#!/usr/bin/env node
/**
 * Pre-render script for TailTrails
 *
 * Renders every route in Puppeteer so crawlers see full HTML content
 * (blogs, landing, legal pages), and injects a unique <title> +
 * <meta name="description"> per page for SEO.
 *
 * Usage: node scripts/prerender.mjs
 * Runs as part of: npm run build
 */
import puppeteer from "puppeteer";
import { createServer } from "http";
import { fileURLToPath } from "url";
import path from "path";
import fs from "fs";

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const DIST_DIR = path.resolve(__dirname, "..", "dist");
const POSTS_DIR = path.resolve(__dirname, "..", "src", "blogs", "posts");
const CONCURRENCY = Number(process.env.PRERENDER_CONCURRENCY) || 6;

// ── Static routes ────────────────────────────────────────────────────────────
const STATIC_ROUTES = [
  "/", "/blog", "/compare",
  "/compare/dog-walking-apps-compared",
  "/compare/tailtrails-vs-wooftrax",
  "/compare/tailtrails-vs-tractive",
  "/compare/tailtrails-vs-alltrails",
  "/compare/tailtrails-vs-fitbark",
  "/compare/tailtrails-vs-pitpat",
  "/privacy", "/terms",
  "/forget-me", "/finalize-forget-me",
];

// ── Per-route SEO metadata ───────────────────────────────────────────────────
const DEFAULT_TITLE = "TailTrails — Life Unleashed";
const DEFAULT_DESC =
  "Discover new trails that match your dog's needs, and turn everyday walks into real adventures. Download TailTrails on iOS and Android.";

const STATIC_SEO = {
  "/": { title: DEFAULT_TITLE, desc: DEFAULT_DESC },
  "/blog": {
    title: "TailTrails Blog — Dog Walking Tips, Trails & Guides",
    desc: "Guides on choosing the right walks for your dog, off-leash rules in Portugal, hidden dangers, and the best hikes in the Algarve.",
  },
  "/privacy": { title: "Privacy Policy — TailTrails", desc: "How TailTrails handles your data and privacy." },
  "/terms": { title: "Terms & Conditions — TailTrails", desc: "The terms and conditions for using TailTrails." },
  "/forget-me": { title: "Delete Your Account — TailTrails", desc: "Request deletion of your TailTrails account and data." },
  "/finalize-forget-me": { title: "Confirm Account Deletion — TailTrails", desc: "Confirm deletion of your TailTrails account." },
  "/download": { title: "Download TailTrails — iOS & Android", desc: "Get TailTrails on the App Store or Google Play." },
};

// ── Discover blog slugs + metadata from src/blogs/posts/*.tsx ────────────────
// ponytail: read slugs from the filesystem so the prerender list can't drift
// from the actual posts. Meta is regex-pulled from each file's `export const meta`.
function discoverPosts() {
  if (!fs.existsSync(POSTS_DIR)) return [];
  return fs.readdirSync(POSTS_DIR)
    .filter((f) => f.endsWith(".tsx"))
    .map((f) => {
      const slug = f.replace(/\.tsx$/, "");
      const src = fs.readFileSync(path.join(POSTS_DIR, f), "utf-8");
      const title = src.match(/title:\s*'([^']*)'/)?.[1];
      const description = src.match(/description:\s*'([^']*)'/)?.[1];
      return { slug, title, description };
    });
}

const posts = discoverPosts();
const BLOG_ROUTES = posts.map((p) => `/blog/${p.slug}`);

// ── Static file server (SPA fallback) ────────────────────────────────────────
function startServer(port) {
  const mimes = {
    ".html": "text/html", ".js": "application/javascript", ".mjs": "application/javascript",
    ".css": "text/css", ".json": "application/json", ".png": "image/png", ".jpg": "image/jpeg",
    ".jpeg": "image/jpeg", ".gif": "image/gif", ".svg": "image/svg+xml", ".ico": "image/x-icon",
    ".woff": "font/woff", ".woff2": "font/woff2", ".ttf": "font/ttf", ".webp": "image/webp",
    ".avif": "image/avif", ".mp4": "video/mp4", ".txt": "text/plain",
  };
  return new Promise((resolve, reject) => {
    const server = createServer((req, res) => {
      let fp = path.join(DIST_DIR, req.url === "/" ? "index.html" : req.url);
      if (!fs.existsSync(fp) || fs.statSync(fp).isDirectory()) fp = path.join(DIST_DIR, "index.html");
      fs.readFile(fp, (err, data) => {
        if (err) { res.writeHead(404); res.end("Not found"); return; }
        res.writeHead(200, { "Content-Type": mimes[path.extname(fp)] || "application/octet-stream" });
        res.end(data);
      });
    });
    server.listen(port, () => resolve(server));
    server.on("error", reject);
  });
}

