// lib/voxels/voxel-data.ts
// VoxelChunk — flat Uint16Array storage with bounds-checked accessors.
// Ported from scripts/voxel-data.js.


/** Callback receiving each voxel's coordinates and id during iteration. */
export type VoxelVisitor = (x: number, y: number, z: number, id: number) => void

/**
 * Cubic voxel chunk: flat `Uint16Array` storage with bounds-checked
 * accessors. Id `0` is empty; any other id is a solid voxel (and indexes
 * the meshing palette).
 *
 * @example
 * const chunk = new VoxelChunk(16)
 * chunk.set(0, 0, 0, 1)
 * const geometry = greedyMesh(chunk)
 */
export class VoxelChunk {
  readonly size: number
  readonly data: Uint16Array

  constructor (size: number) {
    this.size = size
    this.data = new Uint16Array(size * size * size)
  }

  private _idx (x: number, y: number, z: number): number {
    return (y * this.size + z) * this.size + x
  }

  get (x: number, y: number, z: number): number {
    if (x < 0 || y < 0 || z < 0 || x >= this.size || y >= this.size || z >= this.size)
      return 0
    return this.data[this._idx(x, y, z)] as number
  }

  set (x: number, y: number, z: number, id: number): void {
    if (x < 0 || y < 0 || z < 0 || x >= this.size || y >= this.size || z >= this.size)
      return
    this.data[this._idx(x, y, z)] = id
  }

  fill (id: number): void {
    this.data.fill(id)
  }

  forEach (cb: VoxelVisitor): void {
    for (let y = 0; y < this.size; y++)
      for (let z = 0; z < this.size; z++)
        for (let x = 0; x < this.size; x++) {
          const v = this.data[this._idx(x, y, z)] as number
          if (v !== 0)
            cb(x, y, z, v)
        }
  }
}

// perf: cheap. flat typed array, no per-voxel object allocation.
// Memory: 2 bytes per voxel. 32³ = 64 KB.