import type { Ball, Collider, ColliderDesc, Cuboid, EventQueue, QueryFilterFlags, Ray, RigidBody, RigidBodyDesc, World } from '@dimforge/rapier3d-compat';
import { BufferAttribute, BufferGeometry, InterleavedBufferAttribute, LineBasicMaterial, LineSegments, Matrix4, Mesh, Object3D, Quaternion, Vector3, Vector4Like } from 'three'
import * as BufferGeometryUtils from 'three/examples/jsm/utils/BufferGeometryUtils.js'

import { CollisionDetectionMode, PhysicsMaterialCombine } from '../engine/engine_physics.types.js';
import type { Collider as NeedleCollider } from '../engine-components/Collider.js';
import { MeshCollider } from '../engine-components/Collider.js';
import type { Rigidbody as NeedleRigidbody } from '../engine-components/RigidBody.js';
import { isDevEnvironment } from './debug/debug.js';
import { ContextEvent, ContextRegistry } from './engine_context_registry.js';
import { foreachComponent } from './engine_gameobject.js';
import { Gizmos } from './engine_gizmos.js';
import { Mathf } from './engine_math.js';
import { MODULES } from './engine_modules.js';
import type { Physics } from './engine_physics.js';
import { getWorldPosition, getWorldQuaternion, getWorldScale, setWorldPositionXYZ, setWorldQuaternionXYZW } from "./engine_three_utils.js"
import type {
    IBoxCollider,
    ICollider,
    IComponent,
    IContext,
    IGameObject,
    IPhysicsEngine,
    IRigidbody,
    ISphereCollider,
    Vec2,
    Vec3,
} from './engine_types.js';
import { Collision, ContactPoint } from './engine_types.js';
import { ShapeOverlapResult } from './engine_types.js';
import { CircularBuffer, getParam } from "./engine_utils.js"

const debugPhysics = getParam("debugphysics");
const debugColliderPlacement = getParam("debugcolliderplacement");
const debugCollisions = getParam("debugcollisions");
const showColliders = getParam("showcolliders");
const showPhysicsRaycasts = getParam("debugraycasts");


/** on physics body and references the needle component */
const $componentKey = Symbol("needle component");
/** on needle component and references physics body */
const $bodyKey = Symbol("physics body");
const $colliderRigidbody = Symbol("rigidbody");


declare const NEEDLE_USE_RAPIER: boolean;
globalThis["NEEDLE_USE_RAPIER"] = globalThis["NEEDLE_USE_RAPIER"] !== undefined ? globalThis["NEEDLE_USE_RAPIER"] : true;
if (debugPhysics)
    console.log("Use Rapier", NEEDLE_USE_RAPIER, globalThis["NEEDLE_USE_RAPIER"])

if (NEEDLE_USE_RAPIER) {
    ContextRegistry.registerCallback(ContextEvent.ContextCreationStart, evt => {
        if (debugPhysics)
            console.log("Register rapier physics backend")
        evt.context.physics.engine = new RapierPhysics(evt.context);
        // We do not initialize physics immediately to avoid loading the physics engine if it is not needed
    });
}


declare type PhysicsBody = {
    translation(): { x: number, y: number, z: number }
    rotation(): { x: number, y: number, z: number, w: number }
}

/**
 * Rapier physics engine implementation for Needle Engine.  
 *
 * Rapier is a fast, cross-platform physics engine that provides realistic physics simulation  
 * for rigidbodies, colliders, joints, and collision detection. It runs entirely in WebAssembly  
 * for high performance.  
 *
 * **Features:**  
 * - Rigidbody simulation (dynamic, kinematic, static)  
 * - Multiple collider shapes (box, sphere, capsule, mesh, convex hull)  
 * - Raycasting and shape overlap queries against physics colliders  
 * - Collision and trigger events  
 * - Joints (fixed, hinge, etc.)  
 * - Continuous collision detection (CCD)  
 * - Physics materials (friction, bounciness)  
 *
 * **Access:**  
 * The Rapier physics engine is accessible via `this.context.physics.engine` from any component.  
 * Rapier is automatically initialized when physics components are used.  
 *
 * **Using the Rapier Module Directly:**  
 * Rapier is lazy-loaded for performance. You can access the raw Rapier module via {@link MODULES.RAPIER_PHYSICS}.  
 * Use `MODULES.RAPIER_PHYSICS.load()` to load the module, or `MODULES.RAPIER_PHYSICS.ready()` to wait for it without triggering a load.  
 * Once loaded, the module is available at `MODULES.RAPIER_PHYSICS.MODULE`.  
 *
 * **Note:**  
 * This is the low-level physics engine implementation. For general raycasting (against all scene objects),  
 * use {@link Physics.raycast} instead. Use this class for physics-specific operations like applying forces,  
 * raycasting against colliders only, or accessing the Rapier world directly.  
 *
 * @example Applying forces to a rigidbody  
 * ```ts
 * const rb = this.gameObject.getComponent(Rigidbody);
 * if (rb) {
 *   this.context.physics.engine?.addForce(rb, { x: 0, y: 10, z: 0 }, true);
 * }
 * ```
 * @example Raycasting against physics colliders only  
 * ```ts
 * const origin = { x: 0, y: 5, z: 0 };
 * const direction = { x: 0, y: -1, z: 0 };
 * const hit = this.context.physics.engine?.raycast(origin, direction);
 * if (hit) {
 *   console.log("Hit collider:", hit.collider.name);
 * }
 * ```
 * @example Accessing Rapier world directly  
 * ```ts
 * const rapierWorld = this.context.physics.engine?.world;
 * if (rapierWorld) {
 *   // Direct access to Rapier API
 *   console.log("Gravity:", rapierWorld.gravity);
 * }
 * ```
 * @example Using the Rapier module directly  
 * ```ts
 * import { MODULES } from "@needle-tools/engine";
 *
 * // Load the Rapier module
 * const RAPIER = await MODULES.RAPIER_PHYSICS.load();
 *
 * // Now you can use Rapier types and create custom physics objects
 * const rigidBodyDesc = RAPIER.RigidBodyDesc.dynamic()
 *   .setTranslation(0, 10, 0);
 *
 * // Or access the already-loaded module
 * if (MODULES.RAPIER_PHYSICS.MODULE) {
 *   const colliderDesc = MODULES.RAPIER_PHYSICS.MODULE.ColliderDesc.ball(1.0);
 * }
 * ```
 * @see {@link Rigidbody} for physics simulation component
 * @see {@link Collider} for collision detection component
 * @see {@link Physics} for general raycasting and physics utilities
 * @see {@link MODULES.RAPIER_PHYSICS} for direct access to the Rapier module
 * @link https://rapier.rs/docs/ for Rapier documentation
 * @link https://engine.needle.tools/docs/reference/components.html#physics
 * @link https://engine.needle.tools/docs/how-to-guides/scripting/use-physics.html
 */
export class RapierPhysics implements IPhysicsEngine {

    debugRenderColliders: boolean = false;
    debugRenderRaycasts: boolean = false;

    removeBody(obj: IComponent) {
        if (debugPhysics) console.log("REMOVE BODY", obj?.name, obj[$bodyKey]);
        if (!obj) return;
        this.validate();
        const body = obj[$bodyKey];
        obj[$bodyKey] = null;
        if (body && this.world) {
            const index = this.objects.findIndex(o => o === obj);
            if (index >= 0) {
                const rapierBody = this.bodies[index];
                // Remove references
                this.bodies.splice(index, 1);
                this.objects.splice(index, 1);


                // Remove the collider from the physics world
                if (rapierBody instanceof MODULES.RAPIER_PHYSICS.MODULE.Collider) {
                    const rapierCollider = rapierBody as Collider;
                    this.world?.removeCollider(rapierCollider, true);

                    // also remove the rigidbody if it doesnt have colliders anymore
                    const rapierRigidbody: RigidBody | null = rapierCollider.parent();
                    if (rapierRigidbody && rapierRigidbody.numColliders() <= 0) {
                        const rigidbody = rapierRigidbody[$componentKey] as IRigidbody;
                        if (rigidbody) {
                            // If the collider was attached to a rigidbody and this rigidbody now has no colliders anymore we should ignore it - because the Rigidbody component will delete itself
                        }
                        else {
                            // But if there is no explicit rigidbody needle component then the colliders did create it implictly and thus we need to remove it here:
                            this.world?.removeRigidBody(rapierRigidbody);
                        }
                    }
                }
                // Remove the rigidbody from the physics world
                else if (rapierBody instanceof MODULES.RAPIER_PHYSICS.MODULE.RigidBody) {
                    if (rapierBody.numColliders() <= 0) {
                        this.world?.removeRigidBody(rapierBody);
                    }
                    else {
                        if (isDevEnvironment()) {
                            if (!rapierBody["did_log_removing"]) {
                                setTimeout(() => {
                                    if (rapierBody.numColliders() > 0) {
                                        rapierBody["did_log_removing"] = true;
                                        console.warn("RapierPhysics: removing rigidbody with colliders from the physics world is not possible right now, please remove the colliders first");
                                    }
                                }, 1);

