import { readdir } from "node:fs/promises";
import { join } from "node:path";

export async function discoverFiles(root, predicate) {
  const files = [];

  async function visit(directory) {
    let entries;
    try {
      entries = await readdir(directory, { withFileTypes: true });
    } catch (error) {
      if (error?.code === "ENOENT") return;
      throw error;
    }
    for (const entry of entries.sort((left, right) => left.name.localeCompare(right.name))) {
      const path = join(directory, entry.name);
      if (entry.isDirectory()) await visit(path);
      else if (entry.isFile() && predicate(path)) files.push(path);
    }
  }

  await visit(root);
  return files;
}