/**
 * Task 7 (Q4 mermaid check, D3/D21): the built-in VS Code Markdown preview does
 * not render mermaid fences on its own — `previewAnnotations.ts`'s
 * `cowritingMarkdownItPlugin` teaches ```mermaid fences to render as
 * `<pre class="mermaid">SRC</pre>` (via `options.highlight`, the same
 * extension point the built-in preview's own fence rule already calls); this
 * script (contributed via `markdown.previewScripts`) is what actually turns
 * those into diagrams — mermaid needs a DOM, so it runs here, in the preview's
 * webview, never in the extension host. Bundled by esbuild as a standalone
 * IIFE → out/media/preview-mermaid.js, so mermaid never enters the host
 * bundle (matching the sealed webview's `media/preview.ts` precedent).
 *
 * Contributed preview scripts are reloaded on every content change (VS Code
 * docs), so running at module top-level is sufficient; the
 * `vscode.markdown.updateContent` listener is added defensively to also cover
 * in-place content updates that don't reload the script (mirrors the proven
 * `bierner.markdown-mermaid` extension's own approach).
 *
 * SCOPE NOTE (Q4 finding, recorded per the migration plan's Task 7 Step 2.6):
 * this renders the CURRENT diagram only — it does NOT re-emit a changed
 * diagram through `mermaidDiff.ts`'s intra-diagram diff/legend augmentation
 * (the F7.1 feature the sealed webview preview has). That augmentation needs a
 * block-level (not word-hunk-level) diff pass wired into `annotateSource`,
 * which was judged out of scope for this increment — it cannot be verified by
 * the automated E2E harness (the built-in preview's DOM/CSP sandbox isn't
 * queryable from a host test) and shipping it unverified risked a silent
 * regression. Basic mermaid rendering (this file) IS wired and is exercised by
 * the same proven pattern as the real `bierner.markdown-mermaid` extension.
 */
import mermaid from "mermaid";

function theme(): "dark" | "default" {
  return document.body.classList.contains("vscode-dark") || document.body.classList.contains("vscode-high-contrast")
    ? "dark"
    : "default";
}

async function run(): Promise<void> {
  const nodes = Array.from(document.querySelectorAll<HTMLElement>("pre.mermaid"));
  if (nodes.length === 0) return;
  mermaid.initialize({ startOnLoad: false, theme: theme(), securityLevel: "strict" });
  try {
    await mermaid.run({ nodes });
  } catch {
    // mermaid.run already marks failed nodes; ensure a visible chip per failure.
    for (const n of nodes) {
      if (!n.querySelector("svg")) n.setAttribute("data-cw-error", "true");
    }
  }
}

window.addEventListener("vscode.markdown.updateContent", () => void run());
void run();