import sharp from 'sharp'
import { readFileSync } from 'fs'
import { resolve, dirname } from 'path'
import { fileURLToPath } from 'url'

const __dirname = dirname(fileURLToPath(import.meta.url))
const publicDir = resolve(__dirname, '../public')

// og-image: SVG → PNG 1200×630
const svgBuffer = readFileSync(resolve(publicDir, 'og-image.svg'))
await sharp(svgBuffer)
  .resize(1200, 630)
  .png({ quality: 90 })
  .toFile(resolve(publicDir, 'og-image.png'))
console.log('✓ og-image.png (1200×630)')

// apple-touch-icon: logo.png → 180×180
await sharp(resolve(publicDir, 'logo.png'))
  .resize(180, 180, { fit: 'contain', background: { r: 255, g: 255, b: 255, alpha: 1 } })
  .png()
  .toFile(resolve(publicDir, 'apple-touch-icon.png'))
console.log('✓ apple-touch-icon.png (180×180)')

// favicon.ico: logo.png → multi-size ICO (16, 32, 48)
import { writeFileSync } from 'fs'

const icoSizes = [16, 32, 48]
const pngBuffers = await Promise.all(
  icoSizes.map(size =>
    sharp(resolve(publicDir, 'logo.png'))
      .resize(size, size, { fit: 'contain', background: { r: 0, g: 0, b: 0, alpha: 0 } })
      .png()
      .toBuffer()
  )
)

// Build ICO: header + directory + image data
const count = icoSizes.length
const headerSize = 6
const dirEntrySize = 16
const dirSize = count * dirEntrySize
let offset = headerSize + dirSize

const header = Buffer.alloc(headerSize)
header.writeUInt16LE(0, 0)     // reserved
header.writeUInt16LE(1, 2)     // type: 1 = ICO
header.writeUInt16LE(count, 4)

const dirs = []
for (let i = 0; i < count; i++) {
  const dir = Buffer.alloc(dirEntrySize)
  const size = icoSizes[i]
  dir.writeUInt8(size === 256 ? 0 : size, 0)   // width
  dir.writeUInt8(size === 256 ? 0 : size, 1)   // height
  dir.writeUInt8(0, 2)   // color count
  dir.writeUInt8(0, 3)   // reserved
  dir.writeUInt16LE(1, 4)   // color planes
  dir.writeUInt16LE(32, 6)  // bits per pixel
  dir.writeUInt32LE(pngBuffers[i].length, 8)
  dir.writeUInt32LE(offset, 12)
  offset += pngBuffers[i].length
  dirs.push(dir)
}

const ico = Buffer.concat([header, ...dirs, ...pngBuffers])
writeFileSync(resolve(publicDir, 'favicon.ico'), ico)
console.log('✓ favicon.ico (16×16, 32×32, 48×48)')