/*
 * Farseer Physics Engine:
 * Copyright (c) 2012 Ian Qvist
 *
 * Original source Box2D:
 * Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software
 * in a product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * PhysicsComponent is heavily modified from Box2D.
 */

using System;
using System.Linq;
using System.Numerics;
using JetBrains.Annotations;
using Robust.Shared.GameObjects;
using Robust.Shared.GameStates;
using Robust.Shared.Map;
using Robust.Shared.Map.Components;
using Robust.Shared.Maths;
using Robust.Shared.Physics.Components;
using Robust.Shared.Physics.Dynamics;
using Robust.Shared.Physics.Dynamics.Contacts;
using Robust.Shared.Physics.Events;
using Robust.Shared.Utility;

namespace Robust.Shared.Physics.Systems;

public partial class SharedPhysicsSystem
{
    #region Lifetime

    private void OnPhysicsInit(EntityUid uid, PhysicsComponent component, ComponentInit args)
    {
        var xform = Transform(uid);
        var manager = EnsureComp<FixturesComponent>(uid);

        if (component.CanCollide && (_containerSystem.IsEntityOrParentInContainer(uid) || xform.MapID == MapId.Nullspace))
        {
            SetCanCollide(uid, false, false, manager: manager, body: component);
        }

        if (component.CanCollide)
        {
            if (component.BodyType != BodyType.Static)
            {
                SetAwake((uid, component), true);
            }
        }

        // Gets added to broadphase via fixturessystem
        _fixtures.OnPhysicsInit(uid, manager, component);

        if (manager.FixtureCount == 0)
            component.CanCollide = false;

        var ev = new CollisionChangeEvent(uid, component, component.CanCollide);
        RaiseLocalEvent(ref ev);
    }

    private void OnPhysicsGetState(EntityUid uid, PhysicsComponent component, ref ComponentGetState args)
    {
        if (args.FromTick > component.CreationTick && component.LastFieldUpdate >= args.FromTick)
        {
            var slowPath = false;

            for (var i = 0; i < _angularVelocityIndex; i++)
            {
                var field = component.LastModifiedFields[i];

                if (field < args.FromTick)
                    continue;

                slowPath = true;
                break;
            }

            // We can do a smaller delta with no list index overhead.
            if (!slowPath)
            {
                var angularDirty = component.LastModifiedFields[_angularVelocityIndex] >= args.FromTick;

                if (angularDirty)
                {
                    args.State = new PhysicsVelocityDeltaState()
                    {
                        AngularVelocity = component.AngularVelocity,
                        LinearVelocity = component.LinearVelocity,
                    };
                }
                else
                {
                    args.State = new PhysicsLinearVelocityDeltaState()
                    {
                        LinearVelocity = component.LinearVelocity,
                    };
                }

                return;
            }
        }

        args.State = new PhysicsComponentState
        {
            CanCollide = component.CanCollide,
            SleepingAllowed = component.SleepingAllowed,
            FixedRotation = component.FixedRotation,
            Status = component.BodyStatus,
            LinearVelocity = component.LinearVelocity,
            AngularVelocity = component.AngularVelocity,
            BodyType = component.BodyType,
            Friction = component._friction,
            LinearDamping = component.LinearDamping,
            AngularDamping = component.AngularDamping,
            Force = component.Force,
            Torque = component.Torque,
        };
    }

    private void OnPhysicsHandleState(EntityUid uid, PhysicsComponent component, ref ComponentHandleState args)
    {
        if (args.Current == null)
            return;

