Per-hero artifact scoring for NKAI

AI now has better (but not perfect) system for scoring artifacts.

All artifacts now have their base score, based on bonuses provided by
the artifact. For composite artifacts, AI will also consider bonuses
from its components.

When exploring, AI will now weight artifacts as min(base score, price /
5), meaning even artifacts that AI can't score will still have some
priority, if only to sell them or deny them to enemy

AI will now also consider what to equip when trading with heroes or on
the end of AI pass. When considering what to equip, hero will use base
score of an artifact, adjusted by how relevant particular bonus /
artifact for a hero. Some examples:
- Morale-bonusing artifacts have their score reduced based on percentage
of undeads in the army, all the way to 0 for undead-only troops
- Artifacts that give spells (books, hat) will have score reduced based
on how many of these spells are already known by hero
- Land movement artifacts have zero score while on water and vice versa
- Necromancy artifacts will have zero score if hero does not have
necromancy
- Archery artifacts are scaled by amount of ranged troops, and only used
if hero has archery skill

AI may still equip 'bad' artifact, however this should only happen if
hero has no other artifacts to equip into said slot.

TODO's for future PR's (although not sure if / when I will work on
these):
- avoid equipping duplicates of the same artifact. Most notably with
scrolls, but may happen with other misc artifacts or rings.

- consideration for various spell-immunity neclaces

- consideration for birectional artifacts, like Shackles of War, or some
Spheres - since these artifacts need consideration on what our expected
enemy is to correctly estimate whether

- equipping artifacts based on immediate need - for example, equipping
recovery artifacts before end of day, equipping legion pieces only in
town on day 7, preparing for strong / weak enemies (or even preparing
for specific enemy in advance)

- transferring resource-generating artifacts and such to scout heroes,
allowing main hero to focus on combat

- ensure that AI can equip combined artifacts even if non-primary slots
are in use - by considering whether score of combined artifact is higher
than score of all used slots

AI/Nullkiller/AIGateway.cpp

@@ -1092,19 +1092,24 @@ void AIGateway::pickBestArtifacts(const CGHeroInstance * h, const CGHeroInstance
 				}
 				if(!emptySlotFound) //try to put that atifact in already occupied slot
 				{
+					int64_t artifactScore = getArtifactScoreForHero(target, artifact);
+
 					for(auto slot : artifact->getType()->getPossibleSlots().at(target->bearerType()))
 					{
 						auto otherSlot = target->getSlot(slot);
 						if(otherSlot && otherSlot->artifact) //we need to exchange artifact for better one
 						{
+							int64_t otherArtifactScore = getArtifactScoreForHero(target, otherSlot->artifact);
+							logAi->trace( "Comparing artifacts of %s: %s vs %s. Score: %d vs %d", target->getHeroTypeName(), artifact->getType()->getJsonKey(), otherSlot->artifact->getType()->getJsonKey(), artifactScore, otherArtifactScore);
+
 							//if that artifact is better than what we have, pick it
-							if(compareArtifacts(artifact, otherSlot->artifact)
-								&& artifact->canBePutAt(target, slot, true)) //combined artifacts are not always allowed to move
+							//combined artifacts are not always allowed to move
+							if(artifactScore > otherArtifactScore && artifact->canBePutAt(target, slot, true))
 							{
 								logAi->trace(
 									"Exchange artifacts %s <-> %s",
-									artifact->getType()->getNameTranslated(),
-									otherSlot->artifact->getType()->getNameTranslated());
+									artifact->getType()->getJsonKey(),
+									otherSlot->artifact->getType()->getJsonKey());
 
 								if(!otherSlot->artifact->canBePutAt(artHolder, location.slot, true))
 								{

AI/Nullkiller/AIUtility.cpp

@@ -18,6 +18,8 @@
 #include "../../lib/mapping/CMapDefines.h"
 #include "../../lib/gameState/QuestInfo.h"
 #include "../../lib/IGameSettings.h"
+#include "../../lib/bonuses/Limiters.h"
+#include "../../lib/bonuses/Propagators.h"
 
 #include <vcmi/CreatureService.h>
 
@@ -265,15 +267,335 @@ bool compareArmyStrength(const CArmedInstance * a1, const CArmedInstance * a2)
 	return a1->getArmyStrength() < a2->getArmyStrength();
 }
 
