using Content.Shared.CCVar;
using Content.Shared.Friction;
using Content.Shared.Gravity;
using Content.Shared.Inventory;
using Content.Shared.Maps;
using Content.Shared.MobState.EntitySystems;
using Content.Shared.Movement.Components;
using Content.Shared.Movement.Events;
using Content.Shared.Pulling.Components;
using Content.Shared.Tag;
using Robust.Shared.Audio;
using Robust.Shared.Configuration;
using Robust.Shared.Containers;
using Robust.Shared.Map;
using Robust.Shared.Physics;
using Robust.Shared.Physics.Controllers;
using Robust.Shared.Timing;
using Robust.Shared.Utility;
using System.Diagnostics.CodeAnalysis;
using Robust.Shared.Physics.Components;
using Robust.Shared.Physics.Systems;

namespace Content.Shared.Movement.Systems
{
    /// <summary>
    ///     Handles player and NPC mob movement.
    ///     NPCs are handled server-side only.
    /// </summary>
    public abstract partial class SharedMoverController : VirtualController
    {
        [Dependency] private   readonly IConfigurationManager _configManager = default!;
        [Dependency] protected readonly IGameTiming Timing = default!;
        [Dependency] private   readonly IMapManager _mapManager = default!;
        [Dependency] private   readonly ITileDefinitionManager _tileDefinitionManager = default!;
        [Dependency] private   readonly InventorySystem _inventory = default!;
        [Dependency] private   readonly SharedContainerSystem _container = default!;
        [Dependency] private   readonly SharedGravitySystem _gravity = default!;
        [Dependency] private   readonly SharedMobStateSystem _mobState = default!;
        [Dependency] protected readonly SharedAudioSystem Audio = default!;
        [Dependency] private   readonly SharedTransformSystem _transform = default!;
        [Dependency] private   readonly TagSystem _tags = default!;

        private const float StepSoundMoveDistanceRunning = 2;
        private const float StepSoundMoveDistanceWalking = 1.5f;

        private const float FootstepVariation = 0f;
        private const float FootstepVolume = 3f;
        private const float FootstepWalkingAddedVolumeMultiplier = 0f;

        protected ISawmill Sawmill = default!;

        /// <summary>
        /// <see cref="CCVars.StopSpeed"/>
        /// </summary>
        private float _stopSpeed;

        private bool _relativeMovement;

        /// <summary>
        /// Cache the mob movement calculation to re-use elsewhere.
        /// </summary>
        public Dictionary<EntityUid, bool> UsedMobMovement = new();

        public override void Initialize()
        {
            base.Initialize();
            Sawmill = Logger.GetSawmill("mover");
            InitializeFootsteps();
            InitializeInput();
            InitializeMob();
            InitializePushing();
            InitializeRelay();
            _configManager.OnValueChanged(CCVars.RelativeMovement, SetRelativeMovement, true);
            _configManager.OnValueChanged(CCVars.StopSpeed, SetStopSpeed, true);
            UpdatesBefore.Add(typeof(TileFrictionController));
        }

        private void SetRelativeMovement(bool value) => _relativeMovement = value;
        private void SetStopSpeed(float value) => _stopSpeed = value;

        public override void Shutdown()
        {
            base.Shutdown();
            ShutdownInput();
            ShutdownPushing();
            _configManager.UnsubValueChanged(CCVars.RelativeMovement, SetRelativeMovement);
            _configManager.UnsubValueChanged(CCVars.StopSpeed, SetStopSpeed);
        }

        public override void UpdateAfterSolve(bool prediction, float frameTime)
        {
            base.UpdateAfterSolve(prediction, frameTime);
            UsedMobMovement.Clear();
        }

        /// <summary>
        ///     Movement while considering actionblockers, weightlessness, etc.
        /// </summary>
        /// <remarks>
        /// Yes this signature is massive but this is also called a lot.
        /// </remarks>
        protected void HandleMobMovement(
            InputMoverComponent mover,
            PhysicsComponent physicsComponent,
            TransformComponent xform,
            float frameTime,
            EntityQuery<TransformComponent> xformQuery,
            EntityQuery<MobMoverComponent> mobQuery,
            EntityQuery<InventoryComponent> inventoryQuery,
            EntityQuery<ContainerManagerComponent> containerQuery,
            EntityQuery<FootstepModifierComponent> footQuery,
            out bool dirtyMover,
            out Vector2? linearVelocity,
            out SoundSpecifier? sound,
            out AudioParams audio)
        {
            dirtyMover = false;
            linearVelocity = Vector2.Zero;
            sound = null;
            audio = default;

