import { readdir, readFile, stat } from 'node:fs/promises';
import path from 'node:path';

const forbidden = String.fromCodePoint(0x2014);
const root = process.cwd();

const textExtensions = new Set([
  '.astro',
  '.css',
  '.html',
  '.js',
  '.json',
  '.md',
  '.mjs',
  '.ts',
  '.txt',
  '.vtt',
  '.webmanifest',
  '.xml',
]);

const roots = [
  'src',
  'public',
  'scripts',
  'README.md',
  'package.json',
  'astro.config.mjs',
].map((entry) => path.resolve(root, entry));

async function exists(filePath) {
  try {
    await stat(filePath);
    return true;
  } catch {
    return false;
  }
}

async function walk(entryPath) {
  const entryStat = await stat(entryPath);
  if (entryStat.isFile()) return [entryPath];

  const entries = await readdir(entryPath, { withFileTypes: true });
  const files = [];

  for (const entry of entries) {
    const fullPath = path.join(entryPath, entry.name);
    if (entry.isDirectory()) {
      files.push(...(await walk(fullPath)));
    } else if (entry.isFile()) {
      files.push(fullPath);
    }
  }

  return files;
}

function lineAndColumn(text, index) {
  const before = text.slice(0, index);
  const lines = before.split('\n');
  return {
    line: lines.length,
    column: lines.at(-1).length + 1,
  };
}

const files = [];

for (const entry of roots) {
  if (!(await exists(entry))) continue;
  files.push(...(await walk(entry)));
}

const textFiles = files.filter((file) => textExtensions.has(path.extname(file)));

const failures = [];

for (const file of textFiles) {
  const text = await readFile(file, 'utf8');
  let index = text.indexOf(forbidden);

  while (index !== -1) {
    const { line, column } = lineAndColumn(text, index);
    failures.push(`${path.relative(root, file)}:${line}:${column}`);
    index = text.indexOf(forbidden, index + forbidden.length);
  }
}

if (failures.length > 0) {
  console.error(`Em dashes are not allowed:\n${failures.join('\n')}`);
  process.exit(1);
}

console.log('No em dashes found.');