import { maskAnd, maskMinus, morphDilate } from '@/utils/maskOps'

function uniqSorted(lines: number[], extent: number): number[] {
  return Array.from(
    new Set(
      (lines ?? [])
        .filter((v) => Number.isFinite(v))
        .map((v) => Math.round(v))
        .filter((v) => v >= 0 && v <= extent),
    ),
  ).sort((a, b) => a - b)
}

export type GroutMaskResult = {
  groutMask: Uint8Array // 0/255
  width: number
  height: number
}

export function buildGroutMaskFromGrid(opts: {
  width: number
  height: number
  vlines: number[]
  hlines: number[]
  groutWidthPx: number
  tilesMask?: Uint8Array | null // 0/255
  tilesDilatePx?: number // restrict grout to slightly expanded tiles region
}): GroutMaskResult {
  const width = Math.max(1, Math.round(opts.width))
  const height = Math.max(1, Math.round(opts.height))
  const groutWidthPx = Math.max(1, Math.round(opts.groutWidthPx))
  const half = Math.max(0, Math.floor(groutWidthPx / 2))

  const v = uniqSorted(opts.vlines ?? [], width)
  const h = uniqSorted(opts.hlines ?? [], height)

  const groutMask = new Uint8Array(width * height)

  const markVertical = (x0: number) => {
    const xStart = Math.max(0, x0 - half)
    const xEnd = Math.min(width - 1, x0 + half)
    for (let x = xStart; x <= xEnd; x++) {
      for (let y = 0; y < height; y++) {
        groutMask[y * width + x] = 255
      }
    }
  }

  const markHorizontal = (y0: number) => {
    const yStart = Math.max(0, y0 - half)
    const yEnd = Math.min(height - 1, y0 + half)
    for (let y = yStart; y <= yEnd; y++) {
      const row = y * width
      for (let x = 0; x < width; x++) groutMask[row + x] = 255
    }
  }

  for (const x of v) markVertical(x)
  for (const y of h) markHorizontal(y)

  if (opts.tilesMask) {
    const dil = morphDilate(
      opts.tilesMask,
      width,
      height,
      Math.max(0, Math.round(opts.tilesDilatePx ?? 2)),
    )
    const restricted = maskAnd(groutMask, dil)
    return { groutMask: restricted, width, height }
  }

  return { groutMask, width, height }
}

export function subtractGroutFromTiles(tilesMask: Uint8Array, groutMask: Uint8Array): Uint8Array {
  return maskMinus(tilesMask, groutMask)
}