Docs: new documentation site (#2723)

This commit adds a VitePress build to the main repository,
aiming to ditch GitHub Wiki. Moving further, we're going to
host our own documentation site eithor on GitHub Pages or
something alike.

docs/.vitepress/config.ts

@@ -0,0 +1,104 @@
+import { defineConfig } from 'vitepress'
+import directoryTree from 'directory-tree'
+import fs from 'fs'
+import metadataParser from 'markdown-yaml-metadata-parser'
+
+function getMetadataFromDoc(path: string): { sidebarTitle?: string, sidebarOrder?: number } {
+  const fileContents = fs.readFileSync(path, 'utf8')
+
+  return metadataParser(fileContents).metadata
+}
+
+function generateSidebarChapter(chapterDirName: string): any {
+  const chapterPath = `./docs/${chapterDirName}`
+  const tree = directoryTree(chapterPath)
+
+  if (!tree || !tree.children) {
+    console.error(tree)
+    throw new Error(`Could not genereate sidebar: invalid chapter at ${chapterPath}`)
+  }
+
+  let items: { sidebarOrder: number, text: string, link: string }[] = []
+
+  // Look into files in the chapter
+  for (const doc of tree.children) {
+    // make sure it's a .md file
+    if (doc.children || !doc.name.endsWith('.md'))
+      continue
+
+    const { sidebarOrder, sidebarTitle } = getMetadataFromDoc(doc.path)
+
+    if (!sidebarOrder)
+      throw new Error('Cannot find sidebarOrder in doc metadata: ' + doc.path)
+
+    if (!sidebarTitle)
+      throw new Error('Cannot find sidebarTitle in doc metadata: ' + doc.path)
+
+    items.push({
+      sidebarOrder,
+      text: sidebarTitle,
+      link: doc.path.replace(/^docs/, '')
+    })
+  }
+
+  items = items.sort((a, b) => a.sidebarOrder - b.sidebarOrder)
+
+  // remove dash and capitalize first character of each word as chapter title
+  const text = chapterDirName.split('-').join(' ').replace(/\b\w/g, l => l.toUpperCase())
+
+  return {
+    text,
+    items,
+  }
+}
+
+const chapters = [
+  'introduction',
+  'configuration',
+  'premium',
+  'runtime',
+  'advanced-usages',
+].map(generateSidebarChapter)
+
+// Override index page link
+chapters[0]['items'][0]['link'] = '/'
+
+// https://vitepress.dev/reference/site-config
+export default defineConfig({
+  title: "Clash",
+  description: "Rule-based Tunnel",
+
+  themeConfig: {
+    outline: 'deep',
+
+    search: {
+      provider: 'local'
+    },
+
+    editLink: {
+      pattern: 'https://github.com/Dreamacro/clash/edit/master/docs/:path',
+      text: 'Edit this page on GitHub'
+    },
+
+    logo: '/logo.png',
+
+    // https://vitepress.dev/reference/default-theme-config
+    nav: [
+      { text: 'Home', link: '/' },
+      { text: 'Configuration', link: '/configuration/configuration-reference.md' },
+      {
+        text: 'Download',
+        items: [
+          { text: 'Open-source Edition', link: 'https://github.com/Dreamacro/clash/releases/' },
+          { text: 'Premium Edition', link: 'https://github.com/Dreamacro/clash/releases/tag/premium' },
+        ]
+      }
+    ],
+
+    socialLinks: [
+      { icon: 'github', link: 'https://github.com/Dreamacro/clash' },
+    ],
+
+    sidebar: chapters
+  }
+})