import { boxBlur } from '@/utils/maskOps'
import { lumaFromRgba } from '@/lib/render/light_map'

export type MapU8 = { data: Uint8Array; width: number; height: number }

/**
 * Builds a specular/highlight map from the original image via a high-pass:
 * spec = clamp(L - blur(L, rSmall), 0..255)
 */
export function buildSpecularMap(opts: {
  rgba: Uint8ClampedArray
  width: number
  height: number
  tilesMask?: Uint8Array | null
  blurRadiusPx?: number
  postBlurPx?: number
  strength?: number // 0..1
}): MapU8 {
  const width = Math.max(1, Math.round(opts.width))
  const height = Math.max(1, Math.round(opts.height))
  const tilesMask = opts.tilesMask ?? null

  const blurRadiusPx = Math.max(0, Math.round(opts.blurRadiusPx ?? 6))
  const postBlurPx = Math.max(0, Math.round(opts.postBlurPx ?? 3))
  const strength = Math.max(0, Math.min(1, opts.strength ?? 0.25))

  const gray = lumaFromRgba(opts.rgba, width, height)
  const low = blurRadiusPx ? boxBlur(gray, width, height, blurRadiusPx) : null

  const spec = new Uint8Array(width * height)
  for (let i = 0; i < spec.length; i++) {
    if (tilesMask && !tilesMask[i]) {
      spec[i] = 0
      continue
    }
    const base = gray[i]
    const blurred = low ? low[i] : base
    const hp = base - (Number.isFinite(blurred) ? blurred : base)
    const v = Math.max(0, Math.min(255, Math.round(hp * strength)))
    spec[i] = v
  }

  if (!postBlurPx) return { data: spec, width, height }

  const post = boxBlur(spec, width, height, postBlurPx)
  const out = new Uint8Array(width * height)
  for (let i = 0; i < out.length; i++) {
    const v = post[i]
    out[i] = Math.max(0, Math.min(255, Math.round(Number.isFinite(v) ? v : 0)))
  }
  return { data: out, width, height }
}