utils for JSON files and RNG/rolling, abstracted arg parsing for commands

BLHX.Server.Common/Utils/RNG.cs

@@ -0,0 +1,63 @@
+namespace BLHX.Server.Common.Utils;
+
+public static class RNG
+{
+    public static readonly SortedDictionary<int, float> ShipRarityRates = new()
+    {
+        {6, 1.2f},  // UR
+        {5, 7f},    // SSR
+        {4, 12f},   // Elite
+        {2, 28.8f}, // Normal
+        {3, 51f},   // Rare
+    };
+
+    static readonly Random random = new Random((int)DateTime.Now.Ticks);
+
+    public static int Next(int min, int max)
+        => random.Next(min, max);
+
+    public static int Next(int max)
+        => random.Next(max);
+    
+    public static float NextFloat(float min, float max)
+    {
+        double range = (double)max - min;
+        double sample = random.NextDouble();
+        double scaled = (sample * range) + min;
+
+        return (float)scaled;
+    }
+
+    public static float NextFloat(float max)
+        => NextFloat(0f, max);
+    
+    public static bool NextBool()
+        => random.Next(2) == 0;
+
+    public static float NextRoll()
+        => NextFloat(100f);
+    
+    public static T NextFromList<T>(IList<T> list)
+        => list[random.Next(list.Count)];
+
+    public static U NextFromDict<T, U>(IDictionary<T, U> dict)
+        => dict.ElementAt(random.Next(dict.Count)).Value;
+
+    public static int NextFromRarityDict(SortedDictionary<int, float> dict)
+    {
+        float roll = NextRoll();
+        float sum = 0f;
+
+        foreach (var pair in dict)
+        {
+            sum += pair.Value;
+            if (roll <= sum)
+                return pair.Key;
+        }
+
+        throw new Exception("NextFromRarityDict() roll failed");
+    }
+
+    public static int NextShipRarity()
+        => NextFromRarityDict(ShipRarityRates);
+}