#!/usr/bin/env node
// Builds a labelled contact sheet of colourways. Names are drawn locally so spelling is exact. No API.
// Usage: node scripts/variant-sheet.mjs --output sheet.jpg --variant "Navy=navy.jpg" --variant "Coral=coral.jpg" [--variant ...] [--columns 2] [--cell 1000]
// Needs the `sharp` package. Between 2 and 6 variants. Cells take the ratio of the first image (--aspect auto, the default) and every image is fitted whole on white, never cropped.
let sharp
try {
  sharp = (await import('sharp')).default
} catch {
  console.error('This script needs the sharp package. Run `npm install sharp` in the Skill folder (Node 20.9 or newer).')
  process.exit(1)
}

const usage = 'Usage: node scripts/variant-sheet.mjs --output sheet.jpg --variant "Name=file.jpg" (2 to 6 times) [--columns 2] [--cell 1000] [--aspect auto|1:1|4:3]'
const allowed = new Set(['output', 'variant', 'columns', 'cell', 'aspect'])
const options = { variant: [] }
const args = process.argv.slice(2)
for (let index = 0; index < args.length; index += 1) {
  const key = args[index]
  if (!key.startsWith('--') || !allowed.has(key.slice(2))) {
    console.error(`Unknown argument: ${key}`)
    console.error(usage)
    process.exit(1)
  }
  const value = args[index + 1]
  if (value === undefined || value.startsWith('--')) {
    console.error(`${key} needs a value.`)
    console.error(usage)
    process.exit(1)
  }
  if (key === '--variant') options.variant.push(value)
  else options[key.slice(2)] = value
  index += 1
}
if (!options.output || options.variant.length < 2 || options.variant.length > 6) {
  console.error(usage)
  process.exit(1)
}
const number = (name, fallback, min, max) => {
  const value = options[name] === undefined ? fallback : Number(options[name])
  if (!Number.isInteger(value) || value < min || value > max) {
    console.error(`--${name} must be a whole number from ${min} to ${max}.`)
    process.exit(1)
  }
  return value
}
const variants = options.variant.map((entry) => {
  const at = entry.lastIndexOf('=')
  if (at < 1) { console.error(`Variant "${entry}" must look like Name=file.jpg`); process.exit(1) }
  return { name: entry.slice(0, at).trim(), file: entry.slice(at + 1).trim() }
})
import { existsSync } from 'node:fs'
for (const variant of variants) if (!existsSync(variant.file)) { console.error(`File not found: ${variant.file}`); process.exit(1) }
const columns = number('columns', options.variant.length === 2 ? 2 : options.variant.length === 3 ? 3 : options.variant.length === 4 ? 2 : 3, 1, 6)
const first = await sharp(variants[0].file).metadata()
let [aw, ah] = [first.width, first.height]
if (options.aspect !== undefined && options.aspect !== 'auto') {
  ;[aw, ah] = options.aspect.split(':').map(Number)
  if (!(aw > 0 && ah > 0)) { console.error('--aspect must be auto or look like 4:3'); process.exit(1) }
}
const cell = Math.round(number('cell', 1000, 200, 2000))
const cellHeight = Math.round((cell * ah) / aw)
const label = Math.round(cell * 0.09)
const rows = Math.ceil(variants.length / columns)
const escapeXml = (value) => value.replace(/[<>&'"]/g, (char) => ({ '<': '&lt;', '>': '&gt;', '&': '&amp;', "'": '&apos;', '"': '&quot;' })[char])

const composites = []
for (const [index, variant] of variants.entries()) {
  const left = (index % columns) * cell
  const top = Math.floor(index / columns) * (cellHeight + label)
  const image = await sharp(variant.file).resize(cell, cellHeight, { fit: 'contain', background: '#ffffff' }).jpeg({ quality: 93 }).toBuffer()
  const svg = `<svg xmlns="http://www.w3.org/2000/svg" width="${cell}" height="${label}"><text x="${cell / 2}" y="${label * 0.68}" text-anchor="middle" font-family="Helvetica, Arial, sans-serif" font-size="${Math.round(label * 0.42)}" letter-spacing="${Math.round(label * 0.04)}" fill="#1a1a1a">${escapeXml(variant.name.toUpperCase())}</text></svg>`
  composites.push({ input: image, left, top }, { input: Buffer.from(svg), left, top: top + cellHeight })
}
await sharp({ create: { width: cell * columns, height: rows * (cellHeight + label), channels: 3, background: '#ffffff' } })
  .composite(composites)
  .jpeg({ quality: 92 })
  .toFile(options.output)
console.log(`${options.output}: ${variants.length} colourways, ${cell * columns}x${rows * (cellHeight + label)}`)