muzika-gromche/MuzikaGromche/SpawnRateManager.cs

using HarmonyLib;
using System;
using UnityEngine;

namespace MuzikaGromche
{
    [HarmonyPatch(typeof(RoundManager))]
    static class SpawnRatePatch
    {
        const string JesterEnemyName = "Jester";

        // If set to null, do not override spawn chances. Otherwise, it is an index of Jester in RoundManager.currentLevel.Enemies
        static int? JesterEnemyIndex = null;
        static float? SpawnTime = null;

        [HarmonyPatch(nameof(RoundManager.AssignRandomEnemyToVent))]
        [HarmonyPrefix]
        static void AssignRandomEnemyToVentPrefix(RoundManager __instance, EnemyVent vent, float spawnTime)
        {
            if (!Config.OverrideSpawnRates.Value)
            {
                return;
            }

            var index = __instance.currentLevel.Enemies.FindIndex(enemy => enemy.enemyType.enemyName == JesterEnemyName);
            if (index == -1)
            {
                return;
            }

            JesterEnemyIndex = index;
            SpawnTime = spawnTime;
        }

        [HarmonyPatch(nameof(RoundManager.AssignRandomEnemyToVent))]
        [HarmonyPostfix]
        static void AssignRandomEnemyToVentPostfix(RoundManager __instance, EnemyVent vent, float spawnTime)
        {
            JesterEnemyIndex = null;
            SpawnTime = null;
        }

        [HarmonyPatch(nameof(RoundManager.GetRandomWeightedIndex))]
        [HarmonyPostfix]
        static void GetRandomWeightedIndexPostfix(RoundManager __instance, ref int[] weights, ref System.Random randomSeed)
        {
            if (JesterEnemyIndex is int index && SpawnTime is float spawnTime)
            {
                if (__instance.EnemyCannotBeSpawned(index))
                {
                    return;
                }

                var minMultiplierTime = 3 * __instance.timeScript.lengthOfHours;
                var maxMultiplierTime = 7 * __instance.timeScript.lengthOfHours;
                var normalizedMultiplierTime = Math.Clamp((spawnTime - minMultiplierTime) / (maxMultiplierTime - minMultiplierTime), 0f, 1f);

                // TODO: Try Expo function instead of Lerp?
                var minMultiplier = Mathf.Max(1, __instance.minEnemiesToSpawn);
                var maxMultiplier = 9 + __instance.minEnemiesToSpawn;
                var multiplier = Mathf.Lerp(minMultiplier, maxMultiplier, normalizedMultiplierTime);

                var newWeight = (int)(weights[index] * multiplier);
                Debug.Log($"{nameof(MuzikaGromche)} Overriding Jester spawn weight {weights[index]} * {multiplier} => {newWeight}");
                weights[index] = newWeight;
            }
        }
    }
}