Danro-Jump/Assets/Scripts/Runtime/Gameplay/Spawning/WeightedPrefabOption.cs

using System.Collections.Generic;
using UnityEngine;

namespace DanroJump.Gameplay
{
    [System.Serializable]
    public sealed class WeightedPrefabOption
    {
        [SerializeField] private GameObject prefab;
        [SerializeField] [Min(0f)] private float weight = 1f;

        public GameObject Prefab => prefab;
        public float Weight => weight;

        public static bool TrySelect(IReadOnlyList<WeightedPrefabOption> options, System.Random random, out GameObject prefab)
        {
            prefab = null;

            var totalWeight = 0f;
            if (options == null)
            {
                return false;
            }

            foreach (var option in options)
            {
                if (option?.Prefab != null && option.Weight > 0f)
                {
                    totalWeight += option.Weight;
                }
            }

            if (totalWeight <= 0f)
            {
                return false;
            }

            var roll = (float)((random != null ? random.NextDouble() : 0d) * totalWeight);
            foreach (var option in options)
            {
                if (option?.Prefab == null || option.Weight <= 0f)
                {
                    continue;
                }

                roll -= option.Weight;
                if (roll <= 0f)
                {
                    prefab = option.Prefab;
                    return true;
                }
            }

            return false;
        }
    }
}