import { readdirSync, statSync } from 'fs';
import { join, relative } from 'path';
import ignore from 'ignore';

const DEFAULT_IGNORE = [
  'node_modules', '.git', 'dist', 'build', 'coverage',
  '.next', '.venv', '__pycache__', '.DS_Store', '*.log'
];

export interface DirectoryEntry {
  dirPath: string;
  relativePath: string;
  files: string[];
}

export function discoverProject(rootPath: string): DirectoryEntry[] {
  const ig = ignore().add(DEFAULT_IGNORE);
  const gitignorePath = join(rootPath, '.gitignore');
  try {
    const gitignoreContent = require('fs').readFileSync(gitignorePath, 'utf8');
    ig.add(gitignoreContent);
  } catch { /* no .gitignore */ }

  const entries: DirectoryEntry[] = [];

  function walk(dir: string) {
    const relDir = relative(rootPath, dir) || '.';
    if (ig.ignores(relDir)) return;

    const items = readdirSync(dir);
    const files: string[] = [];
    const subdirs: string[] = [];

    for (const item of items) {
      const relPath = join(relDir, item);
      if (ig.ignores(relPath)) continue;

      const fullPath = join(dir, item);
      const st = statSync(fullPath);
      if (st.isDirectory()) {
        subdirs.push(fullPath);
      } else {
        files.push(item);
      }
    }

    entries.push({ dirPath: dir, relativePath: relDir, files });

    for (const subdir of subdirs) {
      walk(subdir);
    }
  }

  walk(rootPath);
  return entries;
}