import { MeshDepthMaterial, Scene, Skeleton, SkinnedMesh, WebGLRenderTarget } from 'three'

import { applyInputSourcePoseToIKTargets } from '../../avatar/functions/applyInputSourcePoseToIKTargets'
import { updateLocalAvatarPosition, updateLocalAvatarRotation } from '../../avatar/functions/moveAvatar'
import { World } from '../../ecs/classes/World'
import { getComponent, hasComponent } from '../../ecs/functions/ComponentFunctions'
import { EngineRenderer } from '../../renderer/WebGLRendererSystem'
import { GroupComponent } from '../../scene/components/GroupComponent'
import { VisibleComponent } from '../../scene/components/VisibleComponent'
import { updateXRCamera } from '../../xr/XRCameraSystem'
import { computeTransformMatrix } from './TransformSystem'

/**
 * This system is responsible for updating the local client avatar position and rotation, and updating the XR camera position.
 * @param world
 * @returns
 */
export default async function ReferenceSpaceTransformSystem(world: World) {
  const skeletonForceUpdateScene = new Scene()
  skeletonForceUpdateScene.overrideMaterial = new MeshDepthMaterial()
  const dummyRenderTarget = new WebGLRenderTarget(1, 1)

  const execute = () => {
    const { localClientEntity } = world

    /**
     * 1 - Update local client movement
     */
    if (localClientEntity) {
      updateLocalAvatarPosition()
      updateLocalAvatarRotation()
      computeTransformMatrix(localClientEntity)

      // the following is a workaround for a bug in the multiview rendering implementation, described here:
      // https://github.com/mrdoob/three.js/pull/24048
      // essentially, we are forcing the skeleton of the local client to be uploaded to the GPU here
      if (
        hasComponent(localClientEntity, VisibleComponent) &&
        EngineRenderer.instance.xrManager?.isMultiview &&
        EngineRenderer.instance.xrManager?.isPresenting
      ) {
        const localClientGroup = getComponent(localClientEntity, GroupComponent)
        const renderer = EngineRenderer.instance.renderer
        skeletonForceUpdateScene.children = localClientGroup
        renderer.setRenderTarget(dummyRenderTarget)
        renderer.render(skeletonForceUpdateScene, world.camera)
        renderer.setRenderTarget(null)
      }
    }

    /**
     * 2 - Update XR camera positions based on world origin and viewer pose
     */
    updateXRCamera()

    /**
     * For whatever reason, this must run at the start of the transform system, before the transform system.
     */
    applyInputSourcePoseToIKTargets()
  }

  const cleanup = async () => {}

  return { execute, cleanup }
}