/**
 * 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).
 *
 * RESOLVED SCOPE NOTE (Q4 finding, migration plan Task 7 Step 2.6; wired in a
 * cross-task review follow-up): this script itself only turns `pre.mermaid`
 * nodes into diagrams — it never sees a diff. The intra-diagram diff/legend
 * augmentation (F7.1, INV-29..31) happens one step earlier, source-side,
 * where it CAN be unit-tested without a DOM: `previewAnnotations.ts`'s
 * `cowritingMarkdownItPlugin` re-emits a CHANGED mermaid fence's source
 * through `mermaidDiff.ts` (`buildMermaidQueue`, block-level `diffBlocks`
 * pairing against the F6/F7 baseline) before this script ever runs, so the
 * `pre.mermaid` node this script hands to `mermaid.run` already carries the
 * `classDef`/`class`/`linkStyle` styling directives — this script needn't (and
 * can't, DOM-less-ly) know a diagram changed at all. Basic mermaid rendering
 * (this file) is exercised by the same proven pattern as the real
 * `bierner.markdown-mermaid` extension; the augmentation upstream is exercised
 * by pure unit tests (`test/previewAnnotations.test.ts`).
 */
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();