// Renders the frontpage's social card (the image behind Open Graph / Twitter
// link unfurls) from the brand SVGs, on the same pipeline as the store
// tiles: composed at render time from brand/sticker.svg and the generated
// wordmark, drawn by a headless Chrome, and verified before writing.
//
// 1200x630 is the one size the major unfurl surfaces (Bluesky, Slack,
// Discord, iMessage, X) all display without cropping the safe area.
//
// Run npm run wordmark first when brand sources change (the prek hooks
// order this correctly): the card nests the generated wordmark file.
//
// Usage: node scripts/render-og.mjs   (also: npm run og)
// Set CHROME to point at a specific Chrome/Chromium binary.

import { mkdtempSync, rmSync, writeFileSync } from 'node:fs'
import { tmpdir } from 'node:os'
import { join, resolve } from 'node:path'
import { pathToFileURL } from 'node:url'

import { compose, nest, nestWordmark } from './compose.mjs'
import { findChrome, pngSize } from './render-icons.mjs'
import { rasterize } from './rasterize.mjs'

const CARD = {
  width: 1200,
  height: 630,
  dest: 'web/public/og.png',
  body: () =>
    nest('brand/sticker.svg', 120, 145, 340) +
    nestWordmark(540, 315, 560),
}

function main() {
  const chrome = findChrome()
  const work = mkdtempSync(join(tmpdir(), 'substandard-og-'))
  try {
    const { opaque, png } = rasterize(
      chrome,
      work,
      'og',
      compose(CARD),
      CARD.width,
      CARD.height,
    )
    const dim = pngSize(png)
    if (dim.width !== CARD.width || dim.height !== CARD.height) {
      throw new Error(`og: rendered ${dim.width}x${dim.height}`)
    }
    // The paper ground makes a healthy card fully opaque.
    const fraction = opaque / (CARD.width * CARD.height)
    if (fraction < 0.99) {
      throw new Error(`og: only ${(fraction * 100).toFixed(1)}% opaque — misrender`)
    }
    writeFileSync(resolve(CARD.dest), png)
    console.log(`og: ${png.length} bytes -> ${CARD.dest}`)
  } finally {
    rmSync(work, { recursive: true, force: true })
  }
}

if (process.argv[1] && import.meta.url === pathToFileURL(process.argv[1]).href) {
  main()
}