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

namespace ProjectM.Simulation
{
    /// <summary>
    /// LANTERN 4-socket predicted "fire". On the single fully-predicting pass of each tick, for every player
    /// it loops the 4 ability sockets: a socket whose Spark is set (AbilitySocket.SparkId != 0), whose own
    /// fire event (PlayerInput.Socket0..3) is set this tick, and whose per-socket SocketCooldown has elapsed
    /// fires that Spark. Runs in both worlds: the owning client predict-spawns a Projectile ghost (classified
    /// into the authoritative ghost by ProjectileClassificationSystem via Projectile.SpawnId), and the server
    /// spawns the replicated truth.
    ///
    /// The single AbilityRef/AbilityCooldown/EffectiveAbilityStats model was replaced by the socket kit:
    /// AbilitySocket (loadout), SocketCooldown (hot per-socket cooldown), EffectiveSocketStats (per-socket
    /// folded stats from StatRecomputeSystem). To stay under the 7-type SystemAPI.Query cap, the query holds
    /// only PlayerInput/PlayerFacing/LocalTransform/GhostOwner and reads the socket data by entity via
    /// BufferLookup/ComponentLookup (mirroring the BoonEffects lookup).
    ///
    /// SpawnId key (owner14 | socket2 | fireCount12 | fork4) reserves socket bits so two sockets firing the
    /// same-prefab projectile on one tick classify to DISTINCT ghosts (the review's NP-1/RS-1/DB-3 fix). The
    /// per-socket fire count comes from the replicated command buffer at ServerTick (not a local counter) so
    /// client and server agree. FORK fans extra predicted projectiles, each with a unique fork index in the
    /// low bits; PIERCE/CHAIN/PULL seed the server-only ProjectileEffectState.
    ///
    /// Determinism/idempotency: gated behind IsFirstTimeFullyPredictingTick so a rollback re-sim never
    /// double-spawns. No wall-clock, no System.Random. Predict-spawn is reserved for the Projectile archetype;
        /// Cone/Aoe/Hitscan apply their effect SERVER-ONLY (cooldown predicted on both worlds); the Aoe archetype
        /// instantiates its interpolated ghost server-only. Movement (Blink) falls through to BlinkSystem. Auto-target stays server-only + gamepad-only.
    /// </summary>
    [UpdateInGroup(typeof(PredictedSimulationSystemGroup))]
    [UpdateAfter(typeof(PlayerAimSystem))]
    [BurstCompile]
    public partial struct AbilityFireSystem : ISystem
    {
        // Server-only knockback stamp for the Cone (guarded + boss-immune).
        ComponentLookup<KnockbackState> m_KnockbackLookup;
        ComponentLookup<BossState> m_BossLookup;
        // Owner-replicated mechanic-changer boons, read by the player entity.
        ComponentLookup<BoonEffects> m_BoonEffectsLookup;
        // LANTERN socket kit, read by the player entity so the fire query stays at 4 type args (7-arg cap).
        BufferLookup<AbilitySocket> m_SocketLookup;
        ComponentLookup<SocketCooldown> m_SocketCdLookup;
        BufferLookup<EffectiveSocketStats> m_EffSocketLookup;
        // Prefab-membership + baked transform of an Aoe spawn prefab, read on the PREFAB entity to pick
        // ZoneEffect vs DecoyTag and preserve baked scale. RO; the actual Instantiate is server-only.
        ComponentLookup<ZoneEffect> m_ZoneLookup;
        ComponentLookup<DecoyTag> m_DecoyLookup;
        ComponentLookup<LocalTransform> m_LtLookup;
        // 07-21 G6: server-only scheduled Cone cleave (the MeleeCleavePending idiom on the socket kit).
        ComponentLookup<ConeContactPending> m_ConePendingLookup;

        /// <summary>~9 degree gap between adjacent Split-Shot projectiles (tunable).</summary>
        const float k_ForkSpreadRad = 0.157f;
        const float k_AoeCastAhead = 2.5f;      // world units ahead of the caster to drop an Aoe/zone/decoy ghost
        const float k_HitscanHalfWidth = 0.6f;  // hitscan beam half-width (world units)

