import { createHash } from 'node:crypto';
import { execFile } from 'node:child_process';
import { readFile, stat, writeFile } from 'node:fs/promises';
import path from 'node:path';
import { promisify } from 'node:util';
import { fileURLToPath } from 'node:url';

const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const excludedFiles = new Set(['SOURCE_MANIFEST.txt']);
const execFileAsync = promisify(execFile);

async function collect() {
  const { stdout } = await execFileAsync(
    'git',
    ['ls-files', '--cached', '--others', '--exclude-standard', '-z'],
    { cwd: root, encoding: 'buffer', maxBuffer: 16 * 1024 * 1024 },
  );
  const relativePaths = stdout
    .toString('utf8')
    .split('\0')
    .filter(Boolean)
    .filter((relative) => !excludedFiles.has(relative));

  const existing = [];
  for (const relative of relativePaths) {
    const absolute = path.resolve(root, relative);
    try {
      if ((await stat(absolute)).isFile()) existing.push(absolute);
    } catch (error) {
      if (error?.code !== 'ENOENT') throw error;
    }
  }
  return existing;
}

const packageJson = JSON.parse(await readFile(path.join(root, 'package.json'), 'utf8'));
const files = (await collect()).sort((left, right) => left.localeCompare(right, 'en'));
const lines = [
  `ForgeFlow ${packageJson.version} source manifest`,
  'SHA-256                                                          BYTES  PATH',
  '(The manifest includes tracked and non-ignored source files, excluding itself.)'
];

for (const absolute of files) {
  const bytes = await readFile(absolute);
  const size = (await stat(absolute)).size;
  const digest = createHash('sha256').update(bytes).digest('hex');
  const relative = path.relative(root, absolute).replaceAll('\\', '/');
  lines.push(`${digest}  ${String(size).padStart(12)}  ${relative}`);
}

await writeFile(path.join(root, 'SOURCE_MANIFEST.txt'), `${lines.join('\n')}\n`, 'utf8');
console.log(`Wrote ${files.length} entries for ForgeFlow ${packageJson.version}.`);