CypherCore/Source/Game/Movement/MotionMaster.cs

// Copyright (c) CypherCore <http://github.com/CypherCore> All rights reserved.
// Licensed under the GNU GENERAL PUBLIC LICENSE. See LICENSE file in the project root for full license information.

using Framework.Constants;
using Game.AI;
using Game.DataStorage;
using Game.Entities;
using Game.Scripting.v2;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;

namespace Game.Movement
{
    class MovementGeneratorComparator : IComparer<MovementGenerator>
    {
        public int Compare(MovementGenerator a, MovementGenerator b)
        {
            if (a.Equals(b))
                return 0;

            if (a.Mode > b.Mode)
                return 1;
            else if (a.Mode == b.Mode)
                return a.Priority.CompareTo(b.Priority);

            return -1;
        }
    }

    public struct MovementGeneratorInformation
    {
        public MovementGeneratorType Type;
        public ObjectGuid TargetGUID;
        public string TargetName;

        public MovementGeneratorInformation(MovementGeneratorType type, ObjectGuid targetGUID, string targetName = "")
        {
            Type = type;
            TargetGUID = targetGUID;
            TargetName = targetName;
        }
    }

    class DelayedAction
    {
        Action Action;
        Func<bool> Validator;
        MotionMasterDelayedActionType Type;

        public DelayedAction(Action action, Func<bool> validator, MotionMasterDelayedActionType type)
        {
            Action = action;
            Validator = validator;
            Type = type;
        }

        public DelayedAction(Action action, MotionMasterDelayedActionType type)
        {
            Action = action;
            Validator = () => true;
            Type = type;
        }

        public void Resolve()
        {
            if (Validator())
                Action();
        }
    }

    public class MotionMaster
    {
        public const double gravity = 19.29110527038574;
        public const float SPEED_CHARGE = 42.0f;
        static IdleMovementGenerator staticIdleMovement = new();
        static uint splineId;

        Unit _owner { get; }
        MovementGenerator _defaultGenerator { get; set; }
        SortedSet<MovementGenerator> _generators { get; } = new(new MovementGeneratorComparator());

        MultiMap<uint, MovementGenerator> _baseUnitStatesMap { get; } = new();
        Queue<DelayedAction> _delayedActions { get; } = new();
        MotionMasterFlags _flags { get; set; }

        public MotionMaster(Unit unit)
        {
            _owner = unit;
            _flags = MotionMasterFlags.InitializationPending;
        }

        public void Initialize()
        {
            if (HasFlag(MotionMasterFlags.InitializationPending))
                return;

            if (HasFlag(MotionMasterFlags.Update))
            {
                _delayedActions.Enqueue(new DelayedAction(() => Initialize(), MotionMasterDelayedActionType.Initialize));
                return;
            }

            DirectInitialize();
        }

        public void InitializeDefault()
        {
            Add(AI.AISelector.SelectMovementGenerator(_owner), MovementSlot.Default);
        }

        public void AddToWorld()
        {
            if (!HasFlag(MotionMasterFlags.InitializationPending))
                return;

            AddFlag(MotionMasterFlags.Initializing);
            RemoveFlag(MotionMasterFlags.InitializationPending);

            DirectInitialize();
            ResolveDelayedActions();

            RemoveFlag(MotionMasterFlags.Initializing);
        }

        public bool Empty()
        {
            return _defaultGenerator == null && _generators.Empty();
        }

        public int Size()
        {
            return (_defaultGenerator != null ? 1 : 0) + _generators.Count;
        }

        public List<MovementGeneratorInformation> GetMovementGeneratorsInformation()
        {
            List<MovementGeneratorInformation> list = new();

            if (_defaultGenerator != null)
                list.Add(new MovementGeneratorInformation(_defaultGenerator.GetMovementGeneratorType(), ObjectGuid.Empty, ""));

            foreach (var movement in _generators)
            {
                MovementGeneratorType type = movement.GetMovementGeneratorType();
                switch (type)
                {
                    case MovementGeneratorType.Chase:
                    case MovementGeneratorType.Follow:
                        if (movement is FollowMovementGenerator followInformation)
                        {
                            Unit target = followInformation.GetTarget();
                            if (target != null)
                                list.Add(new MovementGeneratorInformation(type, target.GetGUID(), target.GetName()));
                            else
                                list.Add(new MovementGeneratorInformation(type, ObjectGuid.Empty));
                        }
                        else
                            list.Add(new MovementGeneratorInformation(type, ObjectGuid.Empty));
                        break;
                    default:
                        list.Add(new MovementGeneratorInformation(type, ObjectGuid.Empty));
                        break;
                }
            }

            return list;
        }

        public MovementSlot GetCurrentSlot()
        {
            if (!_generators.Empty())
                return MovementSlot.Active;

            if (_defaultGenerator != null)
                return MovementSlot.Default;

            return MovementSlot.Max;
        }

        public MovementGenerator GetCurrentMovementGenerator()
        {
            if (!_generators.Empty())
                return _generators.FirstOrDefault();

            if (_defaultGenerator != null)
                return _defaultGenerator;

            return null;
        }

        public MovementGeneratorType GetCurrentMovementGeneratorType()
        {
            if (Empty())
                return MovementGeneratorType.Max;

            MovementGenerator movement = GetCurrentMovementGenerator();
            if (movement == null)
                return MovementGeneratorType.Max;

            return movement.GetMovementGeneratorType();
        }

        public MovementGeneratorType GetCurrentMovementGeneratorType(MovementSlot slot)
        {
            if (Empty() || IsInvalidMovementSlot(slot))
                return MovementGeneratorType.Max;

            if (slot == MovementSlot.Active && !_generators.Empty())
                return _generators.FirstOrDefault().GetMovementGeneratorType();

            if (slot == MovementSlot.Default && _defaultGenerator != null)
                return _defaultGenerator.GetMovementGeneratorType();

            return MovementGeneratorType.Max;
        }

        public MovementGenerator GetCurrentMovementGenerator(MovementSlot slot)
        {
            if (Empty() || IsInvalidMovementSlot(slot))
                return null;

            if (slot == MovementSlot.Active && !_generators.Empty())
                return _generators.FirstOrDefault();

            if (slot == MovementSlot.Default && _defaultGenerator != null)
                return _defaultGenerator;

            return null;
        }

        public MovementGenerator GetMovementGenerator(Func<MovementGenerator, bool> filter, MovementSlot slot = MovementSlot.Active)
        {

            if (Empty() || IsInvalidMovementSlot(slot))
                return null;

