refactor(blog): move content gen code to its own package

packages/blog-content/src/parseMarkdown.ts

@@ -0,0 +1,126 @@
+import markdownIt from "markdown-it" // rendering markdown
+import markdownItTexMath from "markdown-it-texmath" // rendering mathematical expression
+import markdownItAnchor from "markdown-it-anchor" // markdown anchor
+import markdownItTaskCheckbox from "markdown-it-task-checkbox" // a TODO list checkboxes
+import markDownItMark from "markdown-it-mark" // text highlighting
+import markdownItSub from "markdown-it-sub" // markdown subscript
+import markdownItSup from "markdown-it-sup" // markdown superscript
+import markdownItFootnote from "markdown-it-footnote" // markdown footnote
+
+import highlightLines from "markdown-it-highlight-lines" // highlighting specific lines in code blocks
+
+import matter from "gray-matter"
+import toc from "markdown-toc" // table of contents generation
+import hljs from "highlight.js" // code block syntax highlighting
+import katex from "katex" // rendering mathematical expression
+import "katex/contrib/mhchem" // chemical formula
+
+import { JSDOM } from "jsdom" // HTML DOM parsing
+
+import { nthIndex } from "./util"
+import { MarkdownData, ParseMode } from "./types/types"
+
+const md = markdownIt({
+	// https://github.com/highlightjs/highlight.js/blob/main/SUPPORTED_LANGUAGES.md
+	highlight: (str, lang) => {
+		if (lang && hljs.getLanguage(lang)) {
+			try {
+				return hljs.highlight(str, { language: lang }).value
+				// eslint-disable-next-line no-empty
+			} catch (error) {}
+		}
+
+		return "" // use external default escaping
+	},
+	html: true,
+})
+	.use(markdownItTexMath, {
+		engine: katex,
+		delimiters: "dollars",
+	})
+	.use(markdownItAnchor, {
+		permalink: markdownItAnchor.permalink.ariaHidden({
+			placement: "before",
+			symbol: "#",
+		}),
+	})
+	.use(markdownItTaskCheckbox)
+	.use(markDownItMark)
+	.use(markdownItSub)
+	.use(markdownItSup)
+	.use(highlightLines)
+	.use(markdownItFootnote)
+
+/**
+ * parse the front matter if it exists
+ *
+ * @param {string} markdownRaw - raw unparsed text data of the markdown file
+ * @param {string} path - filename of the markdown file
+ * @param {ParseMode} mode
+ */
+export default function parseMarkdown(
+	markdownRaw: string,
+	path: string,
+	mode: ParseMode
+): MarkdownData {
+	const fileHasFrontMatter = markdownRaw.startsWith("---")
+
+	const frontMatter = fileHasFrontMatter
+		? matter(markdownRaw.slice(0, nthIndex(markdownRaw, "---", 2) + 3)).data
+		: {}
+
+	if (fileHasFrontMatter) {
+		if (mode != ParseMode.PORTFOLIO) {
+			if (!frontMatter.title)
+				throw Error(`Title is not defined in file: ${path}`)
+
+			if (mode != ParseMode.UNSEARCHABLE && !frontMatter.date)
+				throw Error(`Date is not defined in file: ${path}`)
+		}
+
+		if (mode === ParseMode.PORTFOLIO) {
+			if (frontMatter.overview) {
+				frontMatter.overview = md.render(frontMatter.overview)
+			}
+		}
+	}
+
+	//
+	// work with rendered DOM
+	//
+
+	const dom = new JSDOM(
+		md.render(
+			fileHasFrontMatter
+				? markdownRaw.slice(nthIndex(markdownRaw, "---", 2) + 3)
+				: markdownRaw
+		) || ""
+	)
+
+	// add .hljs class to all block codes
+
+	dom.window.document.querySelectorAll("pre > code").forEach((item) => {
+		item.classList.add("hljs")
+	})
+
+	// add parent div to tables (horizontally scroll table on small displays)
+
+	dom.window.document.querySelectorAll("table").forEach((item) => {
+		// `element` is the element you want to wrap
+		const parent = item.parentNode
+		if (!parent) return // stop if table doesn't have a parent node
+		const wrapper = dom.window.document.createElement("div")
+		wrapper.style.overflowX = "auto"
+
+		parent.replaceChild(wrapper, item)
+		wrapper.appendChild(item)
+	})
+
+	frontMatter.content = dom.window.document.documentElement.innerHTML
+
+	return frontMatter as MarkdownData
+}
+
+export function generateToc(markdownRaw: string): string {
+	return md.render(toc(markdownRaw).content)
+}