/**
 * Post-build prerendering script.
 * Starts a local server from dist/, visits each route with Puppeteer,
 * and saves the fully-rendered HTML so crawlers see real content.
 *
 * Usage: node prerender.js  (run after `vite build`)
 */

import { createServer } from 'http'
import { readFileSync, writeFileSync, mkdirSync, existsSync } from 'fs'
import { join, dirname } from 'path'
import { fileURLToPath } from 'url'
import puppeteer from 'puppeteer'

const __dirname = dirname(fileURLToPath(import.meta.url))
const DIST = join(__dirname, 'dist')
const PORT = 4173

const ROUTES = ['/', '/technical', '/imprint', '/privacy-policy']

/** Minimal static file server that falls back to index.html (SPA). */
function startServer() {
  const mimeTypes = {
    '.html': 'text/html',
    '.js': 'application/javascript',
    '.css': 'text/css',
    '.json': 'application/json',
    '.png': 'image/png',
    '.jpg': 'image/jpeg',
    '.svg': 'image/svg+xml',
    '.pdf': 'application/pdf',
    '.woff2': 'font/woff2',
    '.woff': 'font/woff',
  }

  const server = createServer((req, res) => {
    let filePath = join(DIST, req.url === '/' ? '/index.html' : req.url)

    if (!existsSync(filePath) || !filePath.includes('.')) {
      filePath = join(DIST, 'index.html')
    }

    const ext = '.' + filePath.split('.').pop()
    const contentType = mimeTypes[ext] || 'application/octet-stream'

    try {
      const content = readFileSync(filePath)
      res.writeHead(200, { 'Content-Type': contentType })
      res.end(content)
    } catch {
      res.writeHead(404)
      res.end('Not found')
    }
  })

  return new Promise((resolve) => {
    server.listen(PORT, () => {
      console.log(`  Server running on http://localhost:${PORT}`)
      resolve(server)
    })
  })
}

async function prerender() {
  console.log('\n🔍 Prerendering routes...\n')

  const server = await startServer()
  const browser = await puppeteer.launch({ headless: true })

  for (const route of ROUTES) {
    const page = await browser.newPage()
    const url = `http://localhost:${PORT}${route}`

    console.log(`  Rendering ${route} ...`)
    await page.goto(url, { waitUntil: 'networkidle0', timeout: 15000 })

    // Wait a bit for React to finish any async rendering
    await new Promise((r) => setTimeout(r, 1500))

    const html = await page.content()
    await page.close()

    // Write to dist/<route>/index.html
    const outDir = route === '/' ? DIST : join(DIST, route)
    if (!existsSync(outDir)) {
      mkdirSync(outDir, { recursive: true })
    }
    const outFile = join(outDir, 'index.html')
    writeFileSync(outFile, html, 'utf-8')
    console.log(`  ✓ Saved ${outFile.replace(DIST, 'dist')}`)
  }

  await browser.close()
  server.close()
  console.log('\n✅ Prerendering complete!\n')
}

prerender().catch((err) => {
  console.error('Prerendering failed:', err)
  process.exit(1)
})