            MovementGenerator movement = null;
            switch (slot)
            {
                case MovementSlot.Default:
                    if (_defaultGenerator != null && filter(_defaultGenerator))
                        movement = _defaultGenerator;
                    break;
                case MovementSlot.Active:
                    if (!_generators.Empty())
                    {
                        var itr = _generators.FirstOrDefault(filter);
                        if (itr != null)
                            movement = itr;
                    }
                    break;
                default:
                    break;
            }

            return movement;
        }

        public bool HasMovementGenerator(Func<MovementGenerator, bool> filter, MovementSlot slot = MovementSlot.Active)
        {

            if (Empty() || IsInvalidMovementSlot(slot))
                return false;

            bool value = false;
            switch (slot)
            {
                case MovementSlot.Default:
                    if (_defaultGenerator != null && filter(_defaultGenerator))
                        value = true;
                    break;
                case MovementSlot.Active:
                    if (!_generators.Empty())
                    {
                        var itr = _generators.FirstOrDefault(filter);
                        value = itr != null;
                    }
                    break;
                default:
                    break;
            }

            return value;
        }

        public void Update(uint diff)
        {
            if (_owner == null)
                return;

            if (HasFlag(MotionMasterFlags.InitializationPending | MotionMasterFlags.Initializing))
                return;

            Cypher.Assert(!Empty(), $"MotionMaster:Update: update called without Initializing! ({_owner.GetGUID()})");

            AddFlag(MotionMasterFlags.Update);

            MovementGenerator top = GetCurrentMovementGenerator();
            if (HasFlag(MotionMasterFlags.StaticInitializationPending) && IsStatic(top))
            {
                RemoveFlag(MotionMasterFlags.StaticInitializationPending);
                top.Initialize(_owner);
            }

            if (top.HasFlag(MovementGeneratorFlags.InitializationPending))
                top.Initialize(_owner);
            if (top.HasFlag(MovementGeneratorFlags.Deactivated))
                top.Reset(_owner);

            Cypher.Assert(!top.HasFlag(MovementGeneratorFlags.InitializationPending | MovementGeneratorFlags.Deactivated), $"MotionMaster:Update: update called on an uninitialized top! ({_owner.GetGUID()}) (type: {top.GetMovementGeneratorType()}, flags: {top.Flags})");

            if (!top.Update(_owner, diff))
            {
                Cypher.Assert(top == GetCurrentMovementGenerator(), $"MotionMaster::Update: top was modified while updating! ({_owner.GetGUID()})");

                // Since all the actions that modify any slot are delayed, this movement is guaranteed to be top
                Pop(true, true); // Natural, and only, call to MovementInform
            }

            RemoveFlag(MotionMasterFlags.Update);

            ResolveDelayedActions();
        }

        void Add(MovementGenerator movement, MovementSlot slot = MovementSlot.Active)
        {
            if (movement == null)
                return;

            if (IsInvalidMovementSlot(slot))
                return;

            if (HasFlag(MotionMasterFlags.Delayed))
                _delayedActions.Enqueue(new DelayedAction(() => Add(movement, slot), MotionMasterDelayedActionType.Add));
            else
                DirectAdd(movement, slot);
        }

        public void Remove(MovementGenerator movement, MovementSlot slot = MovementSlot.Active)
        {
            if (movement == null || IsInvalidMovementSlot(slot))
                return;

            if (HasFlag(MotionMasterFlags.Delayed))
            {
                _delayedActions.Enqueue(new DelayedAction(() => Remove(movement, slot), MotionMasterDelayedActionType.Remove));
                return;
            }

            if (Empty())
                return;

            switch (slot)
            {
                case MovementSlot.Default:
                    if (_defaultGenerator != null && _defaultGenerator == movement)
                        DirectClearDefault();
                    break;
                case MovementSlot.Active:
                    if (!_generators.Empty())
                    {
                        if (_generators.Contains(movement))
                            Remove(movement, GetCurrentMovementGenerator() == movement, false);
                    }
                    break;
                default:
                    break;
            }
        }

        public void Remove(MovementGeneratorType type, MovementSlot slot = MovementSlot.Active)
        {
            if (IsInvalidMovementGeneratorType(type) || IsInvalidMovementSlot(slot))
                return;

            if (HasFlag(MotionMasterFlags.Delayed))
            {
                _delayedActions.Enqueue(new DelayedAction(() => Remove(type, slot), MotionMasterDelayedActionType.RemoveType));
                return;
            }

            if (Empty())
                return;

            switch (slot)
            {
                case MovementSlot.Default:
                    if (_defaultGenerator != null && _defaultGenerator.GetMovementGeneratorType() == type)
                        DirectClearDefault();
                    break;
                case MovementSlot.Active:
                    if (!_generators.Empty())
                    {
                        var itr = _generators.FirstOrDefault(a => a.GetMovementGeneratorType() == type);
                        if (itr != null)
                            Remove(itr, GetCurrentMovementGenerator() == itr, false);
                    }
                    break;
                default:
                    break;
            }
        }

        public void Clear()
        {
            if (HasFlag(MotionMasterFlags.Delayed))
            {
                _delayedActions.Enqueue(new DelayedAction(() => Clear(), MotionMasterDelayedActionType.Clear));
                return;
            }

            if (!Empty())
                DirectClear();
        }

        public void Clear(MovementSlot slot)
        {
            if (IsInvalidMovementSlot(slot))
                return;

            if (HasFlag(MotionMasterFlags.Delayed))
            {
                _delayedActions.Enqueue(new DelayedAction(() => Clear(slot), MotionMasterDelayedActionType.ClearSlot));
                return;
            }

            if (Empty())
                return;

            switch (slot)
            {
                case MovementSlot.Default:
                    DirectClearDefault();
                    break;
                case MovementSlot.Active:
                    DirectClear();
                    break;
                default:
                    break;
            }
        }

        public void Clear(MovementGeneratorMode mode)
        {
            if (HasFlag(MotionMasterFlags.Delayed))
            {
                _delayedActions.Enqueue(new DelayedAction(() => Clear(mode), MotionMasterDelayedActionType.ClearMode));
                return;
            }

            if (Empty())
                return;