            // Update relative movement
            if (mover.LerpTarget < Timing.CurTime)
            {
                if (TryUpdateRelative(mover, xform, xformQuery))
                {
                    dirtyMover = true;
                }
            }

            var angleDiff = Angle.ShortestDistance(mover.RelativeRotation, mover.TargetRelativeRotation);

            // if we've just traversed then lerp to our target rotation.
            if (!angleDiff.EqualsApprox(Angle.Zero, 0.001))
            {
                var adjustment = angleDiff * 5f * frameTime;
                var minAdjustment = 0.01 * frameTime;

                if (angleDiff < 0)
                {
                    adjustment = Math.Min(adjustment, -minAdjustment);
                    adjustment = Math.Clamp(adjustment, angleDiff, -angleDiff);
                }
                else
                {
                    adjustment = Math.Max(adjustment, minAdjustment);
                    adjustment = Math.Clamp(adjustment, -angleDiff, angleDiff);
                }

                mover.RelativeRotation += adjustment;
                mover.RelativeRotation.FlipPositive();
                dirtyMover = true;
            }
            else if (!angleDiff.Equals(Angle.Zero))
            {
                mover.TargetRelativeRotation.FlipPositive();
                mover.RelativeRotation = mover.TargetRelativeRotation;
                dirtyMover = true;
            }

            if (!UseMobMovement(mover, physicsComponent))
            {
                UsedMobMovement[mover.Owner] = false;
                return;
            }

            UsedMobMovement[mover.Owner] = true;
            // Specifically don't use mover.Owner because that may be different to the actual physics body being moved.
            var weightless = _gravity.IsWeightless(physicsComponent.Owner, physicsComponent, xform);
            var (walkDir, sprintDir) = GetVelocityInput(mover);
            var touching = false;

            // Handle wall-pushes.
            if (weightless)
            {
                if (xform.GridUid != null)
                    touching = true;

                if (!touching)
                {
                    var ev = new CanWeightlessMoveEvent();
                    RaiseLocalEvent(xform.Owner, ref ev);
                    // No gravity: is our entity touching anything?
                    touching = ev.CanMove;

                    if (!touching && mobQuery.TryGetComponent(xform.Owner, out var mobMover))
                        touching |= IsAroundCollider(PhysicsSystem, xform, mobMover, physicsComponent);
                }
            }

            // Regular movement.
            // Target velocity.
            // This is relative to the map / grid we're on.
            var moveSpeedComponent = CompOrNull<MovementSpeedModifierComponent>(mover.Owner);

            var walkSpeed = moveSpeedComponent?.CurrentWalkSpeed ?? MovementSpeedModifierComponent.DefaultBaseWalkSpeed;
            var sprintSpeed = moveSpeedComponent?.CurrentSprintSpeed ?? MovementSpeedModifierComponent.DefaultBaseSprintSpeed;

            var total = walkDir * walkSpeed + sprintDir * sprintSpeed;

            var parentRotation = GetParentGridAngle(mover, xformQuery);
            var worldTotal = _relativeMovement ? parentRotation.RotateVec(total) : total;

            DebugTools.Assert(MathHelper.CloseToPercent(total.Length, worldTotal.Length));

            var velocity = physicsComponent.LinearVelocity;
            float friction;
            float weightlessModifier;
            float accel;

            if (weightless)
            {
                if (worldTotal != Vector2.Zero && touching)
                    friction = moveSpeedComponent?.WeightlessFriction ?? MovementSpeedModifierComponent.DefaultWeightlessFriction;
                else
                    friction = moveSpeedComponent?.WeightlessFrictionNoInput ?? MovementSpeedModifierComponent.DefaultWeightlessFrictionNoInput;