-bool compareArtifacts(const CArtifactInstance * a1, const CArtifactInstance * a2)
+double getArtifactBonusRelevance(const CGHeroInstance * hero, const std::shared_ptr<Bonus> & bonus)
 {
-	auto art1 = a1->getType();
-	auto art2 = a2->getType();
+	if (bonus->propagator && bonus->limiter && bonus->propagator->getPropagatorType() == CBonusSystemNode::BATTLE)
+	{
+		// assume that this is battle wide / other side propagator+limiter
+		// consider it as fully relevant since we don't know about future combat when equipping artifacts
+		return 1.0;
+	}
+
+	const auto & getArmyRatioAffectedByLimiter = [&]()
+	{
+		if (!bonus->limiter)
+			return 1.0;
+
+		uint64_t totalStrength = 0;
+		uint64_t affectedStrength = 0;
+
+		const BonusList stillUndecided;
+
+		for (const auto & slot : hero->Slots())
+		{
+			const auto allBonuses = slot.second->getAllBonuses(Selector::all, Selector::all);
+			BonusLimitationContext context = {*bonus, *slot.second, *allBonuses, stillUndecided};
+
+			uint64_t unitStrength = slot.second->getPower();
+
+			if (bonus->limiter->limit(context) == ILimiter::EDecision::ACCEPT)
+				affectedStrength += unitStrength;
+			totalStrength += unitStrength;
+		}
+
+		if (totalStrength == 0)
+			return 0.0;
+
+		return static_cast<double>(affectedStrength) / totalStrength;
+	};
+
+	const auto & getArmyPercentageWithBonus = [&](BonusType type)
+	{
+		uint64_t totalStrength = 0;
+		uint64_t affectedStrength = 0;
+
+		for (const auto & slot : hero->Slots())
+		{
+			uint64_t unitStrength = slot.second->getPower();
+			if (slot.second->hasBonusOfType(type))
+				affectedStrength += unitStrength;
+			totalStrength += unitStrength;
+		}
+
+		if (totalStrength == 0)
+			return 0.0;
+
+		return static_cast<double>(affectedStrength) / totalStrength;
+	};
 
