import { existsSync, statSync } from 'node:fs';
import { basename, isAbsolute, join, relative, resolve } from 'node:path';
import { envOr } from '../../common/env';

/**
 * Directory files are written to and served from.
 *
 * Default matches docker-compose's `api_uploads:/app/storage/uploads` volume.
 * A nested leftover (`storage/uploads/uploads/`) is also checked when serving,
 * because copying a folder named `uploads` into the volume creates that extra
 * directory and the previous static root then 404'd every file.
 */
export function getUploadDir(): string {
  return resolve(envOr('UPLOAD_DIR', join(process.cwd(), 'storage', 'uploads')));
}

const UPLOAD_MIME: Record<string, string> = {
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.gif': 'image/gif',
  '.webp': 'image/webp',
  '.avif': 'image/avif',
  '.svg': 'image/svg+xml',
  '.pdf': 'application/pdf',
};

export function mimeForUpload(filePath: string): string | undefined {
  const dot = filePath.lastIndexOf('.');
  const ext = dot >= 0 ? filePath.slice(dot).toLowerCase() : '';
  return UPLOAD_MIME[ext];
}

/** Resolve a public filename to an on-disk file, or null if it is missing/unsafe. */
export function resolveStoredUpload(rawName: string): string | null {
  const safe = basename(rawName);
  if (!safe || safe === '.' || safe === '..') return null;

  const dir = getUploadDir();
  const candidates = [join(dir, safe), join(dir, 'uploads', safe)];

  for (const candidate of candidates) {
    const resolved = resolve(candidate);
    const rel = relative(dir, resolved);
    if (!rel || rel.startsWith('..') || isAbsolute(rel)) continue;
    if (existsSync(resolved) && statSync(resolved).isFile()) return resolved;
  }
  return null;
}