feat(destroyable): enemy preconditions from the level, as the client

An object's EnemyPrecondition (level config) decides who it is an enemy of:
whoever asks and doesn't meet the preconditions, whatever the factions
(LWODestroyableComponent::msgIsEnemy 0x00c9e930; ',' ';' ':' join groups
that must all pass, '|' alternatives). Forbidden Valley Siege's objects use
it today; any level object can.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dGame/dComponents/DestroyableComponent.cpp

@@ -28,6 +28,7 @@
 #include "BaseCombatAIComponent.h"
 #include "TeamManager.h"
 #include "BuffComponent.h"
+#include "Preconditions.h"
 #include "SkillComponent.h"
 #include "Item.h"
 #include "Amf3.h"
@@ -163,6 +164,9 @@ void DestroyableComponent::LoadDataFromTemplate() {
 // The level config (LWODestroyableComponent::LoadConfigData 0x00c44cb0 reads it for every destroyable): is_smashable,
 // set_faction / override_faction and the smashable loot matrix
 void DestroyableComponent::LoadConfigData() {
+	const auto enemyPrecondition = m_Parent->GetVarAsString(u"EnemyPrecondition");
+	if (!enemyPrecondition.empty()) m_EnemyPrecondition = std::make_unique<PreconditionExpression>(enemyPrecondition);
+
 	const bool isSmashable = m_Parent->GetVarAs<int32_t>(u"is_smashable") != 0;
 	const bool isCharacter = m_Parent->GetCharacter() != nullptr;
 	if (!isCharacter) {
@@ -536,6 +540,10 @@ bool DestroyableComponent::IsEnemy(const Entity* other) const {
 		return false;
 	}
 	const auto* otherDestroyableComponent = other->GetComponent<DestroyableComponent>();
+	// An object with enemy preconditions is an enemy unless this one meets them; factions don't count then
+	if (otherDestroyableComponent && otherDestroyableComponent->GetEnemyPrecondition()) {
+		return !otherDestroyableComponent->GetEnemyPrecondition()->Check(m_Parent);
+	}
 	if (otherDestroyableComponent != nullptr) {
 		for (const auto enemyFaction : m_EnemyFactionIDs) {
 			for (const auto otherFaction : otherDestroyableComponent->GetFactionIDs()) {

dGame/dComponents/DestroyableComponent.h

@@ -2,6 +2,7 @@
 #define DESTROYABLECOMPONENT_H
 
 #include "RakNetTypes.h"
+#include <memory>
 #include <optional>
 #include <vector>
 #include "tinyxml2.h"
@@ -10,6 +11,8 @@
 #include "eReplicaComponentType.h"
 #include "Implementation.h"
 
+class PreconditionExpression;
+
 struct ObjectLoadState;
 
 namespace GameMessages {
@@ -471,6 +474,10 @@ public:
 	 */
 	static void Resurrect(Entity& entity);
 
+	// The level's EnemyPrecondition: an object asking whether this one is its enemy must meet it, or it is one
+	// (LWODestroyableComponent::msgIsEnemy 0x00c9e930); its factions don't count then
+	const PreconditionExpression* GetEnemyPrecondition() const { return m_EnemyPrecondition.get(); }
+
 	// Whether a resurrection has started and not finished (the client's isResurrecting)
 	bool GetIsResurrecting() const { return m_IsResurrecting; }
 
@@ -640,6 +647,9 @@ private:
 	// A resurrection has started (Resurrect) and its respawn animation hasn't finished
 	bool m_IsResurrecting = false;
 
+	// The level config's EnemyPrecondition, when it has one
+	std::unique_ptr<PreconditionExpression> m_EnemyPrecondition;
+
 	/**
 	 * Whether this entity is smashed. Unused, here for serialization
 	 */

tests/dGameTests/dComponentsTests/DestroyableComponentTests.cpp

@@ -731,3 +731,23 @@ TEST_F(DestroyableTest, RequestResurrectOnlyWhenDead) {
 	request.Handle(*baseEntity, UNASSIGNED_SYSTEM_ADDRESS);
 	EXPECT_TRUE(destroyableComponent->GetIsResurrecting());
 }
+
+// LWODestroyableComponent::msgIsEnemy: a target with enemy preconditions is an enemy of whoever doesn't meet them,
+// whatever its factions
+TEST_F(DestroyableTest, EnemyPreconditionDecidesEnemies) {
+	if (!CDClientDatabase::isConnected) CDClientDatabase::Connect(":memory:");
+	CDClientDatabase::ExecuteDML("CREATE TABLE IF NOT EXISTS Preconditions (id INTEGER, type INTEGER, targetLOT TEXT, targetCount INTEGER);");
+	CDClientDatabase::ExecuteDML("INSERT INTO Preconditions VALUES (90201, 2, '6194', 1);"); // has an item the asker lacks
+	CDClientDatabase::ExecuteDML("INSERT INTO Preconditions VALUES (90202, 2, '', 1);"); // always met
+
+	Entity target(0x0102030405060709LL, info);
+	auto* targetDestroyable = target.AddComponent<DestroyableComponent>(-1);
+
+	target.SetVar<std::string>(u"EnemyPrecondition", "90201");
+	targetDestroyable->LoadConfigData();
+	EXPECT_TRUE(destroyableComponent->IsEnemy(&target));
+
+	target.SetVar<std::string>(u"EnemyPrecondition", "90202");
+	targetDestroyable->LoadConfigData();
+	EXPECT_FALSE(destroyableComponent->IsEnemy(&target));
+}