                            }
                        }
                    }
                }
            }
        }
    }

    updateBody(comp: ICollider | IRigidbody, translation: boolean, rotation: boolean) {
        this.validate();
        if (!this.enabled) return;
        if (comp.destroyed || !comp.gameObject) return;
        if (!translation && !rotation) return;

        if ((comp as ICollider).isCollider === true) {
            // const collider = comp as ICollider;
            console.warn("TODO: implement updating collider position");
        }
        else {
            const rigidbody = comp as IRigidbody;
            const body = rigidbody[$bodyKey];
            if (body) {
                this.syncPhysicsBody(rigidbody.gameObject, body, translation, rotation);
            }
        }
    }

    updateProperties(obj: IRigidbody | ICollider) {
        this.validate();

        if ((obj as ICollider).isCollider) {
            const col = obj as ICollider;
            const body = col[$bodyKey];
            if (body) {
                this.internalUpdateColliderProperties(col, body);
                if (col.sharedMaterial)
                    this.updatePhysicsMaterial(col);
            }
        }
        else {
            const rb = obj as IRigidbody;
            const physicsBody = this.internal_getRigidbody(rb);
            if (physicsBody) {
                this.internalUpdateRigidbodyProperties(rb, physicsBody);
            }
        }
    }
    addForce(rigidbody: IRigidbody, force: Vec3, wakeup: boolean) {
        this.validate();
        const body = this.internal_getRigidbody(rigidbody);
        if (body) body.addForce(force, wakeup)
        else if (this._isInitialized) console.warn("Physics Body doesn't exist: can not apply force (does your object with the Rigidbody have a collider?)");
    }
    addImpulse(rigidbody: IRigidbody, force: Vec3, wakeup: boolean) {
        this.validate();
        const body = this.internal_getRigidbody(rigidbody);
        if (body) body.applyImpulse(force, wakeup);
        else if (this._isInitialized) console.warn("Physics Body doesn't exist: can not apply impulse (does your object with the Rigidbody have a collider?)");
    }
    getLinearVelocity(comp: IRigidbody | ICollider): Vec3 | null {
        this.validate();
        const body = this.internal_getRigidbody(comp);
        if (body) {
            const vel = body.linvel();
            return vel;
        }
        // else console.warn("Rigidbody doesn't exist: can not get linear velocity (does your object with the Rigidbody have a collider?)");
        return null;
    }
    getAngularVelocity(rb: IRigidbody): Vec3 | null {
        this.validate();
        const body = this.internal_getRigidbody(rb);
        if (body) {
            const vel = body.angvel();
            return vel;
        }
        // else console.warn("Rigidbody doesn't exist: can not get angular velocity (does your object with the Rigidbody have a collider?)");
        return null;
    }
    resetForces(rb: IRigidbody, wakeup: boolean) {
        this.validate();
        const body = this.internal_getRigidbody(rb);
        body?.resetForces(wakeup);
    }
    resetTorques(rb: IRigidbody, wakeup: boolean) {
        this.validate();
        const body = this.internal_getRigidbody(rb);
        body?.resetTorques(wakeup);
    }
    applyImpulse(rb: IRigidbody, vec: Vec3, wakeup: boolean) {
        this.validate();
        const body = this.internal_getRigidbody(rb);
        if (body) body.applyImpulse(vec, wakeup);
        else if (this._isInitialized) console.warn("Rigidbody doesn't exist: can not apply impulse (does your object with the Rigidbody have a collider?)");
    }

    wakeup(rb: IRigidbody) {
        this.validate();
        const body = this.internal_getRigidbody(rb);
        if (body) body.wakeUp();
        else if (this._isInitialized) console.warn("Rigidbody doesn't exist: can not wake up (does your object with the Rigidbody have a collider?)");
    }
    isSleeping(rb: IRigidbody) {
        this.validate();
        const body = this.internal_getRigidbody(rb);
        return body?.isSleeping();
    }
    setAngularVelocity(rb: IRigidbody, vec: Vec3, wakeup: boolean) {
        this.validate();
        const body = this.internal_getRigidbody(rb);
        if (body) body.setAngvel(vec, wakeup);
        else if (this._isInitialized) console.warn("Rigidbody doesn't exist: can not set angular velocity (does your object with the Rigidbody have a collider?)");
    }
    setLinearVelocity(rb: IRigidbody, vec: Vec3, wakeup: boolean) {
        this.validate();
        const body = this.internal_getRigidbody(rb);
        if (body) body.setLinvel(vec, wakeup);
        else if (this._isInitialized) console.warn("Rigidbody doesn't exist: can not set linear velocity (does your object with the Rigidbody have a collider?)");
    }

    private readonly context?: IContext;
    private _initializePromise?: Promise<boolean>;
    private _isInitialized: boolean = false;

    constructor(ctx: IContext) {
        this.context = ctx;
    }

    get isInitialized() { return this._isInitialized; }

    async initialize() {
        if (!this._initializePromise)
            this._initializePromise = this.internalInitialization();
        return this._initializePromise;
    }

    private async internalInitialization() {
        if (getParam("__nophysics")) {
            console.warn("Physics are disabled");
            return false;
        }
        if (debugPhysics) console.log("Initialize rapier physics engine");
        // NEEDLE_PHYSICS_INIT_START
        // use .env file with VITE_NEEDLE_USE_RAPIER=false to treeshake rapier
        // @ts-ignore
        if ("env" in import.meta && import.meta.env.VITE_NEEDLE_USE_RAPIER === "false") {
            if (debugPhysics) console.log("Rapier disabled");
            return false;
        }
        // Can be transformed during build time to disable rapier
        if (!NEEDLE_USE_RAPIER) return false;
        if (this._hasCreatedWorld) {
            console.error("Invalid call to create physics world: world is already created");
            return true;
        }
        this._hasCreatedWorld = true;
        if (MODULES.RAPIER_PHYSICS.MAYBEMODULE == undefined) {
            if (debugPhysics) console.trace("Loading rapier physics engine");
            const module = await MODULES.RAPIER_PHYSICS.load();
            // https://github.com/dimforge/rapier/issues/811 < but single object parameter still warns
            await module.init();
        }
        if (debugPhysics) console.log("Physics engine initialized, creating world...");
        this._world = new MODULES.RAPIER_PHYSICS.MODULE.World(this._gravity);
        this.rapierRay = new MODULES.RAPIER_PHYSICS.MODULE.Ray({ x: 0, y: 0, z: 0 }, { x: 0, y: 0, z: 1 });
        this.enabled = true;
        this._isInitialized = true;
        if (debugPhysics) console.log("Physics world created");
        return true;
        // NEEDLE_PHYSICS_INIT_END
    }

    /** Check is the physics engine has been initialized and the call can be made */
    private validate() {
        if (!this._isInitialized) {
            if (debugPhysics) {
                this["_lastWarnTime"] = this["_lastWarnTime"] ?? 0;
                if (Date.now() - this["_lastWarnTime"] > 1000) {
                    this["_lastWarnTime"] = Date.now();
                    console.warn("Physics engine is not initialized");
                }
            }
        }
    }


    private rapierRay!: Ray;
    private raycastVectorsBuffer = new CircularBuffer(() => new Vector3(), 10);

    public raycast(origin?: Vec2 | Vec3, direction?: Vec3, options?: {
        maxDistance?: number,
        /** True if you want to also hit objects when the raycast starts from inside a collider */
        solid?: boolean,
        queryFilterFlags?: QueryFilterFlags,
        filterGroups?: number,
        /** Return false to ignore this collider */
        filterPredicate?: (c: ICollider) => boolean,
        /** When enabled the hit object's layer will be tested. If layer 2 is enabled the object will be ignored (Layer 2 == IgnoreRaycast) 
         * If not set the raycast will ignore objects in the IgnoreRaycast layer (default: true)
         * @default undefined 
        */
        useIgnoreRaycastLayer?: boolean
    })
        : null | { point: Vector3, collider: ICollider } {

        if (!this._isInitialized) {
            console.log("Physics engine is not initialized");
            return null;
        }

