import { lstat, opendir, realpath } from 'node:fs/promises';
import path from 'node:path';

export type WorkPresence = 'empty' | 'possible' | 'unknown';

// Only prove absence. Unknown project formats must retain the existing startup
// path; a missing root index.html or an offline server does not prove emptiness.
const IGNORED_DIRECTORIES = new Set(['.git', '.makelore', '.vscode', '.idea', 'node_modules']);
const IGNORED_FILES = new Set(['.ds_store', 'thumbs.db', '.git', '.gitignore', '.gitattributes', '.editorconfig', 'license', 'readme']);
const MATERIAL_EXTENSIONS = new Set([
  '.md', '.txt', '.pdf', '.doc', '.docx', '.ppt', '.pptx', '.xls', '.xlsx', '.csv',
  '.png', '.jpg', '.jpeg', '.gif', '.webp', '.svg', '.ico', '.bmp', '.avif',
  '.mp3', '.wav', '.ogg', '.m4a', '.mp4', '.webm', '.mov',
  '.woff', '.woff2', '.ttf', '.otf',
]);
const MAX_ENTRIES = 2_000;
const MAX_DEPTH = 8;

/** Inspect names/types only, without reading contents, following links or running a model. */
export async function inspectWorkPresence(projectPath: string): Promise<WorkPresence> {
  try {
    const root = await realpath(projectPath);
    const pending = [{ directory: root, depth: 0 }];
    let visited = 0;
    while (pending.length) {
      const { directory, depth } = pending.pop()!;
      // Revalidate queued directories in case a project edit replaced one with a link.
      if ((await lstat(directory)).isSymbolicLink() || await realpath(directory) !== directory) return 'unknown';
      const entries = await opendir(directory);
      for await (const entry of entries) {
        if (++visited > MAX_ENTRIES) return 'unknown';
        const name = entry.name.toLowerCase();
        if (entry.isSymbolicLink()) return 'unknown';
        if (entry.isDirectory()) {
          if (IGNORED_DIRECTORIES.has(entry.name) || (depth === 0 && entry.name === 'knowledge')) continue;
          if (depth >= MAX_DEPTH) return 'unknown';
          pending.push({ directory: path.join(directory, entry.name), depth: depth + 1 });
        } else if (entry.isFile()) {
          if (!IGNORED_FILES.has(name) && !MATERIAL_EXTENSIONS.has(path.extname(name))) return 'possible';
        } else return 'unknown';
      }
    }
    return 'empty';
  } catch {
    // Unreadable, removed or changing directories are not evidence of no work.
    return 'unknown';
  }
}