        // So transform doesn't apply MapId in the HandleComponentState because ??? so MapId can still be 0.
        // Fucking kill me, please. You have no idea deep the rabbit hole of shitcode goes to make this work.
        _fixturesQuery.TryComp(uid, out var manager);

        if (args.Current is PhysicsLinearVelocityDeltaState linearState)
        {
            SetLinearVelocity(uid, linearState.LinearVelocity, dirty: false, body: component, manager: manager);
        }
        else if (args.Current is PhysicsVelocityDeltaState velocityState)
        {
            SetLinearVelocity(uid, velocityState.LinearVelocity, dirty: false, body: component, manager: manager);
            SetAngularVelocity(uid, velocityState.AngularVelocity, dirty: false, body: component, manager: manager);
        }
        else if (args.Current is PhysicsComponentState newState)
        {
            SetSleepingAllowed(uid, component, newState.SleepingAllowed, dirty: false);
            SetFixedRotation(uid, newState.FixedRotation, body: component, dirty: false);
            SetCanCollide(uid, newState.CanCollide, body: component, dirty: false);
            SetBodyStatus(uid, component, newState.Status, dirty: false);

            SetLinearVelocity(uid, newState.LinearVelocity, dirty: false, body: component, manager: manager);
            SetAngularVelocity(uid, newState.AngularVelocity, dirty: false, body: component, manager: manager);
            SetBodyType(uid, newState.BodyType, manager, component);
            SetFriction(uid, component, newState.Friction, dirty: false);
            SetLinearDamping(uid, component, newState.LinearDamping, dirty: false);
            SetAngularDamping(uid, component, newState.AngularDamping, dirty: false);
            component.Force = newState.Force;
            component.Torque = newState.Torque;
        }
    }

    #endregion

    private bool IsMoveable(PhysicsComponent body)
    {
        return (body.BodyType & (BodyType.Dynamic | BodyType.KinematicController)) != 0x0;
    }

    #region Impulses

    public void ApplyAngularImpulse(EntityUid uid, float impulse, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body) || !IsMoveable(body) || !WakeBody(uid, manager: manager, body: body))
        {
            return;
        }

        SetAngularVelocity(uid, body.AngularVelocity + impulse * body.InvI, body: body);
    }

    public void ApplyForce(EntityUid uid, Vector2 force, Vector2 point, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body) || !IsMoveable(body) || !WakeBody(uid, manager: manager, body: body))
        {
            return;
        }

        body.Force += force;
        body.Torque += Vector2Helpers.Cross(point - body._localCenter, force);
    }

    public void ApplyForce(EntityUid uid, Vector2 force, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body) || !IsMoveable(body) || !WakeBody(uid, manager: manager, body: body))
        {
            return;
        }

        body.Force += force;
    }

    public void ApplyTorque(EntityUid uid, float torque, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body) || !IsMoveable(body) || !WakeBody(uid, manager: manager, body: body))
        {
            return;
        }

        body.Torque += torque;
        DirtyField(uid, body, nameof(PhysicsComponent.Torque));
    }

    public void ApplyLinearImpulse(EntityUid uid, Vector2 impulse, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body) || !IsMoveable(body) || !WakeBody(uid, manager: manager, body: body))
        {
            return;
        }

        SetLinearVelocity(uid, body.LinearVelocity + impulse * body._invMass, body: body);
    }

    public void ApplyLinearImpulse(EntityUid uid, Vector2 impulse, Vector2 point, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body) || !IsMoveable(body) || !WakeBody(uid, manager: manager, body: body))
        {
            return;
        }

        SetLinearVelocity(uid, body.LinearVelocity + impulse * body._invMass, body: body);
        var matrix = _transform.GetWorldMatrix(uid);
        SetAngularVelocity(uid, body.AngularVelocity + body.InvI * Vector2Helpers.Cross(Vector2.Transform(point, matrix) - Vector2.Transform(body._localCenter, matrix), impulse), body: body);
    }

    #endregion

    #region Setters

    public void DestroyContacts(PhysicsComponent body)
    {
        if (body.Contacts.Count == 0)
            return;

        var node = body.Contacts.First;

        while (node != null)
        {
            var contact = node.Value;