        let maxDistance = options?.maxDistance;
        let solid = options?.solid;

        if (maxDistance === undefined) maxDistance = Infinity;
        if (solid === undefined) solid = true;

        const ray = this.getPhysicsRay(this.rapierRay, origin, direction);
        if (!ray) return null;

        if (this.debugRenderRaycasts || showPhysicsRaycasts) Gizmos.DrawRay(ray.origin, ray.dir, 0x0000ff, 1);

        const hit = this.world?.castRay(ray, maxDistance, solid, options?.queryFilterFlags, options?.filterGroups, undefined, undefined, (c) => {
            const component = c[$componentKey];
            if (options?.filterPredicate) return options.filterPredicate(component);
            if (options?.useIgnoreRaycastLayer !== false) {
                // ignore objects in the IgnoreRaycast=2 layer
                return !component?.gameObject.layers.isEnabled(2);
            }
            return true;
        });
        if (hit) {
            const point = ray.pointAt(hit.timeOfImpact);
            const vec = this.raycastVectorsBuffer.get();
            vec.set(point.x, point.y, point.z);
            return { point: vec, collider: hit.collider[$componentKey] };
        }

        return null;
    }

    public raycastAndGetNormal(origin?: Vec2 | Vec3, direction?: Vec3, options?: {
        maxDistance?: number,
        /** True if you want to also hit objects when the raycast starts from inside a collider */
        solid?: boolean,
        queryFilterFlags?: QueryFilterFlags,
        filterGroups?: number,
        /** Return false to ignore this collider */
        filterPredicate?: (c: ICollider) => boolean,
        /** When enabled the hit object's layer will be tested. If layer 2 is enabled the object will be ignored (Layer 2 == IgnoreRaycast) 
         * If not set the raycast will ignore objects in the IgnoreRaycast layer (default: true)
         * @default undefined 
        */
        useIgnoreRaycastLayer?: boolean
    })
        : null | { point: Vector3, normal: Vector3, collider: ICollider } {

        if (!this._isInitialized) {
            return null;
        }

        let maxDistance = options?.maxDistance;
        let solid = options?.solid;

        if (maxDistance === undefined) maxDistance = Infinity;
        if (solid === undefined) solid = true;

        const ray = this.getPhysicsRay(this.rapierRay, origin, direction);
        if (!ray) return null;

        if (this.debugRenderRaycasts || showPhysicsRaycasts) Gizmos.DrawRay(ray.origin, ray.dir, 0x0000ff, 1);

        const hit = this.world?.castRayAndGetNormal(ray, maxDistance, solid, options?.queryFilterFlags, options?.filterGroups, undefined, undefined, (c) => {
            const component = c[$componentKey];
            if (options?.filterPredicate) return options.filterPredicate(component);
            if (options?.useIgnoreRaycastLayer !== false) {
                // ignore objects in the IgnoreRaycast=2 layer
                return !component?.gameObject.layers.isEnabled(2);
            }
            return true;
        });
        if (hit) {
            const point = ray.pointAt(hit.timeOfImpact);
            const normal = hit.normal;
            const vec = this.raycastVectorsBuffer.get();
            const nor = this.raycastVectorsBuffer.get();
            vec.set(point.x, point.y, point.z);
            nor.set(normal.x, normal.y, normal.z);
            return { point: vec, normal: nor, collider: hit.collider[$componentKey] };
        }
        return null;
    }

    private getPhysicsRay(ray: Ray, origin?: Vec2 | Vec3, direction?: Vec3): Ray | null {
        const cam = this.context?.mainCamera;
        if (origin === undefined) {
            const pos = this.context?.input.getPointerPosition(0);
            if (pos) origin = pos;
            else return null;
        }
        // if we get origin in 2d space we need to project it to 3d space
        if (origin["z"] === undefined) {
            if (!cam) {
                console.error("Can not perform raycast from 2d point - no main camera found");
                return null;
            }
            const vec3 = this.raycastVectorsBuffer.get();
            vec3.x = origin.x;
            vec3.y = origin.y;
            vec3.z = 0;
            // if the origin is in screen space we need to convert it to raycaster space
            if (vec3.x > 1 || vec3.y > 1 || vec3.y < -1 || vec3.x < -1) {
                if (debugPhysics) console.warn("Converting screenspace to raycast space", vec3)
                this.context?.input.convertScreenspaceToRaycastSpace(vec3);
            }
            vec3.unproject(cam);
            origin = vec3;
        }

        const o = origin as Vec3;

        ray.origin.x = o.x;
        ray.origin.y = o.y;
        ray.origin.z = o.z;
        const vec = this.raycastVectorsBuffer.get();
        if (direction)
            vec.set(direction.x, direction.y, direction.z);
        else {
            if (!cam) {
                console.error("Can not perform raycast - no camera found");
                return null;
            }
            vec.set(ray.origin.x, ray.origin.y, ray.origin.z);
            const camPosition = getWorldPosition(cam);
            vec.sub(camPosition);
        }
        // we need to normalize the ray because our input is a max travel length and the direction may be not normalized
        vec.normalize();
        ray.dir.x = vec.x;
        ray.dir.y = vec.y;
        ray.dir.z = vec.z;
        // Gizmos.DrawRay(ray.origin, ray.dir, 0xff0000, Infinity);
        return ray;
    }


    private rapierSphere: Ball | null = null;
    private rapierBox: Cuboid | null = null;
    private readonly rapierColliderArray: Array<ShapeOverlapResult> = [];
    private readonly rapierIdentityRotation = { x: 0, y: 0, z: 0, w: 1 };
    private readonly rapierForwardVector = { x: 0, y: 0, z: 1 };
    /** Precice sphere overlap detection using rapier against colliders
     * @param point center of the sphere in worldspace
     * @param radius radius of the sphere
     * @returns array of colliders that overlap with the sphere. Note: they currently only contain the collider and the gameobject
     */
    public sphereOverlap(point: Vector3, radius: number): Array<ShapeOverlapResult> {
        this.rapierSphere ??= new MODULES.RAPIER_PHYSICS.MODULE.Ball(radius);
        this.rapierSphere.radius = radius;
        if (this.debugRenderRaycasts || showPhysicsRaycasts) Gizmos.DrawWireSphere(point, radius, 0x3344ff, 1);
        return this.shapeOverlap(point, this.rapierIdentityRotation, this.rapierSphere);
    }

    /** box overlap detection using rapier against colliders
     * @param point center of the box in worldspace
     * @param size size of the box
     * @param rotation quaternion representation of the rotation in world space
     * @returns array of colliders that overlap with the box. Note: they currently only contain the collider and the gameobject
     */
    public boxOverlap(point: Vector3, size: Vector3, rotation: Vector4Like | null = null): Array<ShapeOverlapResult> {
        if (rotation === null) rotation = this.rapierIdentityRotation;
        this.rapierBox ??= new MODULES.RAPIER_PHYSICS.MODULE.Cuboid(1, 1, 1);
        this.rapierBox.halfExtents.x = size.x * 0.5;
        this.rapierBox.halfExtents.y = size.y * 0.5;
        this.rapierBox.halfExtents.z = size.z * 0.5;
        if (this.debugRenderRaycasts || showPhysicsRaycasts) Gizmos.DrawWireBox(point, size, 0x3344ff, 1, true, rotation as Quaternion);
        return this.shapeOverlap(point, rotation!, this.rapierBox);
    }

    private shapeOverlap(point: Vector3, rotation: Vector4Like, shape: Ball | Cuboid): Array<ShapeOverlapResult> {
        this.rapierColliderArray.length = 0;
        if (!this._isInitialized) {
            return this.rapierColliderArray;
        }
        if (!this.world) return this.rapierColliderArray;

        this.world.intersectionsWithShape(point,
            rotation,
            shape,
            col => {
                const collider = col[$componentKey] as ICollider
                // if (collider.gameObject.layers.isEnabled(2)) return true;
                const intersection = new ShapeOverlapResult(collider.gameObject, collider);
                this.rapierColliderArray.push(intersection);
                return true; // Return `false` instead if we want to stop searching for other colliders that contain this point.
            },
            // TODO: it seems as QueryFilterFlags.EXCLUDE_SENSORS also excludes DYNAMIC Rigidbodies (only if they're set to kinematic)
            undefined, // QueryFilterFlags.EXCLUDE_SENSORS, 
            undefined, undefined, undefined,
            col => {
                // we don't want to raycast against triggers (see comment about Exclude Sensors above)
                if (col.isSensor()) return false;
                const collider = col[$componentKey] as ICollider
                return collider.gameObject.layers.isEnabled(2) == false
            }
        );
        return this.rapierColliderArray;


