import path from 'node:path'
import { fileURLToPath } from 'node:url'
import sharp from 'sharp'

const scriptDirectory = path.dirname(fileURLToPath(import.meta.url))
const projectRoot = path.resolve(scriptDirectory, '..', '..')
const sourcePath = path.join(projectRoot, 'static', 'assets', 'modules', 'genealogy', 'opaque', 'g01-empty-panel.png')
const outputPath = path.join(projectRoot, 'static', 'assets', 'modules', 'genealogy', 'transparent', 'g01-empty-panel-frame.png')
const borderBand = 110

const { data, info } = await sharp(sourcePath)
  .ensureAlpha()
  .raw()
  .toBuffer({ resolveWithObject: true })

for (let y = 0; y < info.height; y += 1) {
  for (let x = 0; x < info.width; x += 1) {
    const offset = (y * info.width + x) * info.channels
    const red = data[offset]
    const green = data[offset + 1]
    const blue = data[offset + 2]
    const alpha = data[offset + 3]
    const distanceToEdge = Math.min(x, y, info.width - 1 - x, info.height - 1 - y)
    const isWarmGold = red > green
      && green > blue
      && red - green >= 15
      && green - blue >= 12
      && red - blue >= 35
      && red < 245
      && blue < 180

    if (distanceToEdge >= borderBand || !isWarmGold) {
      data[offset + 3] = 0
      continue
    }

    const edgeAlpha = Math.max(0, Math.min(255, (red - blue - 25) * 6))
    data[offset + 3] = Math.min(alpha, edgeAlpha)
  }
}

await sharp(data, {
  raw: {
    width: info.width,
    height: info.height,
    channels: info.channels
  }
}).png().toFile(outputPath)

process.stdout.write(`BUILT ${path.relative(projectRoot, outputPath)}\n`)