From af3a386eada49949488e93ffe7dd50a53f15211f Mon Sep 17 00:00:00 2001
From: Sukka <isukkaw@gmail.com>
Date: Wed, 18 Dec 2019 16:50:30 +0800
Subject: [PATCH] feat(tocObj): bring up (#137)

* feat(tocObj): bring up toc parser

https://github.com/hexojs/hexo-util/issues/136

* docs(tocObj): bring up

* feat(tocObj): export tocObj

* refactor(tocObj): update min_depth

* docs(tocObj): 'min_depth' defaults to 1

* test(tocObj): fix escape test

* style: eslint

* test(tocObj): fix escape test

* style: arrow-parens
---
 README.md            | 62 ++++++++++++++++++++++++++++++++++++++++++
 lib/index.js         |  1 +
 lib/toc_obj.js       | 43 +++++++++++++++++++++++++++++
 package.json         |  1 +
 test/toc_obj.spec.js | 65 ++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 172 insertions(+)
 create mode 100644 lib/toc_obj.js
 create mode 100644 test/toc_obj.spec.js

diff --git a/README.md b/README.md
index 3be27e25..ff2341dc 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,7 @@ Utilities for [Hexo].
 - [spawn](#spawncommand-args-options)
 - [stripHTML](#striphtmlstr)
 - [wordWrap](#wordwrapstr-options)
+- [tocObj](#tocobjstr-options)
 - [truncate](#truncatestr-options)
 - [unescapeHTML](#unescapehtmlstr)
 - [url_for](#url_forpath-option)
@@ -467,6 +468,67 @@ wordWrap('Once upon a time', {width: 1})
 // Once\nupon\na\ntime
 ```
 
+### tocObj(str, [options])
+
+Generate a table of contents in JSON format based on the given html string.
+
+Option | Description | Default
+--- | --- | ---
+`min_depth` | The minimum level of TOC | 1
+`max_depth` | The maximum level of TOC | 6
+
+
+``` js
+const html = [
+  '<h1 id="title_1">Title 1</h1>',
+  '<div id="title_1_1"><h2>Title 1.1</h2></div>',
+  '<h3 id="title_1_1_1">Title 1.1.1</h3>',
+  '<h2 id="title_1_2">Title 1.2</h2>',
+  '<h2 id="title_1_3">Title 1.3</h2>',
+  '<h3 id="title_1_3_1">Title 1.3.1</h3>',
+  '<h1 id="title_2">Title 2</h1>',
+  '<h2 id="title_2_1">Title 2.1</h2>'
+].join('\n');
+
+tocObj(html);
+/*
+[
+  { text: 'Title 1', id: 'title_1', level: 1 },
+  { text: 'Title 1.1', id: 'title_1_1', level: 2 },
+  { text: 'Title 1.1.1', id: 'title_1_1_1', level: 3 },
+  { text: 'Title 1.2', id: 'title_1_2', level: 2 },
+  { text: 'Title 1.3', id: 'title_1_3', level: 2 },
+  { text: 'Title 1.3.1', id: 'title_1_3_1', level: 3 },
+  { text: 'Title 2', id: 'title_2', level: 1 },
+  { text: 'Title 2.1', id: 'title_2_1', level: 2 },
+]
+*/
+
+tocObj(html, { min_depth: 2 });
+/*
+[
+  { text: 'Title 1.1', id: 'title_1_1', level: 2 },
+  { text: 'Title 1.1.1', id: 'title_1_1_1', level: 3 },
+  { text: 'Title 1.2', id: 'title_1_2', level: 2 },
+  { text: 'Title 1.3', id: 'title_1_3', level: 2 },
+  { text: 'Title 1.3.1', id: 'title_1_3_1', level: 3 },
+  { text: 'Title 2.1', id: 'title_2_1', level: 2 },
+]
+*/
+
+tocObj(html, { max_depth: 2 });
+/*
+[
+  { text: 'Title 1', id: 'title_1', level: 1 },
+  { text: 'Title 1.1', id: 'title_1_1', level: 2 },
+  { text: 'Title 1.2', id: 'title_1_2', level: 2 },
+  { text: 'Title 1.3', id: 'title_1_3', level: 2 },
+  { text: 'Title 2', id: 'title_2', level: 1 },
+  { text: 'Title 2.1', id: 'title_2_1', level: 2 },
+]
+*/
+```
+
 ### truncate(str, [options])
 
 Truncates a given text after a given `length` if text is longer than `length`. The last characters will be replaced with the `omission` option for a total length not exceeding `length`.
diff --git a/lib/index.js b/lib/index.js
index 5323d2f0..37c5a94e 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -26,6 +26,7 @@ exports.relative_url = require('./relative_url');
 exports.slugize = require('./slugize');
 exports.spawn = require('./spawn');
 exports.stripHTML = require('./strip_html');
+exports.tocObj = require('./toc_obj');
 exports.truncate = require('./truncate');
 exports.unescapeHTML = require('./unescape_html');
 exports.url_for = require('./url_for');
diff --git a/lib/toc_obj.js b/lib/toc_obj.js
new file mode 100644
index 00000000..b219933f
--- /dev/null
+++ b/lib/toc_obj.js
@@ -0,0 +1,43 @@
+'use strict';
