/**
 * INTEGRATION SEAM — owned by integration, not by lanes.
 * Composes lane modules into the playable slice. While lanes are in flight this
 * boots a placeholder ball on a flat floor so `npm run dev` always shows life.
 */
import * as THREE from 'three'
import type { World } from './contracts'

export function installGame(world: World) {
  const { scene, physics, rapier } = world

  // floor
  const floor = new THREE.Mesh(
    new THREE.BoxGeometry(60, 1, 60),
    new THREE.MeshStandardMaterial({ color: '#e8d9b8' }))
  floor.position.y = -0.5
  floor.receiveShadow = true
  scene.add(floor)
  physics.createCollider(rapier.ColliderDesc.cuboid(30, 0.5, 30)
    .setTranslation(0, -0.5, 0))

  // placeholder blob-ball (replaced by lane A's createBlob at integration)
  const ball = new THREE.Mesh(
    new THREE.SphereGeometry(0.6, 32, 24),
    new THREE.MeshStandardMaterial({ color: '#F5F5F7', roughness: 0.35 }))
  ball.castShadow = true
  scene.add(ball)
  const body = physics.createRigidBody(
    rapier.RigidBodyDesc.dynamic().setTranslation(0, 3, 0))
  physics.createCollider(
    rapier.ColliderDesc.ball(0.6).setRestitution(0.4).setFriction(1.0), body)

  const keys = new Set<string>()
  addEventListener('keydown', (e) => keys.add(e.code))
  addEventListener('keyup', (e) => keys.delete(e.code))

  world.addSystem({
    update() {
      const f = 18
      const impulse = { x: 0, y: 0, z: 0 }
      if (keys.has('KeyW') || keys.has('ArrowUp')) impulse.z -= f
      if (keys.has('KeyS') || keys.has('ArrowDown')) impulse.z += f
      if (keys.has('KeyA') || keys.has('ArrowLeft')) impulse.x -= f
      if (keys.has('KeyD') || keys.has('ArrowRight')) impulse.x += f
      body.applyImpulse({ x: impulse.x / 60, y: 0, z: impulse.z / 60 }, true)
      const p = body.translation()
      ball.position.set(p.x, p.y, p.z)
      const q = body.rotation()
      ball.quaternion.set(q.x, q.y, q.z, q.w)
    },
  })

  world.onFrame(() => {
    world.camera.lookAt(ball.position)
  })
}