            // The Start/End collide events can result in other contacts in this list being destroyed, and maybe being
            // created elsewhere. We want to ensure that the "next" node from a previous iteration wasn't somehow
            // destroyed, returned to the pool, and then re-assigned to a new body.
            // AFAIK this shouldn't be possible anymore, now that the next node is returned by DestroyContacts() after
            // all events were raised.
            DebugTools.Assert(contact.BodyA == body || contact.BodyB == body || contact.Flags == ContactFlags.Deleted);
            DebugTools.AssertNotEqual(node, node.Next);

            DestroyContact(contact, node, out var next);
            DebugTools.AssertNotEqual(node, next);
            node = next;
        }

        // It is possible that this DestroyContacts was called while another DestroyContacts was still being processed.
        // The only remaining contacts should be those that are still getting deleted.
        DebugTools.Assert(body.Contacts.All(x => (x.Flags & ContactFlags.Deleting) != 0));
    }

    /// <summary>
    /// Completely resets a dynamic body.
    /// </summary>
    public void ResetDynamics(EntityUid uid, PhysicsComponent body, bool dirty = true)
    {
        body.Torque = 0f;
        body.AngularVelocity = 0f;
        body.Force = Vector2.Zero;
        body.LinearVelocity = Vector2.Zero;
        if (dirty)
            DirtyFields(uid, body, null, nameof(PhysicsComponent.Torque), nameof(PhysicsComponent.AngularVelocity), nameof(PhysicsComponent.Force), nameof(PhysicsComponent.LinearVelocity));
    }

    public void ResetMassData(EntityUid uid, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body))
            return;

        if (!_fixturesQuery.Resolve(uid, ref manager))
            return;

        var oldMass = body._mass;
        var oldInertia = body._inertia;

        body._mass = 0.0f;
        body._invMass = 0.0f;
        body._inertia = 0.0f;
        body.InvI = 0.0f;
        var localCenter = Vector2.Zero;

        foreach (var fixture in manager.Fixtures.Values)
        {
            if (fixture.Density <= 0.0f) continue;

            var data = new MassData();
            FixtureSystem.GetMassData(fixture.Shape, ref data, fixture.Density);

            body._mass += data.Mass;
            localCenter += data.Center * data.Mass;
            body._inertia += data.I;
        }

        if (body._mass > 0.0f)
        {
            body._invMass = 1.0f / body._mass;
            localCenter *= body._invMass;
        }
        else
        {
            // Always need positive mass.
            body._mass = 1.0f;
            body._invMass = 1.0f;
        }

        if (body._inertia > 0.0f && !body.FixedRotation)
        {
            // Center inertia about center of mass.
            body._inertia -= body._mass * Vector2.Dot(localCenter, localCenter);

            DebugTools.Assert(body._inertia > 0.0f);
            body.InvI = 1.0f / body._inertia;
        }
        else
        {
            body._inertia = 0.0f;
            body.InvI = 0.0f;
        }

        var oldCenter = body._localCenter;
        body._localCenter = localCenter;

        if (((int)body.BodyType & (int)(BodyType.Kinematic | BodyType.Static)) == 0)
        {
            // Update center of mass velocity.
            var comVelocityDiff = Vector2Helpers.Cross(body.AngularVelocity, localCenter - oldCenter);

            if (comVelocityDiff != Vector2.Zero)
            {
                body.LinearVelocity += comVelocityDiff;
                DirtyField(uid, body, nameof(PhysicsComponent.LinearVelocity));
            }
        }

        if (body._mass == oldMass && body._inertia == oldInertia && oldCenter == localCenter)
            return;

        // we always do the full mass and COM calculation and raise this, even for static bodies as content may need the info
        // examples are stations anchored with the station anchor, shuttles landed on planets, or grids getting an atmosphere above a certain mass threshold
        var ev = new MassDataChangedEvent((uid, body, manager), oldMass, oldInertia, oldCenter);
        RaiseLocalEvent(uid, ref ev);
    }

    public bool SetAngularVelocity(EntityUid uid, float value, bool dirty = true, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body))
            return false;

        if (body.BodyType == BodyType.Static)
            return false;

        if (value * value > 0.0f)
        {
            if (!WakeBody(uid, manager: manager, body: body))
                return false;
        }

