// 本地扫码自检：把生成的色号网格渲染成像素，用 jsQR 解码并比对内容
// jsQR 比微信扫码更“挑剔”，自检通过基本可以放心；未通过时提示用户调整
const jsQR = require('./vendor/jsqr')
const { hexToRgb } = require('./color')

function selfCheck(artwork, expectedText) {
  const { size, cells, pal } = artwork
  const px = size > 90 ? 4 : 5
  const margin = 4
  const dim = (size + margin * 2) * px
  const data = new Uint8ClampedArray(dim * dim * 4).fill(255)
  const colors = pal.hexes.map(hexToRgb)
  for (let y = 0; y < size; y += 1) {
    for (let x = 0; x < size; x += 1) {
      const c = cells[y * size + x]
      if (c < 0) continue // 空钉位视为白底
      const [r, g, b] = colors[c]
      for (let dy = 0; dy < px; dy += 1) {
        let o = (((y + margin) * px + dy) * dim + (x + margin) * px) * 4
        for (let dx = 0; dx < px; dx += 1) {
          data[o] = r; data[o + 1] = g; data[o + 2] = b
          o += 4
        }
      }
    }
  }
  try {
    const result = jsQR(data, dim, dim, { inversionAttempts: 'dontInvert' })
    if (!result) return { ok: false, reason: 'unreadable' }
    return { ok: result.data === expectedText, reason: result.data === expectedText ? '' : 'mismatch' }
  } catch (e) {
    return { ok: false, reason: 'error' }
  }
}

module.exports = { selfCheck }