        // TODO: this only returns one hit
        // let filterGroups = 0xffffffff;
        // filterGroups &= ~(1 << 2);
        // const hit: ShapeColliderTOI | null = this.world.castShape(point,
        //     this.rapierIdentityRotation,
        //     this.rapierForwardVector,
        //     this.rapierSphere,
        //     0,
        //     QueryFilterFlags.EXCLUDE_SENSORS,
        //     // filterGroups,
        // );
        // // console.log(hit);
        // if (hit) {
        //     const collider = hit.collider[$componentKey] as ICollider
        //     const intersection = new SphereOverlapResult(collider.gameObject);
        //     this.rapierColliderArray.push(intersection);
        //     // const localpt = hit.witness2;
        //     // // const normal = hit.normal2;
        //     // const hitPoint = new Vector3(localpt.x, localpt.y, localpt.z);
        //     // // collider.gameObject.localToWorld(hitPoint);
        //     // // const normalPt = new Vector3(normal.x, normal.y, normal.z);
        //     // // const mat = new Matrix4().setPosition(point).scale(new Vector3(radius, radius, radius));
        //     // // hitPoint.applyMatrix4(mat);
        //     // console.log(hit.witness2)
        //     // // hitPoint.add(point);
        //     // const dist = hitPoint.distanceTo(point);
        // }

        // return this.rapierColliderArray;
    }




    // physics simulation

    enabled: boolean = false;
    /** Get access to the rapier world */
    public get world(): World | undefined { return this._world };

    private _tempPosition: Vector3 = new Vector3();
    private _tempQuaternion: Quaternion = new Quaternion();
    private _tempScale: Vector3 = new Vector3();
    private _tempMatrix: Matrix4 = new Matrix4();

    private static _didLoadPhysicsEngine: boolean = false;

    private _isUpdatingPhysicsWorld: boolean = false;
    get isUpdating(): boolean { return this._isUpdatingPhysicsWorld; }


    private _world?: World;
    private _hasCreatedWorld: boolean = false;
    private eventQueue?: EventQueue;
    private collisionHandler?: PhysicsCollisionHandler;


    private objects: IComponent[] = [];
    private bodies: PhysicsBody[] = [];

    private _meshCache: Map<string, Float32Array> = new Map<string, Float32Array>();

    private _gravity = { x: 0.0, y: -9.81, z: 0.0 };

    get gravity() {
        return this.world?.gravity ?? this._gravity;
    }

    set gravity(value: Vec3) {
        if (this.world) {
            this.world.gravity = value;
        }
        else {
            this._gravity = value;
        }
    }

    clearCaches() {
        this._meshCache.clear();
        if (this.eventQueue?.raw)
            this.eventQueue?.free();
        if (this.world?.bodies)
            this.world?.free();
    }

    async addBoxCollider(collider: ICollider, size: Vector3) {
        if (!this._isInitialized)
            await this.initialize();
        if (!collider.activeAndEnabled) return;

        if (!this.enabled) {
            if (debugPhysics) console.warn("Physics are disabled");
            return;
        }
        const obj = collider.gameObject;
        const scale = getWorldScale(obj, this._tempPosition).multiply(size);
        scale.multiplyScalar(0.5);

        // prevent negative scale
        if (scale.x < 0) scale.x = Math.abs(scale.x);
        if (scale.y < 0) scale.y = Math.abs(scale.y);
        if (scale.z < 0) scale.z = Math.abs(scale.z);

        // prevent zero scale - seems normals are flipped otherwise
        const minSize = 0.0000001;
        if (scale.x < minSize) scale.x = minSize;
        if (scale.y < minSize) scale.y = minSize;
        if (scale.z < minSize) scale.z = minSize;

        const desc = MODULES.RAPIER_PHYSICS.MODULE.ColliderDesc.cuboid(scale.x, scale.y, scale.z);
        // const objectLayerMask = collider.gameObject.layers.mask;
        // const mask = objectLayerMask & ~2;
        // TODO: https://rapier.rs/docs/user_guides/javascript/colliders/#collision-groups-and-solver-groups
        // desc.setCollisionGroups(objectLayerMask);
        this.createCollider(collider, desc);
    }

    async addSphereCollider(collider: ICollider) {
        if (!this._isInitialized)
            await this.initialize();
        if (!collider.activeAndEnabled) return;
        if (!this.enabled) {
            if (debugPhysics) console.warn("Physics are disabled");
            return;
        }
        const desc = MODULES.RAPIER_PHYSICS.MODULE.ColliderDesc.ball(.5);
        this.createCollider(collider, desc);
        this.updateProperties(collider);
    }

    async addCapsuleCollider(collider: ICollider, height: number, radius: number) {
        if (!this._isInitialized)
            await this.initialize();
        if (!collider.activeAndEnabled) return;
        if (!this.enabled) {
            if (debugPhysics) console.warn("Physics are disabled");
            return;
        }
        const obj = collider.gameObject;
        const scale = obj.worldScale;
        // Prevent negative scales
        scale.x = Math.abs(scale.x);
        scale.y = Math.abs(scale.y);
        const finalRadius = radius * scale.x;
        // half height = distance between capsule origin and top sphere origin (not the top end of the capsule)
        height = Math.max(height, finalRadius);
        const hh = Mathf.clamp((height * .5 * scale.y) - (radius * scale.x), 0, Number.MAX_SAFE_INTEGER);
        const desc = MODULES.RAPIER_PHYSICS.MODULE.ColliderDesc.capsule(hh, finalRadius);
        this.createCollider(collider, desc);
    }

    async addMeshCollider(collider: ICollider, mesh: Mesh, convex: boolean, extraScale?: Vector3) {

        // capture the geometry before waiting for phyiscs engine
        let geo = mesh.geometry;
        if (!geo) {
            if (debugPhysics) console.warn("Missing mesh geometry", mesh.name);
            return;
        }

        // check if mesh is indexed, if not generate indices
        if (!geo.index?.array?.length) {
            console.warn(`Your MeshCollider is missing vertices or indices in the assined mesh \"${mesh.name}\". Consider providing an indexed geometry.`);
            geo = BufferGeometryUtils.mergeVertices(geo);
        }

        let positions: Float32Array | null = null;

        const positionAttribute = geo.getAttribute("position") as BufferAttribute | InterleavedBufferAttribute;
        if (positionAttribute instanceof InterleavedBufferAttribute) {
            const count = positionAttribute.count;
            positions = new Float32Array(count * 3);
            for (let i = 0; i < count; i++) {
                const x = positionAttribute.getX(i);
                const y = positionAttribute.getY(i);
                const z = positionAttribute.getZ(i);
                positions[i * 3] = x;
                positions[i * 3 + 1] = y;
                positions[i * 3 + 2] = z;
            }
        }
        else {
            positions = positionAttribute.array as Float32Array;
        }

        await this.initialize();

        if (!this.enabled) {
            if (debugPhysics) console.warn("Physics are disabled");
            return;
        }

        if (!collider.activeAndEnabled) return;


        // let positions = geo.getAttribute("position").array as Float32Array;
        const indices = geo.index?.array as Uint32Array;

        const scale = collider.gameObject.worldScale.clone();
        if (extraScale) scale.multiply(extraScale);

        // scaling seems not supported yet https://github.com/dimforge/rapier/issues/243
        if (Math.abs(scale.x - 1) > 0.0001 || Math.abs(scale.y - 1) > 0.0001 || Math.abs(scale.z - 1) > 0.0001) {
            const key = `${geo.uuid}_${scale.x}_${scale.y}_${scale.z}_${convex}`;
            if (this._meshCache.has(key)) {
                if (debugPhysics) console.warn("Use cached mesh collider")
                positions = this._meshCache.get(key)!;
            }
            else {
                if (debugPhysics || isDevEnvironment()) console.debug(`[Performance] Your MeshCollider \"${collider.name}\" is scaled: consider applying the scale to the collider mesh instead (${scale.x}, ${scale.y}, ${scale.z})`);
                const scaledPositions = new Float32Array(positions.length);
                for (let i = 0; i < positions.length; i += 3) {
                    scaledPositions[i] = positions[i] * scale.x;
                    scaledPositions[i + 1] = positions[i + 1] * scale.y;
                    scaledPositions[i + 2] = positions[i + 2] * scale.z;
                }
                positions = scaledPositions;
                this._meshCache.set(key, scaledPositions);
            }
        }
        const desc = convex
            ? MODULES.RAPIER_PHYSICS.MODULE.ColliderDesc.convexHull(positions)
            : MODULES.RAPIER_PHYSICS.MODULE.ColliderDesc.trimesh(positions, indices);
        if (desc) {
            this.createCollider(collider, desc);
            // col.setMassProperties(1, { x: 0, y: 0, z: 0 }, { x: 0, y: 0, z: 0 }, { x: 0, y: 0, z: 0, w: 1 });
            // rb?.setTranslation({ x: 0, y: 2, z: 0 });
            // col.setTranslationWrtParent(new Vector3(0,2,0));