        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<AbilityDatabase>();
            state.RequireForUpdate<NetworkTime>();
            m_KnockbackLookup = state.GetComponentLookup<KnockbackState>(isReadOnly: false);
            m_BossLookup = state.GetComponentLookup<BossState>(isReadOnly: true);
            m_BoonEffectsLookup = state.GetComponentLookup<BoonEffects>(isReadOnly: true);
            m_SocketLookup = state.GetBufferLookup<AbilitySocket>(isReadOnly: true);
            m_SocketCdLookup = state.GetComponentLookup<SocketCooldown>(isReadOnly: false);
            m_EffSocketLookup = state.GetBufferLookup<EffectiveSocketStats>(isReadOnly: true);
            m_ZoneLookup = state.GetComponentLookup<ZoneEffect>(isReadOnly: true);
            m_DecoyLookup = state.GetComponentLookup<DecoyTag>(isReadOnly: true);
            m_LtLookup = state.GetComponentLookup<LocalTransform>(isReadOnly: true);
            m_ConePendingLookup = state.GetComponentLookup<ConeContactPending>(isReadOnly: false);
        }

        [BurstCompile]
        public void OnUpdate(ref SystemState state)
        {
            var networkTime = SystemAPI.GetSingleton<NetworkTime>();
            if (!networkTime.IsFirstTimeFullyPredictingTick)
                return;
            var serverTick = networkTime.ServerTick;
            if (!serverTick.IsValid)
                return;

            var dbEntity = SystemAPI.GetSingletonEntity<AbilityDatabase>();
            var abilityPrefabs = SystemAPI.GetBuffer<AbilityPrefabElement>(dbEntity);
            var abilityDb = SystemAPI.GetSingleton<AbilityDatabase>();
            ref var adb = ref abilityDb.Value.Value;

            bool isServer = state.WorldUnmanaged.IsServer();
            // 07-21 G6: cone contact knob (0 = legacy immediate). Defaults() fallback matches release servers.
            var tcfg = SystemAPI.TryGetSingleton<TuningConfig>(out var tcv) ? tcv : TuningConfig.Defaults();
            uint coneContact = (uint)math.max(0f, tcfg.ConeContactTicks);
            m_KnockbackLookup.Update(ref state);
            m_BossLookup.Update(ref state);
            m_BoonEffectsLookup.Update(ref state);
            m_SocketLookup.Update(ref state);
            m_SocketCdLookup.Update(ref state);
            m_EffSocketLookup.Update(ref state);
            m_ZoneLookup.Update(ref state);
            m_DecoyLookup.Update(ref state);
            m_LtLookup.Update(ref state);
            m_ConePendingLookup.Update(ref state);

            // Server-only LIVING-enemy target set (auto-target assist + Cone cleave), collected once.
            var candidatePositions = new NativeList<float3>(Allocator.Temp);
            var coneTargets = new NativeList<Entity>(Allocator.Temp);
            var coneTargetPos = new NativeList<float3>(Allocator.Temp);
            if (isServer)
            {
                foreach (var (tx, th, te) in
                         SystemAPI.Query<RefRO<LocalTransform>, RefRO<Health>>().WithAll<EnemyTag>().WithEntityAccess())
                {
                    if (th.ValueRO.Current <= 0f) continue; // corpses are neither aim magnets nor cleave targets
                    candidatePositions.Add(tx.ValueRO.Position);
                    coneTargets.Add(te); coneTargetPos.Add(tx.ValueRO.Position);
                }
            }
            var candidates = candidatePositions.AsArray();

            var ecb = new EntityCommandBuffer(state.WorldUpdateAllocator);

            foreach (var (input, facing, xform, owner, entity) in
                     SystemAPI.Query<RefRO<PlayerInput>, RefRO<PlayerFacing>, RefRO<LocalTransform>, RefRO<GhostOwner>>()
                         .WithAll<Simulate>().WithDisabled<Dead>()
                         .WithEntityAccess())
            {
                if (!m_SocketLookup.HasBuffer(entity) || !m_SocketCdLookup.HasComponent(entity) || !m_EffSocketLookup.HasBuffer(entity))
                    continue;
                var sockets = m_SocketLookup[entity];
                var effSockets = m_EffSocketLookup[entity];
                var cd = m_SocketCdLookup[entity]; // struct copy; written back after mutation

