add buff timer for xp potions

frontend/src/components/UI/Inventory.svelte

@@ -8,21 +8,51 @@
     FrozenFlames,
   } from "../../../wailsjs/go/main/App.js";
 
+  function calculateXPTimer() {
+    let endsAt = new Date(endTime);
+    // @ts-ignore
+    let timeLeft = endsAt - new Date(Date.now());
+
+    let minutes = Math.floor((timeLeft % (1000 * 60 * 60)) / (1000 * 60));
+    let seconds = Math.floor((timeLeft % (1000 * 60)) / 1000);
+
+    timer = `${minutes}:${seconds}`;
+  }
+
+  let timer = null;
+  let endTime;
+
   onMount(() => {
     // Call all inventory-related functions and load it up
     SeerStones().then((result) => ($User.seerStones = result));
     BakedSalmon().then((result) => ($User.bakedSalmon = result));
     XPPotion().then((result) => {
+      // Using ts-ignore here as my IDE doesn't like the properties on result
       // @ts-ignore
       $User.xpPotion = result.NumUnusedXPPotion;
+      // @ts-ignore
+      // last entry holds the "newest" xp potion, which has
+      // the ExpiresAt for when the buff drops off
+      const timerLen = result.ActiveXPPotions.length - 1;
+      endTime = result.ActiveXPPotions[timerLen].ExpiresAt;
+      // @ts-ignore
+      $User.xpTimer = calculateXPTimer();
     });
     FrozenFlames().then((result) => ($User.frozenFlame = result));
+
+    // If there is a buff timer, display the countdown
+    const interval = setInterval(calculateXPTimer, 1000);
+
+    return () => {
+      clearInterval(interval);
+    };
   });
 </script>
 
 <main>
   <div class="flex items-center">
-    <div class="mr-4 flex">
+    <div id="timer">{timer !== null ? timer : "00:00"}</div>
+    <div class="mx-4 flex">
       <img
         src="src/assets/images/xppotion.webp"
         alt="XP Potions"

inventory.go

@@ -3,7 +3,6 @@ package main
 import (
 	"encoding/json"
 	"io"
-	"log"
 	"net/http"
 	"strconv"
 
@@ -120,8 +119,6 @@ func (a *App) FrozenFlames() (int, error) {
 	}
 	defer resp.Body.Close()
 
-	log.Printf("frozen flames: %#v", resp.Body)
-
 	decoder := json.NewDecoder(resp.Body)
 	err = decoder.Decode(&frozenFlames)