        }
    }

    updatePhysicsMaterial(col: ICollider) {
        if (!col) return;
        const physicsMaterial = col.sharedMaterial;
        const rapier_collider = col[$bodyKey] as Collider;
        if (!rapier_collider) return;

        if (physicsMaterial) {
            if (physicsMaterial.bounciness !== undefined)
                rapier_collider.setRestitution(physicsMaterial.bounciness);

            if (physicsMaterial.bounceCombine !== undefined) {
                switch (physicsMaterial.bounceCombine) {
                    case PhysicsMaterialCombine.Average:
                        rapier_collider.setRestitutionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Average);
                        break;
                    case PhysicsMaterialCombine.Maximum:
                        rapier_collider.setRestitutionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Max);
                        break;
                    case PhysicsMaterialCombine.Minimum:
                        rapier_collider.setRestitutionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Min);
                        break;
                    case PhysicsMaterialCombine.Multiply:
                        rapier_collider.setRestitutionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Multiply);
                        break;
                }
            }

            if (physicsMaterial.dynamicFriction !== undefined)
                rapier_collider.setFriction(physicsMaterial.dynamicFriction);

            if (physicsMaterial.frictionCombine !== undefined) {
                switch (physicsMaterial.frictionCombine) {
                    case PhysicsMaterialCombine.Average:
                        rapier_collider.setFrictionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Average);
                        break;
                    case PhysicsMaterialCombine.Maximum:
                        rapier_collider.setFrictionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Max);
                        break;
                    case PhysicsMaterialCombine.Minimum:
                        rapier_collider.setFrictionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Min);
                        break;
                    case PhysicsMaterialCombine.Multiply:
                        rapier_collider.setFrictionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Multiply);
                        break;
                }
            }
        }
    }

    /** Get the rapier body for a Needle component */
    getBody(obj: ICollider | IRigidbody): null | any {
        if (!obj) return null;
        const body = obj[$bodyKey];
        return body;
    }

    /** Get the Needle Engine component for a rapier object */
    getComponent(rapierObject: object): IComponent | null {
        if (!rapierObject) return null;
        const component = rapierObject[$componentKey];
        return component;
    }

    /**
     * Creates a collider in the physics world.
     * 
     * @param collider - The collider component.
     * @param desc - The collider description.
     * @returns The created collider.
     * 
     * @throws Will throw an error if the physics world is not initialized. Make sure to call `initialize()` before creating colliders.  
     */
    createCollider(collider: ICollider, desc: ColliderDesc) {
        if (!this.world) throw new Error("Physics world not initialized");
        const matrix = this._tempMatrix;
        let rigidBody: RigidBody | undefined = undefined;
        if (!collider.attachedRigidbody) {
            if (debugPhysics) console.log("Create collider without rigidbody", collider.name);
            matrix.makeRotationFromQuaternion(getWorldQuaternion(collider.gameObject));
            matrix.setPosition(getWorldPosition(collider.gameObject));
        }
        else {
            rigidBody = this.getRigidbody(collider, this._tempMatrix);
        }

        matrix.decompose(this._tempPosition, this._tempQuaternion, this._tempScale);
        this.tryApplyCenter(collider, this._tempPosition);
        desc.setTranslation(this._tempPosition.x, this._tempPosition.y, this._tempPosition.z);
        desc.setRotation(this._tempQuaternion);
        desc.setSensor(collider.isTrigger);

        // TODO: we might want to update this if the material changes
        const physicsMaterial = collider.sharedMaterial;
        if (physicsMaterial) {

            if (physicsMaterial.bounciness !== undefined)
                desc.setRestitution(physicsMaterial.bounciness);

            if (physicsMaterial.bounceCombine !== undefined) {
                switch (physicsMaterial.bounceCombine) {
                    case PhysicsMaterialCombine.Average:
                        desc.setRestitutionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Average);
                        break;
                    case PhysicsMaterialCombine.Maximum:
                        desc.setRestitutionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Max);
                        break;
                    case PhysicsMaterialCombine.Minimum:
                        desc.setRestitutionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Min);
                        break;
                    case PhysicsMaterialCombine.Multiply:
                        desc.setRestitutionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Multiply);
                        break;
                }
            }

            if (physicsMaterial.dynamicFriction !== undefined)
                desc.setFriction(physicsMaterial.dynamicFriction);

            if (physicsMaterial.frictionCombine !== undefined) {
                switch (physicsMaterial.frictionCombine) {
                    case PhysicsMaterialCombine.Average:
                        desc.setFrictionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Average);
                        break;
                    case PhysicsMaterialCombine.Maximum:
                        desc.setFrictionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Max);
                        break;
                    case PhysicsMaterialCombine.Minimum:
                        desc.setFrictionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Min);
                        break;
                    case PhysicsMaterialCombine.Multiply:
                        desc.setFrictionCombineRule(MODULES.RAPIER_PHYSICS.MODULE.CoefficientCombineRule.Multiply);
                        break;
                }
            }
        }

        // if we want to use explicit mass properties, we need to set the collider density to 0
        // otherwise rapier will compute the mass properties based on the collider shape and density
        // https://rapier.rs/docs/user_guides/javascript/rigid_bodies#mass-properties
        if (collider.attachedRigidbody?.autoMass === false) {
            desc.setDensity(.000001);
            desc.setMass(.000001);
        }

        try {
            const col = this.world.createCollider(desc, rigidBody);
            col[$componentKey] = collider;
            collider[$bodyKey] = col;
            col.setActiveEvents(MODULES.RAPIER_PHYSICS.MODULE.ActiveEvents.COLLISION_EVENTS);
            // We want to receive collisitons between two triggers too
            col.setActiveCollisionTypes(MODULES.RAPIER_PHYSICS.MODULE.ActiveCollisionTypes.ALL);
            this.objects.push(collider);
            this.bodies.push(col);

            // set the collider layers
            this.updateColliderCollisionGroups(collider);

            if (debugPhysics) console.log("Created collider", collider.name, col);

            return col;
        }
        catch (e) {
            console.error("Error creating collider \"" + collider.name + "\"\nError:", e);
            return null;
        }
    }

    /**
     * Updates the collision groups of a collider.
     * 
     * @param collider - The collider to update.
     */
    private updateColliderCollisionGroups(collider: ICollider) {
        const body = collider[$bodyKey] as Collider;
        const members = collider.membership;
        let memberMask = 0;
        if (members == undefined) {
            memberMask = 0xffff;
        }
        else {
            for (let i = 0; i < members.length; i++) {
                const member = members[i];
                if (member > 31) console.error(`Rapier only supports 32 layers, layer ${member} is not supported`);
                else memberMask |= 1 << Math.floor(member);
            }
        }

        const mask = collider.filter;
        let filterMask = 0;
        if (mask == undefined) {
            filterMask = 0xffff;
        }
        else {
            for (let i = 0; i < mask.length; i++) {
                const member = mask[i];
                if (member > 31) console.error(`Rapier only supports 32 layers, layer ${member} is not supported`);
                else filterMask |= 1 << Math.floor(member);
            }
        }
        body.setCollisionGroups((memberMask << 16) | filterMask);
    }

    private getRigidbody(collider: ICollider, _matrix: Matrix4): RigidBody {

        if (!this.world) throw new Error("Physics world not initialized");
        let rigidBody: RigidBody | null = null;