-	if(art1->getPrice() == art2->getPrice())
-		return art1->valOfBonuses(BonusType::PRIMARY_SKILL) > art2->valOfBonuses(BonusType::PRIMARY_SKILL);
+	const auto & getSpellSchoolKnownSpellsFactor = [&](SpellSchool school)
+	{
+		uint64_t totalWeight = 0;
+		uint64_t knownWeight = 0;
+
+		for (auto spellID : VLC->spellh->getDefaultAllowed())
+		{
+			auto spell = spellID.toEntity(VLC);
+			if (!spell->hasSchool(school))
+				continue;
+
+			uint64_t spellLevel = spell->getLevel();
+			uint64_t spellWeight = spellLevel * spellLevel;
+			if (!hero->spellbookContainsSpell(spellID))
+				knownWeight += spellWeight;
+			totalWeight += spellWeight;
+		}
+		if (totalWeight == 0)
+			return 0.0;
+
+		return static_cast<double>(knownWeight) / totalWeight;
+	};
+
+	const auto & getSpellLevelKnownSpellsFactor = [&](int level)
+	{
+		uint64_t totalWeight = 0;
+		uint64_t knownWeight = 0;
+
+		for (auto spellID : VLC->spellh->getDefaultAllowed())
+		{
+			auto spell = spellID.toEntity(VLC);
+			if (spell->getLevel() != level)
+				continue;
+
+			if (!hero->spellbookContainsSpell(spellID))
+				knownWeight += 1;
+			totalWeight += 1;
+		}
+		if (totalWeight == 0)
+			return 0.0;
+
+		return static_cast<double>(knownWeight) / totalWeight;
+	};
+
+	constexpr double notRelevant = 0.0;  // artifact is not useful in current conditions
+	constexpr double relevant = 1.0;
+	constexpr double veryRelevant = 2.0; // for very situational artifacts, e.g. skill-specific, or army composition-specific
+
+	switch (bonus->type)
+	{
+		case BonusType::MOVEMENT:
+			if (hero->boat && bonus->subtype == BonusCustomSubtype::heroMovementSea)
+				return veryRelevant;
+
+			if (!hero->boat && bonus->subtype == BonusCustomSubtype::heroMovementLand)
+				return relevant;
+			return notRelevant;
+		case BonusType::STACKS_SPEED:
+		case BonusType::STACK_HEALTH:
+			return getArmyRatioAffectedByLimiter();
+		case BonusType::MORALE:
+			return getArmyRatioAffectedByLimiter() * (1 - getArmyPercentageWithBonus(BonusType::UNDEAD)); // TODO: other unaffected, e.g. Golems
+		case BonusType::LUCK:
+			return getArmyRatioAffectedByLimiter(); // Do we have luck?
+		case BonusType::PRIMARY_SKILL:
+			if (bonus->subtype == PrimarySkill::ATTACK || bonus->subtype == PrimarySkill::DEFENSE)
+				return getArmyRatioAffectedByLimiter(); // e.g. Vial of Dragonblood - consider only affected unit
+			else
+				return relevant; // spellpower / knowledge - always relevant
+		case BonusType::WATER_WALKING:
+		case BonusType::FLYING_MOVEMENT:
+			return hero->boat ? notRelevant : relevant; // boat can't fly
+		case BonusType::WHIRLPOOL_PROTECTION:
+			return hero->boat ? relevant : notRelevant;
+		case BonusType::UNDEAD_RAISE_PERCENTAGE:
+			return hero->hasBonusOfType(BonusType::IMPROVED_NECROMANCY) ? veryRelevant : notRelevant;
+		case BonusType::SPELL_DAMAGE:
+		case BonusType::SPELL_DURATION:
+			return hero->hasSpellbook() ? relevant : notRelevant;
+		case BonusType::PERCENTAGE_DAMAGE_BOOST:
+			if (bonus->subtype == BonusCustomSubtype::damageTypeRanged)
+				return veryRelevant * getArmyPercentageWithBonus(BonusType::SHOOTER);
+			if (bonus->subtype == BonusCustomSubtype::damageTypeMelee)
+				return veryRelevant * (1 - getArmyPercentageWithBonus(BonusType::SHOOTER));
+			return 0;
+		case BonusType::FULL_MANA_REGENERATION:
+		case BonusType::MANA_REGENERATION:
+			return hero->mana < hero->manaLimit() ? relevant : notRelevant;
+		case BonusType::LEARN_BATTLE_SPELL_CHANCE:
+			return hero->hasBonusOfType(BonusType::LEARN_BATTLE_SPELL_LEVEL_LIMIT) ? relevant : notRelevant;
+		case BonusType::NO_DISTANCE_PENALTY:
+		case BonusType::NO_WALL_PENALTY:
+			return getArmyPercentageWithBonus(BonusType::SHOOTER) * veryRelevant;
+		case BonusType::SPELLS_OF_SCHOOL:
+			if (!hero->hasSpellbook())
+				return notRelevant;
+			return 1 - getSpellSchoolKnownSpellsFactor(bonus->subtype.as<SpellSchool>());
+		case BonusType::SPELLS_OF_LEVEL:
+			if (!hero->hasSpellbook())
+				return notRelevant;
+			return 1 - getSpellLevelKnownSpellsFactor(bonus->subtype.getNum());
+// Potential TODO's
+//		case BonusType::MAGIC_RESISTANCE:
+//		case BonusType::FREE_SHIP_BOARDING:
+//		case BonusType::GENERATE_RESOURCE:
+//		case BonusType::CREATURE_GROWTH:
+//
+//		case BonusType::SPELLS_OF_LEVEL:
+//		case BonusType::SIGHT_RADIUS:
+	}
+
+	return 1.0;
+}
+
+int32_t getArtifactBonusScoreImpl(const std::shared_ptr<Bonus> & bonus)
+{
+	switch (bonus->type)
+	{
+		case BonusType::MOVEMENT:
+			if (bonus->subtype == BonusCustomSubtype::heroMovementLand)
+				return bonus->val * 20;
+			if (bonus->subtype == BonusCustomSubtype::heroMovementSea)
+				return bonus->val * 10;
+			return 0;
+		case BonusType::STACKS_SPEED:
+			return bonus->val * 8000;
+		case BonusType::MORALE:
+			return bonus->val * 1500;
+		case BonusType::LUCK:
+			return bonus->val * 1000;
+		case BonusType::PRIMARY_SKILL:
+			return bonus->val * 1000;
+		case BonusType::SURRENDER_DISCOUNT:
+			return 0; // irrelevant in gameplay
+		case BonusType::WATER_WALKING:
+			return 5000;
+		case BonusType::FREE_SHIP_BOARDING:
+			return 10000;
+		case BonusType::WHIRLPOOL_PROTECTION:
+			return 5000;
+		case BonusType::FLYING_MOVEMENT:
+			return 20000;
+		case BonusType::UNDEAD_RAISE_PERCENTAGE:
+			return bonus->val * 400;
+		case BonusType::GENERATE_RESOURCE:
+			return bonus->val * VLC->objh->resVals.at(bonus->subtype.as<GameResID>().getNum()) * 10;
+		case BonusType::SPELL_DURATION:
+			return bonus->val * 200;
+		case BonusType::MAGIC_RESISTANCE:
+			return bonus->val * 400;
+		case BonusType::PERCENTAGE_DAMAGE_BOOST:
+			if (bonus->subtype == BonusCustomSubtype::damageTypeRanged)
+				return bonus->val * 200;
+			if (bonus->subtype == BonusCustomSubtype::damageTypeMelee)
+				return bonus->val * 500;
+			return 0;
+		case BonusType::CREATURE_GROWTH:
+			return (1+bonus->subtype.getNum()) * bonus->val * 400;
+		case BonusType::FULL_MANA_REGENERATION:
+			return 15000;
+		case BonusType::MANA_REGENERATION:
+			return bonus->val * 500;
+		case BonusType::SPELLS_OF_SCHOOL:
+			return 20000;
+		case BonusType::SPELLS_OF_LEVEL:
+			return bonus->subtype.getNum() * 6000;
+		case BonusType::SPELL_DAMAGE:
+			return bonus->val * 120;
+		case BonusType::SIGHT_RADIUS:
+			return bonus->val * 1000;
+		case BonusType::LEARN_BATTLE_SPELL_CHANCE:
+			return 0; // irrelevant in gameplay
+		case BonusType::STACK_HEALTH:
+			return bonus->val * 5000;
+		case BonusType::NO_DISTANCE_PENALTY:
+			return 10000;
+		case BonusType::NO_WALL_PENALTY:
+			return 5000;
+	}
+	return 0;
+	// Additional bonuses to consider from H3 artifacts:
+	// MIND_IMMUNITY
+	// BLOCK_MAGIC_ABOVE
+	// SPELL_IMMUNITY
+	// NEGATE_ALL_NATURAL_IMMUNITIES
+	// SPELL_RESISTANCE_AURA
+	// SPELL
+	// BATTLE_NO_FLEEING
+	// BLOCK_ALL_MAGIC
+	// NONEVIL_ALIGNMENT_MIX
+	// OPENING_BATTLE_SPELL
+	// IMPROVED_NECROMANCY
+	// HP_REGENERATION
+	// CREATURE_GROWTH_PERCENT
+	// LEVEL_SPELL_IMMUNITY
+	// FREE_SHOOTING
+	// FULL_MANA_REGENERATION
+}
+
+int32_t getArtifactBonusScore(const std::shared_ptr<Bonus> & bonus)
+{
+	if (bonus->propagator && bonus->propagator->getPropagatorType() == CBonusSystemNode::BATTLE)
+	{
+		if (bonus->limiter)
+		{
+			// assume that this is battle wide / other side propagator+limiter -> invert value
+			return -getArtifactBonusScoreImpl(bonus);
+		}
+		else
+		{
+			return 0; // TODO? How to consider battle-wide bonuses that affect everyone?
+		}
+	}
 	else
-		return art1->getPrice() > art2->getPrice();
+	{
+		return getArtifactBonusScoreImpl(bonus);
+	}
+
+}
+
+int64_t getPotentialArtifactScore(const CArtifact * type)
+{
+	int64_t totalScore = 0;
+
+	for (const auto & bonus : type->getExportedBonusList())
+		totalScore += getArtifactBonusScore(bonus);
+
+	if (type->hasParts())
+	{
+		for (const auto & part : type->getConstituents())
+		{
+			for (const auto & bonus : part->getExportedBonusList())
+				totalScore += getArtifactBonusScore(bonus);
+		}
+	}
+
+	int64_t finalScore = std::max<int64_t>(type->getPrice() / 5, totalScore );
+
+	return finalScore;
+}
+
+int64_t getArtifactScoreForHero(const CGHeroInstance * hero, const CArtifactInstance * artifact)
+{
+	if (artifact->isScroll())
+	{
+		auto spellID = artifact->getScrollSpellID();
+		auto spell = spellID.toEntity(VLC);
+
+		if (hero->getSpellsInSpellbook().count(spellID))
+			return 0;
+		else
+			return spell->getLevel() * 100;
+	}
+
+	const CArtifact * type = artifact->getType();
+	int64_t totalScore = 0;
+
+	if (type->getId() == ArtifactID::SPELLBOOK)
+		return 0;
+
+	for (const auto & bonus : type->getExportedBonusList())
+		totalScore += getArtifactBonusRelevance(hero, bonus) * getArtifactBonusScore(bonus);
+
+	if (type->hasParts())
+	{
+		for (const auto & part : type->getConstituents())
+		{
+			for (const auto & bonus : part->getExportedBonusList())
+				totalScore += getArtifactBonusRelevance(hero, bonus) * getArtifactBonusScore(bonus);
+		}
+	}
+
+	return totalScore;
 }
 
