Expo Docs MCP Server

import { spawn } from 'node:child_process'; import { readFile, writeFile, mkdir, rm } from 'node:fs/promises'; import { existsSync } from 'node:fs'; import { join, dirname } from 'node:path'; import TurndownService from 'turndown'; import type { GitFile } from './git-downloader.js'; export interface CompiledFile { path: string; content: string; relativePath: string; html?: string; } export class MDXCompiler { private verbose: boolean; private turndownService: TurndownService; constructor(verbose = false) { this.verbose = verbose; // Configure Turndown for better markdown conversion this.turndownService = new TurndownService({ headingStyle: 'atx', hr: '---', bulletListMarker: '-', codeBlockStyle: 'fenced', fence: '```', }); // Add custom rules for better conversion this.addTurndownRules(); } private addTurndownRules(): void { // Preserve code blocks with language info this.turndownService.addRule('codeBlocks', { filter: ['pre'], replacement: (content, node) => { const codeElement = node.querySelector('code'); if (!codeElement) return '```\n' + content + '\n```'; const className = codeElement.className || ''; const languageMatch = className.match(/language-(\w+)/); const language = languageMatch ? languageMatch[1] : ''; return '```' + language + '\n' + codeElement.textContent + '\n```'; } }); // Handle inline code this.turndownService.addRule('inlineCode', { filter: ['code'], replacement: (content) => { return '`' + content + '`'; } }); // Remove script and style tags this.turndownService.addRule('removeScripts', { filter: ['script', 'style', 'noscript'], replacement: () => '' }); // Convert tables properly this.turndownService.addRule('tables', { filter: 'table', replacement: (content, node) => { // Let turndown handle table conversion return (this.turndownService as any).defaultRules.table.replacement.call(this, content, node); } }); } /** * Compile MDX files using Expo's Next.js build system */ async compileMDXFiles(mdxFiles: Map<string, GitFile>, _version: string): Promise<Map<string, CompiledFile>> { const tempDir = join(process.cwd(), '.temp-expo-build'); const compiledFiles = new Map<string, CompiledFile>(); try { // Setup temporary build environment await this.setupTempBuildEnv(tempDir, mdxFiles); // Run Next.js build to compile MDX await this.runNextBuild(tempDir); // Extract compiled HTML from build output const htmlFiles = await this.extractCompiledHTML(tempDir); // Convert HTML to clean markdown for (const [relativePath, htmlContent] of htmlFiles) { const cleanMarkdown = this.convertHTMLToMarkdown(htmlContent); const originalFile = mdxFiles.get(relativePath.replace('.html', '.mdx')); if (originalFile) { compiledFiles.set(relativePath.replace('.html', '.md'), { path: originalFile.path, content: cleanMarkdown, relativePath: relativePath.replace('.html', '.md'), html: htmlContent, }); } } return compiledFiles; } finally { // Cleanup temp directory if (existsSync(tempDir)) { await rm(tempDir, { recursive: true, force: true }); if (this.verbose) { console.log(`🧹 Cleaned up temp directory: ${tempDir}`); } } } } /** * Setup temporary build environment with Expo's dependencies */ private async setupTempBuildEnv(tempDir: string, mdxFiles: Map<string, GitFile>): Promise<void> { if (this.verbose) { console.log(`📁 Setting up temp build environment: ${tempDir}`); } // Create temp directory await mkdir(tempDir, { recursive: true }); // Copy essential Expo docs files const expoDocsPath = join(process.cwd(), 'expo-repo', 'docs'); // Copy package.json and essential config files await this.copyFile(join(expoDocsPath, 'package.json'), join(tempDir, 'package.json')); await this.copyFile(join(expoDocsPath, 'next.config.ts'), join(tempDir, 'next.config.ts')); await this.copyFile(join(expoDocsPath, 'tsconfig.json'), join(tempDir, 'tsconfig.json')); // Copy essential directories await this.copyDirectory(join(expoDocsPath, 'components'), join(tempDir, 'components')); await this.copyDirectory(join(expoDocsPath, 'ui'), join(tempDir, 'ui')); await this.copyDirectory(join(expoDocsPath, 'common'), join(tempDir, 'common')); await this.copyDirectory(join(expoDocsPath, 'providers'), join(tempDir, 'providers')); await this.copyDirectory(join(expoDocsPath, 'mdx-plugins'), join(tempDir, 'mdx-plugins')); await this.copyDirectory(join(expoDocsPath, 'constants'), join(tempDir, 'constants')); await this.copyDirectory(join(expoDocsPath, 'public'), join(tempDir, 'public')); await this.copyDirectory(join(expoDocsPath, 'styles'), join(tempDir, 'styles')); // Create pages directory and copy MDX files const pagesDir = join(tempDir, 'pages'); await mkdir(pagesDir, { recursive: true }); // Copy _app.tsx and other essential page files await this.copyFile(join(expoDocsPath, 'pages', '_app.tsx'), join(pagesDir, '_app.tsx')); await this.copyFile(join(expoDocsPath, 'pages', '_document.tsx'), join(pagesDir, '_document.tsx')); // Copy MDX files to pages directory for (const [relativePath, gitFile] of mdxFiles) { const targetPath = join(pagesDir, relativePath); const targetDir = dirname(targetPath); if (!existsSync(targetDir)) { await mkdir(targetDir, { recursive: true }); } await writeFile(targetPath, gitFile.content, 'utf-8'); } if (this.verbose) { console.log(`📄 Copied ${mdxFiles.size} MDX files to temp build environment`); } } /** * Run Next.js build process */ private async runNextBuild(tempDir: string): Promise<void> { if (this.verbose) { console.log('🔧 Installing dependencies in temp environment...'); } // Install dependencies await this.runCommand('npm', ['install'], tempDir); if (this.verbose) { console.log('🏗️ Running Next.js build...'); } // Run Next.js build await this.runCommand('npm', ['run', 'build'], tempDir); } /** * Extract compiled HTML from Next.js build output */ private async extractCompiledHTML(tempDir: string): Promise<Map<string, string>> { const htmlFiles = new Map<string, string>(); const outDir = join(tempDir, 'out'); if (!existsSync(outDir)) { throw new Error('Next.js build output directory not found'); } // Recursively find all HTML files in the out directory await this.findHTMLFiles(outDir, '', htmlFiles); if (this.verbose) { console.log(`📄 Found ${htmlFiles.size} compiled HTML files`); } return htmlFiles; } /** * Recursively find HTML files */ private async findHTMLFiles(dir: string, relativePath: string, htmlFiles: Map<string, string>): Promise<void> { const { readdir } = await import('node:fs/promises'); const entries = await readdir(dir, { withFileTypes: true }); for (const entry of entries) { const fullPath = join(dir, entry.name); const entryRelativePath = relativePath ? join(relativePath, entry.name) : entry.name; if (entry.isDirectory()) { await this.findHTMLFiles(fullPath, entryRelativePath, htmlFiles); } else if (entry.isFile() && entry.name.endsWith('.html')) { const content = await readFile(fullPath, 'utf-8'); htmlFiles.set(entryRelativePath, content); } } } /** * Convert HTML to clean markdown */ private convertHTMLToMarkdown(html: string): string { // Extract main content from Next.js HTML structure const contentMatch = html.match(/<main[^>]*>([\s\S]*?)<\/main>/); const mainContent = contentMatch ? contentMatch[1] : html; // Convert to markdown let markdown = this.turndownService.turndown(mainContent || ''); // Clean up the markdown markdown = this.cleanupMarkdown(markdown); return markdown; } /** * Clean up markdown output */ private cleanupMarkdown(markdown: string): string { // Remove excessive newlines markdown = markdown.replace(/\n{3,}/g, '\n\n'); // Fix code block spacing markdown = markdown.replace(/```(\w+)?\n\n+/g, '```$1\n'); markdown = markdown.replace(/\n\n+```/g, '\n```'); // Remove empty headings markdown = markdown.replace(/^#+\s*$/gm, ''); // Clean up list formatting markdown = markdown.replace(/^(\s*[-*+])\s+$/gm, ''); // Remove HTML comments markdown = markdown.replace(/<!--[\s\S]*?-->/g, ''); // Trim whitespace markdown = markdown.trim(); return markdown; } /** * Helper to run shell commands */ private async runCommand(command: string, args: string[], cwd: string): Promise<void> { return new Promise((resolve, reject) => { const childProcess = spawn(command, args, { cwd, stdio: this.verbose ? 'inherit' : 'pipe', env: { ...process.env, NODE_ENV: 'production' } }); childProcess.on('close', (code) => { if (code === 0) { resolve(); } else { reject(new Error(`Command failed with exit code ${code}: ${command} ${args.join(' ')}`)); } }); childProcess.on('error', reject); }); } /** * Helper to copy files */ private async copyFile(src: string, dest: string): Promise<void> { if (existsSync(src)) { const content = await readFile(src); const destDir = dirname(dest); if (!existsSync(destDir)) { await mkdir(destDir, { recursive: true }); } await writeFile(dest, content); } } /** * Helper to copy directories recursively */ private async copyDirectory(src: string, dest: string): Promise<void> { if (!existsSync(src)) return; await mkdir(dest, { recursive: true }); const { readdir } = await import('node:fs/promises'); const entries = await readdir(src, { withFileTypes: true }); for (const entry of entries) { const srcPath = join(src, entry.name); const destPath = join(dest, entry.name); if (entry.isDirectory()) { await this.copyDirectory(srcPath, destPath); } else { await this.copyFile(srcPath, destPath); } } } }