        // CloseToPercent tolerance needs to be small enough such that an angular velocity just above
        // sleep-tolerance can damp down to sleeping.

        if (MathHelper.CloseToPercent(body.AngularVelocity, value, 0.00001f))
            return false;

        body.AngularVelocity = value;
        if (dirty)
            DirtyField(uid, body, nameof(PhysicsComponent.AngularVelocity));

        return true;
    }

    /// <summary>
    /// Attempts to set the body to collidable, wake it, then move it.
    /// </summary>
    public bool SetLinearVelocity(EntityUid uid, Vector2 velocity, bool dirty = true, bool wakeBody = true, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body))
            return false;

        if (body.BodyType == BodyType.Static)
            return false;

        if (wakeBody && Vector2.Dot(velocity, velocity) > 0.0f)
        {
            if (!WakeBody(uid, manager: manager, body: body))
                return false;
        }

        if (body.LinearVelocity.EqualsApprox(velocity, 0.0000001f))
            return false;

        body.LinearVelocity = velocity;
        if (dirty)
            DirtyField(uid, body, nameof(PhysicsComponent.LinearVelocity));

        return true;
    }

    public void SetAngularDamping(EntityUid uid, PhysicsComponent body, float value, bool dirty = true)
    {
        if (MathHelper.CloseTo(body.AngularDamping, value))
            return;

        body.AngularDamping = value;
        if (dirty)
            DirtyField(uid, body, nameof(PhysicsComponent.AngularDamping));
    }

    public void SetLinearDamping(EntityUid uid, PhysicsComponent body, float value, bool dirty = true)
    {
        if (MathHelper.CloseTo(body.LinearDamping, value))
            return;

        body.LinearDamping = value;
        if (dirty)
            DirtyField(uid, body, nameof(PhysicsComponent.LinearDamping));
    }

    [Obsolete("Use SetAwake with EntityUid<PhysicsComponent>")]
    public void SetAwake(EntityUid uid, PhysicsComponent body, bool value, bool updateSleepTime = true)
    {
        SetAwake(new Entity<PhysicsComponent>(uid, body), value, updateSleepTime);
    }

    public void SetAwake(Entity<PhysicsComponent> ent, bool value, bool updateSleepTime = true)
    {
        var (uid, body) = ent;
        var canWake = body.BodyType != BodyType.Static && body.CanCollide;

        if (body.Awake == value)
        {
            DebugTools.Assert(!body.Awake || canWake);
            return;
        }

        if (value && !canWake)
            return;

        body.Awake = value;

        if (value)
        {
            var ev = new PhysicsWakeEvent(uid, body);
            RaiseLocalEvent(uid, ref ev, true);
        }
        else
        {
            var ev = new PhysicsSleepEvent(uid, body);
            RaiseLocalEvent(uid, ref ev, true);
            ResetDynamics(ent, body, dirty: false);
        }

        // Update wake system last, if sleeping but still colliding.
        if (!value && body.CanCollide)
            _wakeSystem.UpdateCanCollide(ent, checkTerminating: false, dirty: false);

        if (updateSleepTime)
            SetSleepTime(body, 0);

        if (body.Awake != value)
        {
            Log.Error($"Found a corrupted physics awake state for {ToPrettyString(ent)}! Did you forget to cancel the sleep subscription? Forcing body awake");
            DebugTools.Assert(false);
            body.Awake = true;
        }

        if (body.Awake)
            AddAwakeBody((uid, body, Transform(uid)));
        else
            RemoveSleepBody((uid, body, Transform(uid)));
    }

