#!/usr/bin/env node
// Prints the request for the optional relight step (a badly lit photo, before the grade). It does not call any API.
// Usage:
//   node scripts/build-relight-input.mjs --photo photo.jpg [--light "soft late-afternoon sun"] [--out relight.json]
// --photo takes a local file (embedded as a data URI, so it never has to be uploaded publicly) or a public https URL.
import { readFileSync, writeFileSync, existsSync } from 'node:fs'
import { dirname, join, extname } from 'node:path'
import { fileURLToPath } from 'node:url'

const root = join(dirname(fileURLToPath(import.meta.url)), '..')
const usage = 'Usage: node scripts/build-relight-input.mjs --photo <local file or https URL> [--light "soft, even daylight"] [--out relight.json]'
const VALUE_FLAGS = new Set(['photo', 'light', 'out'])
const fail = (message) => { console.error(`${message}\n${usage}`); process.exit(1) }

const options = {}
const args = process.argv.slice(2)
for (let i = 0; i < args.length; i += 1) {
  const arg = args[i]
  if (!arg.startsWith('--')) fail(`Unexpected argument "${arg}".`)
  const key = arg.slice(2)
  if (!VALUE_FLAGS.has(key)) fail(`Unknown flag --${key}.`)
  const value = args[i + 1]
  if (value === undefined || value.startsWith('--')) fail(`--${key} needs a value.`)
  options[key] = value
  i += 1
}
if (!options.photo) fail('--photo is required.')

const MIME = { '.jpg': 'image/jpeg', '.jpeg': 'image/jpeg', '.png': 'image/png', '.webp': 'image/webp' }
let photo = options.photo
if (!/^https:\/\//.test(photo)) {
  if (!existsSync(photo)) fail(`Photo not found: ${photo}`)
  const mime = MIME[extname(photo).toLowerCase()]
  if (!mime) fail('The photo must be .jpg, .png or .webp.')
  photo = `data:${mime};base64,${readFileSync(photo).toString('base64')}`
}

const settings = JSON.parse(readFileSync(join(root, 'assets/generation-input.json'), 'utf8')).relight
const template = readFileSync(join(root, 'assets/prompt-template.md'), 'utf8').trim()
const light = options.light ?? settings.default_light
// A replacer function keeps any "$" in the text literal.
const prompt = template.replace('{{light}}', () => light)
const output = JSON.stringify({ model: settings.model, input: { ...settings.input, image_urls: [photo], prompt } }, null, 2)
if (options.out) {
  writeFileSync(options.out, output)
  console.log(`Wrote the relight request to ${options.out}`)
} else console.log(output)