import fs from "node:fs";
import path from "node:path";
import {
  HISTORY_DIR,
  MIRROR_DIR,
  TARBALL_HREF,
  parseSourceManifest,
  type SourceManifest,
} from "yt-dlp-transcript-common/lib/sourceManifest";

// The published source's manifest, written LAST by `archilyzer source publish`
// (common/publish/source.ts) into public/source/, or null when this build has
// none. The /source/ page renders an honest empty state for null — the mirror,
// the tree and the tarball are gitignored build artefacts, so a fresh clone
// (or `archilyzer build homepage --no-source`) has none of them.
//
// Believed only when the files it describes are here too (the snapshot.ts
// rule): a manifest beside a missing mirror or tarball would advertise a
// clone that fails and a download that 404s. The same for the history block
// (release 15 slice SG): without its log page beside it, the manifest is
// returned WITHOUT it, and the page shows no History links. A malformed or
// wrong-version manifest is null too (parseSourceManifest checks every number
// the page reads), so a bad file is the empty state, never a crash in `next
// build`. `pub` is the test's seam.
//
// The default is a DIRECTORY join on `process.cwd()`, which Turbopack would
// trace as every file under `public/` (the source mirror among them, and it
// grows with every publish): the opt-out keeps it a plain run-time path
// (plans/FACTS.md, "A path joined from `process.cwd()` …").
export function loadSourceManifest(
  pub: string = sourcePublicDir(
    process.env,
    path.join(/* turbopackIgnore: true */ process.cwd(), "public"),
  ),
): SourceManifest | null {
  try {
    const manifest = parseSourceManifest(
      JSON.parse(fs.readFileSync(path.join(/* turbopackIgnore: true */ pub, "source", "manifest.json"), "utf8")),
    );
    if (!manifest) return null;
    if (!fs.statSync(path.join(/* turbopackIgnore: true */ pub, "source", MIRROR_DIR, "info", "refs")).isFile()) return null;
    if (!fs.statSync(path.join(/* turbopackIgnore: true */ pub, TARBALL_HREF.replace(/^\//, ""))).isFile()) return null;
    if (manifest.history && !isFile(path.join(/* turbopackIgnore: true */ pub, "source", HISTORY_DIR, "log.html"))) {
      const without: SourceManifest = { ...manifest };
      delete without.history;
      return without;
    }
    return manifest;
  } catch {
    return null;
  }
}

function isFile(p: string): boolean {
  try {
    return fs.statSync(p).isFile();
  } catch {
    return false;
  }
}

// The directory loadSourceManifest reads: `public/`, or the one
// E2E_SOURCE_PUBLIC_DIR names when it holds a manifest — but ONLY outside a
// production build. The homepage e2e's `next dev` points it at a fixture
// publish its spec writes and removes (e2e/fixture-source.ts), so the page's
// states with and without a history are exercised whatever this checkout has
// published; with the fixture gone, the page reads `public/` again. `next
// build` runs with NODE_ENV=production and ignores it (the summary.ts rule).
export function sourcePublicDir(
  env: Readonly<Record<string, string | undefined>>,
  publicDir: string,
): string {
  const fixture = env.NODE_ENV !== "production" ? env.E2E_SOURCE_PUBLIC_DIR : undefined;
  if (fixture && isFile(path.join(/* turbopackIgnore: true */ fixture, "source", "manifest.json"))) return fixture;
  return publicDir;
}