using System.Buffers.Binary;
using Ananta.SDK.Network;
using Ananta.SDK.Serialization;
using Ananta.Server.Configuration;
using Ananta.Server.Protocol.Client4229938;
using Ananta.Server.RpcTypes.Client4229938;
using GameMethods = Ananta.Server.RpcTypes.Client4229938.Methods.Game;

namespace Ananta.Server.Handlers.Game;

// T1-16 载具骇入 — ported from donor_7k GameRouter.VehicleControls.cs.
// Client actions 1..6 arrive through AskHackVehicle and are forwarded to the stock
// vehicle AI as SyncAssignVehicleAITask. Action 0 is an internal stop, never client-sent.
internal sealed partial class GameRouter
{
    // Client actions 1..6. Action 0 is an explicit GM-only stop, not a client hack.
    internal static bool TryDecodeVehicleControl(byte[] body, out ulong vehicleId, out byte action, out ulong targetId)
    {
        vehicleId = targetId = 0;
        action = 0;
        if (body.Length < 10) return false;
        var id = BinaryPrimitives.ReadUInt64LittleEndian(body);
        var kind = body[8];
        if (id == 0 || kind is < 1 or > 6) return false;
        ulong target = 0;
        if (kind == 5)
        {
            // Native WriteVehicleHackChaseTargetParameter_Check: type mark 2,
            // u64 target, nullable uint[] (00 or FF + biased Int7 + values).
            if (body.Length < 19 || body[9] != 2) return false;
            target = BinaryPrimitives.ReadUInt64LittleEndian(body.AsSpan(10));
            if (target == 0 || target == id) return false;
            if (body[18] == 0)
            {
                if (body.Length != 19) return false;
            }
            else
            {
                // Bound the array before parsing. Buff IDs are never applied from client input.
                if (body[18] != 255 || body.Length < 20 || body[19] is < 1 or > 17
                    || body.Length != 20 + (body[19] - 1) * 4) return false;
            }
        }
        else if (body.Length != 10 || body[9] != 0) return false;
        vehicleId = id; action = kind; targetId = target;
        return true;
    }

    internal static bool IsValidVehicleChaseTarget(VehicleRuntimeState runtime, VehicleRecord vehicle, ulong targetId)
    {
        if (targetId == vehicle.EntityId || !runtime.Vehicles.TryGetValue(targetId, out var target)
            || !target.AetherRegistered || !target.Interactable) return false;
        var dx = target.Position.X - vehicle.Position.X;
        var dy = target.Position.Y - vehicle.Position.Y;
        var dz = target.Position.Z - vehicle.Position.Z;
        var distanceSquared = dx * dx + dy * dy + dz * dz;
        return float.IsFinite(distanceSquared) && distanceSquared <= 100f * 100f;
    }

    internal static Vec3 VehicleReverseDestination(Vec3 position, float facing)
    {
        var yaw = facing * MathF.PI / 180f;
        // Unity forward is (sin(yaw), 0, cos(yaw)); retreat 6m, not a teleport.
        return new(position.X - MathF.Sin(yaw) * 6f, position.Y, position.Z - MathF.Cos(yaw) * 6f);
    }

