1 files changed, 56 insertions, 0 deletions
diff --git a/web_src/js/markup/mermaid.js b/web_src/js/markup/mermaid.js
new file mode 100644
index 0000000000..d0aefd1aff
--- /dev/null
+++ b/web_src/js/markup/mermaid.js
@@ -0,0 +1,56 @@
+const MAX_SOURCE_CHARACTERS = 5000;
+
+function displayError(el, err) {
+  el.closest('pre').classList.remove('is-loading');
+  const errorNode = document.createElement('div');
+  errorNode.setAttribute('class', 'ui message error markup-block-error mono');
+  errorNode.textContent = err.str || err.message || String(err);
+  el.closest('pre').before(errorNode);
+}
+
+export async function renderMermaid(els) {
+  if (!els || !els.length) return;
+
+  const mermaid = await import(/* webpackChunkName: "mermaid" */'mermaid');
+
+  mermaid.initialize({
+    mermaid: {
+      startOnLoad: false,
+    },
+    flowchart: {
+      useMaxWidth: true,
+      htmlLabels: false,
+    },
+    theme: 'neutral',
+    securityLevel: 'strict',
+  });
+
+  for (const el of els) {
+    if (el.textContent.length > MAX_SOURCE_CHARACTERS) {
+      displayError(el, new Error(`Mermaid source of ${el.textContent.length} characters exceeds the maximum allowed length of ${MAX_SOURCE_CHARACTERS}.`));
+      continue;
+    }
+
+    let valid;
+    try {
+      valid = mermaid.parse(el.textContent);
+    } catch (err) {
+      displayError(el, err);
+    }
+
+    if (!valid) {
+      el.closest('pre').classList.remove('is-loading');
+      continue;
+    }
+
+    try {
+      mermaid.init(undefined, el, (id) => {
+        const svg = document.getElementById(id);
+        svg.classList.add('mermaid-chart');
+        svg.closest('pre').replaceWith(svg);
+      });
+    } catch (err) {
+      displayError(el, err);
+    }
+  }
+}