                BoonEffects bfx = m_BoonEffectsLookup.HasComponent(entity) ? m_BoonEffectsLookup[entity] : default;
                bool pull = (bfx.Flags & BoonFlag.KnockToPull) != 0;

                // 07-21 G6 (review wf_98bf1268): fire a DUE scheduled cone BEFORE the cast loop (the
                // MeleeCleavePending idiom — wrap-safe elapsed compare, tick-batch-proof, consumed by zeroing).
                // Server-only state; the client copy stays zero (contact cues are presentation-side). The armed
                // socket is RE-VALIDATED (SetClass can swap the loadout mid-flight) — consume-drop on mismatch.
                bool hasConePending = m_ConePendingLookup.HasComponent(entity);
                if (isServer && hasConePending)
                {
                    var pend = m_ConePendingLookup[entity];
                    if (pend.ResolveTick != 0u && !new NetworkTick(pend.ResolveTick).IsNewerThan(serverTick))
                    {
                        if (pend.Socket < sockets.Length && pend.Socket < effSockets.Length
                            && adb.TryGetAbility(sockets[pend.Socket].SparkId, out var pendDef)
                            && pendDef.Archetype == (byte)AbilityArchetype.Cone)
                        {
                            float2 pFace = FacingMath.ResolveAim(input.ValueRO.Aim, facing.ValueRO.Direction);
                            FireCone(xform.ValueRO.Position, pFace, effSockets[pend.Socket], owner.ValueRO.NetworkId,
                                     serverTick, pull, coneTargets, coneTargetPos, ref ecb, ref m_KnockbackLookup, m_BossLookup);
                        }
                        m_ConePendingLookup[entity] = default; // consume (drop on mismatch)
                    }
                }

                // Replicated command buffer (windup resolve + per-socket fire count for the SpawnId + scheme for aim assist).
                var inputBuffer = SystemAPI.GetBuffer<InputBufferData<PlayerInput>>(entity);

                bool cdDirty = false;
                int socketCount = math.min(SocketId.Count, sockets.Length);
                for (int sk = 0; sk < socketCount; sk++)
                {
                    byte sparkId = sockets[sk].SparkId;
                    if (sparkId == 0) continue;                       // empty socket

                    EffectiveSocketStats es = sk < effSockets.Length ? effSockets[sk] : default;
                    byte archetype = adb.TryGetAbility(sparkId, out var adef) ? adef.Archetype : (byte)AbilityArchetype.Projectile;

                    // MANUAL-AIM WINDUP (Build Spec §4/DB-6): resolve when the command WindupTicks ago had this socket
                    // set, so the resolve tick is a pure fn of replicated data on both worlds (no local fireAtTick that
                    // diverges under reprediction). fireCount comes from THAT command; the spawn uses the CURRENT tick's
                    // aim/position. WindupTicks == 0 = instant. A history gap (older than the buffer window) = no-fire.
                    NetworkTick resolveTick = serverTick;
                    if (adef.WindupTicks > 0)
                    {
                        uint riNow = serverTick.TickIndexForValidTick;
                        if (riNow <= (uint)adef.WindupTicks) continue;   // not enough history yet -> no-fire
                        resolveTick = new NetworkTick(riNow - (uint)adef.WindupTicks);
                    }
                    if (!inputBuffer.GetDataAtTick(resolveTick, out var applied)) continue; // history gap -> no-fire
                    // 07-21 AUTO-RECAST FIX (live repro: one press → a recast at EVERY cooldown reopen, forever):
                    // the netcode copy layer ACCUMULATES InputEvent counts on the wire — a raw buffer entry's
                    // IsSet means "ever pressed", not "pressed THIS tick" (only the decoded COMPONENT is
                    // delta-corrected). A press AT resolveTick = a count STEP vs the previous tick's command
                    // (Netcode's own decode semantics). Missing previous command → no-fire (dropping a
                    // buffer-edge windup press beats an infinite recast loop).
                    var prevTick = resolveTick;
                    prevTick.Decrement();
                    if (!inputBuffer.GetDataAtTick(prevTick, out var prevCmd)) continue;
                    if (applied.InternalInput.GetSocket(sk).Count == prevCmd.InternalInput.GetSocket(sk).Count)
                        continue;                                                       // no NEW press at the resolve tick