    internal static byte[] BuildVehicleControlPacket(ulong id, ulong token, byte action, ulong target, Vec3 position, float facing)
    {
        var tail = new GameMethods.VehicleTaskTail4229938 { Token = token };
        byte[] Pack<T>(T parameters) where T : new() => UxSerializer.Serialize(
            new GameMethods.AssignVehicleControl4229938<T> { VehicleUId = id, Parameters = parameters });
        switch (action)
        {
            case 0:
                tail.DefaultSpeed = 0f;
                return Pack(new GameMethods.VehicleStopParameters4229938 { Base = tail });
            case 1:
                // Keep the in-game verified accelerate packet byte-for-byte unchanged.
                return UxSerializer.Serialize(new GameMethods.AssignVehicleRush4229938
                    { VehicleUId = id, Parameters = new() { Token = token } });
            case 2:
            case 3:
                return Pack(new GameMethods.VehicleTurnParameters4229938 { TurnAction = (byte)(action - 2), Base = tail });
            case 4:
                var destination = VehicleReverseDestination(position, facing);
                tail.DefaultSpeed = 4f;
                tail.DrivingFlags = 1 | 1024 | 16777216; // StopForCars, DriveInReverse, ForceStraightLine.
                return Pack(new GameMethods.VehicleCruiseParameters4229938
                    { TargetPointList = [new(destination.X, destination.Y, destination.Z)], Base = tail });
            case 5:
                if (target == 0 || target == id) throw new ArgumentException("Invalid chase target");
                return Pack(new GameMethods.VehicleChaseParameters4229938 { TargetUid = target, Base = tail });
            case 6:
                // Native TaskFactory initial speed provides the momentum needed to drift from rest.
                tail.InitSpeed = 8f;
                return Pack(new GameMethods.VehicleDriftParameters4229938 { Base = tail });
            default: throw new ArgumentOutOfRangeException(nameof(action));
        }
    }

    internal static string VehicleControlName(byte action) => action switch
    {
        0 => "停止", 1 => "加速", 2 => "左冲", 3 => "右冲", 4 => "后冲/倒车", 5 => "追赶目标车辆", 6 => "漂移", _ => "未知",
    };

    internal static bool CanStopHackVehicle(VehicleRuntimeState runtime, VehicleRecord vehicle, ulong expectedToken = 0)
        => vehicle.ControllerPid == Profile.PlayerPid && vehicle.HackTaskToken != 0
            && vehicle.TaskToken == vehicle.HackTaskToken
            && (expectedToken == 0 || expectedToken == vehicle.HackTaskToken)
            && runtime.CurrentVehicleId != vehicle.EntityId && !vehicle.IsDriving
            && runtime.StoryEnterVehicleId != vehicle.EntityId
            && vehicle.SeatOccupants.Count == 0 && vehicle.SeatReservations.Count == 0;

    internal static async Task<(bool Ok, string Message)> ExecuteVehicleControlAsync(
        TcpSession session, ulong vehicleId, byte action, ulong targetId, ulong expectedToken = 0)
    {
        if (action > 6) return (false, "不支持的车辆动作");
        var state = GetStateIfExists(session);
        if (state is null) return (false, "角色尚未进入场景");
        Vec3 player;
        lock (state.SyncRoot)
        {
            if (!state.HasLastReportedPlayerTransform) return (false, "尚未收到角色位置");
            player = state.LastReportedPlayerPosition;
        }
        var runtime = GetVehicleRuntimeState(session);
        await runtime.HackDispatchGate.WaitAsync();
        try
        {
            ulong token;
            byte[] packet;
            VehicleRecord? trafficTarget = null;
            lock (runtime.SyncRoot)
            {
                if (!runtime.Vehicles.TryGetValue(vehicleId, out var vehicle)) return (false, "车辆不在当前服务端场景记录中");
                if (action == 0)
                {
                    if (!CanStopHackVehicle(runtime, vehicle, expectedToken)) return (false, "没有可停止的空车骇入任务，或任务已被替换");
                }
                else
                {
                    if (!CanRushVehicle(runtime, vehicle, player.X, player.Y, player.Z, DateTime.UtcNow)
                        || runtime.StoryEnterVehicleId == vehicleId || !float.IsFinite(vehicle.Facing))
                    {
                        // ★ 诊断（2026-09-22）：返回给客户端的这句话把六种原因合并成一句，无法定位。
                        //   用户实测「很靠近车按加速也无效」，已排除「距离」这个猜测，
                        //   所以把每个子条件的实际值打出来，跑一次就能定性（不再靠猜）。
                        var ddx = vehicle.Position.X - player.X;
                        var ddy = vehicle.Position.Y - player.Y;
                        var ddz = vehicle.Position.Z - player.Z;
                        session.Log.Warn($"[VEHICLE-HACK] rush-deny entity={vehicleId} " +
                            $"dist={MathF.Sqrt(ddx * ddx + ddy * ddy + ddz * ddz):F1}m " +
                            $"aether={vehicle.AetherRegistered} interactable={vehicle.Interactable} " +
                            $"ctrl={vehicle.ControllerPid} cur={runtime.CurrentVehicleId} " +
                            $"occ={vehicle.SeatOccupants.Count} res={vehicle.SeatReservations.Count} " +
                            $"driving={vehicle.IsDriving} busy={vehicle.HackBusyUntilUtc > DateTime.UtcNow} " +
                            $"storyEnter={runtime.StoryEnterVehicleId} facing={vehicle.Facing} " +
                            $"player=({player.X:F1},{player.Y:F1},{player.Z:F1}) " +
                            $"car=({vehicle.Position.X:F1},{vehicle.Position.Y:F1},{vehicle.Position.Z:F1})");
                        return (false, "车辆未登记、被占用、超出30米、其他玩家主控或仍在冷却");
                    }
                    if (action == 5 && !IsValidVehicleChaseTarget(runtime, vehicle, targetId))
                        return (false, "请选择100米内另一辆已登记的汽车作为追赶目标");
                }
                token = unchecked((ulong)IdCounterStore.Next(VehicleTokenCounter, VehicleTokenFloor));
                packet = BuildVehicleControlPacket(vehicleId, token, action, targetId, vehicle.Position, vehicle.Facing);
                if (action == 0)
                {
                    vehicle.TaskToken = vehicle.HackTaskToken = token;
                    vehicle.HackTaskStatus = 0;
                }
                else if (!TryPrepareVehicleRush(runtime, vehicle, player.X, player.Y, player.Z, DateTime.UtcNow, token))
                    return (false, "车辆状态已变化，请重新尝试");
                vehicle.HackBusyUntilUtc = DateTime.UtcNow.AddSeconds(action == 6 ? 3 : 2);
                // out var 出不了 lock 块，用外层变量把记录带出去给下面的摘出逻辑。
                if (vehicle.IsTraffic)
                    trafficTarget = vehicle;
            }

