// fixtures/build-bundles.mjs — run by a person, output committed.
// The app performs no build step (spec §6.5); this produces the
// artifact that makes that true: a single, minified, content-hashed
// JS bundle committed to internal/docs/static/, embedded into the Go
// binary by internal/docs/assets.go's //go:embed static.
//
// internal/docs/static/, not a top-level static/: Go's //go:embed
// cannot reach outside (or above) the directory of the .go file doing
// the embedding — no ".." is allowed in an embed pattern — so the
// tree assets.go embeds has to live under internal/docs/, the same
// way internal/docs/views/*.html already does for this app's page
// templates.
//
// Paths below are resolved from this file's own location
// (fixtures/generate.mjs's own pattern), not from the caller's
// working directory, so `node build-bundles.mjs` works the same
// whether it's run from fixtures/ or anywhere else.
import { build } from 'esbuild'
import { createHash } from 'node:crypto'
import { readFileSync, writeFileSync, rmSync, readdirSync, mkdirSync } from 'node:fs'
import { join, dirname } from 'node:path'
import { fileURLToPath } from 'node:url'

const here = dirname(fileURLToPath(import.meta.url))
const staticDir = join(here, '..', 'internal', 'docs', 'static')

mkdirSync(staticDir, { recursive: true })

// Two bundles, built and hashed the same way but kept separate on
// purpose. The editor is ProseMirror and Yjs — about 300KB — and only
// a document page needs it. The jump-to palette is a few KB and every
// signed-in page needs it, including the list. Bundling them together
// would make opening the list download an editor in order to offer a
// keyboard shortcut.
//
// The names here are the names internal/docs/assets.go's bundleKinds
// expects; that file panics at init if one of them has no committed
// file, so a build that silently stopped emitting one cannot start.
const bundles = [
  { name: 'editor', entry: 'editor-entry.js' },
  { name: 'jumpto', entry: 'jump-to.mjs' },
  // The share page's Copy button: a few hundred bytes, and only that
  // page needs it.
  { name: 'share', entry: 'share-link.mjs' },
]

for (const { name, entry } of bundles) {
  const outfile = join(staticDir, `${name}.js`)
  await build({
    entryPoints: [join(here, entry)],
    bundle: true,
    format: 'esm',
    minify: true,
    target: 'es2020',
    outfile
  })

  // Content hash in the filename so the asset is immutable-cacheable
  // and a stale browser cache cannot serve a bundle that disagrees
  // with the server (internal/docs/assets.go's own doc comment).
  const bytes = readFileSync(outfile)
  const hash = createHash('sha256').update(bytes).digest('hex').slice(0, 16)

  // Exactly one file per bundle must ever be committed — assets.go
  // panics at init if it finds more or less than one — so a rebuild
  // must remove every previous hashed file for THIS name before
  // writing the new one. The regex is anchored to the name so
  // rebuilding one bundle never deletes the other's.
  const stale = new RegExp(`^${name}\\.[0-9a-f]{16}\\.js$`)
  for (const f of readdirSync(staticDir)) {
    if (stale.test(f)) rmSync(join(staticDir, f))
  }
  writeFileSync(join(staticDir, `${name}.${hash}.js`), bytes)
  rmSync(outfile)

  console.log(`wrote internal/docs/static/${name}.${hash}.js (${bytes.length} bytes)`)
}