    public void TrySetBodyType(EntityUid uid, BodyType value, FixturesComponent? manager = null, PhysicsComponent? body = null, TransformComponent? xform = null)
    {
        if (_fixturesQuery.Resolve(uid, ref manager, false) &&
           PhysicsQuery.Resolve(uid, ref body, false) &&
           XformQuery.Resolve(uid, ref xform, false))
        {
            SetBodyType(uid, value, manager, body, xform);
        }
    }

    public void SetBodyType(EntityUid uid, BodyType value, FixturesComponent? manager = null, PhysicsComponent? body = null, TransformComponent? xform = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body))
            return;

        if (body.BodyType == value)
            return;

        var oldType = body.BodyType;
        body.BodyType = value;

        body.Force = Vector2.Zero;
        body.Torque = 0f;

        if (body.BodyType == BodyType.Static)
        {
            SetAwake((uid, body), false);

            body.LinearVelocity = Vector2.Zero;
            body.AngularVelocity = 0f;

            DirtyFields(uid, body, null,
                nameof(PhysicsComponent.LinearVelocity),
                nameof(PhysicsComponent.AngularVelocity),
                nameof(PhysicsComponent.Force),
                nameof(PhysicsComponent.Torque));
        }
        // Even if it's dynamic if it can't collide then don't force it awake.
        else if (body.CanCollide)
        {
            SetAwake((uid, body), true);
            DirtyFields(uid, body, null, nameof(PhysicsComponent.Force), nameof(PhysicsComponent.Torque));
        }

        _broadphase.RegenerateContacts((uid, body, manager, xform));

        if (body.Initialized)
        {
            var ev = new PhysicsBodyTypeChangedEvent(uid, body.BodyType, oldType, body);
            RaiseLocalEvent(uid, ref ev, true);
        }
    }

    public void SetBodyStatus(EntityUid uid, PhysicsComponent body, BodyStatus status, bool dirty = true)
    {
        if (body.BodyStatus == status)
            return;

        var oldStatus = body.BodyStatus;
        body.BodyStatus = status;

        var ev = new PhysicsBodyStatusChangedEvent(body, oldStatus, status);
        RaiseLocalEvent(uid, ref ev);

        if (dirty)
            DirtyField(uid, body, nameof(PhysicsComponent.BodyStatus));
    }

    /// <summary>
    /// Sets the <see cref="PhysicsComponent.CanCollide"/> property; this handles whether the body is enabled.
    /// </summary>
    /// <returns>CanCollide</returns>
    /// <param name="force">Bypasses fixture and container checks</param>
    public bool SetCanCollide(
        EntityUid uid,
        bool value,
        bool dirty = true,
        bool force = false,
        FixturesComponent? manager = null,
        PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body))
            return false;

        if (body.CanCollide == value)
            return value;

        if (value)
        {
            if (!force)
            {
                // If we're recursively in a container then never set this.
                if (_containerSystem.IsEntityOrParentInContainer(uid))
                    return false;

                if (!_fixturesQuery.Resolve(uid, ref manager) || manager.FixtureCount == 0 && !_gridQuery.HasComp(uid))
                    return false;
            }
            else
            {
                DebugTools.Assert(!_containerSystem.IsEntityOrParentInContainer(uid));
                DebugTools.Assert((Resolve(uid, ref manager) && manager.FixtureCount > 0) || _gridQuery.HasComp(uid));
            }
        }

        // Need to do this before SetAwake to avoid double-changing it.
        body.CanCollide = value;

        if (!value)
            SetAwake((uid, body), false);

        if (body.Initialized)
        {
            var ev = new CollisionChangeEvent(uid, body, value);
            RaiseLocalEvent(ref ev);
        }

        if (dirty)
            DirtyField(uid, body, nameof(PhysicsComponent.CanCollide));

        return value;
    }

    public void SetFixedRotation(EntityUid uid, bool value, bool dirty = true, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body) || body.FixedRotation == value)
            return;

        body.FixedRotation = value;
        body.AngularVelocity = 0.0f;

        if (dirty)
            DirtyFields(uid, body, null, nameof(PhysicsComponent.FixedRotation), nameof(PhysicsComponent.AngularVelocity));