            // ★ 车流车（T3-7）：玩家接管前必须先摘出车道流。
            //   否则服务端每 50ms 的 SyncAetherAIVehicleLaneDatas 会持续覆盖里程，
            //   把刚下发的 AI 任务瞬间拽回去 —— 就是「能显示骇入但加速没反应」。
            //   必须在 SyncAssignVehicleAITask 之前做，且幂等（非车流车不会进到这里）。
            if (trafficTarget is not null)
                await DetachTrafficVehicleFromLaneAsync(session, trafficTarget);

            await session.NotifyAsync(MethodId.SyncChangeVehicleController, UxSerializer.Serialize(
                new GameMethods.SyncChangeVehicleController4229938
                    { vehicleInstanceId = vehicleId, controllerPid = Profile.PlayerPid }), CancellationToken.None);
            session.Log.Info($"[VEHICLE-HACK] physics host assigned entity={vehicleId} pid={Profile.PlayerPid} token={token}");
            await session.NotifyAsync(MethodId.SyncAssignVehicleAITask, packet, CancellationToken.None);
            session.Log.Info($"[VEHICLE-HACK] control sent action={action} name={VehicleControlName(action)} entity={vehicleId} target={targetId} token={token} bytes={packet.Length}");
            if (action is 4 or 5 or 6)
                _ = StopVehicleControlAfterAsync(session, vehicleId, token, action == 5 ? 10_000 : action == 4 ? 4_000 : 3_000);
            return (true, $"已下发{VehicleControlName(action)}：车辆 {vehicleId}，任务 {token}；实际效果请在游戏内确认");
        }
        finally { runtime.HackDispatchGate.Release(); }
    }

    private static async Task StopVehicleControlAfterAsync(TcpSession session, ulong id, ulong token, int milliseconds)
    {
        try
        {
            await Task.Delay(milliseconds);
            // Token, current scene membership, seats and ownership are revalidated
            // inside the same dispatch gate. Never stop a newer task or a player's car.
            await ExecuteVehicleControlAsync(session, id, 0, 0, token);
        }
        catch (Exception ex) { session.Log.Warn($"[VEHICLE-HACK] bounded stop ended entity={id}: {ex.Message}"); }
    }
}