From 9bb4d3fd7efb1b219e878597c7949d50ecd04b2b Mon Sep 17 00:00:00 2001
From: Billie Hilton <wmhilton@gmail.com>
Date: Mon, 16 May 2022 14:08:16 -0700
Subject: [PATCH] feat: getTitle supports raw strings now (#77)

---
 src/getters/__tests__/get-title.test.ts | 101 ++++++++++++++++++------
 src/getters/get-title.ts                |  28 ++++++-
 2 files changed, 102 insertions(+), 27 deletions(-)

diff --git a/src/getters/__tests__/get-title.test.ts b/src/getters/__tests__/get-title.test.ts
index b26f5ce..bb691cb 100644
--- a/src/getters/__tests__/get-title.test.ts
+++ b/src/getters/__tests__/get-title.test.ts
@@ -1,52 +1,103 @@
 import { parse } from '../../parse';
 import { getTitle } from '../get-title';
 
-describe('get-title', () => {
-  it('should return frontmatter title if present', () => {
-    const title = getTitle(
-      parse(`---
+const titleInFrontMatter = `---
 title: hello
 ---
 
 # Other Title
 
 Yo
-`),
-    );
-
-    expect(title).toBe('hello');
-  });
+`;
 
-  it('should return heading if present', () => {
-    const title = getTitle(
-      parse(`---
+const titleInH1 = `---
 summary: what it is about
 ---
 
 # Other Title
 
 Yo
-`),
-    );
+`;
 
-    expect(title).toBe('Other Title');
-  });
+const titleInUnderlineH1 = `---
+summary: what it is about
+---
+
+Other Title
+===========
 
-  it('should return headings other than h1 if present', () => {
-    const title = getTitle(
-      parse(`what it is about
+Yo
+`;
+
+const titleInH2 = `what it is about
 
 ## Other Title 2
 
 Yo
-`),
-    );
+`;
+
+const noTitle = `what it is about`;
+
+describe('get-title', () => {
+  describe('parsed', () => {
+    it('should return frontmatter title if present', () => {
+      const title = getTitle(parse(titleInFrontMatter));
+
+      expect(title).toBe('hello');
+    });
+
+    it('should return # heading if present', () => {
+      const title = getTitle(parse(titleInH1));
 
-    expect(title).toBe('Other Title 2');
+      expect(title).toBe('Other Title');
+    });
+
+    it('should return underlined heading if present', () => {
+      const title = getTitle(parse(titleInUnderlineH1));
+
+      expect(title).toBe('Other Title');
+    });
+
+    it('should return headings other than h1 if present', () => {
+      const title = getTitle(parse(titleInH2));
+
+      expect(title).toBe('Other Title 2');
+    });
+
+    it('should return undefined if no frontmatter title and no headings', () => {
+      const title = getTitle(parse(noTitle));
+      expect(title).toBe(undefined);
+    });
   });
 
-  it('should return undefined if no frontmatter title and no headings', () => {
-    const title = getTitle(parse(`what it is about`));
-    expect(title).toBe(undefined);
+  describe('raw string', () => {
+    it('should return frontmatter title if present', () => {
+      const title = getTitle(titleInFrontMatter);
+
+      expect(title).toBe('hello');
+    });
+
+    it('should return # heading if present', () => {
+      const title = getTitle(titleInH1);
+
+      expect(title).toBe('Other Title');
+    });
+
+    it('should not detect underlined headings, sorry not sorry', () => {
+      const title = getTitle(titleInUnderlineH1);
+
+      expect(title).toBe(undefined);
+    });
+
+    it('should return headings other than h1 if present', () => {
+      const title = getTitle(titleInH2);
+
+      expect(title).toBe('Other Title 2');
+    });
+
+    it('should return undefined if no frontmatter title and no headings', () => {
+      const title = getTitle(noTitle);
+      expect(title).toBe(undefined);
+    });
   });
 });
diff --git a/src/getters/get-title.ts b/src/getters/get-title.ts
index 606321d..dca0271 100644
--- a/src/getters/get-title.ts
+++ b/src/getters/get-title.ts
@@ -1,7 +1,31 @@
 import { MDAST } from '../ast-types';
+import { Frontmatter } from '../frontmatter';
 import { getProperty } from './get-property';
 
 // Priority: yaml title, then first heading
-export const getTitle = (data?: MDAST.Root) => {
-  return getProperty('title', 'heading', data);
+export const getTitle = (data?: MDAST.Root | string) => {
+  if (typeof data === 'string') {
+    return getTitleFromRaw(data);
+  } else {
+    return getProperty('title', 'heading', data);
+  }
 };
+
+function getTitleFromRaw(raw?: string) {
+  if (!raw) return raw;
+
+  const frontmatterBlock = Frontmatter.getFrontmatterBlock(raw);
+
+  if (frontmatterBlock) {
+    const title = new Frontmatter(frontmatterBlock).get('title');
+    if (title) {
+      return String(title);
+    }
+  }
+
+  // Note: This only supports #-style headings, but underlined headings are much rarer
+  // Sonar Cloud flagged the original version /^#+\s*(.*)$/m as super-linear, so it has
+  // become this rather nasty regex to emulate atomic groups / possessive qualifiers.
+  const match = raw?.match(/^(?=(#+))\1(?=(\s*))\2(?=(.*))\3$/m);
+  return match ? match[3] : void 0;
+}