                weightlessModifier = moveSpeedComponent?.WeightlessModifier ?? MovementSpeedModifierComponent.DefaultWeightlessModifier;
                accel = moveSpeedComponent?.WeightlessAcceleration ?? MovementSpeedModifierComponent.DefaultWeightlessAcceleration;
            }
            else
            {
                if (worldTotal != Vector2.Zero || moveSpeedComponent?.FrictionNoInput == null)
                {
                    friction = moveSpeedComponent?.Friction ?? MovementSpeedModifierComponent.DefaultFriction;
                }
                else
                {
                    friction = moveSpeedComponent.FrictionNoInput ?? MovementSpeedModifierComponent.DefaultFrictionNoInput;
                }

                weightlessModifier = 1f;
                accel = moveSpeedComponent?.Acceleration ?? MovementSpeedModifierComponent.DefaultAcceleration;
            }

            var minimumFrictionSpeed = moveSpeedComponent?.MinimumFrictionSpeed ?? MovementSpeedModifierComponent.DefaultMinimumFrictionSpeed;
            Friction(minimumFrictionSpeed, frameTime, friction, ref velocity);

            if (worldTotal != Vector2.Zero)
            {
                // This should have its event run during island solver soooo
                xform.DeferUpdates = true;
                _transform.SetWorldRotation(xform, worldTotal.ToWorldAngle(), xformQuery);
                xform.DeferUpdates = false;

                if (!weightless && TryComp<MobMoverComponent>(mover.Owner, out var mobMover) &&
                    TryGetSound(weightless, mover, mobMover, xform, inventoryQuery, containerQuery, footQuery, out var soundSpec))
                {
                    var soundModifier = mover.Sprinting ? 1.0f : FootstepWalkingAddedVolumeMultiplier;

                    var audioParams = soundSpec.Params
                        .WithVolume(FootstepVolume * soundModifier)
                        .WithVariation(soundSpec.Params.Variation ?? FootstepVariation);

                    sound = soundSpec;
                    audio = audioParams;
                }
            }

            worldTotal *= weightlessModifier;

            if (!weightless || touching)
                Accelerate(ref velocity, in worldTotal, accel, frameTime);

            if (physicsComponent.LinearVelocity.EqualsApprox(velocity, 0.0001f) &&
                MathHelper.CloseTo(physicsComponent.AngularVelocity, 0f))
            {
                return;
            }

            linearVelocity = velocity;
        }

        private void Friction(float minimumFrictionSpeed, float frameTime, float friction, ref Vector2 velocity)
        {
            var speed = velocity.Length;

            if (speed < minimumFrictionSpeed) return;

            var drop = 0f;

            var control = MathF.Max(_stopSpeed, speed);
            drop += control * friction * frameTime;

            var newSpeed = MathF.Max(0f, speed - drop);

            if (newSpeed.Equals(speed)) return;

            newSpeed /= speed;
            velocity *= newSpeed;
        }

        private void Accelerate(ref Vector2 currentVelocity, in Vector2 velocity, float accel, float frameTime)
        {
            var wishDir = velocity != Vector2.Zero ? velocity.Normalized : Vector2.Zero;
            var wishSpeed = velocity.Length;

            var currentSpeed = Vector2.Dot(currentVelocity, wishDir);
            var addSpeed = wishSpeed - currentSpeed;

            if (addSpeed <= 0f) return;

            var accelSpeed = accel * frameTime * wishSpeed;
            accelSpeed = MathF.Min(accelSpeed, addSpeed);

            currentVelocity += wishDir * accelSpeed;
        }

        public bool UseMobMovement(EntityUid uid)
        {
            return UsedMobMovement.TryGetValue(uid, out var used) && used;
        }

        protected bool UseMobMovement(InputMoverComponent mover, PhysicsComponent body)
        {
            return mover.CanMove &&
                   body.BodyStatus == BodyStatus.OnGround &&
                   HasComp<InputMoverComponent>(body.Owner) &&
                   // If we're being pulled then don't mess with our velocity.
                   (!TryComp(body.Owner, out SharedPullableComponent? pullable) || !pullable.BeingPulled);
        }

        /// <summary>
        ///     Used for weightlessness to determine if we are near a wall.
        /// </summary>
        private bool IsAroundCollider(SharedPhysicsSystem broadPhaseSystem, TransformComponent transform, MobMoverComponent mover, IPhysBody collider)
        {
            var enlargedAABB = collider.GetWorldAABB().Enlarged(mover.GrabRangeVV);

            foreach (var otherCollider in broadPhaseSystem.GetCollidingEntities(transform.MapID, enlargedAABB))
            {
                if (otherCollider == collider) continue; // Don't try to push off of yourself!

