From 5b1d4cdd3e305845479922566271edc7d637d906 Mon Sep 17 00:00:00 2001
From: Sainan <63328889+Sainan@users.noreply.github.com>
Date: Tue, 1 Apr 2025 13:58:15 +0200
Subject: [PATCH] respect vendor offer seed for innate damage

---
 src/services/inventoryService.ts | 35 +++++++++++++++++++++-----------
 src/services/purchaseService.ts  | 14 ++++++++++---
 src/services/rngService.ts       |  9 ++++++++
 3 files changed, 43 insertions(+), 15 deletions(-)

diff --git a/src/services/inventoryService.ts b/src/services/inventoryService.ts
index 6eba1872..e62e51b9 100644
--- a/src/services/inventoryService.ts
+++ b/src/services/inventoryService.ts
@@ -69,7 +69,7 @@ import { addStartingGear } from "@/src/controllers/api/giveStartingGearControlle
 import { addQuestKey, completeQuest } from "@/src/services/questService";
 import { handleBundleAcqusition } from "./purchaseService";
 import libraryDailyTasks from "@/static/fixed_responses/libraryDailyTasks.json";
-import { getRandomElement, getRandomInt } from "./rngService";
+import { getRandomElement, getRandomInt, SRng } from "./rngService";
 import { createMessage } from "./inboxService";
 
 export const createInventory = async (
@@ -230,7 +230,8 @@ export const addItem = async (
     inventory: TInventoryDatabaseDocument,
     typeName: string,
     quantity: number = 1,
-    premiumPurchase: boolean = false
+    premiumPurchase: boolean = false,
+    seed?: bigint
 ): Promise<IInventoryChanges> => {
     // Bundles are technically StoreItems but a) they don't have a normal counterpart, and b) they are used in non-StoreItem contexts, e.g. email attachments.
     if (typeName in ExportBundles) {
@@ -380,21 +381,31 @@ export const addItem = async (
                 defaultOverwrites.Features = EquipmentFeatures.DOUBLE_CAPACITY;
             }
             if (weapon.maxLevelCap == 40 && typeName.indexOf("BallasSword") == -1) {
+                if (!seed) {
+                    seed = BigInt(Math.round(Math.random() * Number.MAX_SAFE_INTEGER));
+                }
+                const rng = new SRng(seed);
+                const tag = rng.randomElement([
+                    "InnateElectricityDamage",
+                    "InnateFreezeDamage",
+                    "InnateHeatDamage",
+                    "InnateImpactDamage",
+                    "InnateMagDamage",
+                    "InnateRadDamage",
+                    "InnateToxinDamage"
+                ]);
+                const WeaponUpgradeValueAttenuationExponent = 2.25;
+                let value = Math.pow(rng.randomFloat(), WeaponUpgradeValueAttenuationExponent);
+                if (value >= 0.941428) {
+                    value = 1;
+                }
                 defaultOverwrites.UpgradeType = "/Lotus/Weapons/Grineer/KuvaLich/Upgrades/InnateDamageRandomMod";
                 defaultOverwrites.UpgradeFingerprint = JSON.stringify({
                     compat: typeName,
                     buffs: [
                         {
-                            Tag: getRandomElement([
-                                "InnateElectricityDamage",
-                                "InnateFreezeDamage",
-                                "InnateHeatDamage",
-                                "InnateImpactDamage",
-                                "InnateMagDamage",
-                                "InnateRadDamage",
-                                "InnateToxinDamage"
-                            ]),
-                            Value: Math.trunc(Math.random() * 0x40000000)
+                            Tag: tag,
+                            Value: Math.trunc(value * 0x40000000)
                         }
                     ]
                 });
diff --git a/src/services/purchaseService.ts b/src/services/purchaseService.ts
index f2b71427..04525704 100644
--- a/src/services/purchaseService.ts
+++ b/src/services/purchaseService.ts
@@ -51,6 +51,7 @@ export const handlePurchase = async (
     logger.debug("purchase request", purchaseRequest);
 
     const prePurchaseInventoryChanges: IInventoryChanges = {};
+    let seed: bigint | undefined;
     if (purchaseRequest.PurchaseParams.Source == 7) {
         const rawManifest = getVendorManifestByOid(purchaseRequest.PurchaseParams.SourceId!);
         if (rawManifest) {
@@ -74,6 +75,9 @@ export const handlePurchase = async (
                     prePurchaseInventoryChanges
                 );
             }
+            if (offer.LocTagRandSeed !== undefined) {
+                seed = BigInt(offer.LocTagRandSeed);
+            }
             if (!config.noVendorPurchaseLimits && ItemId) {
                 inventory.RecentVendorPurchases ??= [];
                 let vendorPurchases = inventory.RecentVendorPurchases.find(
@@ -136,7 +140,10 @@ export const handlePurchase = async (
     const purchaseResponse = await handleStoreItemAcquisition(
         purchaseRequest.PurchaseParams.StoreItem,
         inventory,
-        purchaseRequest.PurchaseParams.Quantity
+        purchaseRequest.PurchaseParams.Quantity,
+        undefined,
+        undefined,
+        seed
     );
     combineInventoryChanges(purchaseResponse.InventoryChanges, prePurchaseInventoryChanges);
 
@@ -324,7 +331,8 @@ export const handleStoreItemAcquisition = async (
     inventory: TInventoryDatabaseDocument,
     quantity: number = 1,
     durability: TRarity = "COMMON",
-    ignorePurchaseQuantity: boolean = false
+    ignorePurchaseQuantity: boolean = false,
+    seed?: bigint
 ): Promise<IPurchaseResponse> => {
     let purchaseResponse = {
         InventoryChanges: {}
@@ -345,7 +353,7 @@ export const handleStoreItemAcquisition = async (
         }
         switch (storeCategory) {
             default: {
-                purchaseResponse = { InventoryChanges: await addItem(inventory, internalName, quantity, true) };
+                purchaseResponse = { InventoryChanges: await addItem(inventory, internalName, quantity, true, seed) };
                 break;
             }
             case "Types":
diff --git a/src/services/rngService.ts b/src/services/rngService.ts
index cb8f2cba..b98f7bd3 100644
--- a/src/services/rngService.ts
+++ b/src/services/rngService.ts
@@ -127,4 +127,13 @@ export class SRng {
         }
         return min;
     }
+
+    randomElement<T>(arr: T[]): T {
+        return arr[this.randomInt(0, arr.length - 1)];
+    }
+
+    randomFloat(): number {
+        this.state = (0x5851f42d4c957f2dn * this.state + 0x14057b7ef767814fn) & 0xffffffffffffffffn;
+        return (Number(this.state >> 38n) & 0xffffff) * 0.000000059604645;
+    }
 }