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
    /// CharacterStatsRef / the AbilitySocket loadout) with its replicated StatModifier buffer into the
    /// EffectiveCharacterStats / EffectiveSocketStats components - every predicted tick, on both worlds.
    /// (The legacy single AbilityRef -> EffectiveAbilityStats fold is deleted — LANTERN purge.)
    ///
    /// 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 (charRef, mods, effChar) in
                     SystemAPI.Query<RefRO<CharacterStatsRef>, DynamicBuffer<StatModifier>,
                             RefRW<EffectiveCharacterStats>>()
                         .WithAll<Simulate>())
            {
                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),
                    };
                }
            }

            // LANTERN Phase 1 (Step 1b): per-socket fold - each socket's Spark base folded with the SHARED
            // StatModifier band into its EffectiveSocketStats row (uniform band; per-Spark warping is Phase 4).
            // Separate query so this system stays under the 7-arg cap.
            foreach (var (sockets, socketMods, effSockets) in
                     SystemAPI.Query<DynamicBuffer<AbilitySocket>, DynamicBuffer<StatModifier>, DynamicBuffer<EffectiveSocketStats>>()
                         .WithAll<Simulate>())
            {
                var effBuf = effSockets; // copy the buffer handle to a mutable local (foreach var is readonly -> CS1654)
                for (int i = 0; i < SocketId.Count && i < sockets.Length && i < effBuf.Length; i++)
                {
                    if (db.TryGetAbility(sockets[i].SparkId, out var sa))
                    {
                        effBuf[i] = new EffectiveSocketStats
                        {
                            Damage = StatMath.Apply(sa.Damage, StatTarget.Damage, socketMods),
                            ProjectileSpeed = StatMath.Apply(sa.ProjectileSpeed, StatTarget.ProjectileSpeed, socketMods),
                            Range = StatMath.Apply(sa.Range, StatTarget.Range, socketMods),
                            AutoTargetRange = StatMath.Apply(sa.AutoTargetRange, StatTarget.AutoTargetRange, socketMods),
                            AutoTargetConeRadians = StatMath.Apply(sa.AutoTargetConeRadians, StatTarget.AutoTargetConeRadians, socketMods),
                            CooldownTicks = (int)math.round(StatMath.Apply(sa.CooldownTicks, StatTarget.CooldownTicks, socketMods)),
                        };
                    }
                    else
                    {
                        effBuf[i] = default;
                    }
                }
            }
        }
    }
}