                // Only allow pushing off of anchored things that have collision.
                if (otherCollider.BodyType != BodyType.Static ||
                    !otherCollider.CanCollide ||
                    ((collider.CollisionMask & otherCollider.CollisionLayer) == 0 &&
                    (otherCollider.CollisionMask & collider.CollisionLayer) == 0) ||
                    (TryComp(otherCollider.Owner, out SharedPullableComponent? pullable) && pullable.BeingPulled))
                {
                    continue;
                }

                return true;
            }

            return false;
        }

        protected abstract bool CanSound();

        private bool TryGetSound(
            bool weightless,
            InputMoverComponent mover,
            MobMoverComponent mobMover,
            TransformComponent xform,
            EntityQuery<InventoryComponent> inventoryQuery,
            EntityQuery<ContainerManagerComponent> containerQuery,
            EntityQuery<FootstepModifierComponent> footQuery,

        [NotNullWhen(true)] out SoundSpecifier? sound)
        {
            sound = null;

            if (!CanSound() || !_tags.HasTag(mover.Owner, "FootstepSound")) return false;

            var coordinates = xform.Coordinates;
            var distanceNeeded = mover.Sprinting ? StepSoundMoveDistanceRunning : StepSoundMoveDistanceWalking;

            // Handle footsteps.
            if (!weightless)
            {
                // Can happen when teleporting between grids.
                if (!coordinates.TryDistance(EntityManager, mobMover.LastPosition, out var distance) ||
                    distance > distanceNeeded)
                {
                    mobMover.StepSoundDistance = distanceNeeded;
                }
                else
                {
                    mobMover.StepSoundDistance += distance;
                }
            }
            else
            {
                // In space no one can hear you squeak
                return false;
            }

            mobMover.LastPosition = coordinates;

            if (mobMover.StepSoundDistance < distanceNeeded) return false;

            mobMover.StepSoundDistance -= distanceNeeded;
            EntityUid? shoes = null;

            if (inventoryQuery.TryGetComponent(mover.Owner, out var inventory) &&
                containerQuery.TryGetComponent(mover.Owner, out var containerManager) &&
                _inventory.TryGetSlotEntity(mover.Owner, "shoes", out shoes, inventory, containerManager) &&
                footQuery.TryGetComponent(shoes, out var modifier))
            {
                sound = modifier.Sound;
                return true;
            }

            return TryGetFootstepSound(coordinates, shoes != null, footQuery, out sound);
        }

        private bool TryGetFootstepSound(EntityCoordinates coordinates, bool haveShoes, EntityQuery<FootstepModifierComponent> footQuery, [NotNullWhen(true)] out SoundSpecifier? sound)
        {
            sound = null;
            var gridUid = coordinates.GetGridUid(EntityManager);

            // Fallback to the map
            if (gridUid == null)
            {
                if (footQuery.TryGetComponent(coordinates.GetMapUid(EntityManager), out var modifier))
                {
                    sound = modifier.Sound;
                    return true;
                }

                return false;
            }

            var grid = _mapManager.GetGrid(gridUid.Value);
            var tile = grid.GetTileRef(coordinates);

            if (tile.IsSpace(_tileDefinitionManager))
                return false;

            // If the coordinates have a FootstepModifier component
            // i.e. component that emit sound on footsteps emit that sound
            var anchoredEnumerator = grid.GetAnchoredEntitiesEnumerator(tile.GridIndices);

            while (anchoredEnumerator.MoveNext(out var maybeFootstep))
            {
                if (!footQuery.TryGetComponent(maybeFootstep, out var footstep))
                    continue;

                sound = footstep.Sound;
                return true;
            }

            // Walking on a tile.
            var def = (ContentTileDefinition) _tileDefinitionManager[tile.Tile.TypeId];
            sound = haveShoes ? def.FootstepSounds : def.BarestepSounds;
            return sound != null;
        }
    }
}