        if (collider.attachedRigidbody) {
            const rb = collider.attachedRigidbody;
            rigidBody = rb[$bodyKey];
            if (!rigidBody) {
                const kinematic = rb.isKinematic && !debugColliderPlacement;
                if (debugPhysics)
                    console.log("Create rigidbody", kinematic);
                const rigidBodyDesc = (kinematic ? MODULES.RAPIER_PHYSICS.MODULE.RigidBodyDesc.kinematicPositionBased() : MODULES.RAPIER_PHYSICS.MODULE.RigidBodyDesc.dynamic()) as RigidBodyDesc;
                const pos = getWorldPosition(collider.attachedRigidbody.gameObject);
                rigidBodyDesc.setTranslation(pos.x, pos.y, pos.z);
                rigidBodyDesc.setRotation(getWorldQuaternion(collider.attachedRigidbody.gameObject));
                rigidBodyDesc.centerOfMass = new MODULES.RAPIER_PHYSICS.MODULE.Vector3(rb.centerOfMass.x, rb.centerOfMass.y, rb.centerOfMass.z);
                rigidBody = this.world.createRigidBody(rigidBodyDesc);
                this.bodies.push(rigidBody);
                this.objects.push(rb);
            }
            rigidBody[$componentKey] = rb;
            rb[$bodyKey] = rigidBody;
            this.internalUpdateRigidbodyProperties(rb, rigidBody);
            this.getRigidbodyRelativeMatrix(collider.gameObject, rb.gameObject, _matrix);
            collider[$colliderRigidbody] = rigidBody;
        }
        else {
            const rigidBodyDesc = MODULES.RAPIER_PHYSICS.MODULE.RigidBodyDesc.kinematicPositionBased();
            const pos = getWorldPosition(collider.gameObject);
            rigidBodyDesc.setTranslation(pos.x, pos.y, pos.z);
            rigidBodyDesc.setRotation(getWorldQuaternion(collider.gameObject));
            rigidBody = this.world.createRigidBody(rigidBodyDesc);
            _matrix.identity();
            rigidBody[$componentKey] = null;
        }


        return rigidBody;
    }

    private internal_getRigidbody(rb: IRigidbody | ICollider): RigidBody | null {
        if ((rb as ICollider).isCollider === true) return rb[$colliderRigidbody] as RigidBody;
        return rb[$bodyKey] as RigidBody;
    }

    private internalUpdateColliderProperties(col: ICollider, collider: Collider) {
        const shape = collider.shape;
        let sizeHasChanged = false;
        switch (shape.type) {
            // Sphere Collider
            case MODULES.RAPIER_PHYSICS.MODULE.ShapeType.Ball:
                {
                    const ball = shape as Ball;
                    const sc = col as ISphereCollider;
                    const obj = col.gameObject;
                    const scale = getWorldScale(obj, this._tempPosition);
                    const radius = Math.abs(sc.radius * scale.x);
                    sizeHasChanged = ball.radius !== radius;
                    ball.radius = radius;
                    if (sizeHasChanged) {
                        collider.setShape(ball);
                    }
                    break;
                }
            case MODULES.RAPIER_PHYSICS.MODULE.ShapeType.Cuboid:
                const cuboid = shape as Cuboid;
                const sc = col as IBoxCollider;
                const obj = col.gameObject;
                const scale = getWorldScale(obj, this._tempPosition);
                const newX = Math.abs(sc.size.x * 0.5 * scale.x);
                const newY = Math.abs(sc.size.y * 0.5 * scale.y);
                const newZ = Math.abs(sc.size.z * 0.5 * scale.z);
                sizeHasChanged = cuboid.halfExtents.x !== newX || cuboid.halfExtents.y !== newY || cuboid.halfExtents.z !== newZ;
                cuboid.halfExtents.x = newX;
                cuboid.halfExtents.y = newY;
                cuboid.halfExtents.z = newZ;
                if (sizeHasChanged) {
                    collider.setShape(cuboid);
                }
                break;
        }

        if (sizeHasChanged) {
            const rb = col.attachedRigidbody;
            if (rb?.autoMass) {
                const ph = this.getBody(rb) as RigidBody
                ph?.recomputeMassPropertiesFromColliders();
            }
        }

        this.updateColliderCollisionGroups(col);

        if (col.isTrigger !== collider.isSensor())
            collider.setSensor(col.isTrigger);
    }

    private internalUpdateRigidbodyProperties(rb: IRigidbody, rigidbody: RigidBody) {
        // continuous collision detection 
        // https://rapier.rs/docs/user_guides/javascript/rigid_bodies#continuous-collision-detection
        rigidbody.enableCcd(rb.collisionDetectionMode !== CollisionDetectionMode.Discrete);
        rigidbody.setLinearDamping(rb.drag);
        rigidbody.setAngularDamping(rb.angularDrag);
        rigidbody.setGravityScale(rb.useGravity ? rb.gravityScale : 0, true);

        // https://rapier.rs/docs/user_guides/javascript/rigid_bodies#dominance
        if (rb.dominanceGroup <= 127 && rb.dominanceGroup >= -127)
            rigidbody.setDominanceGroup(Math.floor(rb.dominanceGroup))
        else rigidbody.setDominanceGroup(0);

        if (rb.autoMass) {
            rigidbody.setAdditionalMass(0, false);
            for (let i = 0; i < rigidbody.numColliders(); i++) {
                const col = rigidbody.collider(i);
                col.setDensity(1);
            }
            rigidbody.recomputeMassPropertiesFromColliders();
        }
        else {
            rigidbody.setAdditionalMass(rb.mass, false);
            for (let i = 0; i < rigidbody.numColliders(); i++) {
                const col = rigidbody.collider(i);
                col.setDensity(0.0000001);
            }
            rigidbody.recomputeMassPropertiesFromColliders();
        }

        // https://rapier.rs/docs/user_guides/javascript/rigid_bodies#mass-properties
        // rigidbody.setAdditionalMass(rb.mass, true);
        // for (let i = 0; i < rigidbody.numColliders(); i++) {
        //     const collider = rigidbody.collider(i);
        //     if (collider) {
        //         collider.setMass(rb.mass);
        //         // const density = rb.mass / collider.shape.computeMassProperties().mass;
        //     }
        // }

        // lock rotations
        rigidbody.setEnabledRotations(!rb.lockRotationX, !rb.lockRotationY, !rb.lockRotationZ, false);
        rigidbody.setEnabledTranslations(!rb.lockPositionX, !rb.lockPositionY, !rb.lockPositionZ, false);

        if (rb.isKinematic) {
            rigidbody.setBodyType(MODULES.RAPIER_PHYSICS.MODULE.RigidBodyType.KinematicPositionBased, false);
        }
        else {
            rigidbody.setBodyType(MODULES.RAPIER_PHYSICS.MODULE.RigidBodyType.Dynamic, false);
        }
    }

    // private _lastStepTime: number | undefined = 0;
    private lines?: LineSegments;

    public step(dt?: number) {
        if (!this.world) return;
        if (!this.enabled) return;
        this._isUpdatingPhysicsWorld = true;
        if (!this.eventQueue) {
            this.eventQueue = new MODULES.RAPIER_PHYSICS.MODULE.EventQueue(false);
        }
        if (dt === undefined || dt <= 0) {
            this._isUpdatingPhysicsWorld = false;
            return;
        }
        else if (dt !== undefined) {
            // if we make to sudden changes to the timestep the physics can get unstable
            // https://rapier.rs/docs/user_guides/javascript/integration_parameters/#dt
            const newTimestamp = Mathf.lerp(this.world.timestep, dt, 0.8);
            this.world.timestep = newTimestamp;
        }
        try {
            this.world.step(this.eventQueue);
        }
        catch (e) {
            console.warn("Error running physics step", { timestep: this.world.timestep }, e);
        }
        this._isUpdatingPhysicsWorld = false;
    }

    public postStep() {
        if (!this.world) return;
        if (!this.enabled) return;
        this._isUpdatingPhysicsWorld = true;
        this.syncObjects();
        this._isUpdatingPhysicsWorld = false;

        if (this.eventQueue && !this.collisionHandler) {
            this.collisionHandler = new PhysicsCollisionHandler(this.world, this.eventQueue);
        }
        if (this.collisionHandler) {
            this.collisionHandler.handleCollisionEvents();
            this.collisionHandler.update();
        }
        this.updateDebugRendering(this.world);
    }

    private updateDebugRendering(world: World) {
        if (debugPhysics || debugColliderPlacement || showColliders || this.debugRenderColliders === true) {
            if (!this.lines) {
                const material = new LineBasicMaterial({
                    color: 0x77dd77,
                    fog: false,
                    // vertexColors: VertexColors
                });
                const geometry = new BufferGeometry();
                this.lines = new LineSegments(geometry, material);
                this.lines.layers.disableAll();
                this.lines.layers.enable(2);
            }
            if (this.lines.parent !== this.context?.scene)
                this.context?.scene.add(this.lines);
            const buffers = world.debugRender();
            this.lines.geometry.setAttribute('position', new BufferAttribute(buffers.vertices, 3));
            this.lines.geometry.setAttribute('color', new BufferAttribute(buffers.colors, 4));
            // If a scene has no colliders at all at the start of the scene
            // the bounding sphere radius will be 0 and the lines will not be rendered
            // so we need to update the bounding sphere (perhaps it's enough to do this once...)
            if (this.context!.time.frame % 30 === 0 || this.lines.geometry.boundingSphere?.radius === 0) {
                this.lines.geometry.computeBoundingSphere();
            }
        }
        else {
            if (this.lines) {
                this.context?.scene.remove(this.lines);
            }
        }
    }

