const fs = require("fs");
const path = require("path");
const http = require("http");
const readline = require("readline");

const BASE_URL = "http://127.0.0.1:1313";
const CONTENT_DIR = path.join(__dirname, "..", "content");
const SITE_ROOT = path.resolve(__dirname, "..");
const BAD_LINKS = [];

function isInternalLink(link) {
  return !link.includes("://") && !link.startsWith("mailto:") && !link.startsWith("tel:");
}

function extractLinksFromLine(line) {
  const regex = /\]\(([^)]+)\)/g;
  let match;
  const links = [];
  while ((match = regex.exec(line)) !== null) {
    links.push(match[1]);
  }
  return links;
}

function getBundleRelativeUrl(mdPath, link) {
  const bundleRoot = path.dirname(mdPath);
  let urlPath;

  if (link.startsWith("/")) {
    urlPath = link;
  } else {
    const fullPath = path.resolve(bundleRoot, link);
    const relative = path.relative(CONTENT_DIR, fullPath);
    urlPath = "/" + relative.replace(/\\/g, "/");
  }

  return urlPath;
}

async function checkLink(file, lineNumber, link) {
  const relativeUrl = getBundleRelativeUrl(file, link);
  const fullUrl = `${BASE_URL}${relativeUrl}`;
  return new Promise((resolve) => {
    http.get(fullUrl, (res) => {
      if (res.statusCode !== 200) {
        BAD_LINKS.push([path.relative(SITE_ROOT, file), link, lineNumber]);
      }
      res.resume();
      resolve();
    }).on("error", () => {
      BAD_LINKS.push([path.relative(SITE_ROOT, file), link, lineNumber]);
      resolve();
    });
  });
}

async function processFile(filePath) {
  const fileStream = fs.createReadStream(filePath);
  const rl = readline.createInterface({ input: fileStream, crlfDelay: Infinity });
  let lineNumber = 0;

  for await (const line of rl) {
    lineNumber++;
    const links = extractLinksFromLine(line);
    for (const link of links) {
      if (isInternalLink(link)) {
        process.stdout.write(".");
        await checkLink(filePath, lineNumber, link);
      }
    }
  }
}

function walk(dir) {
  let results = [];
  const list = fs.readdirSync(dir);
  list.forEach((file) => {
    file = path.resolve(dir, file);
    const stat = fs.statSync(file);
    if (stat && stat.isDirectory()) {
      results = results.concat(walk(file));
    } else if (file.endsWith(".md")) {
      results.push(file);
    }
  });
  return results;
}

(async () => {
  const files = walk(CONTENT_DIR);
  console.log(`Analyzing ${files.length} Markdown files...`);
  for (const file of files) {
    await processFile(file);
  }

  console.log("\n\n=== Broken Internal Links Report ===");
  if (BAD_LINKS.length === 0) {
    console.log("✅ No broken internal links found.");
  } else {
    console.table(BAD_LINKS.map(([f, u, l]) => ({ File: f, URL: u, Line: l })));
  }
})();