Normalize imported column rows and validate MJML documents

packages/email-renderer/src/mjml.ts

@@ -1,11 +1,14 @@
 import { createRequire } from "node:module";
 import {
   DEFAULT_LIMITS,
+  registryForKind,
+  validateDocument,
   type BlockDocument,
   type BlockNode,
   type Diagnostic,
   type Result,
 } from "@wrnexus/blocks";
+import { emailKind } from "./email.ts";
 
 interface MjmlAst {
   tagName: string;
@@ -98,6 +101,43 @@ export function importMjml(
     };
   }
   const errors: MjmlDiagnostic[] = [];
+  if (!ast || ast.tagName !== "mjml") return { ok: false, errors: [{ code: "mjml.root", message: "MJML requires an mjml root element.", severity: "error" }] };
+  const pending = [{ node: ast, depth: 0 }];
+  let nodeCount = 0;
+  while (pending.length) {
+    const { node, depth } = pending.pop()!;
+    if (++nodeCount > DEFAULT_LIMITS.maxNodes || depth > DEFAULT_LIMITS.maxDepth) {
+      return { ok: false, errors: [{ code: "mjml.limits", message: "MJML exceeds document node or depth limits.", severity: "error" }] };
+    }
+    for (const child of node.children ?? []) pending.push({ node: child, depth: depth + 1 });
+  }
+  const wrapColumns = (nodes: BlockNode[]): BlockNode[] => {
+    const output: BlockNode[] = [];
+    for (let index = 0; index < nodes.length;) {
+      if (nodes[index]!.type !== "layout.column") { output.push(nodes[index++]!); continue; }
+      const columns: BlockNode[] = [];
+      while (index < nodes.length && nodes[index]!.type === "layout.column") columns.push(nodes[index++]!);
+      let explicit = 0;
+      const missing = columns.filter(column => !column.props.width);
+      for (const column of columns) {
+        const width = String(column.props.width || "");
+        if (!width) continue;
+        if (!/^\d+(?:\.\d+)?%$/.test(width) || Number.parseFloat(width) <= 0 || Number.parseFloat(width) > 100) {
+          errors.push({ code: "mjml.column-width", message: "Column width must be a percentage between 0 and 100.", severity: "error", element: "mj-column", attribute: "width" });
+        } else explicit += Number.parseFloat(width);
+      }
+      if (explicit > 100 || (!missing.length && Math.abs(explicit - 100) > 0.001) || (missing.length && explicit >= 100)) {
+        errors.push({ code: "mjml.column-width", message: "Column widths must fill one 100% row.", severity: "error", element: "mj-column", attribute: "width" });
+      }
+      let assigned = 0;
+      missing.forEach((column, position) => {
+        const width = position === missing.length - 1 ? 100 - explicit - assigned : Math.round((100 - explicit) / missing.length * 100) / 100;
+        column.props.width = `${width}%`; assigned += width;
+      });
+      output.push({ id: options.id(), type: "layout.columns", version: 1, props: {}, styles: {}, slots: { columns } });
+    }
+    return output;
+  };
   const convert = (node: MjmlAst): BlockNode[] => {
     if (!supported.has(node.tagName)) {
       errors.push({
@@ -108,7 +148,8 @@ export function importMjml(
       });
       return [];
     }
-    const children = (node.children ?? []).flatMap(convert);
+    const converted = (node.children ?? []).flatMap(convert);
+    const children = containers.has(node.tagName) && node.tagName !== "mj-column" ? wrapColumns(converted) : converted;
     if (node.tagName === "mjml" || node.tagName === "mj-head" || node.tagName === "mj-body")
       return children;
     if (
@@ -137,7 +178,7 @@ export function importMjml(
           id,
           type: "layout.column",
           version: 1,
-          props: { width: a.width ?? "100%" },
+          props: { width: a.width ?? "" },
           styles: {},
           slots: { content: children },
         },
@@ -219,15 +260,18 @@ export function importMjml(
       ),
     },
   };
-  return {
-    ok: true,
-    value: {
+  const document: BlockDocument = {
       schemaVersion: 1,
       kind: "email",
       meta: { subject: options.subject, preheader: options.preheader ?? "", lang: "en" },
       theme: { tokens: {} },
       root,
-    },
+  };
+  const validated = validateDocument(document, emailKind, registryForKind(emailKind).freeze());
+  if (!validated.ok) return { ok: false, errors: validated.errors };
+  return {
+    ok: true,
+    value: document,
   };
 }