    /** sync rendered objects with physics world (except for colliders without rigidbody) */
    private syncObjects() {
        if (debugColliderPlacement) return;
        for (let i = 0; i < this.bodies.length; i++) {
            const obj = this.objects[i];
            const body = this.bodies[i] as Collider;

            // if the collider is not attached to a rigidbody
            // it means that its kinematic so we need to update its position
            const col = (obj as ICollider);
            if (col?.isCollider === true && !col.attachedRigidbody) {
                const rigidbody = body.parent();
                if (rigidbody)
                    this.syncPhysicsBody(obj.gameObject, rigidbody, true, true);
                else
                    this.syncPhysicsBody(obj.gameObject, body, true, true);
                continue;
            }


            // sync
            const pos = body.translation();
            const rot = body.rotation();
            if (Number.isNaN(pos.x) || Number.isNaN(rot.x)) {
                if (!col["__COLLIDER_NAN"] && isDevEnvironment()) {
                    console.warn("Collider has NaN values", col.name, col.gameObject, body);
                    col["__COLLIDER_NAN"] = true;
                }
                continue;
            }

            // make sure to keep the collider offset
            const center = obj["center"] as Vector3;
            if (center && center.isVector3) {
                this._tempQuaternion.set(rot.x, rot.y, rot.z, rot.w);
                const offset = this._tempPosition.copy(center).applyQuaternion(this._tempQuaternion);
                const scale = getWorldScale(obj.gameObject);
                offset.multiply(scale);
                pos.x -= offset.x;
                pos.y -= offset.y;
                pos.z -= offset.z;
            }
            setWorldPositionXYZ(obj.gameObject, pos.x, pos.y, pos.z);
            setWorldQuaternionXYZW(obj.gameObject, rot.x, rot.y, rot.z, rot.w);
        }
    }

    private syncPhysicsBody(obj: Object3D, body: RigidBody | Collider, translation: boolean, rotation: boolean) {

        // const bodyType = body.bodyType();
        // const previous = physicsBody.translation();
        // const vel = physicsBody.linvel();

        if (body instanceof MODULES.RAPIER_PHYSICS.MODULE.RigidBody) {
            const worldPosition = getWorldPosition(obj, this._tempPosition);
            const worldQuaternion = getWorldQuaternion(obj, this._tempQuaternion);
            const type = body.bodyType();
            switch (type) {
                case MODULES.RAPIER_PHYSICS.MODULE.RigidBodyType.Fixed:
                case MODULES.RAPIER_PHYSICS.MODULE.RigidBodyType.KinematicPositionBased:
                case MODULES.RAPIER_PHYSICS.MODULE.RigidBodyType.KinematicVelocityBased:
                    if (translation)
                        body.setNextKinematicTranslation(worldPosition);
                    if (rotation)
                        body.setNextKinematicRotation(worldQuaternion);
                    break;
                default:
                    if (translation)
                        body.setTranslation(worldPosition, false);
                    if (rotation)
                        body.setRotation(worldQuaternion, false);
                    break;

            }
        }
        else if (body instanceof MODULES.RAPIER_PHYSICS.MODULE.Collider) {
            if (obj.matrixWorldNeedsUpdate) {
                obj.updateWorldMatrix(true, false);
            }
            obj.matrixWorld.decompose(this._tempPosition, this._tempQuaternion, this._tempScale);
            const wp = this._tempPosition;
            const wq = this._tempQuaternion;
            // const wp = getWorldPosition(obj, this._tempPosition);
            // const wq = getWorldQuaternion(obj, this._tempQuaternion);
            const collider = body[$componentKey] as ICollider;
            this.tryApplyCenter(collider, wp);

            // we need to check if translation or rotation have changed, otherwise the physics engine will wakeup rigidbody that are in contact with this collider
            if (translation) {
                const ct = body.translation();
                if (ct.x !== wp.x || ct.y !== wp.y || ct.z !== wp.z)
                    body.setTranslation(wp);
            }
            if (rotation) {
                const cr = body.rotation();
                if (cr.x !== wq.x || cr.y !== wq.y || cr.z !== wq.z || cr.w !== wq.w)
                    body.setRotation(wq);
            }
        }

        // physicsBody.setBodyType(RAPIER.RigidBodyType.Fixed);
        // physicsBody.setLinvel(vel, false);

        // update velocity
        // const pos = physicsBody.translation();
        // pos.x -= previous.x;
        // pos.y -= previous.y;
        // pos.z -= previous.z;
        // // threhold
        // const t = 1;
        // const canUpdateVelocity = Math.abs(pos.x) < t && Math.abs(pos.y) < t && Math.abs(pos.z) < t;
        // if (canUpdateVelocity) {
        //     const damping = 1 + this.context.time.deltaTime;
        //     vel.x *= damping;
        //     vel.y *= damping;
        //     vel.z *= damping;
        //     vel.x += pos.x;
        //     vel.y += pos.y;
        //     vel.z += pos.z;
        //     console.log(vel);
        //     physicsBody.setLinvel(vel, true);
        // }
        // else if(debugPhysics) console.warn("Movement exceeded threshold, not updating velocity", pos);

        // body.setBodyType(bodyType);
    }

    private readonly _tempCenterPos: Vector3 = new Vector3();
    private readonly _tempCenterVec: Vector3 = new Vector3();
    private readonly _tempCenterQuaternion: Quaternion = new Quaternion();
    private tryApplyCenter(collider: ICollider, targetVector: Vector3) {
        const center = collider.center;
        if (center && collider.gameObject) {
            if (center.x !== 0 || center.y !== 0 || center.z !== 0) {
                // TODO: fix export of center in editor integrations so we dont have to flip here
                this._tempCenterPos.x = center.x;
                this._tempCenterPos.y = center.y;
                this._tempCenterPos.z = center.z;
                getWorldScale(collider.gameObject, this._tempCenterVec);
                this._tempCenterPos.multiply(this._tempCenterVec);
                if (!collider.attachedRigidbody) {
                    getWorldQuaternion(collider.gameObject, this._tempCenterQuaternion);
                    this._tempCenterPos.applyQuaternion(this._tempCenterQuaternion);
                }
                else {
                    this._tempCenterPos.applyQuaternion(collider.gameObject.quaternion);
                }
                targetVector.x += this._tempCenterPos.x;
                targetVector.y += this._tempCenterPos.y;
                targetVector.z += this._tempCenterPos.z;
            }
        }
    }

    private static _matricesBuffer: Matrix4[] = [];
    private getRigidbodyRelativeMatrix(comp: Object3D, rigidbody: Object3D, mat: Matrix4, matrices?: Matrix4[]): Matrix4 {
        // collect all matrices to the rigidbody and then build the rigidbody relative matrix
        if (matrices === undefined) {
            matrices = RapierPhysics._matricesBuffer;
            matrices.length = 0;
        }
        if (comp === rigidbody) {
            const scale = getWorldScale(comp, this._tempPosition);
            mat.makeScale(scale.x, scale.y, scale.z);
            for (let i = matrices.length - 1; i >= 0; i--) {
                mat.multiply(matrices[i]);
            }
            return mat;
        }
        matrices.push(comp.matrix);
        if (comp.parent) {
            this.getRigidbodyRelativeMatrix(comp.parent, rigidbody, mat, matrices);
        }
        return mat;
    }

    private static centerConnectionPos = { x: 0, y: 0, z: 0 };
    private static centerConnectionRot = { x: 0, y: 0, z: 0, w: 1 };



    addFixedJoint(body1: IRigidbody, body2: IRigidbody) {
        if (!this.world) {
            console.error("Physics world not initialized");
            return;
        }
        const b1 = body1[$bodyKey] as RigidBody;
        const b2 = body2[$bodyKey] as RigidBody;

        this.calculateJointRelativeMatrices(body1.gameObject, body2.gameObject, this._tempMatrix);
        this._tempMatrix.decompose(this._tempPosition, this._tempQuaternion, this._tempScale);

        const params = MODULES.RAPIER_PHYSICS.MODULE.JointData.fixed(
            RapierPhysics.centerConnectionPos, RapierPhysics.centerConnectionRot,
            this._tempPosition, this._tempQuaternion,
        );
        const joint = this.world.createImpulseJoint(params, b1, b2, true);
        if (debugPhysics)
            console.log("ADD FIXED JOINT", joint)
    }


