DebugSpawnItem: Ensure item uses valid monster level

Source/items.cpp

@@ -4585,26 +4585,56 @@ std::string DebugSpawnItem(std::string itemName)
 
 	Item testItem;
 
+	// get all valid monster levels
+	std::vector<uint8_t> monsterLevels {};
+	for (int16_t i = 0; i < static_cast<int16_t>(NUM_MTYPES); i++) {
+		const auto &monsterData = MonstersData[i];
+		auto monsterLevel = static_cast<uint8_t>(monsterData.level);
+
+		if (i == MT_DIABLO) {
+			if (!gbIsHellfire) {
+				// Adjust The Dark Lord's mlvl if the item isn't a Hellfire item to match the Diablo mlvl
+				monsterLevel -= 15;
+			}
+		} else {
+			if (monsterData.availability == MonsterAvailability::Never) {
+				// Skip monsters that are unable to appear in the game
+				continue;
+			}
+			if (!gbIsHellfire && monsterData.minDunLvl > 16) {
+				// Skip hellfire monsters in diablo
+				continue;
+			}
+		}
+
+		if (std::find(monsterLevels.begin(), monsterLevels.end(), monsterLevel) == monsterLevels.end()) {
+			monsterLevels.push_back(monsterLevel);
+		}
+	}
+
 	uint32_t begin = SDL_GetTicks();
 	int i = 0;
 	for (;; i++) {
 		// using a better rng here to seed the item to prevent getting stuck repeating same values using old one
 		std::uniform_int_distribution<int32_t> dist(0, INT_MAX);
+		std::uniform_int_distribution<int32_t> distLevel(0, static_cast<int>(monsterLevels.size()) - 1);
 		SetRndSeed(dist(BetterRng));
 		if (SDL_GetTicks() - begin > max_time)
 			return StrCat("Item not found in ", max_time / 1000, " seconds!");
 
 		if (i > max_iter)
 			return StrCat("Item not found in ", max_iter, " tries!");
 
-		const int8_t monsterLevel = dist(BetterRng) % CF_LEVEL + 1;
+		const int8_t monsterLevel = monsterLevels[distLevel(BetterRng)];
 		_item_indexes idx = RndItemForMonsterLevel(monsterLevel);
 		if (IsAnyOf(idx, IDI_NONE, IDI_GOLD))
 			continue;
 
 		testItem = {};
 		SetupAllItems(*MyPlayer, testItem, idx, AdvanceRndSeed(), monsterLevel, 1, false, false, false);
 
+		assert(IsDungeonItemValid(testItem._iCreateInfo, testItem.dwBuff));
+
 		std::string tmp = AsciiStrToLower(testItem._iIName);
 		if (tmp.find(itemName) != std::string::npos)
 			break;