                    // Per-socket cooldown gate (0 = ready).
                    uint nextFireRaw = cd.Get(sk);
                    if (nextFireRaw != 0)
                    {
                        var nextTick = new NetworkTick(nextFireRaw);
                        if (nextTick.IsValid && nextTick.IsNewerThan(serverTick)) continue;
                    }

                    // CONE (SpecialSlam): no projectile ghost. Predict the cooldown on both worlds; server-only cleave.
                    // 07-21 G6 (review wf_98bf1268): with the contact knob armed, damage lands at the slam's visual
                    // contact via ConeContactPending (schedule-and-consume); knob 0 / missing slot = legacy at-fire.
                    if (archetype == (byte)AbilityArchetype.Cone)
                    {
                        if (isServer)
                        {
                            if (coneContact > 0u && hasConePending)
                            {
                                // EARLY-FLUSH a still-armed pending (re-validated) so no knob combination can lose a slam.
                                var armed = m_ConePendingLookup[entity];
                                if (armed.ResolveTick != 0u
                                    && armed.Socket < sockets.Length && armed.Socket < effSockets.Length
                                    && adb.TryGetAbility(sockets[armed.Socket].SparkId, out var flushDef)
                                    && flushDef.Archetype == (byte)AbilityArchetype.Cone)
                                {
                                    float2 fFace = FacingMath.ResolveAim(input.ValueRO.Aim, facing.ValueRO.Direction);
                                    FireCone(xform.ValueRO.Position, fFace, effSockets[armed.Socket], owner.ValueRO.NetworkId,
                                             serverTick, pull, coneTargets, coneTargetPos, ref ecb, ref m_KnockbackLookup, m_BossLookup);
                                }
                                m_ConePendingLookup[entity] = new ConeContactPending
                                {
                                    ResolveTick = TickUtil.NonZero(serverTick.TickIndexForValidTick + coneContact),
                                    Socket = (byte)sk,
                                };
                            }
                            else
                            {
                                // Legacy immediate (knob 0, or a plain test world without the baked pending slot).
                                float2 cFace = FacingMath.ResolveAim(input.ValueRO.Aim, facing.ValueRO.Direction); // manual-aim (07-15): cursor wins; facing fallback = resting gamepad stick
                                FireCone(xform.ValueRO.Position, cFace, es, owner.ValueRO.NetworkId,
                                         serverTick, pull, coneTargets, coneTargetPos, ref ecb, ref m_KnockbackLookup, m_BossLookup);
                            }
                        }
                        cd.Set(sk, TickUtil.NonZero(serverTick.TickIndexForValidTick + (uint)math.max(1, es.CooldownTicks)));
                        cdDirty = true;
                        continue;
                    }
                    // AOE / ZONE / DECOY (decoy-wisp, vortex, light-zone): predict the cooldown on BOTH worlds;
                    // instantiate the interpolated ownerless ghost SERVER-ONLY -- the client must NEVER instantiate it (Build Spec §5).
                    if (archetype == (byte)AbilityArchetype.Aoe)
                    {
                        if (isServer)
                        {
                            Entity aoePrefab = Entity.Null;
                            for (int i = 0; i < abilityPrefabs.Length; i++)
                                if (abilityPrefabs[i].Id == sparkId) { aoePrefab = abilityPrefabs[i].Prefab; break; }
                            if (aoePrefab != Entity.Null)
                            {
                                float2 aFace = FacingMath.ResolveAim(input.ValueRO.Aim, facing.ValueRO.Direction); // manual-aim (07-15)