+const { DomHandler, DomUtils, Parser } = require('htmlparser2');
+const escapeHTML = require('./escape_html');
+
+const parseHtml = html => {
+  const handler = new DomHandler(null, {});
+  new Parser(handler, {}).end(html);
+  return handler.dom;
+};
+
+const getId = ele => {
+  const { id } = ele.attribs;
+  const { parent } = ele;
+  return id || (parent.length < 1 ? null : getId(parent));
+};
+
+function tocObj(str, options = {}) {
+  options = Object.assign({
+    min_depth: 1,
+    max_depth: 6
+  }, options);
+
+  const headingsSelector = ['h1', 'h2', 'h3', 'h4', 'h5', 'h6'].slice(options.min_depth - 1, options.max_depth).join(',');
+
+  const dom = parseHtml(str);
+  const headings = DomUtils.find(el => headingsSelector.includes(el.tagName), dom, true);
+
+  const result = [];
+
+  if (!headings.length) return result;
+
+  for (const el of headings) {
+    const level = +el.name[1];
+    const id = getId(el);
+    const text = escapeHTML(DomUtils.getText(el));
+
+    result.push({ text, id, level });
+  }
+
+  return result;
+}
+
+module.exports = tocObj;
diff --git a/package.json b/package.json
index 492d002f..adc2994a 100644
--- a/package.json
+++ b/package.json
@@ -48,6 +48,7 @@
     "cross-spawn": "^7.0.0",
     "deepmerge": "^4.2.2",
     "highlight.js": "^9.13.1",
+    "htmlparser2": "^4.0.0",
     "punycode.js": "^2.1.0",
     "striptags": "^3.1.1"
   },
diff --git a/test/toc_obj.spec.js b/test/toc_obj.spec.js
new file mode 100644
index 00000000..d8fdf614
--- /dev/null
+++ b/test/toc_obj.spec.js
@@ -0,0 +1,65 @@
+'use strict';
+
+require('chai').should();
+
+describe('tocObj', () => {
+  const tocObj = require('../lib/toc_obj');
+
+  const html = [
+    '<h1 id="title_1">Title 1</h1>',
+    '<div id="title_1_1"><h2>Title 1.1</h2></div>',
+    '<h3 id="title_1_1_1">Title 1.1.1</h3>',
+    '<h2 id="title_1_2">Title 1.2</h2>',
+    '<h2 id="title_1_3">Title 1.3</h2>',
+    '<h3 id="title_1_3_1">Title 1.3.1</h3>',
+    '<h1 id="title_2">Title 2</h1>',
+    '<h2 id="title_2_1">Title 2.1</h2>',
+    '<h1 id="title_3">Title should escape &, \', < and "</h1>',
+    '<h1 id="title_4"><a name="chapter1">Chapter 1 should be printed to toc</a></h1>'
+  ].join('');
+
+  it('default', () => {
+    const expected = [
+      { text: 'Title 1', id: 'title_1', level: 1 },
+      { text: 'Title 1.1', id: 'title_1_1', level: 2 },
+      { text: 'Title 1.1.1', id: 'title_1_1_1', level: 3 },
+      { text: 'Title 1.2', id: 'title_1_2', level: 2 },
+      { text: 'Title 1.3', id: 'title_1_3', level: 2 },
+      { text: 'Title 1.3.1', id: 'title_1_3_1', level: 3 },
+      { text: 'Title 2', id: 'title_2', level: 1 },
+      { text: 'Title 2.1', id: 'title_2_1', level: 2 },
+      { text: 'Title should escape &amp;, &#39;, &lt; and &quot;', id: 'title_3', level: 1 },
+      { text: 'Chapter 1 should be printed to toc', id: 'title_4', level: 1 }
+    ];
+
+    tocObj(html).should.eql(expected);
+  });
+
+  it('options - min_depth', () => {
+    const expected = [
+      { text: 'Title 1.1', id: 'title_1_1', level: 2 },
+      { text: 'Title 1.1.1', id: 'title_1_1_1', level: 3 },
+      { text: 'Title 1.2', id: 'title_1_2', level: 2 },
+      { text: 'Title 1.3', id: 'title_1_3', level: 2 },
+      { text: 'Title 1.3.1', id: 'title_1_3_1', level: 3 },
+      { text: 'Title 2.1', id: 'title_2_1', level: 2 }
+    ];
+
+    tocObj(html, { min_depth: 2 }).should.eql(expected);
+  });
+
+  it('options - max_depth', () => {
+    const expected = [
+      { text: 'Title 1', id: 'title_1', level: 1 },
+      { text: 'Title 1.1', id: 'title_1_1', level: 2 },
+      { text: 'Title 1.2', id: 'title_1_2', level: 2 },
+      { text: 'Title 1.3', id: 'title_1_3', level: 2 },
+      { text: 'Title 2', id: 'title_2', level: 1 },
+      { text: 'Title 2.1', id: 'title_2_1', level: 2 },
+      { text: 'Title should escape &amp;, &#39;, &lt; and &quot;', id: 'title_3', level: 1 },
+      { text: 'Chapter 1 should be printed to toc', id: 'title_4', level: 1 }
+    ];
+
+    tocObj(html, { max_depth: 2 }).should.eql(expected);
+  });
+});