using Unity.Collections;
using Unity.Entities;

namespace ProjectM.Simulation
{
    /// <summary>
    /// Pure, deterministic folding of a StatModifier set into an effective value for one StatTarget:
    /// effective = (base + sum flat) * (1 + sum percentAdd) * product(1 + percentMult).
    /// Order-independent within each op class, Burst-friendly, and unit-tested like AutoTarget.Resolve.
    /// Returns the raw fold; consumers clamp domain bounds (e.g. cooldown >= 1 tick).
    /// </summary>
    public static class StatMath
    {
        public static float Apply(float baseValue, StatTarget target, in DynamicBuffer<StatModifier> mods)
        {
            return Apply(baseValue, target, mods.AsNativeArray());
        }

        public static float Apply(float baseValue, StatTarget target, in NativeArray<StatModifier> mods)
        {
            float flat = 0f;
            float percentAdd = 0f;
            float percentMult = 1f;
            byte t = (byte)target;

            for (int i = 0; i < mods.Length; i++)
            {
                var m = mods[i];
                if (m.Target != t)
                    continue;
                switch ((ModOp)m.Op)
                {
                    case ModOp.Flat: flat += m.Value; break;
                    case ModOp.PercentAdd: percentAdd += m.Value; break;
                    case ModOp.PercentMult: percentMult *= 1f + m.Value; break;
                }
            }

            return (baseValue + flat) * (1f + percentAdd) * percentMult;
        }
    }
}