🔥 Add a new helper to extract meta from body nodes (title + headers l…

…ist)

packages/helpers-transform/src/__tests__/__snapshots__/extractMetaFromBodyNode.js.snap

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+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`should guess partial data from body AST 1`] = `
+Object {
+  "headers": Array [
+    Array [
+      1,
+      "Auto title",
+    ],
+    Array [
+      2,
+      "Sub title",
+    ],
+    Array [
+      2,
+      "Another Level 2",
+    ],
+    Array [
+      3,
+      "A level 3",
+    ],
+  ],
+  "title": "Auto title",
+}
+`;

packages/helpers-transform/src/__tests__/extractMetaFromBodyNode.js

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+// @flow
+
+import extractMetaFromBodyNode from "../extractMetaFromBodyNode.js";
+
+it("should guess partial data from body AST", () => {
+  expect(
+    extractMetaFromBodyNode({
+      c: [
+        {
+          c: [
+            {
+              c: [
+                {
+                  p: {
+                    className: "icon icon-link"
+                  },
+                  t: "span"
+                }
+              ],
+              p: {
+                "aria-hidden": true,
+                href: "#auto-title"
+              },
+              t: "a"
+            },
+            "Auto title"
+          ],
+          p: {
+            id: "auto-title"
+          },
+          t: "h1"
+        },
+        "\n",
+        {
+          c: [
+            {
+              c: [
+                {
+                  p: {
+                    className: "icon icon-link"
+                  },
+                  t: "span"
+                }
+              ],
+              p: {
+                "aria-hidden": true,
+                href: "#sub-title"
+              },
+              t: "a"
+            },
+            "Sub title"
+          ],
+          p: {
+            id: "sub-title"
+          },
+          t: "h2"
+        },
+        "\n",
+        {
+          c: ["Content"],
+          t: "p"
+        },
+        "\n",
+        {
+          c: [
+            {
+              c: [
+                {
+                  p: {
+                    className: "icon icon-link"
+                  },
+                  t: "span"
+                }
+              ],
+              p: {
+                "aria-hidden": true,
+                href: "#another-level-2"
+              },
+              t: "a"
+            },
+            "Another Level 2"
+          ],
+          p: {
+            id: "another-level-2"
+          },
+          t: "h2"
+        },
+        "\n",
+        {
+          c: [
+            {
+              c: [
+                {
+                  p: {
+                    className: "icon icon-link"
+                  },
+                  t: "span"
+                }
+              ],
+              p: {
+                "aria-hidden": true,
+                href: "#a-level-3"
+              },
+              t: "a"
+            },
+            "A level 3"
+          ],
+          p: {
+            id: "a-level-3"
+          },
+          t: "h3"
+        }
+      ],
+      t: "div"
+    })
+  ).toMatchSnapshot();
+});

packages/helpers-transform/src/extractMetaFromBodyNode.js

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+// @flow
+
+type Node =
+  | string
+  | {|
+      t?: string,
+      p?: Object,
+      c?: Node | $ReadOnlyArray<Node>
+    |};
+
+const renderText = (node?: Node) => {
+  if (!node) return "";
+  if (typeof node === "string") return node;
+  return Array.isArray(node.c)
+    ? node.c.map((child: Node) => renderText(child)).join("")
+    : renderText(node.c);
+};
+
+const getHeaders = (node?: Node) => {
+  if (!node) return [];
+  if (typeof node.t === "string") {
+    const tag = node.t;
+    const level = parseInt(tag[1], 10);
+    if (tag[0] === "h" && !isNaN(level)) {
+      return [[level, renderText(node)]];
+    }
+  }
+  return (Array.isArray(node.c)
+    ? // $FlowFixMe stfu
+      node.c.reduce((acc, child: Node) => acc.concat(getHeaders(child)), [])
+    : // $FlowFixMe stfu
+      getHeaders(node.c)
+  ).filter(h => h);
+};
+
+export default (node: Node) => {
+  const headers = getHeaders(node);
+  const firstH1 = headers.find(h => h[0] === 1);
+  return {
+    ...(firstH1 ? { title: firstH1[1] } : {}),
+    ...(headers.length > 0 ? { headers } : {})
+  };
+};