this, nor have the necessity to implement something like that. I'll mark this as question and close this.

[westnordost]

Due to the work done in 15d1e90, this should be easier now. But it will not work for "complex" quest types (that return null in isApplicableTo).

Care to implement it?

[matkoniecz]

It would require making special function with separate query that would be capable of detecting that quest is now supposed to be disabled.

So for example bikeway quest would have both the current overpass query and a new separate query checking only tags (with code for querries at least partially shared to avoid duplication). Would it be OK?

[westnordost]

No, that would not be ok. As I said, the "locking quests" feature would not work for quest types that return null in isApplicableTo.

[westnordost]

Closing this in favor of #1131