import { readFile, readdir, writeFile } from 'node:fs/promises';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const LICENSE_FILE = /^(?:licen[cs]e|copying|notice)(?:[._-].*)?$/iu;
const RUNTIME_PACKAGES = [
  '@add-ideas/toolbox-contract',
  'react',
  'react-dom',
  'scheduler',
];

function compareCodePoints(left, right) {
  return left < right ? -1 : left > right ? 1 : 0;
}

export async function createRuntimeLicenseBundle(
  projectRoot,
  packageNames = RUNTIME_PACKAGES
) {
  const sections = [];
  for (const packageName of [...new Set(packageNames)].sort(
    compareCodePoints
  )) {
    const packageDirectory = path.join(
      projectRoot,
      'node_modules',
      ...packageName.split('/')
    );
    const packageJson = JSON.parse(
      await readFile(path.join(packageDirectory, 'package.json'), 'utf8')
    );
    const licenseFiles = await collectLicenseFiles(packageDirectory);
    if (licenseFiles.length === 0)
      throw new Error(`No license text found for ${packageName}.`);

    const contents = [];
    for (const licenseFile of licenseFiles) {
      const text = await readFile(
        path.join(packageDirectory, ...licenseFile.split('/')),
        'utf8'
      );
      contents.push(
        `--- ${licenseFile} ---\n${text.replaceAll('\r\n', '\n').trim()}\n`
      );
    }
    sections.push(
      [
        '================================================================================',
        `${packageJson.name ?? packageName}@${packageJson.version ?? 'unknown'}`,
        `Declared license: ${String(packageJson.license ?? 'unspecified')}`,
        '================================================================================',
        ...contents,
      ].join('\n')
    );
  }
  return [
    'Third-party software license texts bundled with add·ideas Toolbox',
    'Generated deterministically from the installed runtime packages.',
    '',
    ...sections,
    '',
  ].join('\n');
}

async function collectLicenseFiles(directory, prefix = '') {
  const matches = [];
  const entries = await readdir(directory, { withFileTypes: true });
  entries.sort((left, right) => compareCodePoints(left.name, right.name));
  for (const entry of entries) {
    if (entry.name === 'node_modules') continue;
    const relativePath = path.posix.join(prefix, entry.name);
    const absolutePath = path.join(directory, entry.name);
    if (entry.isDirectory())
      matches.push(...(await collectLicenseFiles(absolutePath, relativePath)));
    else if (entry.isFile() && LICENSE_FILE.test(entry.name))
      matches.push(relativePath);
  }
  return matches;
}

async function main() {
  const projectRoot = path.resolve(
    path.dirname(fileURLToPath(import.meta.url)),
    '..'
  );
  const output = path.join(projectRoot, 'public', 'THIRD_PARTY_LICENSES.txt');
  await writeFile(
    output,
    await createRuntimeLicenseBundle(projectRoot),
    'utf8'
  );
  process.stdout.write('Generated public/THIRD_PARTY_LICENSES.txt\n');
}

if (
  process.argv[1] &&
  path.resolve(process.argv[1]) === fileURLToPath(import.meta.url)
)
  await main();