[Freeciv-Dev] (PR#14923) Stupid AI Building Wants

["Benedict Adamson" <badamson@xxxxxxxxxxx>]

<URL: http://bugs.freeciv.org/Ticket/Display.html?id=14923 >

The computation of building_want by the AI is questionable in some cases.

The AI subtracts part of an improvement's production cost from its 
building_want score for that improvement. It should instead be 
amortising by the production time.

The AI ignores the upkeep cost when computing want; arguably this is 
more important than the production cost.

The AI considers the presence of an entertainer (Elvis) to be just as 
bad as an unhappy citizen. Entertainers probably ought to score worse, 
because each entertainer is also a loss in production.

The AI considers a Granary (EFT_GROWTH_FOOD effect) to be more 
worthwhile in cities with large food surpluses. That is possibly the 
wrong way around; Granary helps a city grow faster, which is most 
helpful in cities that grow slowly because they have a low food surplus.

Airports (EFT_AIRLIFT effect) are most useful for empires with many 
cities and relatively few land units, because the land units must move 
to the threatened cities. The AI, however, computes a want proportional 
to the number of land units. Note that the AI uses airlifts only to help 
defend cities.

The want for the protection that city walls afford the civilians inside 
(EFT_UNIT_NO_LOSE_POP effect) depends on the number of units in the 
city, which makes no sense to me. The effect is most useful for very 
small cities, which are in danger of being destroyed because of civilian 
casualties.

The want for barracks (EFT_VETERAN_BUILD effect) depends on the number 
of units in the entire empire. An AI with a large empire will want to 
build barracks everywhere, even in cities that are not productive enough 
to be useful. The building want should depend on how productive the city 
is: its shields surplus.

The computation of the want for Leonardo's Workshop (EFT_UPGRADE_UNIT 
effect) multiplies the existing want value (v), rather than adding to 
it. This is unlike any other effect and means that, if an improvement 
had multiple effects, one of which was EFT_UPGRADE_UNIT, the 
building_want for that improvement would depend on the (essentially 
arbitrary) order that those effects were examined: a Bad Thing.