reworks (thx dargkkast), more consistent lib functions, total item rework

src/lib/items.ts

@@ -0,0 +1,24 @@
+import { HelixUser } from "@twurple/api"
+import { getInventory, updateInventory } from "../lib/userHelper"
+
+const ITEMS = ['blaster', 'silverbullet', 'grenade', 'tnt', 'watergun', 'clipboard', 'lootbox']
+
+interface itemChangeResult {
+    result: boolean,
+    reason: string
+    count: number,
+}
+
+export async function changeItemCount(user: HelixUser, item: string, amount = -1): Promise<itemChangeResult> {
+    if (!ITEMS.includes(item)) return { result: false, reason: 'noexist', count: 0 }
+    let inv = await getInventory(user)
+
+    if (amount < 0 && inv[item] + amount < 0) return { result: false, reason: 'negative', count: inv[item] }
+    const newcount: number = inv[item] + amount
+
+    Object.defineProperty(inv, item, {
+        value: newcount,
+    })
+    await updateInventory(user, inv)
+    return { result: true, reason: '', count: inv[item] }
+}