            DirectClear(a => a.Mode == mode);
        }

        public void Clear(MovementGeneratorPriority priority)
        {

            if (HasFlag(MotionMasterFlags.Delayed))
            {
                _delayedActions.Enqueue(new DelayedAction(() => Clear(priority), MotionMasterDelayedActionType.ClearPriority));
                return;
            }

            if (Empty())
                return;

            DirectClear(a => a.Priority == priority);
        }

        public void PropagateSpeedChange()
        {
            if (Empty())
                return;

            MovementGenerator movement = GetCurrentMovementGenerator();
            if (movement == null)
                return;

            movement.UnitSpeedChanged();
        }

        public bool GetDestination(out float x, out float y, out float z)
        {
            x = 0f;
            y = 0f;
            z = 0f;
            if (_owner.MoveSpline.Finalized())
                return false;

            Vector3 dest = _owner.MoveSpline.FinalDestination();
            x = dest.X;
            y = dest.Y;
            z = dest.Z;
            return true;
        }

        public bool StopOnDeath()
        {
            MovementGenerator movementGenerator = GetCurrentMovementGenerator();
            if (movementGenerator != null)
                if (movementGenerator.HasFlag(MovementGeneratorFlags.PersistOnDeath))
                    return false;

            if (_owner.IsInWorld)
            {
                // Only clear MotionMaster for entities that exists in world
                // Avoids crashes in the following conditions :
                //  * Using 'call pet' on dead pets
                //  * Using 'call stabled pet'
                //  * Logging in with dead pets
                Clear();
                MoveIdle();
            }

            _owner.StopMoving();

            return true;
        }

        public void MoveIdle()
        {
            Add(GetIdleMovementGenerator(), MovementSlot.Default);
        }

        public void MoveTargetedHome()
        {
            Creature owner = _owner.ToCreature();
            if (owner == null)
            {
                Log.outError(LogFilter.Movement, $"MotionMaster::MoveTargetedHome: '{_owner.GetGUID()}', attempted to move towards target home.");
                return;
            }

            Clear();

            Unit target = owner.GetCharmerOrOwner();
            if (target == null)
                Add(new HomeMovementGenerator<Creature>());
            else
                Add(new FollowMovementGenerator(target, SharedConst.PetFollowDist, new ChaseAngle(SharedConst.PetFollowAngle), null));
        }

        public void MoveRandom(float wanderDistance = 0.0f, TimeSpan? duration = null, MovementSlot slot = MovementSlot.Default, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            if (_owner.IsTypeId(TypeId.Unit))
                Add(new RandomMovementGenerator(wanderDistance, duration, scriptResult), slot);
            else if (scriptResult != null)
                scriptResult.SetResult(MovementStopReason.Interrupted);
        }

        public void MoveFollow(Unit target, float dist, float angle = 0.0f, TimeSpan? duration = null, MovementSlot slot = MovementSlot.Active, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            MoveFollow(target, dist, new ChaseAngle(angle), duration, slot, scriptResult);
        }

        public void MoveFollow(Unit target, float dist, ChaseAngle angle, TimeSpan? duration = null, MovementSlot slot = MovementSlot.Active, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            // Ignore movement request if target not exist
            if (target == null || target == _owner)
            {
                if (scriptResult != null)
                    scriptResult.SetResult(MovementStopReason.Interrupted);
                return;
            }

            Add(new FollowMovementGenerator(target, dist, angle, duration, scriptResult), slot);
        }

        public void MoveChase(Unit target, float dist, float angle = 0.0f) { MoveChase(target, new ChaseRange(dist), new ChaseAngle(angle)); }
        public void MoveChase(Unit target, ChaseRange? dist = null, ChaseAngle? angle = null)
        {
            // Ignore movement request if target not exist
            if (target == null || target == _owner)
                return;

            Add(new ChaseMovementGenerator(target, dist, angle));
        }

        public void MoveConfused()
        {
            if (_owner.IsTypeId(TypeId.Player))
                Add(new ConfusedMovementGenerator<Player>());
            else
                Add(new ConfusedMovementGenerator<Creature>());
        }

        public void MoveFleeing(Unit enemy, TimeSpan time = default, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            if (enemy == null)
            {
                if (scriptResult != null)
                    scriptResult.SetResult(MovementStopReason.Interrupted);
                return;
            }

            if (_owner.IsCreature() && time > TimeSpan.Zero)
                Add(new TimedFleeingMovementGenerator(enemy.GetGUID(), time, scriptResult));
            else
                Add(new FleeingMovementGenerator(enemy.GetGUID(), scriptResult));
        }

        public void MovePoint(uint id, Position pos, bool generatePath = true, float? finalOrient = null, float? speed = null, MovementWalkRunSpeedSelectionMode speedSelectionMode = MovementWalkRunSpeedSelectionMode.Default, float? closeEnoughDistance = null, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            MovePoint(id, pos.posX, pos.posY, pos.posZ, generatePath, finalOrient, speed, speedSelectionMode, closeEnoughDistance, scriptResult);
        }

        public void MovePoint(uint id, float x, float y, float z, bool generatePath = true, float? finalOrient = null, float? speed = null, MovementWalkRunSpeedSelectionMode speedSelectionMode = MovementWalkRunSpeedSelectionMode.Default, float? closeEnoughDistance = null, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            Log.outDebug(LogFilter.Movement, $"MotionMaster::MovePoint: '{_owner.GetGUID()}', targeted point Id: {id} (X: {x}, Y: {y}, Z: {z})");
            Add(new PointMovementGenerator(id, x, y, z, generatePath, speed, finalOrient, null, null, speedSelectionMode, closeEnoughDistance, scriptResult));
        }

        public void MoveCloserAndStop(uint id, Unit target, float distance)
        {
            float distanceToTravel = _owner.GetExactDist2d(target) - distance;
            if (distanceToTravel > 0.0f)
            {
                float angle = _owner.GetAbsoluteAngle(target);
                float destx = _owner.GetPositionX() + distanceToTravel * (float)Math.Cos(angle);
                float desty = _owner.GetPositionY() + distanceToTravel * (float)Math.Sin(angle);
                MovePoint(id, destx, desty, target.GetPositionZ());
            }
            else
            {
                // We are already close enough. We just need to turn toward the target without changing position.
                var initializer = (MoveSplineInit init) =>
                {
                    init.MoveTo(_owner.GetPositionX(), _owner.GetPositionY(), _owner.GetPositionZ());
                    Unit refreshedTarget = Global.ObjAccessor.GetUnit(_owner, target.GetGUID());
                    if (refreshedTarget != null)
                        init.SetFacing(refreshedTarget);
                };
                Add(new GenericMovementGenerator(initializer, MovementGeneratorType.Effect, id));
            }
        }

