import {
  BufferGeometry,
  BufferAttribute
} from 'three'
import { MeshBVH } from '../core/MeshBVH.js'

onmessage = ({ data }) => {
  let prevTime = performance.now()
  function onProgressCallback(progress) {
    // account for error
    progress = Math.min(progress, 1)

    const currTime = performance.now()
    if (currTime - prevTime >= 10 && progress !== 1.0) {
      postMessage({

        error: null,
        serialized: null,
        position: null,
        progress

      })
      prevTime = currTime
    }
  }

  const { index, position, options } = data
  try {
    const geometry = new BufferGeometry()
    geometry.setAttribute('position', new BufferAttribute(position, 3, false))
    if (index) {
      geometry.setIndex(new BufferAttribute(index, 1, false))
    }

    if (options.includedProgressCallback) {
      options.onProgress = onProgressCallback
    }

    if (options.groups) {
      const groups = options.groups
      for (const i in groups) {
        const group = groups[ i ]
        geometry.addGroup(group.start, group.count, group.materialIndex)
      }
    }

    const bvh = new MeshBVH(geometry, options)
    const serialized = MeshBVH.serialize(bvh, { copyIndexBuffer: false })
    let toTransfer = [position.buffer, ...serialized.roots]
    if (serialized.index) {
      toTransfer.push(serialized.index.buffer)
    }

    toTransfer = toTransfer.filter(v => (typeof SharedArrayBuffer === 'undefined') || !(v instanceof SharedArrayBuffer))

    if (bvh._indirectBuffer) {
      toTransfer.push(serialized.indirectBuffer.buffer)
    }

    postMessage({

      error: null,
      serialized,
      position,
      progress: 1

    }, toTransfer)
  } catch (error) {
    postMessage({

      error,
      serialized: null,
      position: null,
      progress: 1

    })
  }
}