import fs from "node:fs";
import path from "node:path";

const repoRoot = process.cwd();
const websiteRoot = path.join(repoRoot, "website");

function listTopLevelHtml() {
  return fs
    .readdirSync(websiteRoot, { withFileTypes: true })
    .filter((entry) => entry.isFile() && entry.name.endsWith(".html"))
    .map((entry) => entry.name);
}

function destinationFor(filename) {
  if (filename === "archive-speeches.html") {
    return "speeches/index.html";
  }

  let match = filename.match(/^archive-speeches-rev-dr-sun-myung-moon-(.+)\.html$/);
  if (match) {
    return `speeches/rev-dr-sun-myung-moon/${match[1]}.html`;
  }

  match = filename.match(/^blog-category-speeches-of-rev-sun-myung-moon(?:-(.+))?\.html$/);
  if (match) {
    return `speeches/categories/rev-sun-myung-moon${match[1] ? `-${match[1]}` : ""}.html`;
  }

  if (filename === "blog-category-speeches-of-mrs-hak-ja-han-moon.html") {
    return "speeches/categories/mrs-hak-ja-han-moon.html";
  }

  match = filename.match(/^blog-category-(.+)\.html$/);
  if (match) {
    return `blog/categories/${match[1]}.html`;
  }

  match = filename.match(/^blog-tag-(.+)\.html$/);
  if (match) {
    return `blog/tags/${match[1]}.html`;
  }

  match = filename.match(/^blog-(\d{4})-(\d{2})-(\d{2})-(.+)\.html$/);
  if (match) {
    return `blog/${match[1]}/${match[2]}/${match[3]}/${match[4]}.html`;
  }

  return null;
}

function splitUrl(value) {
  const match = value.match(/^([^?#]*)([?#].*)?$/);
  return { pathname: match?.[1] ?? value, suffix: match?.[2] ?? "" };
}

function stripLeadingParentDirs(value) {
  return value.replace(/^(\.\/)?/, "").replace(/^(\.\.\/)+/, "");
}

function shouldSkipUrl(value) {
  return (
    value === "" ||
    value.startsWith("#") ||
    value.startsWith("/") ||
    /^[a-z][a-z0-9+.-]*:/i.test(value)
  );
}

function rewriteUrl(value, movedPaths) {
  if (shouldSkipUrl(value)) {
    return value;
  }

  const { pathname, suffix } = splitUrl(value);
  const normalized = stripLeadingParentDirs(pathname);

  if (normalized.startsWith("assets/") || normalized.startsWith("css/") || normalized.startsWith("js/")) {
    return `/${normalized}${suffix}`;
  }

  if (movedPaths.has(normalized)) {
    return `/${movedPaths.get(normalized)}${suffix}`;
  }

  if (normalized.endsWith(".html")) {
    return `/${normalized}${suffix}`;
  }

  return value;
}

function rewriteHtml(html, movedPaths) {
  let output = html.replace(
    /\b(href|src|action)=(["'])([^"']+)\2/g,
    (_match, attr, quote, value) => `${attr}=${quote}${rewriteUrl(value, movedPaths)}${quote}`
  );

  output = output.replace(/\burl\((["']?)(\.\.\/(?:assets|css|js)\/[^"')]+)\1\)/g, (_match, quote, value) => {
    const rewritten = rewriteUrl(value, movedPaths);
    return `url(${quote}${rewritten}${quote})`;
  });

  return output;
}

const movedPaths = new Map();

for (const filename of listTopLevelHtml()) {
  const destination = destinationFor(filename);
  if (destination) {
    movedPaths.set(filename, destination);
  }
}

for (const [filename, destination] of movedPaths) {
  const sourcePath = path.join(websiteRoot, filename);
  const destinationPath = path.join(websiteRoot, destination);
  fs.mkdirSync(path.dirname(destinationPath), { recursive: true });
  fs.renameSync(sourcePath, destinationPath);
}

function walk(dir) {
  return fs.readdirSync(dir, { withFileTypes: true }).flatMap((entry) => {
    const fullPath = path.join(dir, entry.name);
    if (entry.isDirectory()) {
      return walk(fullPath);
    }
    return fullPath.endsWith(".html") || fullPath.endsWith(".md") ? [fullPath] : [];
  });
}

let rewritten = 0;

for (const filePath of [...walk(websiteRoot), path.join(repoRoot, "README.md"), path.join(repoRoot, "docs", "SITE-STRUCTURE.md")]) {
  if (!fs.existsSync(filePath)) {
    continue;
  }
  const original = fs.readFileSync(filePath, "utf8");
  const updated = rewriteHtml(original, movedPaths);
  if (updated !== original) {
    fs.writeFileSync(filePath, updated);
    rewritten += 1;
  }
}

console.log(`Moved ${movedPaths.size} HTML files into blog/ and speeches/.`);
console.log(`Rewrote links in ${rewritten} files.`);