        public void MoveLand(uint id, Position pos, uint? tierTransitionId = null, float? velocity = null, MovementWalkRunSpeedSelectionMode speedSelectionMode = MovementWalkRunSpeedSelectionMode.Default, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            var initializer = (MoveSplineInit init) =>
            {
                init.MoveTo(pos, false);
                init.SetAnimation(AnimTier.Ground, tierTransitionId.GetValueOrDefault(1));
                init.SetFly(); // ensure smooth animation even if gravity is enabled before calling this function
                init.SetSmooth();
                switch (speedSelectionMode)
                {
                    case MovementWalkRunSpeedSelectionMode.ForceRun:
                        init.SetWalk(false);
                        break;
                    case MovementWalkRunSpeedSelectionMode.ForceWalk:
                        init.SetWalk(true);
                        break;
                    case MovementWalkRunSpeedSelectionMode.Default:
                    default:
                        break;
                }
                if (velocity.HasValue)
                    init.SetVelocity(velocity.Value);
            };

            Add(new GenericMovementGenerator(initializer, MovementGeneratorType.Effect, id, new() { ScriptResult = scriptResult }));
        }

        public void MoveTakeoff(uint id, Position pos, uint? tierTransitionId = null, float? velocity = null, MovementWalkRunSpeedSelectionMode speedSelectionMode = MovementWalkRunSpeedSelectionMode.Default, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            var initializer = (MoveSplineInit init) =>
            {
                init.MoveTo(pos, false);
                init.SetAnimation(AnimTier.Fly, tierTransitionId.GetValueOrDefault(2));
                init.SetFly(); // ensure smooth animation even if gravity is disabled after calling this function
                switch (speedSelectionMode)
                {
                    case MovementWalkRunSpeedSelectionMode.ForceRun:
                        init.SetWalk(false);
                        break;
                    case MovementWalkRunSpeedSelectionMode.ForceWalk:
                        init.SetWalk(true);
                        break;
                    case MovementWalkRunSpeedSelectionMode.Default:
                    default:
                        break;
                }
                if (velocity.HasValue)
                    init.SetVelocity(velocity.Value);
            };

            Add(new GenericMovementGenerator(initializer, MovementGeneratorType.Effect, id, new() { ScriptResult = scriptResult }));
        }

        public void MoveCharge(float x, float y, float z, float speed = SPEED_CHARGE, uint id = EventId.Charge, bool generatePath = false, Unit target = null, SpellEffectExtraData spellEffectExtraData = null)
        {
            /*
            if (_slot[(int)MovementSlot.Controlled] != null && _slot[(int)MovementSlot.Controlled].GetMovementGeneratorType() != MovementGeneratorType.Distract)
                return;
            */

            Log.outDebug(LogFilter.Movement, $"MotionMaster::MoveCharge: '{_owner.GetGUID()}', charging point Id: {id} (X: {x}, Y: {y}, Z: {z})");
            PointMovementGenerator movement = new PointMovementGenerator(id, x, y, z, generatePath, speed, null, target, spellEffectExtraData);
            movement.Priority = MovementGeneratorPriority.Highest;
            movement.BaseUnitState = UnitState.Charging;
            Add(movement);
        }

        public void MoveCharge(PathGenerator path, float speed = SPEED_CHARGE, Unit target = null, SpellEffectExtraData spellEffectExtraData = null)
        {
            Vector3 dest = path.GetActualEndPosition();

            MoveCharge(dest.X, dest.Y, dest.Z, SPEED_CHARGE, EventId.ChargePrepath);

            // If this is ever changed to not happen immediately then all spell effect handlers that use this must be updated

            // Charge movement is not started when using EVENT_CHARGE_PREPATH
            MoveSplineInit init = new(_owner);
            init.MovebyPath(path.GetPath());
            init.SetVelocity(speed);
            if (target != null)
                init.SetFacing(target);
            if (spellEffectExtraData != null)
                init.SetSpellEffectExtraData(spellEffectExtraData);
            init.Launch();
        }

        public void MoveKnockbackFrom(Position origin, float speedXY, float speedZ, SpellEffectExtraData spellEffectExtraData = null)
        {
            //This function may make players fall below map
            if (_owner.IsTypeId(TypeId.Player))
                return;

            if (speedXY < 0.01f)
                return;

            Position dest = _owner.GetPosition();
            float moveTimeHalf = (float)(speedZ / gravity);
            float dist = 2 * moveTimeHalf * speedXY;
            float max_height = -MoveSpline.ComputeFallElevation(moveTimeHalf, false, -speedZ);

            // Use a mmap raycast to get a valid destination.
            _owner.MovePositionToFirstCollision(dest, dist, _owner.GetRelativeAngle(origin) + MathF.PI);

            var initializer = (MoveSplineInit init) =>
            {
                init.MoveTo(dest.GetPositionX(), dest.GetPositionY(), dest.GetPositionZ(), false);
                init.SetParabolic(max_height, 0);
                init.SetOrientationFixed(true);
                init.SetVelocity(speedXY);
                if (spellEffectExtraData != null)
                    init.SetSpellEffectExtraData(spellEffectExtraData);
            };

            GenericMovementGenerator movement = new(initializer, MovementGeneratorType.Effect, 0);
            movement.Priority = MovementGeneratorPriority.Highest;
            movement.AddFlag(MovementGeneratorFlags.PersistOnDeath);
            Add(movement);
        }

        public void MoveJumpTo(float angle, float speedXY, float speedZ)
        {
            //This function may make players fall below map
            if (_owner.IsTypeId(TypeId.Player))
                return;

            float moveTimeHalf = (float)(speedZ / gravity);
            float dist = 2 * moveTimeHalf * speedXY;
            _owner.GetNearPoint2D(null, out float x, out float y, dist, _owner.GetOrientation() + angle);
            float z = _owner.GetPositionZ();
            _owner.UpdateAllowedPositionZ(x, y, ref z);
            MoveJump(x, y, z, 0.0f, speedXY, speedZ);
        }