 bool isWeeklyRevisitable(const Nullkiller * ai, const CGObjectInstance * obj)

AI/Nullkiller/AIUtility.h

@@ -213,7 +213,8 @@ bool isSafeToVisit(const CGHeroInstance * h, const CCreatureSet *, uint64_t dang
 
 bool compareHeroStrength(const CGHeroInstance * h1, const CGHeroInstance * h2);
 bool compareArmyStrength(const CArmedInstance * a1, const CArmedInstance * a2);
-bool compareArtifacts(const CArtifactInstance * a1, const CArtifactInstance * a2);
+int64_t getArtifactScoreForHero(const CGHeroInstance * hero, const CArtifactInstance * artifact);
+int64_t getPotentialArtifactScore(const CArtifact * art);
 bool townHasFreeTavern(const CGTownInstance * town);
 
 uint64_t getHeroArmyStrengthWithCommander(const CGHeroInstance * hero, const CCreatureSet * heroArmy);

AI/Nullkiller/Engine/Nullkiller.cpp

@@ -547,6 +547,9 @@ void Nullkiller::makeTurn()
 			return;
 		}
 
+		for (auto heroInfo : cb->getHeroesInfo())
+			gateway->pickBestArtifacts(heroInfo);
+
 		if(i == settings->getMaxPass())
 		{
 			logAi->warn("Maxpass exceeded. Terminating AI turn.");

AI/Nullkiller/Engine/PriorityEvaluator.cpp

@@ -250,36 +250,7 @@ static uint64_t evaluateArtifactArmyValue(const CArtifact * art)
 	if(art->getId() == ArtifactID::SPELL_SCROLL)
 		return 1500;
 
-	auto statsValue =
-		10 * art->valOfBonuses(BonusType::MOVEMENT, BonusCustomSubtype::heroMovementLand)
-		+ 1200 * art->valOfBonuses(BonusType::STACKS_SPEED)
-		+ 700 * art->valOfBonuses(BonusType::MORALE)
-		+ 700 * art->valOfBonuses(BonusType::PRIMARY_SKILL, BonusSubtypeID(PrimarySkill::ATTACK))
-		+ 700 * art->valOfBonuses(BonusType::PRIMARY_SKILL, BonusSubtypeID(PrimarySkill::DEFENSE))
-		+ 700 * art->valOfBonuses(BonusType::PRIMARY_SKILL, BonusSubtypeID(PrimarySkill::KNOWLEDGE))
-		+ 700 * art->valOfBonuses(BonusType::PRIMARY_SKILL, BonusSubtypeID(PrimarySkill::SPELL_POWER))
-		+ 500 * art->valOfBonuses(BonusType::LUCK);
-
-	auto classValue = 0;
-
-	switch(art->aClass)
-	{
-	case CArtifact::EartClass::ART_TREASURE:
-		//FALL_THROUGH
-	case CArtifact::EartClass::ART_MINOR:
-		classValue = 1000;
-		break;
-
-	case CArtifact::EartClass::ART_MAJOR:
-		classValue = 3000;
-		break;
-	case CArtifact::EartClass::ART_RELIC:
-	case CArtifact::EartClass::ART_SPECIAL:
-		classValue = 8000;
-		break;
-	}
-
-	return statsValue > classValue ? statsValue : classValue;
+	return getPotentialArtifactScore(art);
 }
 
 uint64_t RewardEvaluator::getArmyReward(