---
import { normalizeBase } from '../src/lib/nav-href';
import bookConfig from 'virtual:book-scaffold/book-config';
import { corpusBookIdFromPath, selectBookArtifact } from '../src/lib/corpus';
// XRef — resolves a `\cref{label}` LaTeX reference to a hyperlink.
//
// Reads src/data/labels.json built by scripts/build-labels.mjs
// (Phase 2.6). For each known id, the map provides:
//   { href: "/chapters/week04#thm-w4-stability", display: "Theorem 4.2" }
//
// Runtime: renders `<a href>` for known ids; renders an inline `[?id]`
// placeholder for unknown ids so the Astro dev server stays running while
// chapters are being authored or labels are being added.
//
// CI: `book-scaffold validate` (Phase 2.6, shipped) catches unknown ids
// and **fails the build with a non-zero exit code** before unresolved
// placeholders can reach production. The placeholder is a dev-ergonomic
// affordance, not a soft-degradation path on the deploy critical line.
//
// Bootstrapping note: when porting a book chapter-by-chapter, early
// chapters that reference yet-to-be-ported targets need either plain-prose
// substitutes or a temporarily-commented `{/* <XRef …/> */}` until the
// target chapter (and its `id="…"` attributes) exists. MDX uses JSX-style
// expression comments — the HTML `<` + bang + `--` form is NOT valid MDX.
//
// NB: these are `//` line comments, not a `/** */` block, on purpose — the
// literal `*/` in the example above would otherwise close a block comment
// early and break esbuild on every MDX import (the v4.9.0 fix).
//
// Usage:
//   By <XRef id="thm:w4:stability" />, the discretized eigenvalues …
type LabelEntry = { href: string; display: string };

// Resolve labels.json from the consumer's project root (Vite resolves `/`
// to project root, not the package). Missing file -> empty map -> [?id]
// placeholders (silent degrade for dev ergonomics; validator catches at CI).
const labelsModules = import.meta.glob<{ default: unknown }>(
  '/src/data/labels.json',
  { eager: true },
);
const labelsModule = labelsModules['/src/data/labels.json'];
const currentBook = bookConfig.corpus
  ? corpusBookIdFromPath(bookConfig.corpus, Astro.url.pathname, import.meta.env.BASE_URL)
  : null;
const map = labelsModule
  ? selectBookArtifact<Record<string, LabelEntry>>(
      labelsModule.default,
      bookConfig.corpus,
      currentBook,
      'src/data/labels.json',
    )
  : {};

interface Props {
  id: string;
}

const { id } = Astro.props;
const entry = map[id];
// #142: labels.json stores a base-less `chapters/<slug>#<id>` ref; prefix
// BASE_URL at render. The leading-slash strip tolerates a labels.json built
// by an older (pre-#142) build-labels that still emits a root-absolute href.
const baseUrl = normalizeBase(import.meta.env.BASE_URL);
---
{entry ? (
  <a href={`${baseUrl}${entry.href.replace(/^\//, '')}`} class="xref">{entry.display}</a>
) : (
  <span class="xref xref-unknown" title={`Unknown label: ${id}`}>[?{id}]</span>
)}