        public void MoveJump(Position pos, float speedXY, float speedZ, uint id = EventId.Jump, bool hasOrientation = false, JumpArrivalCastArgs arrivalCast = null, SpellEffectExtraData spellEffectExtraData = null, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            MoveJump(pos.GetPositionX(), pos.GetPositionY(), pos.GetPositionZ(), pos.GetOrientation(), speedXY, speedZ, id, hasOrientation, arrivalCast, spellEffectExtraData, scriptResult);
        }

        public void MoveJump(float x, float y, float z, float o, float speedXY, float speedZ, uint id = EventId.Jump, bool hasOrientation = false, JumpArrivalCastArgs arrivalCast = null, SpellEffectExtraData spellEffectExtraData = null, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            Log.outDebug(LogFilter.Server, "Unit ({0}) jump to point (X: {1} Y: {2} Z: {3})", _owner.GetGUID().ToString(), x, y, z);
            if (speedXY < 0.01f)
            {
                if (scriptResult != null)
                    scriptResult.SetResult(MovementStopReason.Interrupted);
                return;
            }

            float moveTimeHalf = (float)(speedZ / gravity);
            float max_height = -MoveSpline.ComputeFallElevation(moveTimeHalf, false, -speedZ);

            var initializer = (MoveSplineInit init) =>
            {
                init.MoveTo(x, y, z, false);
                init.SetParabolic(max_height, 0);
                init.SetVelocity(speedXY);
                if (hasOrientation)
                    init.SetFacing(o);
                if (spellEffectExtraData != null)
                    init.SetSpellEffectExtraData(spellEffectExtraData);
            };

            uint arrivalSpellId = 0;
            ObjectGuid arrivalSpellTargetGuid = ObjectGuid.Empty;
            if (arrivalCast != null)
            {
                arrivalSpellId = arrivalCast.SpellId;
                arrivalSpellTargetGuid = arrivalCast.Target;
            }

            GenericMovementGenerator movement = new(initializer, MovementGeneratorType.Effect, id, new GenericMovementGeneratorArgs() { ArrivalSpellId = arrivalSpellId, ArrivalSpellTarget = arrivalSpellTargetGuid, ScriptResult = scriptResult });
            movement.Priority = MovementGeneratorPriority.Highest;
            movement.BaseUnitState = UnitState.Jumping;
            Add(movement);
        }

        public void MoveJumpWithGravity(Position pos, float speedXY, float gravity, uint id = EventId.Jump, bool hasOrientation = false, JumpArrivalCastArgs arrivalCast = null, SpellEffectExtraData spellEffectExtraData = null, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            Log.outDebug(LogFilter.Movement, $"MotionMaster.MoveJumpWithGravity: '{_owner.GetGUID()}', jumps to point Id: {id} ({pos})");
            if (speedXY < 0.01f)
            {
                if (scriptResult != null)
                    scriptResult.SetResult(MovementStopReason.Interrupted);
                return;
            }

            var initializer = (MoveSplineInit init) =>
            {
                init.MoveTo(pos.GetPositionX(), pos.GetPositionY(), pos.GetPositionZ(), false);
                init.SetParabolicVerticalAcceleration(gravity, 0);
                init.SetUncompressed();
                init.SetVelocity(speedXY);
                init.SetUnlimitedSpeed();
                if (hasOrientation)
                    init.SetFacing(pos.GetOrientation());
                if (spellEffectExtraData != null)
                    init.SetSpellEffectExtraData(spellEffectExtraData);
            };

            uint arrivalSpellId = 0;
            ObjectGuid arrivalSpellTargetGuid = default;
            if (arrivalCast != null)
            {
                arrivalSpellId = arrivalCast.SpellId;
                arrivalSpellTargetGuid = arrivalCast.Target;
            }

            GenericMovementGenerator movement = new GenericMovementGenerator(initializer, MovementGeneratorType.Effect, id, new GenericMovementGeneratorArgs() { ArrivalSpellId = arrivalSpellId, ArrivalSpellTarget = arrivalSpellTargetGuid, ScriptResult = scriptResult });
            movement.Priority = MovementGeneratorPriority.Highest;
            movement.BaseUnitState = UnitState.Jumping;
            movement.AddFlag(MovementGeneratorFlags.PersistOnDeath);
            Add(movement);
        }

        public void MoveCirclePath(float x, float y, float z, float radius, bool clockwise, byte stepCount, TimeSpan? duration = null, float? speed = null, MovementWalkRunSpeedSelectionMode speedSelectionMode = MovementWalkRunSpeedSelectionMode.Default, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            var initializer = (MoveSplineInit init) =>
            {
                float step = 2 * MathFunctions.PI / stepCount * (clockwise ? -1.0f : 1.0f);
                Position pos = new(x, y, z, 0.0f);
                float angle = pos.GetAbsoluteAngle(_owner.GetPositionX(), _owner.GetPositionY());

                // add the owner's current position as starting point as it gets removed after entering the cycle
                init.Path().Add(new Vector3(_owner.GetPositionX(), _owner.GetPositionY(), _owner.GetPositionZ()));

                for (byte i = 0; i < stepCount; angle += step, ++i)
                {
                    Vector3 point = new();
                    point.X = (float)(x + radius * Math.Cos(angle));
                    point.Y = (float)(y + radius * Math.Sin(angle));

                    if (_owner.IsFlying())
                        point.Z = z;
                    else
                        point.Z = _owner.GetMapHeight(point.X, point.Y, z) + _owner.GetHoverOffset();

                    init.Path().Add(point);
                }

                init.SetCyclic();
                if (_owner.IsFlying())
                {
                    init.SetFly();
                    init.SetAnimation(AnimTier.Hover);
                }
                else
                    init.SetWalk(true);

                switch (speedSelectionMode)
                {
                    case MovementWalkRunSpeedSelectionMode.ForceRun:
                        init.SetWalk(false);
                        break;
                    case MovementWalkRunSpeedSelectionMode.ForceWalk:
                        init.SetWalk(true);
                        break;
                    case MovementWalkRunSpeedSelectionMode.Default:
                    default:
                        break;
                }

                if (speed.HasValue)
                    init.SetVelocity(speed.Value);
            };

            Add(new GenericMovementGenerator(initializer, MovementGeneratorType.Effect, 0, new GenericMovementGeneratorArgs() { Duration = duration, ScriptResult = scriptResult }));
        }

        public void MoveSmoothPath(uint pointId, Vector3[] pathPoints, int pathSize, bool walk = false, bool fly = false)
        {
            var initializer = (MoveSplineInit init) =>
            {
                init.MovebyPath(pathPoints);
                init.SetWalk(walk);
                if (fly)
                {
                    init.SetFly();
                    init.SetUncompressed();
                    init.SetSmooth();
                }
            };

