/**
 * Assets branding Authentik (logo + favicon light/dark).
 * Sortie : ulti-backend/deploy/authentik/branding/
 *
 * pnpm run brand:authentik
 */
import { existsSync, mkdirSync } from "node:fs"
import { dirname, join } from "node:path"
import { fileURLToPath } from "node:url"
import sharp from "sharp"

const __dirname = dirname(fileURLToPath(import.meta.url))
const root = join(__dirname, "..")
const brandDir = join(root, "public/brand")
const outDir = join(root, "../ulti-backend/deploy/authentik/branding")

function findOriginalPng() {
  const a = join(brandDir, "ultimail-original.png")
  const b = join(brandDir, "utlimail-original.png")
  if (existsSync(a)) return a
  if (existsSync(b)) return b
  throw new Error("Missing public/brand/ultimail-original.png — run: pnpm run brand:build")
}

function headerIconPath() {
  const p = join(brandDir, "ultimail-header-icon.png")
  if (!existsSync(p)) {
    throw new Error("Missing ultimail-header-icon.png — run: pnpm run brand:header-icon")
  }
  return p
}

async function extractWordmarkTextStrip(originalPath) {
  const meta = await sharp(originalPath).metadata()
  const W = meta.width ?? 0
  const H = meta.height ?? 0
  if (!W || !H) throw new Error("Could not read original dimensions")

  const splitY = Math.min(H - 32, Math.max(80, Math.round(H * 0.62)))
  const strip = await sharp(originalPath)
    .extract({ left: 0, top: splitY, width: W, height: H - splitY })
    .flatten({ background: "#ffffff" })
    .png()
    .toBuffer()

  return sharp(strip).trim({ threshold: 12 }).png().toBuffer()
}

/** Bandeau texte clair sur fond transparent (thème sombre Authentik). */
async function invertTextStripForDark(stripBuf) {
  const { data, info } = await sharp(stripBuf).ensureAlpha().raw().toBuffer({ resolveWithObject: true })
  if (info.channels !== 4) throw new Error("expected RGBA")

  for (let i = 0; i < data.length; i += 4) {
    const r = data[i]
    const g = data[i + 1]
    const b = data[i + 2]
    if (r >= 235 && g >= 235 && b >= 235) {
      data[i + 3] = 0
      continue
    }
    data[i] = Math.min(255, 255 - r + 40)
    data[i + 1] = Math.min(255, 255 - g + 40)
    data[i + 2] = Math.min(255, 255 - b + 40)
    data[i + 3] = 255
  }

  return sharp(Buffer.from(data), {
    raw: { width: info.width, height: info.height, channels: 4 },
  })
    .png()
    .toBuffer()
}

async function buildHorizontalWordmark(iconPath, textBuf, { transparent = false } = {}) {
  const iconH = 120
  const iconBuf = await sharp(iconPath)
    .resize({ height: iconH, fit: "inside" })
    .png()
    .toBuffer()
  const textResized = await sharp(textBuf)
    .resize({ height: Math.round(iconH * 0.72), fit: "inside" })
    .png()
    .toBuffer()

  const iw = (await sharp(iconBuf).metadata()).width ?? 0
  const ih = (await sharp(iconBuf).metadata()).height ?? 0
  const tw = (await sharp(textResized).metadata()).width ?? 0
  const th = (await sharp(textResized).metadata()).height ?? 0
  const padX = 24
  const gap = 28
  const canvasW = iw + tw + padX * 2 + gap
  const canvasH = Math.max(ih, th) + 16

  const bg = transparent
    ? { r: 0, g: 0, b: 0, alpha: 0 }
    : { r: 255, g: 255, b: 255, alpha: 1 }

  return sharp({
    create: {
      width: canvasW,
      height: canvasH,
      channels: 4,
      background: bg,
    },
  })
    .composite([
      { input: iconBuf, left: padX, top: Math.round((canvasH - ih) / 2) },
      { input: textResized, left: padX + iw + gap, top: Math.round((canvasH - th) / 2) },
    ])
    .png({ compressionLevel: 9 })
    .toBuffer()
}

async function writeFavicon(iconPath, outPath, { bg } = {}) {
  const size = 32
  const iconSize = 26
  const iconBuf = await sharp(iconPath)
    .resize(iconSize, iconSize, {
      fit: "contain",
      background: { r: 0, g: 0, b: 0, alpha: 0 },
    })
    .png()
    .toBuffer()

  const background =
    bg === "light"
      ? { r: 255, g: 255, b: 255, alpha: 1 }
      : bg === "dark"
        ? { r: 24, g: 24, b: 27, alpha: 1 }
        : { r: 0, g: 0, b: 0, alpha: 0 }

  await sharp({
    create: {
      width: size,
      height: size,
      channels: 4,
      background,
    },
  })
    .composite([{ input: iconBuf, left: Math.round((size - iconSize) / 2), top: Math.round((size - iconSize) / 2) }])
    .png({ compressionLevel: 9 })
    .toFile(outPath)
}

async function main() {
  mkdirSync(outDir, { recursive: true })

  const original = findOriginalPng()
  const headerIcon = headerIconPath()
  const textStrip = await extractWordmarkTextStrip(original)

  const lightLogo = await buildHorizontalWordmark(headerIcon, textStrip, { transparent: false })
  await sharp(lightLogo).toFile(join(outDir, "ultimail-logo-light.png"))

  const darkText = await invertTextStripForDark(textStrip)
  const darkLogo = await buildHorizontalWordmark(headerIcon, darkText, { transparent: true })
  await sharp(darkLogo).toFile(join(outDir, "ultimail-logo-dark.png"))

  await writeFavicon(headerIcon, join(outDir, "ultimail-favicon-light.png"), { bg: "light" })
  await writeFavicon(headerIcon, join(outDir, "ultimail-favicon-dark.png"), { bg: "dark" })
  // Favicon tab : URL statique (Authentik ne remplace pas %(theme)s dans <link rel="icon"> SSR).
  await writeFavicon(headerIcon, join(outDir, "ultimail-favicon.png"))

  console.log("Wrote Authentik branding to", outDir)
  console.log("  ultimail-logo-light.png / ultimail-logo-dark.png")
  console.log("  ultimail-favicon.png (+ light/dark variants)")
}

main().catch((e) => {
  console.error(e)
  process.exit(1)
})