using Unity.Burst;
using Unity.Entities;
using Unity.Mathematics;
using Unity.NetCode;

namespace ProjectM.Simulation
{
    /// <summary>
    /// Folds each modifiable entity's authored base stats (from the AbilityDatabase blob, keyed by
    /// AbilityRef / CharacterStatsRef) with its replicated StatModifier buffer into the
    /// EffectiveAbilityStats / EffectiveCharacterStats components - every predicted tick, on both worlds.
    ///
    /// Runs at the head of the predicted group (UpdateBefore PlayerAimSystem;
    /// AbilityFireSystem runs after PlayerAimSystem, so it sees fresh values too). Recompute is
    /// unconditional every tick: it is a pure function of (blob base + replicated buffer), both of which
    /// are restored on rollback, so predicted and server results always agree. A dirty-flag / change
    /// filter would be WRONG here - the Effective* components are NOT in the ghost snapshot and would go
    /// stale across reprediction.
    /// </summary>
    [UpdateInGroup(typeof(PredictedSimulationSystemGroup))]
    [UpdateBefore(typeof(PlayerAimSystem))]
    [BurstCompile]
    public partial struct StatRecomputeSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<AbilityDatabase>();
        }

        [BurstCompile]
        public void OnUpdate(ref SystemState state)
        {
            var database = SystemAPI.GetSingleton<AbilityDatabase>();
            ref var db = ref database.Value.Value;

            foreach (var (abilityRef, charRef, mods, effAbility, effChar) in
                     SystemAPI.Query<RefRO<AbilityRef>, RefRO<CharacterStatsRef>, DynamicBuffer<StatModifier>,
                             RefRW<EffectiveAbilityStats>, RefRW<EffectiveCharacterStats>>()
                         .WithAll<Simulate>())
            {
                if (db.TryGetAbility(abilityRef.ValueRO.Id, out var a))
                {
                    effAbility.ValueRW = new EffectiveAbilityStats
                    {
                        Damage = StatMath.Apply(a.Damage, StatTarget.Damage, mods),
                        ProjectileSpeed = StatMath.Apply(a.ProjectileSpeed, StatTarget.ProjectileSpeed, mods),
                        Range = StatMath.Apply(a.Range, StatTarget.Range, mods),
                        AutoTargetRange = StatMath.Apply(a.AutoTargetRange, StatTarget.AutoTargetRange, mods),
                        AutoTargetConeRadians = StatMath.Apply(a.AutoTargetConeRadians, StatTarget.AutoTargetConeRadians, mods),
                        CooldownTicks = (int)math.round(StatMath.Apply(a.CooldownTicks, StatTarget.CooldownTicks, mods)),
                    };
                }

                if (db.TryGetCharacter(charRef.ValueRO.Id, out var c))
                {
                    effChar.ValueRW = new EffectiveCharacterStats
                    {
                        MoveSpeed = StatMath.Apply(c.MoveSpeed, StatTarget.MoveSpeed, mods),
                        TurnRateRadiansPerSec = StatMath.Apply(c.TurnRateRadiansPerSec, StatTarget.TurnRate, mods),
                        MaxHealth = StatMath.Apply(c.MaxHealth, StatTarget.MaxHealth, mods),
                    };
                }
            }
        }
    }
}