// ── Fallback-only SEO injection ─────────────────────────────────────────────
// Every prerendered route now mounts a <SEO> component that sets <title>,
// description, OG, Twitter, canonical and JSON-LD during the Puppeteer render.
// This only fills in the gaps if a page forgot to mount <SEO> (title still the
// index.html placeholder "Tail Trails", or no description meta present).
function injectSeo(html, title, desc) {
  let out = html;
  if (title && /<title>Tail Trails<\/title>/i.test(out)) {
    out = out.replace(/<title>Tail Trails<\/title>/i, `<title>${title}</title>`);
  }
  if (desc && !/<meta\s+name="description"\s+content="[^"]*"/i.test(out)) {
    out = out.replace("<head>", `<head><meta name="description" content="${desc}">`);
  }
  return out;
}

function seoFor(route) {
  if (STATIC_SEO[route]) return STATIC_SEO[route];
  const post = route.startsWith("/blog/") ? posts.find((p) => `/blog/${p.slug}` === route) : null;
  if (post) {
    return {
      title: post.title ? `${post.title} — TailTrails Blog` : "TailTrails Blog",
      desc: post.description || DEFAULT_DESC,
    };
  }
  return { title: DEFAULT_TITLE, desc: DEFAULT_DESC };
}

// ── Render one page ──────────────────────────────────────────────────────────
async function prerenderRoute(browser, url, route) {
  const page = await browser.newPage();
  try {
    await page.goto(url, { waitUntil: "networkidle0", timeout: 20000 });
    await page.waitForFunction(
      () => { const r = document.getElementById("root"); return r && r.children.length > 0; },
      { timeout: 10000 }
    );
    // let animations / images settle
    await new Promise((r) => setTimeout(r, 400));
    let html = await page.content();
    const { title, desc } = seoFor(route);
    html = injectSeo(html, title, desc);
    const outDir = route === "/" ? DIST_DIR : path.join(DIST_DIR, route);
    fs.mkdirSync(outDir, { recursive: true });
    fs.writeFileSync(path.join(outDir, "index.html"), html, "utf-8");
    return { route, ok: true };
  } catch (err) {
    return { route, ok: false, error: err.message };
  } finally {
    await page.close();
  }
}

// ── Parallel batch renderer ──────────────────────────────────────────────────
async function renderBatch(browser, routes, baseUrl, concurrency) {
  let done = 0;
  const total = routes.length;
  const errors = [];
  for (let i = 0; i < total; i += concurrency) {
    const batch = routes.slice(i, i + concurrency);
    const results = await Promise.all(batch.map((r) => prerenderRoute(browser, `${baseUrl}${r}`, r)));
    for (const r of results) {
      done++;
      r.ok
        ? console.log(`  ✓ [${done}/${total}] ${r.route}`)
        : console.error(`  ✗ [${done}/${total}] ${r.route}: ${r.error}`);
      if (!r.ok) errors.push(r.route);
    }
  }
  return errors;
}

// ── Main ─────────────────────────────────────────────────────────────────────
async function main() {
  if (!fs.existsSync(DIST_DIR)) {
    console.error("Error: dist/ not found. Run 'vite build' first.");
    process.exit(1);
  }

  console.log("🔄 Pre-rendering pages for SEO...\n");
  console.log(`  Discovered ${posts.length} blog post(s): ${posts.map((p) => p.slug).join(", ")}\n`);

  const routes = [...STATIC_ROUTES, ...BLOG_ROUTES];
  const PORT = 4823;
  const BASE = `http://localhost:${PORT}`;
  const server = await startServer(PORT);
  console.log(`  Serving dist/ on ${BASE}`);
  console.log(`  Rendering ${routes.length} pages in Puppeteer (concurrency ${CONCURRENCY})...\n`);

  const browser = await puppeteer.launch({
    headless: true,
    args: ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu"],
  });
  const errors = await renderBatch(browser, routes, BASE, CONCURRENCY);
  await browser.close();
  server.close();

  console.log(`\n✅ Pre-rendered ${routes.length} pages.`);
  if (errors.length) console.log(`  ⚠️  ${errors.length} route(s) failed: ${errors.join(", ")}`);

  // Verify key pages
  console.log("\n📋 Verifying key pages...\n");
  const verify = ["/", "/blog", ...(BLOG_ROUTES.length ? [BLOG_ROUTES[0]] : [])];
  for (const route of verify) {
    const fp = route === "/" ? path.join(DIST_DIR, "index.html") : path.join(DIST_DIR, route, "index.html");
    if (!fs.existsSync(fp)) { console.log(`  ⚠ ${route}: not found`); continue; }
    const html = fs.readFileSync(fp, "utf-8");
    const title = html.match(/<title>(.*?)<\/title>/)?.[1] || "MISSING";
    const desc = html.match(/<meta\s+name="description"\s+content="([^"]+)"/)?.[1]?.slice(0, 70) || "MISSING";
    const rootHasContent = html.includes("Every walk") || html.includes("post-content") || html.includes("Latest Articles");
    console.log(`  ${route}\n    Title: ${title}\n    Desc: ${desc}…\n    Content in HTML: ${rootHasContent}\n`);
  }
}

main().catch((err) => { console.error("Pre-rendering failed:", err); process.exit(1); });