        ResetMassData(uid, manager: manager, body: body);
    }

    public void SetFriction(EntityUid uid, PhysicsComponent body, float value, bool dirty = true)
    {
        if (MathHelper.CloseTo(body.Friction, value))
            return;

        body._friction = value;
        if (dirty)
            DirtyField(uid, body, nameof(PhysicsComponent.Friction));
    }

    public void SetInertia(EntityUid uid, PhysicsComponent body, float value, bool dirty = true)
    {
        DebugTools.Assert(!float.IsNaN(value));

        if (body.BodyType != BodyType.Dynamic) return;

        if (MathHelper.CloseToPercent(body._inertia, value)) return;

        if (value > 0.0f && !body.FixedRotation)
        {
            body._inertia = value - body.Mass * Vector2.Dot(body._localCenter, body._localCenter);
            DebugTools.Assert(body._inertia > 0.0f);
            body.InvI = 1.0f / body._inertia;
            // Not networked
        }
    }

    public void SetLocalCenter(EntityUid uid, PhysicsComponent body, Vector2 value)
    {
        if (body.BodyType != BodyType.Dynamic) return;

        if (value.EqualsApprox(body._localCenter)) return;

        body._localCenter = value;
        // Not networked
    }

    public void SetSleepingAllowed(EntityUid uid, PhysicsComponent body, bool value, bool dirty = true)
    {
        if (body.SleepingAllowed == value)
            return;

        if (!value)
            SetAwake((uid, body), true);

        body.SleepingAllowed = value;
        if (dirty)
            DirtyField(uid, body, nameof(PhysicsComponent.SleepingAllowed));
    }

    public void SetSleepTime(PhysicsComponent body, float value)
    {
        DebugTools.Assert(!float.IsNaN(value));

        if (MathHelper.CloseToPercent(value, body.SleepTime))
            return;

        body.SleepTime = value;
    }

    /// <summary>
    /// Tries to enable the body and also set it awake.
    /// </summary>
    /// <param name="force">Bypasses fixture and container checks</param>
    /// <returns>true if the body is collidable and awake</returns>
    public bool WakeBody(EntityUid uid, bool force = false, FixturesComponent? manager = null, PhysicsComponent? body = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body))
            return false;

        if (!SetCanCollide(uid, true, manager: manager, body: body, force: force))
            return false;

        SetAwake((uid, body), true);
        return body.Awake;
    }

    #endregion

    public Transform GetRelativePhysicsTransform(Transform worldTransform, Entity<TransformComponent?> relative)
    {
        if (!XformQuery.Resolve(relative.Owner, ref relative.Comp))
            return Physics.Transform.Empty;

        var (_, broadphaseRot, _, broadphaseInv) = _transform.GetWorldPositionRotationMatrixWithInv(relative.Comp);

        return new Transform(Vector2.Transform(worldTransform.Position, broadphaseInv),
            worldTransform.Quaternion2D.Angle - broadphaseRot);
    }

    /// <summary>
    /// Gets the physics transform relative to another entity.
    /// </summary>
    public Transform GetRelativePhysicsTransform(
        Entity<TransformComponent?> entity,
        Entity<TransformComponent?> relative)
    {
        if (!XformQuery.Resolve(entity.Owner, ref entity.Comp) ||
            !XformQuery.Resolve(relative.Owner, ref relative.Comp))
        {
            return Physics.Transform.Empty;
        }

        var (worldPos, worldRot) = _transform.GetWorldPositionRotation(entity.Comp);
        var (_, broadphaseRot, _, broadphaseInv) = _transform.GetWorldPositionRotationMatrixWithInv(relative.Comp);

        return new Transform(Vector2.Transform(worldPos, broadphaseInv), worldRot - broadphaseRot);
    }