                                float3 spawnPos = xform.ValueRO.Position + new float3(aFace.x, 0f, aFace.y) * k_AoeCastAhead;
                                spawnPos.y = xform.ValueRO.Position.y;
                                uint expire = adef.DurationTicks > 0
                                    ? TickUtil.NonZero(serverTick.TickIndexForValidTick + (uint)adef.DurationTicks) : 0u;
                                var bakedLt = m_LtLookup.HasComponent(aoePrefab) ? m_LtLookup[aoePrefab] : LocalTransform.Identity;
                                var effect = ecb.Instantiate(aoePrefab);
                                ecb.SetComponent(effect, bakedLt.WithPosition(spawnPos));
                                if (m_ZoneLookup.HasComponent(aoePrefab))
                                    ecb.SetComponent(effect, new ZoneEffect
                                    {
                                        CasterNetworkId = owner.ValueRO.NetworkId,
                                        Radius = math.max(0.1f, es.Range),
                                        DamagePerPulse = es.Damage,
                                        NextTick = 0u,               // lazy-stamped born-correct by ZonePulseSystem (never storm-fires)
                                        ExpireTick = expire,
                                        Flags = m_ZoneLookup[aoePrefab].Flags, // Vortex bit baked on the prefab
                                    });
                                else if (m_DecoyLookup.HasComponent(aoePrefab))
                                    ecb.SetComponent(effect, new DecoyTag { ExpireTick = expire });
                            }
                        }
                        cd.Set(sk, TickUtil.NonZero(serverTick.TickIndexForValidTick + (uint)math.max(1, es.CooldownTicks)));
                        cdDirty = true;
                        continue;
                    }
                    // HITSCAN: no ghost on either world; predict the cooldown both worlds; server-only swept-beam damage.
                    // (No Phase-1 Spark uses Hitscan yet; the branch completes the archetype dispatch per Build Spec §5.)
                    if (archetype == (byte)AbilityArchetype.Hitscan)
                    {
                        if (isServer)
                        {
                            float2 hFace = FacingMath.ResolveAim(input.ValueRO.Aim, facing.ValueRO.Direction); // manual-aim (07-15)
                            float hRange = math.max(0.1f, es.Range);
                            uint hStamp = TickUtil.NonZero(serverTick.TickIndexForValidTick);
                            for (int hi = 0; hi < coneTargets.Length; hi++)
                            {
                                float2 rel = coneTargetPos[hi].xz - xform.ValueRO.Position.xz;
                                float t = math.dot(rel, hFace);
                                if (t < 0f || t > hRange) continue;
                                float2 perp = rel - hFace * t;
                                if (math.lengthsq(perp) > k_HitscanHalfWidth * k_HitscanHalfWidth) continue;
                                ecb.AppendToBuffer(coneTargets[hi], new DamageEvent
                                {
                                    Amount = es.Damage,
                                    SourceNetworkId = owner.ValueRO.NetworkId,
                                    SourceTick = hStamp,
                                });
                            }
                        }
                        cd.Set(sk, TickUtil.NonZero(serverTick.TickIndexForValidTick + (uint)math.max(1, es.CooldownTicks)));
                        cdDirty = true;
                        continue;
                    }
                    // MOVEMENT (Blink) + any other non-Projectile: fall through (BlinkSystem owns the movement socket's cooldown row).
                    if (archetype != (byte)AbilityArchetype.Projectile)
                        continue;

