feat(baoyu-md): add Mermaid preprocessing and utility modules

2026-07-31 22:29:48 +08:00 · 2026-05-24 21:27:38 -05:00
parent f60702cc8e
commit 8d2fd7aae0
8 changed files with 867 additions and 10255 deletions
@@ -0,0 +1,131 @@
+import fs from "node:fs";
+import path from "node:path";
+
+import {
+  MERMAID_VERSION,
+  extractMermaidBlocks,
+  hashMermaidCode,
+  replaceMermaidBlocks,
+  type MermaidBlock,
+} from "./mermaid-utils.js";
+
+export interface MermaidRenderOptions {
+  theme?: string;
+  scale?: number;
+  background?: string;
+  minWidth?: number;
+}
+
+export type MermaidRenderFn = (
+  code: string,
+  outputPath: string,
+  options: MermaidRenderOptions,
+) => Promise<void>;
+
+export interface MermaidPreprocessOptions extends MermaidRenderOptions {
+  baseDir: string;
+  imgSubdir?: string;
+  renderFn?: MermaidRenderFn;
+  enabled?: boolean;
+  alt?: string;
+  onError?: (error: unknown, block: MermaidBlock) => void;
+}
+
+export interface MermaidPreprocessedImage {
+  raw: string;
+  code: string;
+  hash: string;
+  localPath: string;
+  mdRef: string;
+  cached: boolean;
+}
+
+export interface MermaidPreprocessResult {
+  markdown: string;
+  images: MermaidPreprocessedImage[];
+}
+
+export async function preprocessMermaidInMarkdown(
+  markdown: string,
+  options: MermaidPreprocessOptions,
+): Promise<MermaidPreprocessResult> {
+  const {
+    baseDir,
+    imgSubdir = "imgs/.mermaid-cache",
+    renderFn,
+    enabled = true,
+    theme,
+    scale,
+    background,
+    minWidth,
+    alt = "Mermaid diagram",
+    onError,
+  } = options;
+
+  if (!enabled || !renderFn) {
+    return { markdown, images: [] };
+  }
+
+  const blocks = extractMermaidBlocks(markdown);
+  if (blocks.length === 0) {
+    return { markdown, images: [] };
+  }
+
+  const cacheDir = path.resolve(baseDir, imgSubdir);
+  fs.mkdirSync(cacheDir, { recursive: true });
+
+  const replacements = new Map<string, string>();
+  const images: MermaidPreprocessedImage[] = [];
+  const renderedHashes = new Set<string>();
+
+  for (const block of blocks) {
+    const hash = hashMermaidCode({
+      code: block.code,
+      theme,
+      scale,
+      background,
+      minWidth,
+      version: MERMAID_VERSION,
+    });
+    const filename = `mermaid-${hash}.png`;
+    const localPath = path.join(cacheDir, filename);
+    const mdRef = `![${alt}](${path.posix.join(imgSubdir, filename)})`;
+
+    const cached = fs.existsSync(localPath);
+
+    if (!cached && !renderedHashes.has(hash)) {
+      try {
+        await renderFn(block.code, localPath, { theme, scale, background, minWidth });
+        renderedHashes.add(hash);
+      } catch (error) {
+        if (onError) {
+          onError(error, block);
+        } else {
+          console.error(
+            `[mermaid] render failed for block (hash ${hash}): ${
+              error instanceof Error ? error.message : String(error)
+            }`,
+          );
+        }
+        continue;
+      }
+    }
+
+    if (!fs.existsSync(localPath)) {
+      continue;
+    }
+
+    replacements.set(block.raw, mdRef);
+    images.push({
+      raw: block.raw,
+      code: block.code,
+      hash,
+      localPath,
+      mdRef,
+      cached,
+    });
+  }
+
+  const newMarkdown = replaceMermaidBlocks(markdown, replacements);
+  return { markdown: newMarkdown, images };
+}