            // This code is not correct
            // GenericMovementGenerator does not affect UNIT_STATE_ROAMING_MOVE
            // need to call PointMovementGenerator with various pointIds
            Add(new GenericMovementGenerator(initializer, MovementGeneratorType.Effect, pointId));
        }

        public void MoveAlongSplineChain(uint pointId, uint dbChainId, bool walk)
        {
            Creature owner = _owner.ToCreature();
            if (owner == null)
            {
                Log.outError(LogFilter.Misc, "MotionMaster.MoveAlongSplineChain: non-creature {0} tried to walk along DB spline chain. Ignoring.", _owner.GetGUID().ToString());
                return;
            }
            List<SplineChainLink> chain = Global.ScriptMgr.GetSplineChain(owner, (byte)dbChainId);
            if (chain.Empty())
            {
                Log.outError(LogFilter.Misc, "MotionMaster.MoveAlongSplineChain: creature with entry {0} tried to walk along non-existing spline chain with DB id {1}.", owner.GetEntry(), dbChainId);
                return;
            }
            MoveAlongSplineChain(pointId, chain, walk);
        }

        void MoveAlongSplineChain(uint pointId, List<SplineChainLink> chain, bool walk)
        {
            Add(new SplineChainMovementGenerator(pointId, chain, walk));
        }

        void ResumeSplineChain(SplineChainResumeInfo info)
        {
            if (info.Empty())
            {
                Log.outError(LogFilter.Movement, "MotionMaster.ResumeSplineChain: unit with entry {0} tried to resume a spline chain from empty info.", _owner.GetEntry());
                return;
            }

            Add(new SplineChainMovementGenerator(info));
        }

        public void MoveFall(uint id = 0, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            // Use larger distance for vmap height search than in most other cases
            float tz = _owner.GetMapHeight(_owner.GetPositionX(), _owner.GetPositionY(), _owner.GetPositionZ(), true, MapConst.MaxFallDistance);
            if (tz <= MapConst.InvalidHeight)
                return;

            // Abort too if the ground is very near
            if (Math.Abs(_owner.GetPositionZ() - tz) < 0.1f)
                return;

            // rooted units don't move (also setting falling+root flag causes client freezes)
            if (_owner.HasUnitState(UnitState.Root | UnitState.Stunned))
                return;

            _owner.SetFall(true);

            // Don't run spline movement for players
            if (_owner.IsTypeId(TypeId.Player))
            {
                _owner.ToPlayer().SetFallInformation(0, _owner.GetPositionZ());
                return;
            }

            var initializer = (MoveSplineInit init) =>
            {
                init.MoveTo(_owner.GetPositionX(), _owner.GetPositionY(), tz + _owner.GetHoverOffset(), false);
                init.SetFall();
            };

            GenericMovementGenerator movement = new(initializer, MovementGeneratorType.Effect, id, new() { ScriptResult = scriptResult });
            movement.Priority = MovementGeneratorPriority.Highest;
            Add(movement);
        }

        public void MoveSeekAssistance(float x, float y, float z)
        {
            Creature creature = _owner.ToCreature();
            if (creature != null)
            {
                Log.outDebug(LogFilter.Movement, $"MotionMaster::MoveSeekAssistance: '{creature.GetGUID()}', seeks assistance (X: {x}, Y: {y}, Z: {z})");
                creature.AttackStop();
                creature.CastStop();
                creature.DoNotReacquireSpellFocusTarget();
                creature.SetReactState(ReactStates.Passive);
                Add(new AssistanceMovementGenerator(EventId.AssistMove, x, y, z));
            }
            else
                Log.outError(LogFilter.Server, $"MotionMaster::MoveSeekAssistance: {_owner.GetGUID()}, attempted to seek assistance");
        }

        public void MoveSeekAssistanceDistract(uint time)
        {
            if (_owner.IsCreature())
                Add(new AssistanceDistractMovementGenerator(time, _owner.GetOrientation()));
            else
                Log.outError(LogFilter.Server, $"MotionMaster::MoveSeekAssistanceDistract: {_owner.GetGUID()} attempted to call distract after assistance");
        }

        public void MoveTaxiFlight(uint path, uint pathnode, float? speed = null, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            if (_owner.IsTypeId(TypeId.Player))
            {
                if (path < CliDB.TaxiPathNodesByPath.Count)
                {
                    Log.outDebug(LogFilter.Server, $"MotionMaster::MoveTaxiFlight: {_owner.GetGUID()} taxi to Path Id: {path} (node {pathnode})");

                    // Only one FLIGHT_MOTION_TYPE is allowed
                    bool hasExisting = HasMovementGenerator(gen => gen.GetMovementGeneratorType() == MovementGeneratorType.Flight);
                    Cypher.Assert(!hasExisting, "Duplicate flight path movement generator");

                    FlightPathMovementGenerator movement = new(speed, scriptResult);
                    movement.LoadPath(_owner.ToPlayer());
                    Add(movement);
                }
                else
                    Log.outError(LogFilter.Movement, $"MotionMaster::MoveTaxiFlight: '{_owner.GetGUID()}', attempted taxi to non-existing path Id: {path} (node: {pathnode})");

            }
            else
                Log.outError(LogFilter.Movement, $"MotionMaster::MoveTaxiFlight: '{_owner.GetGUID()}', attempted taxi to path Id: {path} (node: {pathnode})");
        }

        public void MoveDistract(uint timer, float orientation)
        {
            /*
            if (_slot[(int)MovementSlot.Controlled] != null)
                return;
            */

            Add(new DistractMovementGenerator(timer, orientation));
        }

        public void MovePath(uint pathId, bool repeatable, TimeSpan? duration = null, float? speed = null, MovementWalkRunSpeedSelectionMode speedSelectionMode = MovementWalkRunSpeedSelectionMode.Default,
            (TimeSpan, TimeSpan)? waitTimeRangeAtPathEnd = null, float? wanderDistanceAtPathEnds = null, bool? followPathBackwardsFromEndToStart = null, bool? exactSplinePath = null, bool generatePath = true, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            if (pathId == 0)
            {
                if (scriptResult != null)
                    scriptResult.SetResult(MovementStopReason.Interrupted);
                return;
            }