    /** The joint prevents any relative movement between two rigid-bodies, except for relative rotations along one axis. This is typically used to simulate wheels, fans, etc. They are characterized by one local anchor as well as one local axis on each rigid-body. */
    addHingeJoint(body1: IRigidbody, body2: IRigidbody, anchor: { x: number, y: number, z: number }, axis: { x: number, y: number, z: number }) {
        if (!this.world) {
            console.error("Physics world not initialized");
            return;
        }
        const b1 = body1[$bodyKey] as RigidBody;
        const b2 = body2[$bodyKey] as RigidBody;

        this.calculateJointRelativeMatrices(body1.gameObject, body2.gameObject, this._tempMatrix);
        this._tempMatrix.decompose(this._tempPosition, this._tempQuaternion, this._tempScale);

        const params = MODULES.RAPIER_PHYSICS.MODULE.JointData.revolute(anchor, this._tempPosition, axis);
        const joint = this.world.createImpulseJoint(params, b1, b2, true);
        if (debugPhysics)
            console.log("ADD HINGE JOINT", joint)
    }


    private calculateJointRelativeMatrices(body1: IGameObject, body2: IGameObject, mat: Matrix4) {
        body1.updateWorldMatrix(true, false);
        body2.updateWorldMatrix(true, false);
        const world1 = body1.matrixWorld;
        const world2 = body2.matrixWorld;
        // set scale to 1
        world1.elements[0] = 1;
        world1.elements[5] = 1;
        world1.elements[10] = 1;
        world2.elements[0] = 1;
        world2.elements[5] = 1;
        world2.elements[10] = 1;
        mat.copy(world2).premultiply(world1.invert()).invert();
    }
}



/** responsible of processing collision events for the component system */
class PhysicsCollisionHandler {

    readonly world: World;
    readonly eventQueue: EventQueue;

    constructor(world: World, eventQueue: EventQueue) {
        this.world = world;
        this.eventQueue = eventQueue;
    }

    private activeCollisions: Array<{ collider: ICollider, component: IComponent, collision: Collision }> = [];
    private activeCollisionsStay: Array<{ collider: ICollider, component: IComponent, collision: Collision }> = [];
    private activeTriggers: Array<{ collider: ICollider, component: IComponent, otherCollider: ICollider }> = [];

    handleCollisionEvents() {
        if (!this.eventQueue) return;
        if (!this.world) return;
        this.eventQueue.drainCollisionEvents((handle1, handle2, started) => {
            const col1 = this.world!.getCollider(handle1);
            const col2 = this.world!.getCollider(handle2);
            if (!col1 || !col2) return;
            const colliderComponent1 = col1[$componentKey];
            const colliderComponent2 = col2[$componentKey];
            if (debugCollisions)
                console.log("EVT", colliderComponent1.name, colliderComponent2.name, started, col1, col2);
            if (colliderComponent1 && colliderComponent2) {
                if (started) {
                    this.onCollisionStarted(colliderComponent1, col1, colliderComponent2, col2);
                    this.onCollisionStarted(colliderComponent2, col2, colliderComponent1, col1);
                }
                else {
                    this.onCollisionEnded(colliderComponent1, colliderComponent2);
                    this.onCollisionEnded(colliderComponent2, colliderComponent1);
                }
            }
        });
    }

    update() {
        this.onHandleCollisionStay();
    }

    private onCollisionStarted(self: ICollider, selfBody: Collider, other: ICollider, otherBody: Collider) {
        let collision: Collision | null = null;

        // if one is a trigger we dont get collisions but want to raise the trigger events
        if (self.isTrigger || other.isTrigger) {
            foreachComponent(self.gameObject, (c: IComponent) => {
                if (c.onTriggerEnter && !c.destroyed) {
                    c.onTriggerEnter(other);
                }
                this.activeTriggers.push({ collider: self, component: c, otherCollider: other });
            });
        }
        else {
            const object = self.gameObject;
            // TODO: we dont respect the flip value here!
            this.world.contactPair(selfBody, otherBody, (manifold, _flipped) => {
                foreachComponent(object, (c: IComponent) => {
                    if (c.destroyed) return;
                    const hasDeclaredEventMethod = c.onCollisionEnter || c.onCollisionStay || c.onCollisionExit;
                    if (hasDeclaredEventMethod || debugCollisions) {
                        if (!collision) {
                            const contacts: Array<ContactPoint> = [];
                            const normal = manifold.normal();
                            // invert the normal for convex MeshColliders, NE-2680
                            if (other instanceof MeshCollider && other.convex) {
                                normal.x = -normal.x;
                                normal.y = -normal.y;
                                normal.z = -normal.z;
                            }
                            for (let i = 0; i < manifold.numSolverContacts(); i++) {
                                // solver points are in world space
                                // https://rapier.rs/docs/user_guides/javascript/advanced_collision_detection_js#the-contact-graph
                                const pt = manifold.solverContactPoint(i);
                                const impulse = manifold.contactImpulse(i);
                                if (pt) {
                                    const dist = manifold.contactDist(i);
                                    const friction = manifold.solverContactFriction(i);
                                    const tangentVelocity = manifold.solverContactTangentVelocity(i);
                                    const contact = new ContactPoint(pt, dist, normal, impulse, friction, tangentVelocity);
                                    contacts.push(contact);
                                    if (debugCollisions) {
                                        Gizmos.DrawDirection(pt, normal, 0xff0000, 3, true);
                                    }
                                }
                            }
                            collision = new Collision(object, other, contacts);
                        }

                        // we only need to keep track if any event exists
                        if (hasDeclaredEventMethod) {
                            const info = { collider: self, component: c, collision };

                            this.activeCollisions.push(info);
                            if (c.onCollisionStay) {
                                this.activeCollisionsStay.push(info);
                            }

                            c.onCollisionEnter?.call(c, collision);
                        }

                    }
                });
            });
        }
    }

    private onHandleCollisionStay() {
        for (const active of this.activeCollisionsStay) {
            const c = active.component;
            if (c.destroyed) continue;
            if (c.activeAndEnabled && c.onCollisionStay) {
                if (active.collision.collider.destroyed) continue;
                const arg = active.collision;
                c.onCollisionStay(arg);
            }
        }
        for (const active of this.activeTriggers) {
            const c = active.component;
            if (c.destroyed) continue;
            if (c.activeAndEnabled && c.onTriggerStay) {
                const arg = active.otherCollider;
                if (arg.destroyed) continue;
                c.onTriggerStay(arg);
            }
        }
    }

    private onCollisionEnded(self: ICollider, other: ICollider) {
        if (self.destroyed || other.destroyed) return;
        for (let i = 0; i < this.activeCollisions.length; i++) {
            const active = this.activeCollisions[i];
            const collider = active.collider;
            if (collider.destroyed || active.collision.collider.destroyed) {
                this.activeCollisions.splice(i, 1);
                i--;
                continue;
            }
            if (collider === self && active.collision.collider === other) {
                const c = active.component;
                this.activeCollisions.splice(i, 1);
                i--;
                if (c.activeAndEnabled && c.onCollisionExit) {
                    const collision = active.collision;
                    c.onCollisionExit(collision);
                }
            }
        }
        for (let i = 0; i < this.activeCollisionsStay.length; i++) {
            const active = this.activeCollisionsStay[i];
            const collider = active.collider;
            if (collider.destroyed || active.collision.collider.destroyed) {
                this.activeCollisionsStay.splice(i, 1);
                i--;
                continue;
            }
            if (collider === self && active.collision.collider === other) {
                const c = active.component;
                this.activeCollisionsStay.splice(i, 1);
                i--;
                if (c.activeAndEnabled && c.onCollisionExit) {
                    const collision = active.collision;
                    c.onCollisionExit(collision);
                }
            }
        }
        for (let i = 0; i < this.activeTriggers.length; i++) {
            const active = this.activeTriggers[i];
            const collider = active.collider;
            if (collider.destroyed || active.otherCollider.destroyed) {
                this.activeTriggers.splice(i, 1);
                i--;
                continue;
            }
            if (collider === self && active.otherCollider === other) {
                const c = active.component;
                this.activeTriggers.splice(i, 1);
                i--;
                if (c.activeAndEnabled && c.onTriggerExit) {
                    const collision = active.otherCollider;
                    c.onTriggerExit(collision);
                }
            }
        }
    }
}