                    // Resolve the projectile ghost prefab for this Spark id.
                    Entity prefab = Entity.Null;
                    for (int i = 0; i < abilityPrefabs.Length; i++)
                    {
                        if (abilityPrefabs[i].Id == sparkId) { prefab = abilityPrefabs[i].Prefab; break; }
                    }
                    if (prefab == Entity.Null) continue;

                    uint socketFireCount = applied.InternalInput.GetSocket(sk).Count;

                    // Manual-aim (07-15): the projectile (and the server's auto-target seed below) fires along the
                    // CURRENT tick's replicated Aim — PlayerFacing is body-yaw only under the SoD facing model.
                    float2 rawAim = FacingMath.ResolveAim(input.ValueRO.Aim, facing.ValueRO.Direction);

                    // Client fires along raw aim; only the server applies the gamepad auto-target assist.
                    float2 dir = rawAim;
                    if (isServer && es.AutoTargetRange > 0f && applied.InternalInput.Scheme == InputSchemeId.Gamepad)
                    {
                        dir = AutoTarget.Resolve(xform.ValueRO.Position, rawAim, es.AutoTargetRange, es.AutoTargetConeRadians, candidates);
                    }

                    byte pierce = bfx.Pierce;
                    byte chain = bfx.Chain;
                    byte projFlags = (byte)((pull ? ProjectileEffectFlag.Pull : 0) | adef.EffectFlags);
                    int shots = 1 + math.min((int)bfx.Fork, 8);

                    for (int s = 0; s < shots; s++)
                    {
                        float offset = (s - (shots - 1) * 0.5f) * k_ForkSpreadRad;
                        math.sincos(offset, out float sa, out float ca);
                        float2 sdir = math.normalize(new float2(dir.x * ca - dir.y * sa, dir.x * sa + dir.y * ca));

                        // SpawnId: owner(14) | socket(2) | fireCount(12) | fork(4) -- see ProjectileSpawnId.
                        uint spawnId = ProjectileSpawnId.Pack(owner.ValueRO.NetworkId, sk, socketFireCount, s);

                        var projectile = ecb.Instantiate(prefab);
                        float3 planarDir = new float3(sdir.x, 0f, sdir.y);
                        float3 spawnPos = xform.ValueRO.Position + planarDir * 0.6f;
                        spawnPos.y = xform.ValueRO.Position.y;
                        quaternion rot = quaternion.LookRotationSafe(planarDir, math.up());

                        ecb.SetComponent(projectile, LocalTransform.FromPositionRotation(spawnPos, rot));
                        ecb.SetComponent(projectile, new GhostOwner { NetworkId = owner.ValueRO.NetworkId });
                        ecb.SetComponent(projectile, new Projectile
                        {
                            Direction = sdir,
                            SpawnId = spawnId,
                            Speed = es.ProjectileSpeed,
                            Damage = es.Damage,
                            Range = es.Range,
                            DistanceTravelled = 0f,
                        });
                        ecb.SetComponent(projectile, new ProjectileEffectState
                        {
                            PierceRemaining = pierce,
                            ChainRemaining = chain,
                            Flags = projFlags,
                        });
                    }

                    cd.Set(sk, TickUtil.NonZero(serverTick.TickIndexForValidTick + (uint)math.max(1, es.CooldownTicks)));
                    cdDirty = true;
                }

                if (cdDirty) m_SocketCdLookup[entity] = cd;
            }

            ecb.Playback(state.EntityManager);
            ecb.Dispose();
            candidatePositions.Dispose();
            coneTargets.Dispose();
            coneTargetPos.Dispose();
        }

        /// <summary>Resolve one Cone-socket cleave from LIVE state — shared by the legacy immediate path, the
        /// due-fire and the early-flush (review wf_98bf1268: ONE resolve path, no drift). Server-only callers.</summary>
        static void FireCone(float3 casterPos, float2 face, in EffectiveSocketStats es, int ownerNetId,
                             NetworkTick serverTick, bool pull, in NativeList<Entity> coneTargets,
                             in NativeList<float3> coneTargetPos, ref EntityCommandBuffer ecb,
                             ref ComponentLookup<KnockbackState> knockbackLookup, in ComponentLookup<BossState> bossLookup)
        {
            float cRange = math.max(0.1f, es.Range);
            float cCosHalf = math.cos(math.clamp(es.AutoTargetConeRadians, 0.01f, 3.14159f));
            uint cStamp = TickUtil.NonZero(serverTick.TickIndexForValidTick);
            for (int ci = 0; ci < coneTargets.Length; ci++)
            {
                if (!MeleeConeMath.InCone(casterPos, face, cRange, cCosHalf, coneTargetPos[ci]))
                    continue;
                ecb.AppendToBuffer(coneTargets[ci], new DamageEvent
                {
                    Amount = es.Damage,
                    SourceNetworkId = ownerNetId,
                    SourceTick = cStamp,
                });
                KnockbackUtil.Stamp(ref knockbackLookup, bossLookup, coneTargets[ci],
                    casterPos, coneTargetPos[ci], face, Tuning.KnockbackSpeed,
                    TickUtil.NonZero(serverTick.TickIndexForValidTick + (uint)math.max(1, Tuning.KnockbackDurationTicks)), pull);
            }
        }
    }
}