            Log.outDebug(LogFilter.Movement, $"MotionMaster::MovePath: '{_owner.GetGUID()}', starts moving over path Id: {pathId} (repeatable: {repeatable})");
            Add(new WaypointMovementGenerator(pathId, repeatable, duration, speed, speedSelectionMode, waitTimeRangeAtPathEnd, wanderDistanceAtPathEnds, followPathBackwardsFromEndToStart, exactSplinePath, generatePath, scriptResult), MovementSlot.Default);
        }

        public void MovePath(WaypointPath path, bool repeatable, TimeSpan? duration = null, float? speed = null, MovementWalkRunSpeedSelectionMode speedSelectionMode = MovementWalkRunSpeedSelectionMode.Default,
            (TimeSpan, TimeSpan)? waitTimeRangeAtPathEnd = null, float? wanderDistanceAtPathEnds = null, bool? followPathBackwardsFromEndToStart = null, bool? exactSplinePath = null, bool generatePath = true, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            Log.outDebug(LogFilter.Movement, $"MotionMaster::MovePath: '{_owner.GetGUID()}', starts moving over path Id: {path.Id} (repeatable: {repeatable})");
            Add(new WaypointMovementGenerator(path, repeatable, duration, speed, speedSelectionMode, waitTimeRangeAtPathEnd, wanderDistanceAtPathEnds, followPathBackwardsFromEndToStart, exactSplinePath, generatePath, scriptResult), MovementSlot.Default);
        }

        /// <summary>
        /// Makes the Unit turn in place
        /// </summary>
        /// <param name="id">Movement identifier, later passed to script MovementInform hooks</param>
        /// <param name="direction">Rotation direction</param>
        /// <param name="time">How long should this movement last, infinite if not set</param>
        /// <param name="turnSpeed">How fast should the unit rotate, in radians per second. Uses unit's turn speed if not set</param>
        /// <param name="totalTurnAngle">Total angle of the entire movement, infinite if not set</param>
        public void MoveRotate(uint id, RotateDirection direction, TimeSpan? time = null, float? turnSpeed = null, float? totalTurnAngle = null, ActionResultSetter<MovementStopReason> scriptResult = null)
        {
            Log.outDebug(LogFilter.Movement, $"MotionMaster::MoveRotate: '{_owner.GetGUID()}', starts rotate (time: {time.GetValueOrDefault(TimeSpan.Zero)}ms, turnSpeed: {turnSpeed}, totalTurnAngle: {totalTurnAngle}, direction: {direction})");

            Add(new RotateMovementGenerator(id, direction, time, turnSpeed, totalTurnAngle, scriptResult));
        }

        public void MoveFormation(Unit leader, float range, float angle, uint point1, uint point2)
        {
            if (_owner.GetTypeId() == TypeId.Unit && leader != null)
                Add(new FormationMovementGenerator(leader, range, angle, point1, point2), MovementSlot.Default);
        }

        public void LaunchMoveSpline(Action<MoveSplineInit> initializer, uint id = 0, MovementGeneratorPriority priority = MovementGeneratorPriority.Normal, MovementGeneratorType type = MovementGeneratorType.Effect)
        {
            if (IsInvalidMovementGeneratorType(type))
            {
                Log.outDebug(LogFilter.Movement, $"MotionMaster::LaunchMoveSpline: '{_owner.GetGUID()}', tried to launch a spline with an invalid MovementGeneratorType: {type} (Id: {id}, Priority: {priority})");
                return;
            }

            GenericMovementGenerator movement = new(initializer, type, id);
            movement.Priority = priority;
            Add(movement);
        }

        public void CalculateJumpSpeeds(float dist, UnitMoveType moveType, float speedMultiplier, float minHeight, float maxHeight, out float speedXY, out float speedZ)
        {
            float baseSpeed = _owner.IsControlledByPlayer() ? SharedConst.playerBaseMoveSpeed[(int)moveType] : SharedConst.baseMoveSpeed[(int)moveType];
            Creature creature = _owner.ToCreature();
            if (creature != null)
                baseSpeed *= creature.GetCreatureTemplate().SpeedRun;

            speedXY = Math.Min(baseSpeed * 3.0f * speedMultiplier, Math.Max(28.0f, _owner.GetSpeed(moveType) * 4.0f));

            float duration = dist / speedXY;
            float durationSqr = duration * duration;
            float height;
            if (durationSqr < minHeight * 8 / gravity)
                height = minHeight;
            else if (durationSqr > maxHeight * 8 / gravity)
                height = maxHeight;
            else
                height = (float)(gravity * durationSqr / 8);

            speedZ = (float)Math.Sqrt(2 * gravity * height);
        }

        void ResolveDelayedActions()
        {
            while (_delayedActions.Count != 0)
            {
                _delayedActions.Peek().Resolve();
                _delayedActions.Dequeue();
            }
        }

        void Remove(MovementGenerator movement, bool active, bool movementInform)
        {
            _generators.Remove(movement);
            Delete(movement, active, movementInform);
        }

        void Pop(bool active, bool movementInform)
        {
            if (!_generators.Empty())
                Remove(_generators.FirstOrDefault(), active, movementInform);
        }

        void DirectInitialize()
        {
            // Clear ALL movement generators (including default)
            DirectClearDefault();
            DirectClear();
            InitializeDefault();
        }

        void DirectClear()
        {
            // First delete Top
            if (!_generators.Empty())
                Pop(true, false);

            // Then the rest
            while (!_generators.Empty())
                Pop(false, false);

            // Make sure the storage is empty
            ClearBaseUnitStates();
        }

        void DirectClearDefault()
        {
            if (_defaultGenerator != null)
                DeleteDefault(_generators.Empty(), false);
        }

        void DirectClear(Func<MovementGenerator, bool> filter)
        {
            if (_generators.Empty())
                return;

            MovementGenerator top = GetCurrentMovementGenerator();
            foreach (var movement in _generators.ToList())
            {
                if (filter(movement))
                {
                    _generators.Remove(movement);
                    Delete(movement, movement == top, false);
                }
            }
        }

        void DirectAdd(MovementGenerator movement, MovementSlot slot = MovementSlot.Active)
        {
            /*
            IMovementGenerator curr = _slot[(int)slot];
            if (curr != null)
            {
                _slot[(int)slot] = null; // in case a new one is generated in this slot during directdelete
                if (_top == (int)slot && Convert.ToBoolean(_cleanFlag & MotionMasterCleanFlag.Update))
                    DelayedDelete(curr);
                else
                    DirectDelete(curr);
            }
            else if (_top < (int)slot)
            {
                _top = (int)slot;
            }

