// Third-party license notices for plugin ZIPs (issue #345). A plugin that
// redistributes third-party material must ship the license texts alongside it
// (Apache-2.0 §4(a), MIT's notice clause, OFL §2). The bundled-package list is
// derived from the esbuild metafile — the set of files that actually ended up
// in plugin.js — so the notices can never drift from the bundle the way a
// hand-maintained list would. Non-bundled material (vendored webapps, copied
// font assets) cannot appear in a metafile; callers pass those as `extras`.
import { existsSync, readFileSync, readdirSync } from 'node:fs';
import { dirname, join, resolve, sep } from 'node:path';

const LICENSE_FILE_PATTERN = /^(licen[cs]e|copying|notice)(\.|$)/i;

/** Walk up from `file` to the nearest package.json that names a package. */
function packageRootOf(file) {
  let dir = dirname(resolve(file));
  while (dir !== dirname(dir)) {
    const pj = join(dir, 'package.json');
    if (existsSync(pj)) {
      try {
        const parsed = JSON.parse(readFileSync(pj, 'utf8'));
        if (parsed.name) return { dir, pkg: parsed };
      } catch {
        // unreadable package.json (e.g. a fixture) — keep walking up
      }
    }
    dir = dirname(dir);
  }
  return null;
}

function shippedLicenseText(dir) {
  const names = readdirSync(dir).filter((name) => LICENSE_FILE_PATTERN.test(name));
  return names
    .sort()
    .map((name) => readFileSync(join(dir, name), 'utf8').trim())
    .join('\n\n');
}

/**
 * All third-party npm packages whose files the metafile lists as bundle
 * inputs, deduplicated by name@version. First-party `@dorfteich/*` packages
 * are covered by the repository LICENSE and skipped.
 */
export function bundledPackages(metafile) {
  const seen = new Map();
  for (const input of Object.keys(metafile.inputs)) {
    if (!input.split(sep).includes('node_modules') && !input.includes('/node_modules/')) continue;
    const found = packageRootOf(input);
    if (!found || found.pkg.name.startsWith('@dorfteich/')) continue;
    const key = `${found.pkg.name}@${found.pkg.version}`;
    if (!seen.has(key)) {
      seen.set(key, {
        name: found.pkg.name,
        version: found.pkg.version,
        license: typeof found.pkg.license === 'string' ? found.pkg.license : 'see license text',
        text: shippedLicenseText(found.dir),
      });
    }
  }
  return [...seen.values()].sort((a, b) => a.name.localeCompare(b.name));
}

/**
 * Renders `licenses/THIRD-PARTY-NOTICES.txt` for a plugin ZIP: one section per
 * bundled package (license expression + the license file it ships), then one
 * per caller-supplied extra ({ title, license, note?, text? }).
 */
export function thirdPartyNotices(metafile, extras = []) {
  const rule = '='.repeat(72);
  const sections = [
    'THIRD-PARTY NOTICES\n\nThis plugin package redistributes the third-party components listed\nbelow, each under its own license.\n',
  ];
  for (const pkg of bundledPackages(metafile)) {
    const body = pkg.text || `License: ${pkg.license} (no license file shipped in the npm package)`;
    sections.push(`${rule}\n${pkg.name} ${pkg.version} — ${pkg.license}\n${rule}\n\n${body}\n`);
  }
  for (const extra of extras) {
    const parts = [extra.note, extra.text].filter(Boolean).join('\n\n');
    sections.push(`${rule}\n${extra.title} — ${extra.license}\n${rule}\n\n${parts}\n`);
  }
  return sections.join('\n');
}