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

import type { ACPAgentSourceFile } from './acp-agent';

/**
 * Discovers source files for an ACP agent source revision.
 *
 * Paths in the returned source revision are relative to the current working
 * directory. Run the manifest from its package root and pass the directory
 * containing agent source, such as `src`.
 */
export async function discoverACPAgentSourceFiles(sourceDirectory: string): Promise<ACPAgentSourceFile[]> {
  const root = process.cwd();
  const sourceRoot = path.resolve(root, sourceDirectory);
  const files: ACPAgentSourceFile[] = [];

  async function visit(directory: string): Promise<void> {
    for (const entry of await readdir(directory, { withFileTypes: true })) {
      const fullPath = path.join(directory, entry.name);
      if (entry.isDirectory()) {
        if (entry.name !== 'node_modules' && entry.name !== 'dist') {
          await visit(fullPath);
        }
        continue;
      }
      if (!entry.isFile()) continue;

      files.push({
        path: path.relative(root, fullPath).split(path.sep).join('/'),
        content: await readFile(fullPath, 'utf8'),
        kind: 'typescript',
      });
    }
  }

  await visit(sourceRoot);
  if (files.length === 0) {
    throw new Error(`No source files found under ${sourceDirectory}.`);
  }
  return files.sort((left, right) => left.path.localeCompare(right.path));
}