feat: spawn enemies from reusable definitions

simulation/conflict/CombatantFactory.gd

@@ -0,0 +1,81 @@
+class_name CombatantFactory
+extends RefCounted
+
+var _occupied_ids: Dictionary = {}
+var _next_suffix_by_prefix: Dictionary = {}
+
+
+func reset_allocator() -> void:
+	_occupied_ids.clear()
+	_next_suffix_by_prefix.clear()
+
+
+func restore_allocator(records: Array[CombatantStateRecord]) -> void:
+	reset_allocator()
+	for record in records:
+		if record != null:
+			reserve_id(record.get_combatant_id())
+
+
+func reserve_id(combatant_id: StringName) -> bool:
+	if combatant_id.is_empty() or _occupied_ids.has(combatant_id):
+		return false
+	_occupied_ids[combatant_id] = true
+	_observe_numeric_suffix(combatant_id)
+	return true
+
+
+func create_enemy(enemy_definition_id: StringName, position: Vector3) -> CombatantStateRecord:
+	return create_from_definition(SimulationEnemies.get_enemy(enemy_definition_id), position)
+
+
+func create_from_definition(definition: EnemyDefinition, position: Vector3) -> CombatantStateRecord:
+	if definition == null or not definition.validate().is_empty() or not position.is_finite():
+		return null
+	var combatant_id := _allocate_id(definition.combatant_id_prefix)
+	return CombatantStateRecord.create(
+		combatant_id,
+		definition.kind,
+		definition.faction_id,
+		definition.display_name,
+		position,
+		definition.health,
+		definition.weapon_id,
+		CombatantStateRecord.NO_NPC_ID,
+		definition.hostile,
+		definition.enemy_id
+	)
+
+
+func get_next_suffix(prefix: String) -> int:
+	return int(_next_suffix_by_prefix.get(prefix, 0))
+
+
+func is_reserved(combatant_id: StringName) -> bool:
+	return _occupied_ids.has(combatant_id)
+
+
+func _allocate_id(prefix: String) -> StringName:
+	var suffix := get_next_suffix(prefix)
+	var candidate := StringName("%s_%d" % [prefix, suffix])
+	while _occupied_ids.has(candidate):
+		suffix += 1
+		candidate = StringName("%s_%d" % [prefix, suffix])
+	_occupied_ids[candidate] = true
+	_next_suffix_by_prefix[prefix] = suffix + 1
+	return candidate
+
+
+func _observe_numeric_suffix(combatant_id: StringName) -> void:
+	var text_id := String(combatant_id)
+	var separator_index := text_id.rfind("_")
+	if separator_index <= 0 or separator_index >= text_id.length() - 1:
+		return
+	var suffix_text := text_id.substr(separator_index + 1)
+	if not suffix_text.is_valid_int():
+		return
+	var suffix := int(suffix_text)
+	if suffix < 0:
+		return
+	var prefix := text_id.substr(0, separator_index)
+	_next_suffix_by_prefix[prefix] = maxi(get_next_suffix(prefix), suffix + 1)