            _slot[(int)slot] = m;
            if (_top > (int)slot)
                _initialize[(int)slot] = true;
            else
            {
                _initialize[(int)slot] = false;
                m.Initialize(_owner);
            }
            */

            /*
 * NOTE: This mimics old behaviour: only one MOTION_SLOT_IDLE, MOTION_SLOT_ACTIVE, MOTION_SLOT_CONTROLLED
 * On future changes support for multiple will be added
 */
            switch (slot)
            {
                case MovementSlot.Default:
                    if (_defaultGenerator != null)
                        _defaultGenerator.Finalize(_owner, _generators.Empty(), false);

                    _defaultGenerator = movement;
                    if (IsStatic(movement))
                        AddFlag(MotionMasterFlags.StaticInitializationPending);
                    break;
                case MovementSlot.Active:
                    if (!_generators.Empty())
                    {
                        if (movement.Priority >= _generators.FirstOrDefault().Priority)
                        {
                            var itr = _generators.FirstOrDefault();
                            if (movement.Priority == itr.Priority)
                                Remove(itr, true, false);
                            else
                                itr.Deactivate(_owner);
                        }
                        else
                        {
                            var pointer = _generators.FirstOrDefault(a => a.Priority == movement.Priority);
                            if (pointer != null)
                                Remove(pointer, false, false);
                        }
                    }
                    else
                        _defaultGenerator.Deactivate(_owner);

                    _generators.Add(movement);
                    AddBaseUnitState(movement);
                    break;
                default:
                    break;
            }
        }

        void Delete(MovementGenerator movement, bool active, bool movementInform)
        {
            movement.Finalize(_owner, active, movementInform);
            ClearBaseUnitState(movement);
        }

        void DeleteDefault(bool active, bool movementInform)
        {
            _defaultGenerator.Finalize(_owner, active, movementInform);
            _defaultGenerator = GetIdleMovementGenerator();
            AddFlag(MotionMasterFlags.StaticInitializationPending);
        }

        void AddBaseUnitState(MovementGenerator movement)
        {
            if (movement == null || movement.BaseUnitState == 0)
                return;

            _baseUnitStatesMap.Add((uint)movement.BaseUnitState, movement);
            _owner.AddUnitState(movement.BaseUnitState);
        }

        void ClearBaseUnitState(MovementGenerator movement)
        {
            if (movement == null || movement.BaseUnitState == 0)
                return;

            _baseUnitStatesMap.Remove((uint)movement.BaseUnitState, movement);
            if (!_baseUnitStatesMap.ContainsKey(movement.BaseUnitState))
                _owner.ClearUnitState(movement.BaseUnitState);
        }

        void ClearBaseUnitStates()
        {
            uint unitState = 0;
            foreach (var itr in _baseUnitStatesMap)
                unitState |= itr.Key;

            _owner.ClearUnitState((UnitState)unitState);
            _baseUnitStatesMap.Clear();
        }

        void AddFlag(MotionMasterFlags flag) { _flags |= flag; }
        bool HasFlag(MotionMasterFlags flag) { return (_flags & flag) != 0; }
        void RemoveFlag(MotionMasterFlags flag) { _flags &= ~flag; }

        public static MovementGenerator GetIdleMovementGenerator()
        {
            return staticIdleMovement;
        }

        public static bool IsStatic(MovementGenerator movement)
        {
            return (movement == GetIdleMovementGenerator());
        }

        public static bool IsInvalidMovementGeneratorType(MovementGeneratorType type) { return type == MovementGeneratorType.MaxDB || type >= MovementGeneratorType.Max; }
        public static bool IsInvalidMovementSlot(MovementSlot slot) { return slot >= MovementSlot.Max; }

        public static uint SplineId
        {
            get { return splineId++; }
        }
    }

    public class JumpArrivalCastArgs
    {
        public uint SpellId;
        public ObjectGuid Target;
    }

    public class JumpChargeParams
    {
        public float Speed;

        public bool TreatSpeedAsMoveTimeSeconds;

        public float JumpGravity;

        public uint? SpellVisualId;
        public uint? ProgressCurveId;
        public uint? ParabolicCurveId;
    }

    public struct ChaseRange
    {
        // this contains info that informs how we should path!
        public float MinRange;     // we have to move if we are within this range...    (min. attack range)
        public float MinTolerance; // ...and if we are, we will move this far away
        public float MaxRange;     // we have to move if we are outside this range...   (max. attack range)
        public float MaxTolerance; // ...and if we are, we will move into this range

        public ChaseRange(float range)
        {
            MinRange = range > SharedConst.ContactDistance ? 0 : range - SharedConst.ContactDistance;
            MinTolerance = range;
            MaxRange = range + SharedConst.ContactDistance;
            MaxTolerance = range;
        }

        public ChaseRange(float min, float max)
        {
            MinRange = min;
            MinTolerance = Math.Min(min + SharedConst.ContactDistance, (min + max) / 2);
            MaxRange = max;
            MaxTolerance = Math.Max(max - SharedConst.ContactDistance, MinTolerance);
        }

        public ChaseRange(float min, float tMin, float tMax, float max)
        {
            MinRange = min;
            MinTolerance = tMin;
            MaxRange = max;
            MaxTolerance = tMax;
        }
    }

    public struct ChaseAngle
    {
        public float RelativeAngle; // we want to be at this angle relative to the target (0 = front, M_PI = back)
        public float Tolerance;     // but we'll tolerate anything within +- this much

        public ChaseAngle(float angle, float tol = MathFunctions.PiOver4)
        {
            RelativeAngle = Position.NormalizeOrientation(angle);
            Tolerance = tol;
        }

        public float UpperBound() { return Position.NormalizeOrientation(RelativeAngle + Tolerance); }

        public float LowerBound() { return Position.NormalizeOrientation(RelativeAngle - Tolerance); }

        public bool IsAngleOkay(float relAngle)
        {
            float diff = Math.Abs(relAngle - RelativeAngle);
            return (Math.Min(diff, (2 * MathF.PI) - diff) <= Tolerance);
        }
    }
}