    /// <summary>
    /// Gets broadphase relevant transform.
    /// </summary>
    public Transform GetLocalPhysicsTransform(EntityUid uid, TransformComponent? xform = null)
    {
        if (!XformQuery.Resolve(uid, ref xform) || xform.Broadphase == null)
            return Physics.Transform.Empty;

        var broadphase = xform.Broadphase.Value.Uid;

        if (xform.ParentUid == broadphase)
        {
            return new Transform(xform.LocalPosition, xform.LocalRotation);
        }

        return GetRelativePhysicsTransform((uid, xform), broadphase);
    }

    public Transform GetPhysicsTransform(EntityUid uid, TransformComponent? xform = null)
    {
        if (!XformQuery.Resolve(uid, ref xform))
            return Physics.Transform.Empty;

        var (worldPos, worldRot) = _transform.GetWorldPositionRotation(xform);

        return new Transform(worldPos, worldRot);
    }

    /// <summary>
    /// Gets the physics World AABB, only considering fixtures.
    /// </summary>
    public Box2 GetWorldAABB(EntityUid uid, FixturesComponent? manager = null, PhysicsComponent? body = null, TransformComponent? xform = null)
    {
        if (!Resolve(uid, ref manager, ref body, ref xform))
            return new Box2();

        var (worldPos, worldRot) = _transform.GetWorldPositionRotation(xform);

        var transform = new Transform(worldPos, (float)worldRot.Theta);

        var bounds = new Box2(transform.Position, transform.Position);

        foreach (var fixture in manager.Fixtures.Values)
        {
            for (var i = 0; i < fixture.Shape.ChildCount; i++)
            {
                var boundy = fixture.Shape.ComputeAABB(transform, i);
                bounds = bounds.Union(boundy);
            }
        }

        return bounds;
    }

    public Box2 GetHardAABB(EntityUid uid, FixturesComponent? manager = null, PhysicsComponent? body = null, TransformComponent? xform = null)
    {
        if (!PhysicsQuery.Resolve(uid, ref body)
            || !_fixturesQuery.Resolve(uid, ref manager)
            || !Resolve(uid, ref xform))
        {
            return Box2.Empty;
        }

        var (worldPos, worldRot) = _transform.GetWorldPositionRotation(xform);

        var transform = new Transform(worldPos, (float)worldRot.Theta);

        var bounds = new Box2(transform.Position, transform.Position);

        foreach (var fixture in manager.Fixtures.Values)
        {
            if (!fixture.Hard) continue;

            for (var i = 0; i < fixture.Shape.ChildCount; i++)
            {
                var boundy = fixture.Shape.ComputeAABB(transform, i);
                bounds = bounds.Union(boundy);
            }
        }

        return bounds;
    }

    /// <returns>The collision layer and collision mask of all hard fixtures.</returns>
    [PublicAPI]
    public (int Layer, int Mask) GetHardCollision(EntityUid uid, FixturesComponent? manager = null)
    {
        if (!_fixturesQuery.Resolve(uid, ref manager, false))
        {
            return (0, 0);
        }

        return GetHardCollision(manager);
    }

    /// <inheritdoc cref="GetHardCollision(EntityUid, FixturesComponent?)"/>
    [PublicAPI]
    public static (int Layer, int Mask) GetHardCollision(FixturesComponent manager)
    {
        var layer = 0;
        var mask = 0;

        foreach (var fixture in manager.Fixtures.Values)
        {
            if (!fixture.Hard)
                continue;

            layer |= fixture.CollisionLayer;
            mask |= fixture.CollisionMask;
        }

        return (layer, mask);
    }

    public virtual void UpdateIsPredicted(EntityUid? uid, PhysicsComponent? physics = null)
    {
        // See client-side system
    }
}